Nov 09

Engineering Design of the Chevy Volt’s Two Electric Motors

 
Chevy Volt Powertrain

Chevy Volt Powertrain

[ad#post_ad]I had the following discussion with Alex Cattelan who is the Volt’s Chief Powertrain Engineer. It explains for the first time anywhere in more depth how the Volt’s two separate electric motors function.

The design of the electric motor, is there a separate generator or does the motor itself just turn the other way and act as a generator?

Very interesting question. There are two motors. One is considered the traction motor and the other one is the generator. However, and they are two motors, the traction motor is  higher-powered and designed specifically to meet the traction requirements.  The generator is designed to efficiently couple to the engine to generate what we need and match the efficiency band of the engine as much as possible in all the operating modes. So we look at that motor as coupled with the engine in system and then we also have a traction motor.

Some of the interesting pieces though of this are, for example, in EV operation I have two motors on board and I typically use the traction motor only to drive the vehicle. However, I do have some mechanisms to couple those motors and in some points of operation these two motors can be coupled and have a more efficient state.

Does that produce more power if they’re coupled?

It’s actually not additive for power, it’s actually the way it’s architected, and a lot of this is proprietary so I can’t get into the full architecture, but what it does is optimize the rotating speed and the losses of the motors so in certain states its better to operate both to propel the vehicle and in some states its better to utilize more of the generator and less of the traction motor. In some states its more efficient to use more of the generator and have more of the traction motor actually be a generator. That would be for example in coast down situation often we use our traction motor as a generator on regen.

We do have the ability to utilize both motors in propulsion mode.

The issue is and the direct answer to your question is we do have a primary traction motor and a primary generator motor and they are designed specifically for those levels of operation. However, we have a little bit of flexibility in exactly how we use them.

This entry was posted on Monday, November 9th, 2009 at 7:16 am and is filed under Engineering, Generator. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

COMMENTS: 151


  1. 1
    Herm

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    Nov 9th, 2009 (7:25 am)

    Sheez, lots of talk and no new info..so yes, we have a motor and a generator, but both can switch roles.

    The he dumps this jewel:
    “However, I do have some mechanisms to couple those motors and in some points of operation these two motors can be coupled and have a more efficient state.”

    He is not talking about a mechanical connection between the two motors.


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    RB

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    Nov 9th, 2009 (7:27 am)

    I didn’t understand the question, and I didn’t understand the answer.
    Hope it all is good. :)


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    solo

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    Nov 9th, 2009 (7:30 am)

    I wonder if there is a decoupling device between the generator motor and the crankshaft of the engine, like a large electric clutch. Otherwise the generator would be rotating the engine while trying to provide power to the drive train.


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    Tibor

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    Nov 9th, 2009 (7:35 am)

    Say what? Do I get it correctly that the generator connected to the ICE engine can be used to propel the vehicle? Thus the ICE is in connection with the wheels?
    I was under the impression the ICE was completely isolated from the wheels.

    It might be a better solution, but the ICE+generator, battery+electric motor setup sure sounds less complex.


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    Lee

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    Nov 9th, 2009 (7:36 am)

    This is the most confusing article I’ve read on this site. If I can get past the bad grammar I still am not sure what is being said. I thought I understood the propulsion system. If the engine “generator” can actually act as a “electric motor” I can see how it might assist the ICE. How how can it assist the traction motor? (other then as a generator)
    And–do the “generators” spin backwards when they change to “electric motor funtion”? That question wasn’t answered.


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    Jason M. Hendler

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    Nov 9th, 2009 (7:36 am)

    Lyle,

    Interesting topic. Can you reword the post for more clarity? Some sentences are tongue twisters.


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    ziv

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    Nov 9th, 2009 (7:40 am)

    Did he say anything we didn’t already know or assume? I mean really, the levels of gobbledegook that come out of the GM people lately are approaching Jabberwockian standards.
    Approximately how many AER miles will I get with the heat/AC on?
    What will the approximate EPA city cycle mpg be in CS mode?
    The aspects of the Volt that will make it a huge success or a noteable failure are relatively simple, and they know what the answers are already. Their failure to trumpet their strengths makes me wonder, are they going to fail to get 40 miles AER without hyper miling techniques? Will the AC kill the AER?
    Will the city cycle MPG be 30 mpg?
    Will the Volt be an over priced, underachieving failure?
    I think the Volt will get around 36 miles AER the way I drive. I think it will get 45 mpg in CS mode, the way I drive.
    But GM seems determined to undermine my confidence in the car they are building.


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    RB

     

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    Nov 9th, 2009 (7:50 am)

    Somewhat off topic, over the weekend I got a letter from “Brent Dewar Vice President, Chevrolet” about the closure of my Chevy dealer. It is a poorly printed and grammatically muddled form letter.

    Does anyone know if Mr Dewar is a real person, and if so what his address might be? The only information in the letter is the phone number for the “Customer Care Center,” which I affectionately think of as the “Customer Go-Away Center” The center can provide such gems as “use the gm website” and “any Chevrolet dealer can assist you.”

    I would like to write back to Mr Dewar (very politely of course). I still hope that the new gm would like to listen to its customers, not just talk.


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    Herm

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    Nov 9th, 2009 (7:54 am)

    “We do have the ability to utilize both motors in propulsion mode.”

    He does not mean that the ICE will come on in CD mode to increase the power delivery to the traction motor, like the Prius does.

    “The issue is and the direct answer to your question is we do have a primary traction motor and a primary generator motor and they are designed specifically for those levels of operation. However, we have a little bit of flexibility in exactly how we use them.”

    I think all he means is that they adjust the ways the motors work to optimize the system efficiency.. at some points of ICE operation it makes sense to re-route some of the generator power to recharge the battery a bit instead of just turning the wheels. In other words they want to keep the ICE (when its running) fully loaded to its optimal point. If the ICE was designed to run at a few set points of operation then it could be optimized for those points by mechanical design.. but he maybe saying that they can tweak it with the motors and allow the ICE to run at different set points.

    I think he did not take Lyle seriously in this interview.


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    Herm

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    Nov 9th, 2009 (7:57 am)

    Lee: And–do the “generators” spin backwards when they change to “electric motor funtion”? That question wasn’t answered.  

    The generator always spins in the same direction.. but the traction motor will spin backwards when the car is in reverse.


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    Joe

     

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    Nov 9th, 2009 (7:58 am)

    Tibor: Say what? Do I get it correctly that the generator connected to the ICE engine can be used to propel the vehicle? Thus the ICE is in connection with the wheels?
    I was under the impression the ICE was completely isolated from the wheels.It might be a better solution, but the ICE+generator, battery+electric motor setup sure sounds less complex.  

    (Quote)

    Many times over, GM has said the Volt is a series hybrid so we know the ICE will never provide traction to the wheels. Only an electric motor will do this.


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    RB

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    Nov 9th, 2009 (8:00 am)

    Jason M. Hendler: Lyle,Interesting topic.Can you reword the post for more clarity?Some sentences are tongue twisters.  

    (Quote)

    I take it that Lyle is giving us sentences that are close to a transcript. We can hope that the speaker’s clarity of thinking is much better than his clarity of presentation, because, trying to preserve secrecy, he is garbling things up on purpose. :)


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    Nov 9th, 2009 (8:03 am)

    ziv: I mean really, the levels of gobbledegook that come out of the GM people lately are approaching Jabberwockian standards.

    “Jabberwockian” is a pretty high standard, so I’m not sure. LOL :)


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    Joe

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    Nov 9th, 2009 (8:03 am)

    ziv: Did he say anything we didn’t already know or assume? I mean really, the levels of gobbledegook that come out of the GM people lately are approaching Jabberwockian standards.
    Approximately how many AER miles will I get with the heat/AC on?
    What will the approximate EPA city cycle mpg be in CS mode?
    The aspects of the Volt that will make it a huge success or a noteable failure are relatively simple, and they know what the answers are already. Their failure to trumpet their strengths makes me wonder, are they going to fail to get 40 miles AER without hyper miling techniques? Will the AC kill the AER?
    Will the city cycle MPG be 30 mpg?
    Will the Volt be an over priced, underachieving failure?
    I think the Volt will get around 36 miles AER the way I drive. I think it will get 45 mpg in CS mode, the way I drive.
    But GM seems determined to undermine my confidence in the car they are building.  

    (Quote)

    If the Volt were a Toyota product, you would know a lot less about the lt than what you now know. Toyota is so secretive.


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    Rich R

     

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    Nov 9th, 2009 (8:04 am)

    Unless there is a mode in which the volt can switch between Serial and Parallel then it must mean that the traction motor can act as a generator in braking while Generator can act as a traction motor to start the engine. The parallel option would mean there may be a mechanical connection between the both the engine/generator, and the Traction motor, and or drive train (transaxle\differential). This would allow the best of both world as far as efficiency. I also don’t believe the actual shaft needs to change direction in order to switch to regen mode just the phasing.


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    Loboc

     

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    Nov 9th, 2009 (8:05 am)

    It may be that the ‘more efficient state’ is achieved by using the generator motor to balance the AC operation. In other words, it could be used to modify/help the AC legs (the traction motor is 3-phase?) electrically to balance them out. (Capt’n Jack?)

    The reason this article is so confusing is that he is dancing around proprietary engineering. GM would not want to let the cat out of the bag before a competitor gets one to reverse-engineer. imho, GM is at least a year ahead of anyone else at this point.


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    Herm

     

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    Nov 9th, 2009 (8:17 am)

    Loboc: It may be that the ‘more efficient state’ is achieved by using the generator motor to balance the AC operation. In other words, it could be used to modify/help the AC legs (the traction motor is 3-phase?) electrically to balance them out. (Capt’n Jack?)

    Could be phase balancing or some other trickery with the inverters, but perhaps the coupling is more of a magnetic nature.. two motors can act like a bigger motor when placed in close proximity to each other.. No idea, this proprietary information is how they achieve 130% efficiency.


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    hermant

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    Nov 9th, 2009 (8:23 am)

    I second the motion to declare this the “Most Confusing Article” ever posted on this web site. My best guess is that the author is entirely and completely confused about the interaction of the two motors. He probably understood it for a few seconds right after the engineers last explained it to him but lost it again when asked to repeat it back.

    First, a motor is a generator. Given that, both motors will generate electricity at certain times. The “traction motor” acts as a motor when power is required to propel the vehicle and acts as a generator when limiting (rolling down a hill) or reducing speed (coming to a stop). The “generator motor” acts as a motor when starting the ICE and acts as a generator when CD mode is encountered.

    I think what probably confuses the original author is that these two systems, while mechanically independent, do work together under software control. In software, numerous interaction schemes are used to deal with all of the variability of day to day driving (battery power, ICE power, coasting, regeneration, braking, etc.). Clearly, without computers, this entire automotive development project would never have been undertaken. The basic mechanical design is pretty simple. The software control is much more complex. All of the complexity is necessary in order to provide a seamless operating profile for us, the driving public.


  19. 19
    Lee

     

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    Nov 9th, 2009 (8:23 am)

    Submitted by Rich R.–”I also don’t believe the actual shaft needs to change direction in order to switch to regen mode just the phasing.”

    I think you are correct. No one seems to be able to answer the “reverse spinning question.” I think what happens in regenerative braking is that the electric motor internals decouple during “coast and braking mode” and in so doing convert rotational energy back to batteries. Then when drive energy is called for, drive motor couples back to propulsion mode.–Lee


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    Dave K.

     

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    Nov 9th, 2009 (8:27 am)

    Loboc: reverse-engineer

    Mr. Cattelan said plenty. By the time another year passes we’ll know the Volt down to the brand of windshield wipers.

    I’m curious if the smooth underside of the Volt and rear suspension will be harvested for wing effect. Engineering reported that no (wind tunnel) stone will be left unturned.

    =D~


  21. 21
    Herm

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    Nov 9th, 2009 (8:40 am)

    Lee: I think you are correct. No one seems to be able to answer the “reverse spinning question.” I think what happens in regenerative braking is that the electric motor internals decouple during “coast and braking mode” and in so doing convert rotational energy back to batteries. Then when drive energy is called for, drive motor couples back to propulsion mode.–Lee  

    There is no decoupling, the nature of motors is that are also generators.. a voltage will cause a motor to spin.. but while it is spinning it also is generating a counter voltage (same polarity).. if the voltage it is generating is higher than the voltage of the battery then the motor will force amps into the battery and recharge it, if the battery voltage is higher then it provides the amps and the motor spins faster. When the car is going down hill the motor is forcing current into the battery.

    The inverter controls the voltages given to the motor, thus it can seamlessly force the motor into accepting or generating power.. nothing actually switches or reconfigures itself, its done with voltage levels.

    Do a little experiment.. get yourself a small permanent magnet toy motor, get from a junked toy, hair dryer, electric window motor etc.

    Take the motor and spin the shaft with your fingers.. it should spin freely.. now electrically short out the two terminals of the motor with a paper clip or a piece of copper wire.. now when you spin the shaft you will notice drag and resistance. The motor is now in the regenerative braking mode yet all you did was short out the terminals.. nothing was reconfigured and the motor is still spinning in the same direction.


  22. 22
    Dr. Ibringdoh

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    Nov 9th, 2009 (8:42 am)

    solo: I wonder if there is a decoupling device between the generator motor and the crankshaft of the engine, like a large electric clutch. Otherwise the generator would be rotating the engine while trying to provide power to the drive train.  (Quote)

    I would hope that these engineers are not that blind.

    Respectfully,

    Dr. Ibringdoh


  23. 23
    frankyB

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    Nov 9th, 2009 (8:49 am)

    Rich R: Unless there is a mode in which the volt can switch between Serial and Parallel then it must mean that the traction motor can act as a generator in braking while Generator can act as a traction motor to start the engine. The parallel option would mean there may be a mechanical connection between the both the engine/generator, and the Traction motor, and or drive train (transaxle\differential). This would allow the best of both world as far as efficiency. I also don’t believe the actual shaft needs to change direction in order to switch to regen mode just the phasing.  (Quote)

    It’s not parallel… it’s serie hybrid, the ICE never power the wheels, NEVER.

    As for the Post and Herm comments about not learning anything… well, we do learn that instead of having a complexe clutch like Tesla was trying to build at its early stage, they went with 2 motors that give them more usability range… (You can look at it as 3 Speeds… 1-Traction Motor only 2-Generator (as a motor) only 3- Traction+Generator.) Now play with the motor RPM and voilà a full range of usability to make sure you are always at the most efficient usage. So we do learn more and it is quite clever what they are doing and if I’m not mistaken it will require less mechanicals parts to acheive the same thing as a clutch.


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    Dan Petit

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    Nov 9th, 2009 (8:52 am)

    There are at least 7 distinct advantages described here. But it would not surprise me at all for there to be more than a dozen distinct advantages categorically to the designs’ general description.

    Reread the post several times more slowly with high interest, because each time you do, the various concepts described add to your comprehension, one established concept at a time. It’s well worth your intellectual effort. I can assure you that every other OEM’s engineer who is worth their salt is doing it at this very minute.

    These posts describing the actual technologies are really captivating.

    This is what us techs have to do every day for you when you have a novel problem on any of your vehicles. And, every day, there are indeed a wide array of novel problems out there in the service bays. This is because the patent and trade laws force these wide arrays of entirely different designs to be VERY substantially different than each other.

    But taking really good care of customers is the most important thing after all.


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    kevmark58

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    Nov 9th, 2009 (8:57 am)

    His comments were very difficult to follow, unclear, and seemed rife with protecting proprietary technology, which is completely understandable. The rest of it wasn’t.


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    carcus1

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    Nov 9th, 2009 (8:57 am)

    The first thing to clear up should probably be that “he” is a “she”.


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    BillR

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    Nov 9th, 2009 (9:00 am)

    I actually find this article to be quite interesting. For those who don’t know Alex, she (not he) has been on the Volt team for quite some time, and was at the VoltNation event. She is Canadian and quite intelligent. If you don’t understand what she is saying, its likely due to proprietary reasons.

    First, I notice this comment:

    “We do have the ability to utilize both motors in propulsion mode.”

    So the generator can be used as a motor/generator (MG), and can be used to drive the Volt. This suggests to me that there needs to be a mechanical connection between the MG and the wheels.

    This brings me to the next comment of interest:

    “…a lot of this is proprietary so I can’t get into the full architecture, but what it does is optimized the rotating speed and the losses of the motors so in certain states its better to operate both to propel the vehicle and in some states its better to utilize more of the generator and less of the traction motor.”

    Since at high output or high speed, the traction motor is probably less efficient, this suggests to me that GM may have a clutch mechanism that connects the two motors together with a gear reduction for the traction motor. This reduces the traction motor speed and power so that it is in the “sweet spot”, while the MG picks up the additional power.

    This also suggests to me that in CS mode, the clutch engages and the ICE essentially directly drives the vehicle (through the MG), while the traction motor is used to provide boost for hill climbs or acceleration, and used to generate a small amount of power to regen that batteries at constant speed cruise. This should equate to better mpg in CS mode.

    Perhaps this is the “secret transmission” that Lutz had referred to a long time ago.


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    NZDavid

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    Nov 9th, 2009 (9:13 am)

    This is a great article IMHO. It takes me back a couple of years when we were discussing how things could work together.

    Firstly, from this post, both motors will be three phase. We already know the traction motor is three phase.

    Secondly, in order to ‘directly’ couple the ICE generator with the traction motor, it would be necessary to bypass the Inverter. Therefore the ICE generator must produce AC power at the same voltage as the traction motor is using it. Bypassing the inverter will increase efficiency, but the control logic to do it would not be simple.

    Finally, the type of motor can also be guessed at. Given the complexity of the control logic, I am going to go with two 4-pole electric induction motor’s, which is the same design as the Tesla uses. This type of motor is also computer controlled so, in a way, it would make ‘direct coupling’ easier than it would otherwise be.

    Driving down the highway with cruse control on would be a prime example of everything working together. Looking good for 50mpg at 60mph.

    LJGTVWOTR
    Has plug? Have sale!
    HPHS


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    Flaninacupboard

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    Nov 9th, 2009 (9:13 am)

    It’s very confusing, but i think he is saying:
    In EV mode (engine off) it’s -possible- to use the genset as a 53kw motor, as well as use the 112kw traction motor. sounds as though there is a reduction/final drive box, that has input from both motors before it hits the driveshaft. in my mind this means in EV mode when i accelerate hard the 112kw motor is doing it’s thing. as i hit 70 and ease off, demand is shifted to the 53kw genset-motor, which will supply enough power (~30kw) to maintain my speed. ramping up to 100 the genset-motor can supply the 53kw required to maintain my speed, with the traction motor cutting in to help me up the hills.

    In CS mode, the engine is running. it will be possible to have the final drive box set so that there is a small amount of drive going -into- the genset, reducing load, but keeping a specific RPM for better efficiency.


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    carcus1

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    Nov 9th, 2009 (9:17 am)

    BillR: This also suggests to me that in CS mode, the clutch engages and the ICE essentially directly drives the vehicle (through the MG), while the traction motor is used to provide boost for hill climbs or acceleration, and used to generate a small amount of power to regen that batteries at constant speed cruise. This should equate to better mpg in CS mode.
    Perhaps this is the “secret transmission” that Lutz had referred to a long time ago.  

    If it is a series/parallel hybrid, then Lutz’s implied 40 to 50 mpg in CS mode seems much more plausible. This series/parallel architecture may well be what Ms. Cattelan is skirting around.


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    Jordo P.

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    Nov 9th, 2009 (9:24 am)

    Ahhh I think I got it. So we take the 1.2 jigawatts of electricity and we pass it through the flux capacitor to the traction control motor and then we couple that with a generator… It all makes sense now! So does anyone know where on earth we are going to get the 1.2 jigawatts of electricity. I heard they are working on a product called “Mr. Fusion.” Anyone heard any news on that???


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    Nov 9th, 2009 (9:28 am)

    Jordo P.:
    Ahhh I think I got it. So we take the 1.2 jigawatts of electricityand we pass it through the flux capacitor to the traction control motorand then we couple that with a generator… It all makes sense now! Sodoes anyone know where on earth we are going to get the 1.2 jigawattsof electricity. I heard they are working on a product called “Mr.Fusion.” Anyone heard any news on that???  (Quote)

    Heavy


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    Darius

     

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    Nov 9th, 2009 (9:35 am)

    First of all why you need that? No explanation. Would be rational putting genset on different axis for more efficient reg. braking and using 4×4 on electric mode in certain situations i.e. when you are stuck in the mud or very slippery conditions.


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    Emmett Brown

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    Nov 9th, 2009 (9:44 am)

    There’s that word again. Is there something wrong with Earth’s gravitational field in the future?

    BillR:
    Heavy  

    (Quote)


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    nasaman

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    Nov 9th, 2009 (9:46 am)

    I seem to recall someone at GM (Tony Posawatz?) commenting about similarities between the housing (and perhaps even the two motor/generators used in their FWD 2 mode hybrid transmission?) and the two Volt motor/generators/housing. Both are FWD, thus use a transaxle(s) and both are extremely compact. The view below of the FWD 2 mode transmission 2MT70, shown in a paper at the SAE 2009 World Congress, makes me wonder if Alex Cattelan is possibly “dancing around” a Volt two motor/generators design having some significant similarities to the 2MT70…..

    6a00d8341c4fbe53ef01157076b238970b-800wi

    / BTW, Alex Cattelan is female


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    Rich R

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    Nov 9th, 2009 (9:51 am)

    frankyB: It’s not parallel… it’s serie hybrid, the ICE never power the wheels, NEVER.As for the Post and Herm comments about not learning anything… well, we do learn that instead of having a complexe clutch like Tesla was trying to build at its early stage, they went with 2 motors that give them more usability range… (You can look at it as 3 Speeds… 1-Traction Motor only 2-Generator (as a motor) only 3- Traction+Generator.) Now play with the motor RPM and voilà a full range of usability to make sure you are always at the most efficient usage. So we do learn more and it is quite clever what they are doing and if I’m not mistaken it will require less mechanicals parts to acheive the same thing as a clutch.  (Quote)

    Correct, but a combination of the two would clearly be superior… and may be seen in later generations of the Volt. Although the KISS method is preferred at this point. There will be specific engine RPM’s and loads in which the a direct coupling of mechanical energy to the wheels would prove most efficient, as conversion of energy from one state to another will suffer some loss. There seems to be enough waste in an ICE that optimization of preset RPM ranges (ignition timing, valve cam phasing, porting, crankshaft stoke ect… ) will allow the engine to run as a Genet and nearly make up for the majority of loss found in then energy state conversion waste. It all boils cost, BMW built system to convert some of an ICE’s 70% wasted energy found in heat to mechanical energy to assist the engine, but it is very costly to produce. There will be some very interesting advances in the future generations I am sure….


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    Emmett Brown

     

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    Nov 9th, 2009 (9:54 am)

    Off Topic:

    I’ve finally noticed the tv ad for Chevrolet is running pretty often. It does ‘mention’ that the Cobalt has better mpg than the Civic, and the Malibu has more than the Accord.

    Personally, I’d like to see a commercial where the Kia (or is it the Hyundai) filled with mice are sitting at a stoplight, when an ordinary guy in a Chevy HHR Quarter Panel pulls up with a “Pest Control” logo on the side of it…!

    Football hero spokesmen are great, but isn’t there any creativity left in the GM Marketing Division?


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    N Riley

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    Nov 9th, 2009 (9:55 am)

    Certainly the most interesting of the articles for the weekend. Just thinking of the engineering complexities in such a design boggles my mind. Of course, it doesn’t take as much to boggle my mind these days. From a programming viewpoint, this would be one awesome project to work on. Too bad I am not interested in working for GM in this stage of my life. I would love tackling such a challenge. But not now. Good luck to GM with this Volt project.


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    Van

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    Nov 9th, 2009 (9:56 am)

    I think this was an effort to make the Volt powertrain sound as flexible as the Hybrid Drive from Toyota. I think “coupled” simply means power from the generator is electrically coupled to the traction motor so both are being used to drive the wheels, rather than just the battery and the traction motor. In other words, smoke and mirrors. Time will tell.


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    Nov 9th, 2009 (9:58 am)

    Slightly off topic, it appears that lithium batttery technology may be taking a big leap forward. Dr. Cui of Stanford has formed a company to manufacture a silicon nano wire anode for lithium ion batteries. This alone, he projects, will increase the energy density of a lithium ion battery greatly. The article is somewhat confusing as to how much. In the examples that are given, it increases the energy density by between 75%-90% and later he claims a 40% gain. Lutz has referred to this new technology. I would hope that he would increase the AER of the volt rather than decrease the size of the batteries. Go to this web site for the article in the MIT Technology Review: http://www.technologyreview.com/energy/23893/?a=f


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    Nov 9th, 2009 (10:06 am)

    The basics are understandable but the description is written in technobable. Any translators ?


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    Nov 9th, 2009 (10:07 am)

    RB: Somewhat off topic, over the weekend I got a letter from “Brent Dewar Vice President, Chevrolet” about the closure of my Chevy dealer. It is a poorly printed and grammatically muddled form letter. Does anyone know if Mr Dewar is a real person, and if so what his address might be? The only information in the letter is the phone number for the “Customer Care Center,” which I affectionately think of as the “Customer Go-Away Center” The center can provide such gems as “use the gm website” and “any Chevrolet dealer can assist you.”I would like to write back to Mr Dewar (very politely of course). I still hope that the new gm would like to listen to its customers, not just talk.  (Quote)

    Morning RB,

    Mr. Dewar is a real person. He is part of the ‘old brigade’ though and unlikely to be receptive/put a lot of stock into your response to him. Dewar and Fritz are tight (it would seem at least, given the status afforded Brent since Fritz took over ), they basically started out together (and worked together internationally before they ‘came home’ to HQ).

    Image you had Wagoner’s bravado mixed with Lutz’s um, whatever it is…then you have Brent. (imo)

    You can contact him at brent.dewar@gm.com


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    Starcast

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    Nov 9th, 2009 (10:10 am)

    RB: I didn’t understand the question, and I didn’t understand the answer.Hope it all is good.   (Quote)

    I thought it was just me.


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    Frank D

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    Nov 9th, 2009 (10:20 am)

    the key word is “proprietary”…Glad to know GM is on the ball with innovative design and engineering!


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    Nov 9th, 2009 (10:22 am)

    #19

    Lee: Submitted by Rich R.–”I also don’t believe the actual shaft needs to change direction in order to switch to regen mode just the phasing.”I think you are correct. No one seems to be able to answer the “reverse spinning question.” I think what happens in regenerative braking is that the electric motor internals decouple during “coast and braking mode” and in so doing convert rotationalenergy back to batteries. Then when drive energy is called for, drive motor couples back to propulsion mode.–Lee  

    (Quote)

    Granted the article is a bit hard to understand but the way the system functions is very complex and GM would not want to reveal it proprietary secrets about how it works. As far as Regen is concerned, the current flowing through the windings of a motor generates a magnetic field is such a way to turn the rotor. This magnetic field builds up and drops down as the current level is adjusted to speed up or slow down. As such when the field collapses in current is generated in the stator which needs to go somewhere. The field can not collapse unless this current is drained of to somewhere. In this case it is re-directed back into the battery. A generator is a special type of motor whose design is maximized to create electricity. The only time the rotation direction of the traction motor is reversed is when the vehicle would be backing up. The generator motor never changes direction .

    As far as the coupling of the two motors, putting a load on the generator has a feedback effect that changes the rotation speed (like a drag on the ICE motor) while it is trying to generate a steady current. This effect is what GM has engineered into the Voltec technology. To keep the ICE in a sweat spot, the electronics controls where the electricity the generate produces is used: driving the traction motor or recharging the battery. This is a balancing act. so when you change acceleration or brake, the amount of current directed from the generator to the traction motor or the battery varies. The circuitry keep the load on the generator motor level. Hope this helps you understand this complex issue.

    Happy trails to you ’til to meet again.


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    Nov 9th, 2009 (10:24 am)

    Great article Lyle (more please). I love technical interviews w/engineers.

    BTW, those posting Alex doesnt know what she’s talking about couldn’t be more wrong.


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    Nov 9th, 2009 (10:26 am)

    nasaman: makes me wonder if Alex Cattelan is possibly “dancing around” a Volt two motor/generators design having some significant similarities to the 2MT70…..

    Its basically the same part, but with all five of the clutches and most of the gears missing.. there is no mechanical path between the two motors, or between the ICE and the wheels.


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    Nov 9th, 2009 (10:26 am)

    Let the engineers have some fun and do what they do best–engineer the car! All that matters is that the car won’t use a drop of gas for forty miles, (hopefully more with the hypermilers). I guarantee anyone who is lucky enough to own the finished product will fall deeply in love with the car.


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    Nov 9th, 2009 (10:29 am)

    Russ: I would hope that he would increase the AER of the volt rather than decrease the size of the batteries.

    I would prefer the same AER but a much lower cost. Most people dont drive more than 40 miles a day.. do you?


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    Mike-o-Matic

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    Nov 9th, 2009 (10:31 am)

    Just wanted to clarify something here: For those who don’t know, Alex Cattelan is a woman. This is a picture of her.

    2688805797_ee602426ca.jpg

    EDIT: Apologies to Nasaman (who pointed it out first)… but it drives me nuts trying to figure out people mean by “he” and “Mr.” when they are referring to Alex.


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    Nov 9th, 2009 (10:31 am)

    Confusing to say the least.


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    Nov 9th, 2009 (10:48 am)

    I think what he may been eluding too is that the generator can act as a motor, but will run the AC/heat so that it does not reduce the traction motor efficiency, and it most likely works to start the ICE when needed.


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    Nov 9th, 2009 (10:51 am)

    Just my WAG I think what will happen when the traction motor is calling for a lot of juice, such as climbing a very steep hill during what should be AER the ICE may start so that the battery is not discharging at to high a rate and possibly damage or shorten the life of the battery.
    I don’t think the wheels will ever see more HP than the traction motor can provide.


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    Nov 9th, 2009 (11:00 am)

    NZDavid: Secondly, in order to ‘directly’ couple the ICE generator with the traction motor, it would be necessary to bypass the Inverter. Therefore the ICE generator must produce AC power at the same voltage as the traction motor is using it. Bypassing the inverter will increase efficiency, but the control logic to do it would not be simple.

    Thats a very interesting idea.. so the 3 phases coming out of the generator directly drive the 3 phases of the motor.. without an intervening DC conversion path.. that definitely would be considered a “coupling” and could really boost the efficiency in the CS mode.

    The electronics would be very fancy.. you would basically control the speed of the traction motor by the ICE throttle or by boosting the voltage in each individual phase electronically.


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    Biodieseljeep

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    Nov 9th, 2009 (11:13 am)

    Maybe there is a website that could translate plain english into Evasive English for executives. You type in “The project is over budget, behind schedule, and was unfeasable from the first second some executive idiot suggested it.” and site prints out “In growing the project to commercial scale, emphasis has been added to the p-and-l investigation, leading to expanded investigating of market timing and added product performance for a successful launch.”

    Sombody hire me quick before I go work for the government and really screw things up.


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    Nov 9th, 2009 (11:20 am)

    1. The wheels are always driven by the electric motor.
    2. The traction motor is the thing that propels the wheels via an electric current.
    3. The Engine generates power for the battery.
    4. In cases where the car is coasting down a hill the traction motor creates energy for the battery by utilizing resistance to the car force.


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    Nov 9th, 2009 (11:25 am)

    Sorry for referring to Alex Cattelan as a man. Wasn’t able to attend the Volt meeting last year to listen to the speakers.

    carcus1: The first thing to clear up should probably be that “he” is a “she”.

    =D~


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    Nov 9th, 2009 (11:33 am)

    Please read LRGVProVolt’s response carefully and then re-read the article. It made much more sense to me after doing so.

    My take is that Alex is describing their energy management (production/consumption) architecture as best she can within the constraints place upon her.

    Thanks LRGVProVolt.

    Regards


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    Nov 9th, 2009 (11:38 am)

    Being honest: The wording in this interview leaves the impression of an overly complex system. This is not a great image to paint regarding a gen 1 vehicle. My first reaction to the ‘two electric motors’ statement was HUH(?). After reading the interview my second thought was WHAT(?).

    Many boast about 2 mode hybrid vehicles. In my opinion the gain of 4 or 5 MPG isn’t worth the complexity factor. This is why the Cruze will be appealing to most buyers seeking economy. You’ll see.

    =D~


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    Nov 9th, 2009 (12:05 pm)

    OK, lemme get this straight. They can and/or do coupling and decoupling of the traction motor to the genset’s generator motor?
    But they don’t mention that the gensets “Generator” is ever decoupled from the ICE!
    This tells me that at some point mechanical torque is also applied if the ICE is running.
    Coupling and decoupling of the ICE sounds very familiar. Can you say HSD? HSD does the same thing doesn’t it? When in EV mode it does not use mechanical ICE torque but then later uses it MG1 coupled to MG2.


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    Nov 9th, 2009 (12:12 pm)

    nasaman: I seem to recall someone at GM (Tony Posawatz?) commenting about similarities between the housing (and perhaps even the two motor/generators used in their FWD 2 mode hybrid transmission?) and the two Volt motor/generators/housing. Both are FWD, thus use a transaxle(s) and both are extremely compact. The view below of the FWD 2 mode transmission 2MT70, shown in a paper at the SAE 2009 World Congress, makes me wonder if Alex Cattelan is possibly “dancing around” a Volt two motor/generators design having some significant similarities to the 2MT70…../ BTW, Alex Cattelan is female  (Quote)

    It’s always good when you weigh in nasaman. I was thinking along the same lines. Why reinvent the wheel when with a little tweaking it can do the job!


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    Nov 9th, 2009 (12:29 pm)

    IMO this kind of “articles” – fuzzy, non-technical, evasive, secretive – just undermine the Volt more and more. Bad PR should not have happen in the first place: if you have nothing to say, don’t say anything. Exec Rule #1 – do not take questions you can not answer.


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    Nov 9th, 2009 (12:31 pm)

    I agree that the information is confusing. I think it is something similar to what VW has in a concept car. Try a search for “VW Diesel Hybrid” When the vehicle is moving at highway speed a clutch can engage to drive the car directly and in conjunction with the electric motor. No gear shifting is done because it would only engage at higher speeds. The advantage is that you eliminate the efficiency loss in the generator and motor by direct propulsion as apposed to running the generator and using the electricity generated to supply the electric motor for propulsion.

    That probably makes sense for maximum efficiency. But it all sound very complex and expensive compared to straight battery electric propulsion.


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    Nov 9th, 2009 (12:41 pm)

    Dave K.:
    Mr. Cattelan said plenty. By the time another year passes we’ll know the Volt down to the brand of windshield wipers.I’m curious if the smooth underside of the Volt and rear suspension will be harvested for wing effect. Engineering reported that no (wind tunnel) stone will be left unturned.=D~  

    (Quote)

    What “smooth underside” are you talking about? Cadillac Converj, yes. Volt, no.


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    Nov 9th, 2009 (12:46 pm)

    nasaman: I seem to recall someone at GM (Tony Posawatz?) commenting about similarities between the housing (and perhaps even the two motor/generators used in their FWD 2 mode hybrid transmission?) and the two Volt motor/generators/housing.

    It was on a web chat with the executive in charge of, among other things, the development of electric motors — your friend with the NASA connection. If I remember correctly the exact quote was something like the similarities were “darn intentional”, which I found interesting.

    I’m thinking that BillR is right and this is the “transmission” Bob Lutz was referring to in his comments.


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    Nov 9th, 2009 (12:46 pm)

    Hmmm…while not said in the interview, could the Volt be something different than a series hybrid (or EREV)?

    Maybe the ICE will actually provide power directly to the wheels. I would not be surprised if GM discovered (realized) that more efficiency is possible by connecting the ICE directly to the transmission/wheels during some modes of operation.

    Whatever the case, this article gives evidence that the Volt powertrain is more significantly complicated than a simple EREV design. Which means that more technical expertise and documentation are required to service it. And more cost for parts and labor to assemble the components of the powertrain.


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    Nov 9th, 2009 (12:55 pm)

    if you recall, the generator and the motor are sharing the housing, practically we are talking about a 2 in 1 item. now, with this piece of info in mind, reread the article and everything should be clear. it is obvious that with this kind of setup you can have almost any degree of interaction between the two motors/generators.


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    Nov 9th, 2009 (1:26 pm)

    Herm: NZDavid: Secondly, in order to ‘directly’ couple the ICE generator with the traction motor, it would be necessary to bypass the Inverter. Therefore the ICE generator must produce AC power at the same voltage as the traction motor is using it. Bypassing the inverter will increase efficiency, but the control logic to do it would not be simple.
    Thats a very interesting idea.. so the 3 phases coming out of the generator directly drive the 3 phases of the motor.. without an intervening DC conversion path.. that definitely would be considered a “coupling” and could really boost the efficiency in the CS mode.
    The electronics would be very fancy.. you would basically control the speed of the traction motor by the ICE throttle or by boosting the voltage in each individual phase electronically.  

    So ….. could you say this idea is a sort of series/parallel hybrid where the parallel side contains not planetary gear sets or CVT, but AC power controlled by “fancy electronics” from the generator to the traction motor acting as the “clutch” between the ICE and the driveline?


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    Nov 9th, 2009 (1:28 pm)

    Get you FREE electric car NOW. Offer expires 12/341/09 because that’s when Congress says it does….

    http://www.youtube.com/watch?v=uzrf7sMGsgw&feature=pyv&ad=3266793116&kw=electric%20car&gclid=CJ674I7E_p0CFc5L5QodTVB1pg

    (Game the progressive redistribution system.)


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    Nov 9th, 2009 (1:34 pm)

    The key phrase IMO is that this is in a propriatary area—so he is dancing around not giving up Crown Jewels.

    A little change of pace—the CEO of Reliant Energy was writing in the Dallas Morning News 11-09-09 Business Section re getting into charge stations in homes, garages, parking lot, and streets as a new business.

    He also said he owned a Tesla but encountered Range Anxiety after about 40 miles even tho the range is 240 miles on a single charge.Said it was very, very, very fast.

    This is precisely what the Volt is designed to prevent.


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    Nov 9th, 2009 (1:36 pm)

    carcus1: Herm: NZDavid: Secondly, in order to ‘directly’ couple the ICE generator with the traction motor, it would be necessary to bypass the Inverter. Therefore the ICE generator must produce AC power at the same voltage as the traction motor is using it. Bypassing the inverter will increase efficiency, but the control logic to do it would not be simple.
    Thats a very interesting idea.. so the 3 phases coming out of the generator directly drive the 3 phases of the motor.. without an intervening DC conversion path.. that definitely would be considered a “coupling” and could really boost the efficiency in the CS mode.
    The electronics would be very fancy.. you would basically control the speed of the traction motor by the ICE throttle or by boosting the voltage in each individual phase electronically.

    So ….. could you say this idea is a sort of series/parallel hybrid where the parallel side contains not planetary gear sets or CVT, but AC power controlled by “fancy electronics” from the generator to the traction motor acting as the “clutch” between the ICE and the driveline?

    The 3phase output from the genset can not connect in parallel to the 3phase output of the traction when in regen or power generation. They BOTH have to be rectified to DC first then they can run in DC parallel. If one phase of a 3 phase output generator is 180deg out of phase with the other generator you’ll have a big zero out or a fire/carbque.


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    Nov 9th, 2009 (1:41 pm)

    Joe: If the Volt were a Toyota product, you would know a lot less about the lt than what you now know. Toyota is so secretive.  (Quote)

    Not true. I made an extensive study of the Priuss. Toyota made a lot of detailed design available on net. Like brake system design, complete mechanical design of the drive system, ICE specs,control system block diagrams, etc, I know a lot more about the Priuss than GM will ever release about the Volt.


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    Nov 9th, 2009 (1:43 pm)

    No way around it, the interview implies that the generator motor will be mechanically driving the wheels in some situations.

    PLEASE NO!!!!!!!!

    This would require a mechanical clutch on the generator motor. This is exactly the type of complexity to avoid! Surely they aren’t that stupid!?! This would negate much of the appeal of the Volt.

    I will stand by and hope for a direct denial of this interpretation, from somebody on the Volt team. Lyle, Statik, anybody, can you get a statement from GM on this?


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    Nov 9th, 2009 (1:45 pm)

    CaptJackSparrow: The 3phase output from the genset can not connect in parallel to the 3phase output of the traction when in regen or power generation.

    Hey Capt,

    Can you take the 3 phase AC OUTPUT of the generator and put it to the INPUT of the traction motor — a sort of direct electrical connection (bypassing the battery and conversion to DC)?

    p.s. It gets pretty fuzzy for me as soon when AC and phases start entering into the electrical discussion, simple DC is about all I can grasp.


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    Nov 9th, 2009 (1:49 pm)

    This is a great article. Awesome detail!


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    Nov 9th, 2009 (1:51 pm)

    Tex-Arl: e also said he owned a Tesla but encountered Range Anxiety after about 40 miles even tho the range is 240 miles on a single charge.Said it was very, very, very fast.

    Dude, something wrong with the guy then.
    Unless he was drag racing at every stop and go? Why not, it’s a roadster? But dang dude, range anxiety at 40 miles used where 240 miles is by design and 313 has been achieved? Hommie needs to take a chill pill.


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    Nov 9th, 2009 (2:01 pm)

    carcus1: Hey Capt,

    Can you take the 3 phase AC OUTPUT of the generator and put it to the INPUT of the traction motor — a sort of direct electrical connection (bypassing the battery and conversion to DC)?

    Technically yes. The only “Gotcha” is that it will be “Full On” with the only method of throttling is reducing voltage amplitude and the only way to do that is either slow down the generator or reduce the Vin of the generators induction coils. It’s cheaper to rectify a 3phase signal though. A 3 phase Full wave bridge rectifier at 600VAC and 60-100A only costs less than $150.


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    Nov 9th, 2009 (2:09 pm)

    Wait, is she saying that, with a slight modification to the plasma nozzles, that a fully concordant warp coupling is possible between the ICE and the traction motor without the use of a tacion pulse modulator? If that is true, won’t anti-matter have to be vented out the dorsal vents in order to avoid a time-space deformation?

    Oh, wait, sorry. I think I’ve confused this with the Star Trek forum. My bad. Later…


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    Nov 9th, 2009 (2:18 pm)

    #71 Xzion

    And you knew all this info about the Prius a year before it was FIRST sold?

    Wow! You probably knew more than 90% of the employees at Toyota.


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    Nov 9th, 2009 (2:19 pm)

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    Nov 9th, 2009 (2:29 pm)

    I was going to post something else on the “architecture” but I just ended up confusing myself.

    What I take away from this interview is that there’s more to the design than we’ve been told and a straight “series hybrid” definition may not fit for the volt.

    I would consider this good news for efficiency, but how it will effect complexity, cost, long term maintenance — and therefore the all important viability — ??


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    Nov 9th, 2009 (2:30 pm)

    carcus1: What I take away from this interview is that there’s likely more to the design than we’ve been told, and a straight “series hybrid” definition may not fit for the volt.

    I agree.


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    Nov 9th, 2009 (2:40 pm)

    Frank D: the key word is “proprietary”…Glad to know GM is on the ball with innovative design and engineering!  (Quote)

    Useless stuff can be “proprietary,” too. We are a year away from discovering whether or not there is any real value in the Volt approach to the automobile.


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    Nov 9th, 2009 (2:46 pm)

    Joe: If the Volt were a Toyota product, you would know a lot less about the lt than what you now know. Toyota is so secretive.  (Quote)

    Whether or not Toyota is “secretive” is irrelevant. The chief difference between the Prius and the Volt is that, if you really want to understand the Prius, you can buy one and test it to your heart’s content, put additional instruments on it to measure what happens or even take it apart to see what makes it tick.

    With the Volt, you must rely on gobbledy-gook relayed through third parties to understand how it works… correction… how it will, eventually work… maybe.


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    Nov 9th, 2009 (2:48 pm)

    Lyle,

    You couldn’t follow up with a definitive question: “You make it sound as though the two motors share the driveshaft with the engine. Do they?”

    For evasiveness, by the way, this has nothing on GM’s pronouncements – or lack thereof – concerning the Volt’s fuel economy after the battery charge is gone and the vehicle is in “range-extended” mode.


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    Nov 9th, 2009 (2:52 pm)

    If this helps the Volt beat Prius MPG I will be ecstatic. It will make Toyota just like the old GM– ie a company that has become to old and set in their ways to recognize a good concept and to change the way they do things. Geez-who wants a Prius with only 12 miles AER.


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    Nov 9th, 2009 (2:56 pm)

    statik: Mr. Dewar is a real person. He is part of the ‘old brigade’ though and unlikely to be receptive/put a lot of stock into your response to him. Dewar and Fritz are tight (it would seem at least, given the status afforded Brent since Fritz took over ), they basically started out together (and worked together internationally before they ‘came home’ to HQ).

    Image you had Wagoner’s bravado mixed with Lutz’s um, whatever it is…then you have Brent. (imo)

    statik –> Thank you.,


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    Nov 9th, 2009 (2:57 pm)

    Rich R: Generator can act as a traction motor to start the engine.

    I was under the impression that there was a 12v battery/system for accessories. In other words, a normal starter motor would be used for starting the ICE?

    If the traction battery lost power for some reason (like kicked a circuit breaker), I think you would want the ICE to start independently and provide generator power to the traction motor.


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    Nov 9th, 2009 (2:59 pm)

    Voltec drivetrain technology got another boost today, November 6, 2009, as the Detroit News learns the Cadillac Converj is going into production!

    http://detnews.com/article/20091109/AUTO01/911090394/GM-to-put-Converj-into-production


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    Nov 9th, 2009 (3:08 pm)

    OT,

    Looks like the Converj is a go

    GM to put electric Cadillac Converj into production
    http://detnews.com/article/20091109/AUTO01/911090394/GM-to-put-Converj-into-production


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    Nov 9th, 2009 (4:07 pm)

    NZDavid: This is a great article IMHO.

    NZDavid: Looking good for 50mpg at 60mph.

    +1 for positive attitude!! I would expect no less from you.

    It strikes me that this is going to be THE most sophisticated and complex car on the road. I used to say that the Prius was an engineering tour de force, but this thing will put it on the trailer.


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    Nov 9th, 2009 (4:11 pm)

    Jordo P.: So does anyone know where on earth we are going to get the 1.2 jigawatts of electricity. I heard they are working on a product called “Mr. Fusion.” Anyone heard any news on that???

    #13

    EEstor man! Get up to date.


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    Nov 9th, 2009 (4:16 pm)

    statik: Image you had Wagoner’s bravado mixed with Lutz’s um, whatever it is…

    #42

    I believe B. S. is the phrase you are searching for.


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    Nov 9th, 2009 (4:16 pm)

    carcus1: OT,Looks like the Converj is a goGM to put electric Cadillac Converj into productionhttp://detnews.com/article/20091109/AUTO01/911090394/GM-to-put-Converj-into-production  (Quote)

    Sweet! The Converj is one nice looking car. I want to see how they tweak the Voltec.


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    Nov 9th, 2009 (4:16 pm)

    Herm: I would prefer the same AER but a much lower cost. Most people dont drive more than 40 miles a day.. do you?  (Quote)

    My work is 50 miles a day, plus some extra driving after or before work, so I would need at least a 60 mile range which the Myer Motors car (2-seater) will deliver. There is NO way that I would ever buy a Volt since like other hybrids, it uses gasoline! It’s going to be ALL electric for me and charge it with pv’s on the roof! I don’t know about the rest of the country, but I want to stop using natural resources as fuel. Ecolocap is going to reveal a new carbon nanotech battery (CNT) on Nov. 18th that will store 2.5x lithium-ion. :)


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    Nov 9th, 2009 (4:20 pm)

    Biodieseljeep: Maybe there is a website that could translate plain english into Evasive English for executives.

    #55

    I think it’s called “Dilbert”.


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    Nov 9th, 2009 (5:35 pm)

    Let’s talk a little bit about electric motors. At first, I didn’t even understand the question about the motor turning the other way and acting like a generator. After reading through the comments, I now understand where the question came from and that there is a variety of levels of understanding of how electric motors operate.
    So with apologies to everybody out there that actually works with electric motors (I used to design motor controls oh, 20 years ago) I’ll try to make things simple enough to cover the basic concepts yet still capture important complexities leading up to what I think Alex may be talking about. (Sadly, teaching is not my strongest suit either but I will try my best! :)

    All electric motors operate on the basic principle of magnetic attraction and repulsion. Just like how two basic bar magnets you might have on your fridge attract N to S and repel N to N or S to S. The electric motor has a set of magnets in the rotor (the rotating piece) and a set of magnets on the stator (the housing that doesn’t move). These magnets can be formed either with permanent magnets (just like a bar magnet) or with electromagnets, which are magnets that only exist when a current is applied though a loop of wire. However, at least one of the magnet sets must be electromagnets or you could not control the movement of the motor. The magnets of the rotating set would just align with the opposite magnets of the fixed set and they’d just sit there. To get the rotor to move, you have to change the polarity of the electromagnets on the fixed position set. That will change which magnets the movable set are attracted to, and the rotor will move to re-align N-S again.

    The simplest type of motor from a use standpoint is the DC motor (with integrated commutator). You apply a voltage to it and it spins. Higher voltages spin it faster. However, if you spin the shaft, it will output a voltage as well. There is a relationship between how fast the shaft spins and the voltage on the device. Spin the shaft faster and the voltage it puts out goes up. Apply higher voltage and the shaft speeds up. The key here is that if you try to spin the shaft faster than the corresponding output voltage, it produces power as a generator. If you apply higher voltage than the corresponding shaft speed, it will produce torque as a motor. You don’t have to reverse direction or anything like that. It’s simply a matter of trying to “push” harder electrically which pushes the shaft harder or push the shaft harder which “pushes” the electricity.
    The key to the simplicity of this device is the commutator which is the device that alternates the polarity of the fixed magnetic fields. These are mechanical and you may have had some old car’s alternators “brushes” go bad. Those brushes are part of that mechanical commutator. Those aren’t very popular today for things like car motors because we can do a lot better job varying those electromagnets with electronic controls.

    Which brings us to the next motor, the DC synchronous motor, such as used in the Prius. For this motor, the rotors still have a fixed set of permanent magnets but the coils of the electromagnets have to all be controlled electronically to create the magnets of the desired polarity. Now, you can not only adjust the speed of the motor by adjusting the Voltage, but also by adjusting the speed (frequency) at which you change the polarity of the electromagnets. So, it’s not just a simple voltage relationship, anymore, but otherwise it operates similarly to the DC motor. Given a frequency of field change and voltage applied, it will try to spin at a certain rate. If the spin is less than this rate, it will be a motor. If the spin is greater than this rate, it will be a generator. (For the record, I used to design controllers for these types of motors)

    Which brings us to the last kind relevant kind, which is the AC Induction motor, such as used in the Volt. (And sadly, this is the hardest type of motor to really wrap your brain around. :)
    What is tricky about this motor is that it has NO permanent magnets on its rotor. And it doesn’t have any electrical connections to the rotor to easily control electromagnets, either. And yet, like every other electric motor, the inner rotor DOES have magnets. Those magnets are formed dynamically in response to the magnetic fields created by the electromagnets of the stator. The advantage here is that the rotor is just a big chunk of specially shaped metal. Very simple, indeed! However, controlling that chunk of metal becomes a game of setting up currents in the coils of the stator, which then create magnetic fields, which then INDUCE opposite currents in the rotor which then create opposite magnetic fields to oppose the ones you created in the stator! Now flip the polarity of the stator windings and this will create an opposite polarity magnetic field and for a brief instant the rotor sill has the original field that now repels the new field and the rotor moves. Of course while that is happening the rotor is setting up a new field in response to the opposite field you just created and you have to repeat the whole cycle. Quickly :) So the control of this beast now requires varying the frequency and voltage of the power supplied and estimating what the fields are doing in that chunk of metal that is the rotor. However, much like the DC synchronous motor, there are frequencies and voltages that will combine to try to rotate the shaft at a certain speed and trying to spin the shaft at a certain rate. If the spin is less than that rate it will act as a motor and if the spin is higher than that rate it will try to act as a generator. However, there’s also an additional state beyond the DC synchronous motor/generator. Acting as either motor or generator still requires applying the proper frequency of polarity reversals to the stator coils. If you simply DROP all (time varying) voltage to the coils completely, the magnetic fields stop altogether and the shaft just spins freely.

    So, what does that mean? In order to use an induction motor, you have to be able to apply alternating currents (that’s where the AC comes from) to it. But in order to use it as a generator, guess what, you ALSO have to apply alternating currents to it (or you have no magnetic fields and it just spins freely).

    So, here comes the conjecture and I admit that AC induction motors (and especially generators) are outside my realm (but what the heck :)

    So, when Alex is talking about “coupling” the motors, I believe she is not talking about some kind of mechanical “clutch” type coupling. She’s talking about either magnetic or electric coupling. Frankly, I don’t see how they could have any kind of useful magnetic coupling because it would probably have to couple through air and air simply cannot support the magnetic field strengths required for these kinds of motors. So, that leaves electric coupling such as carcus1 suggested. I think that may be a real possibility.

    CaptJackSparrow: I admit induction motors (and especially induction generators) are not my strong suit, but it seems to me that the output of the generator is related to the “slip” or the rate difference between the gas motor and the electric fields you apply to induce the fields in the generator rotor. So, it is not necessarily fixed to being full ON. There is an additional electronic control element. Basically you wind up controlling the fields in the traction motor with the difference in fields between what you apply electrically to the generator and the shaft speed created by the gas engine. But, holy cow, that makes my head hurt. :)

    Also, I think I’ll comment on something else I read in the threads above, too. I always kind of figured that what Maximum Bob said along time ago about an electric “transmission” had to do with probably the way the potentials are applied to a 3 phase induction motor. If they were hard wired to 3 phase ac power, it would be like the difference between either a ‘wye’ connection or a delta configuration. (which changes the maximum voltage potentials seen inside the motor). but I think they’re going to use frequency modulating controllers so that eliminates a lot of the usefulness in varying the wiring configurations. So, I’ve never really been sure about what that really meant.


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    Nov 9th, 2009 (6:04 pm)

    DaveP,

    Thanks for the lesson. You’ve obviously spent some time at the chalk board. I stayed with you till the last paragraph. . . when the course designation changed from 101 to 303 and I had to go back to shooting spit wads.


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    Nov 9th, 2009 (6:34 pm)

    @DaveP

    I think this opened a can of worms for us to weed through.

    /put straw in mouth and shoots spit wad full of phlem at Carcus1…..


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    Nov 9th, 2009 (7:14 pm)

    Herm: Sheez, lots of talk and no new info..so yes, we have a motor and a generator, but both can switch roles.The he dumps this jewel:“However, I do have some mechanisms to couple those motors and in some points of operation these two motors can be coupled and have a more efficient state.”He is not talking about a mechanical connection between the two motors.  (Quote)

    No time to read all of the comments but this is a good one and I think you are correct Herm.

    My inner reader got pretty much the same thing: yada..yada..I do have some mechanisms to couple those motors and in some points of operation these two motors can be coupled and have a more efficient state…yadaa..yadaa.

    I believe he is referring to the ability to output electricity directly from the generate motor to the traction motor, bypassing the AC/DC/DC conversion and power electronics module in certain ideal situations. Hopefully, this is optimized for 18-25KWH output setpoints so highway driving can be accomplished a little more efficiently. If this is so, then operating within these idealized states should come pretty close to if not outperform the Prius for these situations (loads).


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    Nov 9th, 2009 (7:21 pm)

    carcus1,

    Thanks! That took a while to write. Except for the last paragraph which I should not have included because it is well, not totally unrelated but sufficiently unrelated to warrant a different explanation.

    Which I’ll do right now! :)

    If you look at standard power transmission in the US, by the time it reaches your neighborhood, the power is carried over three wires, each containing one phase of a 3 phase AC system. While each phase looks the same (basically a sine wave of AC voltage) they’re all staggered in time so that they never peak in voltage at the same time. They’re equally spaced by 1/3 of a cycle so that if one is at peak voltage, there is one having already fallen from peak voltage by 1/3 of a cycle and one that is 1/3 of a cycle away from reaching peak voltage. This makes a nice, regular system with each phase reaching peak voltage in turn with nice regular intervals.

    Most of the time, this voltage pattern is illustrated as 3 points around a circular phase diagram and it therefore looks like an equilateral triangle. That’s the real key here, the equilateral triangle. :)

    If you connect loads directly between the phases (it would look like drawing load lines along the sides of the equilateral triangle) you have connected your loads in a Delta configuration. That in the US would typically give you 208V.

    If, instead, you create a “neutral” wire in the center of your equilateral triangle and connect the loads from each outside point to the inside “neutral” point you have connected your loads in a “wye” (named because it looks like a “Y”, possibly upside down depending on how you drew your triangle :) ) configuration.
    The voltage seen by loads in this configuration is now the square root of 3 less than in the delta, or 120V. The magical part is that the “neutral” doesn’t have to be connected to anything else if your loads are balanced as they would be if you were just driving a motor. So you are free to connect your motor in a Delta or just create a “neutral” out of thin air and use it to connect the motor in a Wye connection.

    What that does to the motor is that from the exact same voltage source the motor can see either 208V or 120V depending on the connection type. Why is that important? Well, the thing about induction motors is they are kind of tricky to start. If the motor isn’t moving and you apply a big voltage to it, the motor doesn’t present much of a load to the supply and so the motor sucks down a huge amount of current. That can overheat the motor and takes a lot of power that isn’t doing a whole lot. If instead you apply a lower voltage then the motor doesn’t use as much current but the downside is it doesn’t have as much torque, either. So, there’s no free lunch in this case.

    But remember from our previous lesson ;) that there is more than just voltage to control the speed of the induction motor. If instead of applying a fixed frequency (such as the 60Hz that comes from our power lines in the US) you change the frequency to say, 2 Hz and apply a large voltage then the induction motor gets large start up torque with a small current draw.

    So, if the volt has motor controllers capable of varying frequency and voltage, it doesn’t really make any sense (at least to me but I admit induction motors are not my area) to change the connection configuration as for example between Y and delta. Yet, there you go. I always kind of figured good ‘ol MB was talking about electrically “shifting” the wiring around and maybe they are. I haven’t heard anybody mention that “transmission”-like thing in a long time.


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    Nov 9th, 2009 (7:29 pm)

    Russ: The article is somewhat confusing as to how much. In the examples that are given, it increases the energy density by between 75%-90% and later he claims a 40% gain.

    Wow there is a lot of confusion on this post!!!!

    Dr. Cui’s batteries are expected to increase the anode storage density by 75 to 90 %. Then the anode side could be reduced in size and the cathode side could be correspondingly increased by 30 to 40% which would result which would result in battery capacity increasing by 30 to 40%.

    And Alex is not a he :)


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    Nov 9th, 2009 (7:38 pm)

    Loboc: I was under the impression that there was a 12v battery/system for accessories. In other words, a normal starter motor would be used for starting the ICE?

    If the traction battery lost power for some reason (like kicked a circuit breaker), I think you would want the ICE to start independently and provide generator power to the traction motor.

    In a recent online Q&A, I asked this and they said the Generator that’s coupled to the ICE will start the ICE. No “Starter” motor per se.


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    Nov 9th, 2009 (7:50 pm)

    DaveP: If instead of applying a fixed frequency (such as the 60Hz that comes from our power lines in the US) you change the frequency to say, 2 Hz and apply a large voltage then the induction motor gets large start up torque with a small current draw.

    2Hz would give you an extremely bumpy/jolting ride. Freq will most likely stay constant (most likely not 60Hz but higher) but power delivery will be by voltage Amplitude and Current applied.
    The higher the freq, the smoother the ride. At 2 Hz you would feel a torque jolt twice a second, bump bump till you get to speed but you will still feel the bump bump.


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    Nov 9th, 2009 (7:52 pm)

    DaveP @ 98,

    Ok, that lesson I’ll have to chew on for a while.

    I’m only vaguely familiar with the AC stuff from classroom only and that was quite a while back.

    DaveP: So, if the volt has motor controllers capable of varying frequency and voltage, it doesn’t really make any sense (at least to me but I admit induction motors are not my area) to change the connection configuration

    As for the question, that’s well over my head . . . .

    I can only guess that it might be related to their biggest obstacles which I would say are:

    1. Battery life
    2. Efficiency
    3. Smoooooth ICE wind up (as MB mentioned on Letterman)

    / If the volt systems really are this involved, one has to wonder how many programming oversights have resulted in “smoked” batteries.


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    Nov 9th, 2009 (7:53 pm)

    Jordo P.: I heard they are working on a product called “Mr. Fusion.”Anyone heard any news on that???  

    Sure, it’s almost done:

    Iter.jpg
    The International Thermonuclear Experimental Reactor (ITER) will produce 500 megawatts of fusion energy for 400 seconds at a time

    http://www.iter.org/default.aspx
    Unfortunately, it is 10 meters in diameter. They are working to shrink it down so it can fit in a car, and cut the power to about half a megawatt; experts say it should be ready about the same time as hydrogen fuel cells :)


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    Nov 9th, 2009 (7:53 pm)

    DaveP: So, when Alex is talking about “coupling” the motors, I believe she is not talking about some kind of mechanical “clutch” type coupling. She’s talking about either magnetic or electric coupling. Frankly, I don’t see how they could have any kind of useful magnetic coupling because it would probably have to couple through air and air simply cannot support the magnetic field strengths required for these kinds of motors. So, that leaves electric coupling such as carcus1 suggested. I think that may be a real possibility.

    Exactly, my thoughts as well. It would have to be a electric coupling.

    Sadly, teaching is not my strongest suit either but I will try my best!
    Your best is pretty darn good Dave! Yet another example of what is good about this site.

    sparks: No way around it, the interview implies that the generator motor will be mechanically driving the wheels in some situations.

    PLEASE NO!!!!!!!!

    Calm down Sparks. The article in NO WAY implies a direct coupling. It’s all about a electrical coupling.

    CaptJackSparrow: The only “Gotcha” is that it will be “Full On” with the only method of throttling is reducing voltage amplitude and the only way to do that is either slow down the generator or reduce the Vin of the generators induction coils. It’s cheaper to rectify a 3phase signal though. A 3 phase Full wave bridge rectifier at 600VAC and 60-100A only costs less than $150.

    Capt., the article implies the direct connection would only be in certain circumstances, so whenever you want to give power to, or, recieve power from the battery then the ‘transmission’ would rectify to DC as you suggest.

    Again, my example of a road trip down the freeway with cruise control on, would be a case where a direct AC coupling would improve efficiency.


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    Nov 9th, 2009 (8:13 pm)

    Points to NZDavid (not yours truly) for the origin (in this thread) of the “electric coupling”.

    / . . . are you entitled to points for thinking outside the box when you’re already upside down on the opposite side of the world?

    //puts thumbtack in Capt Jack’s chair while he’s in the hallway “getting a drink”


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    Nov 9th, 2009 (8:28 pm)

    @ CaptJackSparrow #101:

    Well, you wouldn’t move the car with the motor at 2Hz, that’s just something low to start the motor. I made that number up :) . But whatever low frequency you apply, as soon as the motor started to rotate, you’d change the frequency of the applied fields to be relative to the shaft speed of the motor. From what I remember about induction motors, the optimal frequency to apply your fields at is something actually fairly close to the shaft speed. The frequency of the induced field relates to the frequency of the shaft and the frequency of the controlled fields. The torque relates to the difference between the field speeds. The farther apart the field frequencies are, the more torque the motor generates and the less efficient it is as well (since it consumes power to produce that torque). So, what I recall is the motor basically keeps trying to accelerate up to the controlled field frequency.

    @carcus1 #102:
    Yeah. I always kind of thought to myself, “Hmmm. Induction motors. Those are tough.” but the more I think about the details the more I think there is some seriously tricky stuff going on in there that we haven’t even begun to guess at. :)

    I really think Alex just gave us a big hint but we have no idea what it means. I know I don’t. :)


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    Nov 9th, 2009 (8:50 pm)

    DaveP @ 106,

    Wonder how many “seeds” came out of this project?

    http://www.arb.ca.gov/research/icat/projects/acprop.pdf
    p.42 6.4

    “Short of commercializing the entire plug-in hybrid vehicle concept, the technology developed for this project has already created new potential business opportunities . . . “


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    Nov 9th, 2009 (9:02 pm)

    107 add,

    Had another thought, but ran out of edit time on 107, comment should read:

    It is interesting to watch this EREVolution taking place.


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    Nov 9th, 2009 (9:13 pm)

    OK, a bomb was just dropped. Is the Volt really a HHSE (Hybrid Hybrid Serial Electric)?

    If the generator can be used to drive the wheels then maybe they do have some mechanical connection. This would improve the highway mileage tremendously. We need more facts on this.

    This is big news, I hope Alex didn’t just make a blunder that the engineers are just shaking their heads at.

    Dear GM, is this really a HHSE? If so, that would be great!


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    Nov 9th, 2009 (9:28 pm)

    nasaman: I seem to recall someone at GM (Tony Posawatz?) commenting about similarities between the housing (and perhaps even the two motor/generators used in their FWD 2 mode hybrid transmission?) and the two Volt motor/generators/housing. Both are FWD, thus use a transaxle(s) and both are extremely compact. The view below of the FWD 2 mode transmission 2MT70, shown in a paper at the SAE 2009 World Congress, makes me wonder if Alex Cattelan is possibly “dancing around” a Volt two motor/generators design having some significant similarities to the 2MT70…..

    nasaman,

    I was the one who asked the question:

    Rick Hearn: The motor housing of the Volt looks very related to the 2 mode hybrid FWD tranny housing. Is that just a coincidence?

    Jon Bereisa: It is darn deliberate.

    I am going to throw out a possibility for the Volt’s drivetrain configuration that is consistent with Alex’s comments and what we have been told earlier.

    Assume that a clutch (C1) connects the engine to the generator (MG1) which is connected by another clutch (C2) to the planet carrier (C) of a planetary gearset . The required gear reduction of the traction motor (MG2) output to the differential is accomplished by connecting MG2 to the sun (S) of the planetary gearset whose ring (R) drives the differential. A final clutch (C3) can lock the carrier (C) to be stopped. C2 and C3 are operated in an either/or mode: When C2 is closed C3 is open and vice versa.

    When C1 is open, C2 is open, and C3 is closed the planetary gearset just accomplishes a fixed reduction from MG2 to the differential.

    In exchange for the cost, weight, bulk, and complexity of adding the three clutches we get the ability (when C1 is open, C2 is closed, and C3 is open) to use MG1 speed to vary the reduction ratio from MG2 to the differential. (This is an Electronic Continuously Variable Transmission function like the 2 Mode Hybrid and Prius have.) The planetary gearset is mixing the torque from MG1 and MG2 to the differential.

    Note that the engine would never be directly driving the differential if we never close C1 and C2 at the same time. Thus, you can still say the wheels are always driven electrically.

    I don’t know whether the real Volt drivetrain is anything like what I have described here, but it is an interesting way to reconcile Alex’s comments with what GM has previously said.

    ps I drew a diagram of this arrangement in Word, but the file is 26k and the limit for .doc file attachments is 19k. If anyone can tell me how to post the diagram I will be happy to do so. It is a lot easier to follow than my text description!

    I’m interested in anyone’s opinions on this approach. I’m only guessing here! Feel free to say I’m crazy, propose alternatives, or refinements.


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    Nov 10th, 2009 (1:33 am)

    Maybe we’re making things bigger than they really are?

    From what I gather it’s simple:

    The gen gets run at the best speed for the demand. They try to “couple” the gen rpm/output with the traction motor when possible. That way they avoid charging the battery which is inefficient. They never physically connect the two. More like the concept of how automatic transmissions “lock up” to be more fuel efficient when cruising down the highway @ 100 km/h.

    Alex isn’t a French Canadian is she? LOL just going out on a limb here b/c the way the article is written it almost seems like there was a language barrier. I’m not trying to insult her, just that it would make sense.


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    Nov 10th, 2009 (2:19 am)

    nasaman: I seem to recall someone at GM (Tony Posawatz?) commenting about similarities between the housing (and perhaps even the two motor/generators used in their FWD 2 mode hybrid transmission?) and the two Volt motor/generators/housing. Both are FWD, thus use a transaxle(s) and both are extremely compact. The view below of the FWD 2 mode transmission 2MT70, shown in a paper at the SAE 2009 World Congress, makes me wonder if Alex Cattelan is possibly “dancing around” a Volt two motor/generators design having some significant similarities to the 2MT70…../ BTW, Alex Cattelan is female  

    (Quote)

    Thanks Nasaman, a little reminder is better than a lot of talk.

    regards,

    JC NPNS


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    Nov 10th, 2009 (3:08 am)

    A real EV is simple; No IC engine to worry about, essentially just one moving part, the motor rotor.

    What GM is finally admitting, albeit with its usual forked tongue, is that the VOLT-hoax will be forced to engage the engine when high torque demands are made on the battery, for example, when going up hills or accelerating. This is the only explanation for this idiot’s equivocation about how the second motor can help the first motor when needed. Doesn’t anyone here understand it?? Of don’t you dare face facts?

    A real EV, such as the Toyota RAV4-EV, has a battery pack large enough so that it can accelerate on the battery alone; and it has the superior NiMH battery, instead of the short-lived and much more expensive Lithium battery.

    so the VOLT-hoax will be grudgingly released, if at all, with the wrong battery and with an unexciting design that really makes it perform a lot like the Ford hybrid escape.

    GM is inevitably led into this problem, as was predicted years ago, because its design sucks, its managers are iditos, the engineers are second-rate, and it plans to sabotage the EV all over again.

    Our Toyota RAV4-EV, last sold in Nov., 2002, are still running fine, over 100 miles range despite production being stopped by the GM-Chevron lawsuit. To prove GM is still suppressing the EV, ask why GM is still stopping the fully-restored EV1 at WWU from being driven as a real EV, why is GM still killing the EV1.


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    Nov 10th, 2009 (5:06 am)

    Herm: Sheez, lots of talk and no new info..so yes, we have a motor and a generator, but both can switch roles.The he dumps this jewel:“However, I do have some mechanisms to couple those motors and in some points of operation these two motors can be coupled and have a more efficient state.”He is not talking about a mechanical connection between the two motors.  (Quote)

    I am pretty sure he is talking about a mechanical connection.

    That makes the Volt a parallel EV (to everyone’s dismay).

    But it is also serial.

    You want to bet that 95% of the time the ICE is on that it is a PARALLEL power train and the “engineers” voted down a true serial combination?

    One more time duped and fooled by GM. Why is it I dont trust this company? When will I learn?


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    Nov 10th, 2009 (5:27 am)

    GM just managed to “invent” the most godawful complex drive train that has all the issues of a standard ICE vehicle PLUS all the new issues of an EV. It is a maintenance/service disaster waiting to happen.

    I have never seen so much stupidity amassed in one corporation.

    The range extender IS MECHANICALLY COUPLED with a clutch to the wheels. So the ICE can act both in serial and parallel.

    I will bet anyone here that 95% of normal driving, the idiocy will be running in parallel mode. Only when the wheel rev is too low or too high it will decouple and run in series.

    In other words, GM is running the traction motor as a 1st gear or 3rd gear transmission of a 3 gear auto. In “2nd gear” the MF runs in PARALLEL !!!!

    THAT IS WHY they were saying the ICE will run with variable speed. That is why the pictures hinted at a transmission.

    OH I hope so much that VOLT FAILS now.

    Nissan and the Chinese will win, and we will have to bailout this monstrocity AGAIN!

    Obviously GM “genious” engineers convinced the brass that they need a “transmission” (i.e. mechanical coupling) for the Volt, not because its a mechanical necessity, but to make work for the legion of busybodies at GM who will have to learn electronics but were too dumb to do so. PATHETIC.

    This thing is less and less of an EV, as we learn about its secrets.

    Nissan Leaf or Aptera or BYD — to h*** with this beggar corporation.


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    Nov 10th, 2009 (5:51 am)

    sparks: This would require a mechanical clutch on the generator motor. This is exactly the type of complexity to avoid! Surely they aren’t that stupid!?! This would negate much of the appeal of the Volt.

    They are SURELY that stupid – they are building this COMPLEX monstrocity that will keep armies of mechanics and technicians busy, leeching on us good folks wanting a simple range extended EV – telling us this is a “superior” design because it is both Serial AND Parallel – but not telling us that we dont need this complexity.

    We want a simple PC to pull apart and understand, and these people are giving us a cross between a 4 bit Altair and an IBM 360 mainframe, and calling it the best of both worlds.

    And there will be the usual groupies here that will sing their praise as pure ingenuity.

    If backstabbing your friend had any meaning in the engineering world – this is it folks.

    The only way they can claim that this design is superior is by admitting they have undersized the traction motor and the generator.

    The difference between a Prius PHEV and the Volt EREV is now minimal.

    I will not be too surprised if they confess in a few months that there is a full-fledged transmission hidden somewhere in there.

    Any surprise why the Volt is so expensive? It is like 2 cars in one. Both an EV and an ICE powertrain, transmission (possibly) and mechanical clutch (or is it a hydraulic torque converter I BET – cause that would be a forgiving coupling that works with less gears). So much for the 50 MPG that we hear.


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    Nov 10th, 2009 (7:38 am)

    Here is my take after review it again. In the beginning she define the terms of generator and traction motor, “One is considered the traction motor and the other one is the generator…” “..we look at that motor as coupled with the engine in system and then we also have a traction motor. So the generator and engine is considered on system, in her definition.

    So we could have three power delivering combinations in Extended range mode:
    1. Traction motor pulling power from the generator \ battery.
    2. ICE- coupled through the generator freewheeling, through the traction motor also freewheeling.
    3. ICE – coupled through the generator acting as an assist motor and coupled to the traction motor, each applying power as needed in the most efficient method.

    The three motor each have an efficient state and can be combined in nearly infinite combinations through an elaborate algorithm.

    The system, is brilliant, to bad she leak the information. For those of you worried that it is far too technical, shame on you. I believe in the KISS method also, but it is this kind of American engineering that won the WWII and lead us into the 20th century. Although this system is elaborate in programming it is no more complex then today’s 6 speed Automatic transmissions…. Bravo GM….


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    Doug Korthof

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    Nov 10th, 2009 (7:53 am)

    Well, the VOLT-hoax is too expensive for two reasons:
    1. It’s GM, and GM is a crappy company;
    2. It’s too complex, the wrong battery and too small;
    3. GM wants it to fail.

    Oops, that’s three reasons.

    Every 3-ph motor can become a generator without reversing direction; the fields are electronically moved around the stator, to impel the rotor; you just slow down the rotation of the fields, and the rotor will then generate electric current, becoming a generator.

    But it’s obvious what GM is up to; I predicted this to Bob Lutz a long time ago, and posted it on the GM message board. Because the battery is too small, and because it’s the wrong chemistry, they will need an additional source of electric energy when the drive motor pulls its 70 kW, 100 kW or 120 kW (that’s still smaller than my EV hotrod, which has 150 kW, and much smaller than the Tesla, which has 185 kW, but it’s needed for snappy acceleration). Even 50 kW would be a strain on the too-small battery pack; the RAV4-EV lasts over 100K miles by only drawing a maximum of 50 kW from a 30 kWh battery pack, and it’s much sturdier NiMH, not Lithium.

    Lithium, so far, has not proven economical in EVs.

    Here, you’re asking a tiny 16 kWh battery pack to provide up to 120 kW — either you have to dumb it down, only drawing 32 kW, say, or maybe 60 kW — or else provide a second source of kW when under acceleration.

    The Tesla works because it’s got a 56 kWh battery pack. For our tiny conversion battery packs, we usually don’t get much acceleration if using cheap lead batteries; with good lead-acid batteries we can pull 150 kW but not for 100K miles.

    So that’s what’s going on, and there doesn’t seem any way out of the conundrum — GM has placed itself in an impossible position of fulfilling a requirements envelope that’s impossible for the battery-motor configuration it set forth. So that’s why they are starting to backtrack.

    Will they solve the problem? Not without using a better battery, and not without getting some better engineers. Let’s face it, GM knows SQUAT about EVs; it was Hughes and Aerovironment who developed the EV1, and those smart guys are all gone. All GM has left is GMATV, a pale shadow.


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    Nov 10th, 2009 (8:02 am)

    Russ: Slightly off topic, it appears that lithium batttery technology may be taking a big leap forward. Dr. Cui of Stanford has formed a company to manufacture a silicon nano wire anode for lithium ion batteries. This alone, he projects, will increase the energy density of a lithium ion battery greatly. The article is somewhat confusing as to how much. In the examples that are given, it increases the energy density by between 75%-90% and later he claims a 40% gain. Lutz has referred to this new technology. I would hope that he would increase the AER of the volt rather than decrease the size of the batteries. Go to this web site for the article in the MIT Technology Review: http://www.technologyreview.com/energy/23893/?a=f  

    (Quote)

    Hey Russ,
    The advancement is with the anode part of the cell technology. There also needs to be another matching advancement for the cathode side of the cell technology to be able to make use of the anode advancement. They propose to have a thicker cathode since a comparable cathode advancement has not yet occurred, thus only a 40% gain (which anode advancement is tremendous in it’s own right), yet, in theory, there could potentially be as much as a 90% gain if cathode advancement were available to take advantage of the silicone nanowire anode advancement.


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    Doug Korthof

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    Nov 10th, 2009 (8:08 am)

    To drive an EV 1000 miles per month takes 250 kWh of electric energy; this is about what is used by two old refrigerators, about a third of the usage of the average home. Even better, we charge slowly at night, off-peak, when electric goes begging and they are shutting down big generators to “warm start” — an expensive and dirty process.

    Even better, at our latitude, it only takes 1.3 kW solar system to produce 250 kWh of electric energy per month, which is 6 to 12 square meters — smaller than the spot where the car parks at night! So your daytime production would pay for your night time usage, and BOTH would help the grid! It’s a synergistic bonanza.

    Even better than that, it takes 12% of the energy in a barrel of oil to refine it alone, according to a gummint report; not counting oil exploration, extraction, transport, etc.

    Well, that 12%, if used in EVs, would take an EV about the same distance as the other 88% of the barrel takes the average IC car. So you might as well leave the oil in the ground, and use the electric to charge EVs. Not counting natural gas, which oil extraction and refining uses too.

    BTW, it’s nice to have 120 to 160 miles range; 40 miles is not enough, 60 miles is not enough! We have determined this in practice, in daily driving of EVs, which you would figure out too, like we did, if you had the chance to drive an EV. The EV1 was perfect for commuting; up to 160 miles for the NiMH version, and over 100 miles for the Panasonic-lead-acid (not the defective Delco) version.

    Jordo P.: Ahhh I think I got it. So we take the 1.2 jigawatts of electricity and we pass it through the flux capacitor to the traction control motor and then we couple that with a generator… It all makes sense now! So does anyone know where on earth we are going to get the 1.2 jigawatts of electricity. I heard they are working on a product called “Mr. Fusion.” Anyone heard any news on that???  (Quote)


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    Dave K.

     

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    Nov 10th, 2009 (8:15 am)

    Rich R: those of you worried that it is far too technical, shame on you.

    Thanks for the clarification. You’re right, the system is not complicated. Simply difficult to understand as presented. But this inline system is not a new idea. And it’s the right way to go. Good going NGMCO.

    =D~


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    Nov 10th, 2009 (8:39 am)

    I think it is also important to remember that this occurs in Extended Range mode not EV mode….
    What should also be considered “hint” since I think the cat is out of the bag, is a LEARNING mode in which the system can learn several common commuter routes. The ONSTAR GPS learns your route at a certain time of day and if it is beyond the 40 mile range it can choose to maximize efficiency by allowing the ICE to run at particulair load requirements, which would draw more power from the battery then needed. This could have a manual over ride, but for example a daily Commute of 60 miles round trip could run the ICE directly coupled during periods of load in which it is most efficient to do so. The main objective is use the least amount a fuel over the trip, then charge on cheap grid power. This functionality has already be “hinted at”….


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    Dave K.

     

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    Nov 10th, 2009 (8:54 am)

    Rich R: directly coupled during periods of load in which it is most efficient to do so.

    Understood. When this topic was raised 6 months ago I suggested a system using GPS +- sea level measure on a 30 second cycle. The Volt and/or the GPS doesn’t need to know the route. The system needs to know the deamnd. An example would be +20 = 20% boost (coupling).

    =D~


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    Nov 10th, 2009 (9:04 am)

    Dave K.: Understood. When this topic was raised 6 months ago I suggested a system using GPS +- sea level measure on a 30 second cycle. The Volt and/or the GPS doesn’t need to know the route. The system needs to know the deamnd. An example would be +20 = 20% boost (coupling). =D~  (Quote)

    Yes GPS measures Altitude as well; the Real-time engine load requirements could be monitored to determine when not so much as where the particular load is required on the trip. I hope the patents are filed….. Very cool. Older navigational equipment no using GPS used accelerometers to track where they where on a route


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    Nov 10th, 2009 (9:04 am)

    Dave K.: Understood. When this topic was raised 6 months ago I suggested a system using GPS +- sea level measure on a 30 second cycle. The Volt and/or the GPS doesn’t need to know the route. The system needs to know the deamnd. An example would be +20 = 20% boost (coupling). =D~  (Quote)

    Yes GPS measures Altitude as well; the Real-time engine load requirements could be monitored to determine when not so much as where the particular load is required on the trip. I hope the patents are filed….. Very cool. Older navigational equipment not using GPS used accelerometers to track where they where on a route


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    BigBird

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    Nov 10th, 2009 (9:59 am)

    Doug Korthof,

    Take your toxic attitude some place else. I had no idea you were such a professional engineer from one of the major auto manufactures/auto reviewer to make such unshakable statements such as “because its design sucks, its managers are idiots, the engineers are second-rate, and it plans to sabotage the EV all over again.”

    Get over it. The EV1 is dead. It’s time to move on with your life. Your still young (sorta), go on give it one more shot!

    Don’t forget to drink the Kool-Aid on the way out buddy :)


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    Tony J

     

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    Nov 10th, 2009 (1:07 pm)

    Alex definitely knows what she’s talking about. Time will tell, but let’s hope the Voltec isn’t much more complicated but better in fuel economy than a simple series.


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    Nov 10th, 2009 (2:49 pm)

    (4) motors gentlemen.

    (2) drive/regen at front wheels
    (1) gasoline/E85
    (1) gen mechanically connected to gas/E85 for battery recharge only.


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    Mohsen

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    Nov 10th, 2009 (4:25 pm)

    Rich R: The system, is brilliant, to bad she leak the information. For those of you worried that it is far too technical, shame on you. Bravo GM….  (Quote)

    Oh cut the shill Rich. This system is not “too technical”. It is unnecessarily COMPLEX, prone to FAILURE, creates a lot of unwanted engineering issues and problems, hard to maintain, and COSTLY.

    Just because a set of systems look individually good, it does not follow that a combination of said systems is still good. Have you ever heard of “emergence”?

    The VOLT is a HOAX, a SCAM, and destined to failure. Its more GM, now packaged as an EV. If any company could sullify the EV concept, it would have been GM. And they have done it again. First EV1, and now Volt. And the government bought their story.

    What a disaster. Congratulations to GM for perpetrating a hoax. I always said – let this bankrupt company rest in peace. It should never have been extended a lifeline. Now I see why.


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    Nov 10th, 2009 (4:52 pm)

    Mohsen,
    Every looked inside a high bypass jet turbine engine. I guess we should stay with tried and true piston propped DC3…? These motors are Brushless and will propel the car most of time…. Wow you have a fear a complex mechanicals. The Toyota system is no less complex simple…

    Sounds as though there are 3 motors

    The Traction motor can couple to the Generator and runs as larger traction motor allowing it to be more efficient at certain loads. Will there be an actual mechanical connection to the ICE..? that is where it gets a little vague. She does state that ICE and Generator is considered one system in the beginning so it hard to tell. And we also know that the ICE and the Generator must have a mechanical connection of some kind. Also she states in “EV operation” the two motors, assuming electric can be coupled. I would think the ICE would then need to be de-coupled in order to allow for “EV operation”

    I guess the only question is if the ICE will have a mechanical connection to the drive train…..? It would be more efficient to operate it this way at certain times.


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    Nov 10th, 2009 (4:57 pm)

    Go ahead fan the flames it will make victory that much sweeter..


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    Rich R

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    Nov 10th, 2009 (5:02 pm)

    OMG….
    what rock did you crawl out from under…..

    “We want a simple PC to pull apart and understand, and these people are giving us a cross between a 4 bit Altair and an IBM 360 mainframe, and calling it the best of both worlds.”

    Really….? The IBM System/360 (S/360) announced by IBM in 1964


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    Nov 10th, 2009 (5:13 pm)

    Rich R: Mohsen,Wow you have a fear a complex mechanicals. The Toyota system is no less complex simple…Sounds as though there are 3 motorsThe Traction motor can couple to the Generator and runs as larger traction motor allowing it to be more efficient at certain loads. Will there be an actual mechanical connection to the ICE..? that is where it gets a little vague. She does state that ICE and Generator is considered one system in the beginning so it hard to tell. And we also know that the ICE and the Generator must have a mechanical connection of some kind. Also she states in “EV operation” the two motors, assuming electric can be coupled. I would think the ICE would then need to be de-coupled in order to allow for “EV operation” I guess the only question is if the ICE will have a mechanical connection to the drive train…..? It would be more efficient to operate it this way at certain times.  (Quote)

    Rich, the Toyota hybrid system is backed by well… Toyota !! If you don’t know the difference between Toyota technology and GM, you need to start from the ABCs.

    The only way the Traction Motor can be coupled to the Generator is via a mechanical coupler. Then you ask, is there a coupler – contradicting yourself. Obviously according to this idiot Alex going by a man’s name, there is a mechanical coupling (hydraulic, my guess).

    The only way the Generator that is permanently attached to the ICE can drive the wheels directly is through mechanical coupling. By implication (a simple logical inference), the ICE is mechanically connected to the wheels which are mechanically connected to the Traction motor.

    The ICE has a mechanical connection to the Generator that has a mechanical connection to the wheels. So stop the obfuscation – like Alex the obfuscator has been doing. This thing is a scam and a hoax. My guess is that after the ICE ignites, 95% of the time it is directly coupled to the wheels. 5% EREV and 95% hybrid PHEV. You have been taken (again).

    No it is NOT more efficient because you have a torque converter that blows up 10% of your fuel and you are carrying extra weight of a transmission and your ICE is not running at its sweet point anymore.

    Not to mention the service/maintenance/repair complexity and costs.

    The old mechanical fogies at GM managed to pull a coup one more time. Fire THEM all !


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    Nov 10th, 2009 (5:15 pm)

    Rich R: OMG….what rock did you crawl out from under…..“We want a simple PC to pull apart and understand, and these people are giving us a cross between a 4 bit Altair and an IBM 360 mainframe, and calling it the best of both worlds.”Really….? The IBM System/360 (S/360) announced by IBM in 1964  (Quote)

    Exactly – that is how bad the Voltec is. I dont know what IBM calls their mainframes nowadays, but the idea is the same. GM delivered a 1960s ICE and calls it a 2010 EV.


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    Nov 10th, 2009 (8:47 pm)

    I can’t take the bait, you seem deeply troubled please get some therapy. And don’t address my quotes in the future, you seem to have a very odd agenda…


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    Nov 10th, 2009 (10:20 pm)

    “bait” ?? “agenda” ?? You are delusional.

    Why would I want to address incoherent, contradictory, and superficial quotes from a shill?


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    Nov 11th, 2009 (2:23 pm)

    [...] plans to (hopefully) make their Prius killer work … someday … eventually … maybe … I hope. GM-VOLT : Chevy Volt Electric Car Site Blog Archive Engineering Design of the Chevy Volt’s Two… Seems more complex than necessary, but what do I know. [...]


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    Nov 11th, 2009 (10:06 pm)

    Epilogue–

    Although the “electric coupling” exercise was fun and educational . . .

    If you step back for a second and think about the 2mt70 fwd hybrid transaxle (which we’ve seen photographed in the volt), it’s very difficult to speculate in any direction but the obvious: the volt contains a modified version of the 2mt70 and once the volt is in CS mode it is a parallel hybrid.

    GM Previews First Two-Mode, Front-Wheel-Drive Hybrid Transaxle
    http://www.greencarcongress.com/2009/05/2mode-fwd-20090509.html

    This thing (2MT70) is VERY complicated, to think that GM just used the transaxle case for commonality and morphed it into something totally different (series hybrid ) seems naive.


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    Nov 12th, 2009 (12:28 am)

    Herm:
    I would prefer the same AER but a much lower cost. Most people dont drive more than 40 miles a day.. do you?  

    Yes I do…23 miles each way to work…it’s like that in the big city.


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    Nov 12th, 2009 (1:02 am)

    By the way if the Volt contains a transmission and in CS mode the Volt turns into a parallel hybrid that is shocking but it’s not the end of the world.

    If the Volt delivers on it’s main promise of 40 miles AER and 40+ mpg in CS mode I don’t care if they have squirrels coupling the motors as long as it works.


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    Nov 12th, 2009 (3:29 am)

    jscott1000: By the way if the Volt contains a transmission and in CS mode the Volt turns into a parallel hybrid that is shocking but it’s not the end of the world.If the Volt delivers on it’s main promise of 40 miles AER and 40+ mpg in CS mode I don’t care if they have squirrels coupling the motors as long as it works.  (Quote)

    Your point is well taken, until you go for a tunup and maintenance and you find out that it costs twice. Inquiring why, you are told you have two power trains under the hood.


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    Cab Driver

     

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    Nov 12th, 2009 (6:13 am)

    carcus1: Epilogue–Although the “electric coupling” exercise was fun and educational . . . If you step back for a second and think about the 2mt70 fwd hybrid transaxle (which we’ve seen photographed in the volt), it’s very difficult to speculate in any direction but the obvious: the volt contains a modified version of the 2mt70 and once the volt is in CS mode it is a parallel hybrid.GM Previews First Two-Mode, Front-Wheel-Drive Hybrid Transaxlehttp://www.greencarcongress.com/2009/05/2mode-fwd-20090509.htmlThis thing (2MT70) is VERY complicated, to think that GM just used the transaxle case for commonality and morphed it into something totally different (series hybrid ) seems naive.  (Quote)

    I don’t agree that deriving a series hybrid Volt motor case from the 2MT70 Two-Mode Hybrid would be morphing it into something totally different. It seems to me that it is another example of trying to simplify / shorten the Volt development process by reusing as much existing GM design as possible. (Just like reusing the 1.4L engine, even though it is overkill for this application.)

    Have you read the SAE 2009-01-0508 paper “General Motors Front Wheel Drive Two-Mode Hybrid Transmission”? It gives a detailed explanation of the 2MT70 layout and operation. It is well worth the $15 cost to download it from http://www.sae.org .

    If you want a pure series hybrid implementation just leave out the 2MT70′s clutches and its input planetary gearset (therefore losing the engine/MGA to output gearset connection). Make the MGB longer to increase its power to the 110 kW specification. Keep the whole output gearset, transfer gears, and differential just as they are. It seems to me that this is a great way to steal from the existing parts bin to get the Volt to market as quickly as possible.

    On the other hand, as I suggested back in post #113, if you keep 3 clutches you can get the 2MT70′s ECVT functionality which might be what Alex Cattelan was cryptically referring to in this thread’s interview. (I hadn’t read the SAE 2009-01-0508 paper yet when I posted that, so my notation is inconsistent with the paper.)

    Who knows what’s really in the Volt’s motor case?, I sure don’t! GM will eventually see fit to let us know, but it is fun to speculate in the meantime.


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    Jscott1000

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    Nov 12th, 2009 (2:35 pm)

    It seems almost certain to me at this point that the Volt will use a variant of the 2MT70 if not identical to the one previously planned for the Vue hybrid. All they needed to do was beef up MG2, (which we all they can do) and tweak the software to allow the 40 miles AER.

    It’s going to disappoint the purists to realize there is a mechanical connection between the engine and wheels, but with software you can use an infinitely variable amount of ICE and electric motor combinations. I like this architecture if this is in fact what GM has done.

    Since the 2MT70 was planned to be deployed in the Saturn Vue I would assume that GM considers it sufficiently reliable to be in a production vehicle.


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    Rich R

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    Nov 12th, 2009 (3:03 pm)

    Jscott1000: It seems almost certain to me at this point that the Volt will use a variant of the 2MT70 if not identical to the one previously planned for the Vue hybrid. All they needed to do was beef up MG2, (which we all they can do) and tweak the software to allow the 40 miles AER.It’s going to disappoint the purists to realize there is a mechanical connection between the engine and wheels, but with software you can use an infinitely variable amount of ICE and electric motor combinations. I like this architecture if this is in fact what GM has done.Since the 2MT70 was planned to be deployed in the Saturn Vue I would assume that GM considers it sufficiently reliable to be in a production vehicle.  (Quote)

    I agree, I think the reason it was mentioned the engine will operate at a varying rpm is because the so called sweet spot is not so much related to RPMs as it is loads. The Electric motor(s) will step in hold the ICE load at is sweet spot(s)….. Think of what happens when you watch your real-time MPG as you hold a constant rpm\speed and you crest a hill. But who knows for sure, certainly not me just postulating on what is presented.


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    carcus1

     

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    Nov 12th, 2009 (5:34 pm)

    Cab Driver @ 145,

    15 BUCKS! . .. are you MAD??

    That’s a 12 pack of beer AND a box of Swisher Sweets!


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    Cab Driver

     

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    Nov 12th, 2009 (8:06 pm)

    carcus1: Cab Driver @ 145,15 BUCKS! . .. are you MAD??That’s a 12 pack of beer AND a box of Swisher Sweets!  (Quote)

    Life is about priorities… Like the guy said to Dirty Harry: “I’s gots to know!”


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    Ken

     

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    Nov 16th, 2009 (3:41 am)

    A question regarding the motor(s) generating electicity after the 40 miles on battery power only are used up…

    When the gas generator is running can (or will) there be enough electricity produced to re-energize the batteries for another 40 miles (assuming that all the gas in the generator may have to be used).

    It would be “cool” and helpful if the Volt could get another 40 miles on a recharged battery once all the gas has been used up. (Maybe this is just wishfull thinking)


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    LabRat

     

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    Nov 17th, 2009 (7:32 pm)

    More than most, this comment thread was an interesting read. Congratulations to all the folks who unraveled the mystery. If there is any doubt that the 2-mode and the Volt do not share some common architecture parts, just look to these two publicly available photographs:
    http://allworldcars.com/wordpress/wp-content/uploads/2009/01/2009_chevrolet_volt_lg_chem_15.jpg

    http://cache.jalopnik.com/cars/assets/resources/2008/01/2009%20Saturn%20Vue%20Green%20line%202%20mode%20hybrid.jpg

    If anyone took closeup pics of the Volt during the auto shows (like I did), you would see the same exterior features for Volt and 2-mode FWD. (including that auto-trans-like valve body covered by the black case in front)

    Now, what’s inside is the “proprietary information.” GM has so many patents on 2-mode and 4-mode transmissions it would make your head spin. We can only guess what is inside.

    I knew this a long time ago. I was waiting for the day this info would finally break. He he.

    BTW, series HEVs have poor hybrid fuel economy. Power-split always does better. Complexity does provide better efficiency. Plus, as someone pointed out, it is much easier to make money if you have part commonality. Remember, GM needs to make money, badly. (hello? This is car making – its all about mass production, otherwise every car would be >$100k).