Sep 14

Clarification: Chevy Volt Electric Motor is A/C

 

In our previous post, it sounded as though Mr. Tony Posawatz responded that the Volt will use a DC motor, which seemed surprising.

Readers caught that and I questioned Mr. Posawatz again..he indicated that the Volt has an A/C motor.

Sorry for any confusion.

This entry was posted on Friday, September 14th, 2007 at 3:02 pm and is filed under Electric Motor. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

COMMENTS: 14


  1. 1
    AES

     

    Vote -1 Vote +1

    AES
     Says

     

    Sep 14th, 2007 (3:08 pm)

    Lyle-

    It’s electric MOTOR, not engine :)

    And thanks for taking the time to ask the initial question, as well as making the clarification.


  2. 2
    Dave G

     

    Vote -1 Vote +1

    Dave G
     Says

     

    Sep 14th, 2007 (3:38 pm)

    This whole AC vs. DC motor thing really started confusing me, so I found this blog on the Tesla website:
    http://www.teslamotors.com/blog4/?p=45

    After reading this, it’s my impression that both types of motors are powered by pulsing direct current from the batteries at specific intervals. Induction motors don’t seem to require sinusoidal alternating current, and brushless motors don’t use pure DC. So the terms “AC” and “DC” both seem misleading in this case. In fact, Wally Rippel (author of Tesla blog) just starts calling them “brushless” and “induction”.

    Am I interpreting this correctly? If so, I don’t see what all the fuss is about. How does this affect the average driver who has no knowledge of how the car is designed? Why do people seem to have strong feelings about this?


  3. 3
    kent beuchert

     

    Vote -1 Vote +1

    kent beuchert
     Says

     

    Sep 14th, 2007 (4:21 pm)

    Nice to be technically accurate, even if the subject is meaningless to the public.
    And I don’t see any reference to an electric engine from Lyle. Which is just as correct as motor. Websters defines an engine as a mechanical device for converting various forms of energy (as in electricity) into a mechanical force or motion. An electrical motor clearly qualifies as an engine,also.
    And gasoline engines can, and are, also called motors.


  4. 4
    AES

     

    Vote -1 Vote +1

    AES
     Says

     

    Sep 14th, 2007 (4:49 pm)

    Most sources I have ever seen (wiki and howstuffworks, to name a few) use “electric motor” vs “gasoline engine” – at least just for the sake of convention.

    Anyways, I think its an important issue to bring up because great AC induction motors are what defined the EV-1 and the projects that sprung up in its wake (pun intended).

    The Wally Rippel blog on Tesla’s site is really great because of how straightforward and honest it is about the pros and cons of each design. One of the key points he makes is how AC induction tends not to lose efficiency at higher power and at higher loads, unlike brushless DC. So in that regard, it’ll be great for making a 160hp motor for the Volt. DC motors are more expensive to build cuz of the permanent magnets, but it takes way less engineering to get them to work, so in that regard it makes sense why GM used a brushless DC motor to get the autoshow Volt to move 10 feet onto the stage.


  5. 5
    Dave G

     

    Vote -1 Vote +1

    Dave G
     Says

     

    Sep 14th, 2007 (7:21 pm)

    Wally Rippel says:
    “Induction machines are more difficult to control. The control laws are more complex and difficult to understand. Achieving stability over the entire torque-speed range and over temperature is more difficult with induction than with DC brushless. This means added development costs, but likely little or no recurring costs.”

    If GM still has all the induction expertise in house from the EV1, I guess it’s OK. But if the “added development costs” Wally mentions translate into added development time, and this delays the 2010 launch, that would suck.


  6. 6
    Steve F

     

    Vote -1 Vote +1

    Steve F
     Says

     

    Sep 14th, 2007 (7:44 pm)

    I assume the Volt mules that GM is working on and will be testing this spring have the AC induction motor they plan to put into production. Maybe another question for Lyle to confirm with GM.


  7. 7
    Lyle

     

    Vote -1 Vote +1

    Lyle
     Says

     

    Sep 14th, 2007 (8:28 pm)

    I agree that the Tesla blog, Rippel article is a nice review, and well explains why A/C is the way to go with the Volt (as it was for the EV-1).

    Steve F – I’m sure that the same engine in thr prototype, the only question right now is what the generators config will be..Tony says GM will make that public after the new year.


  8. 8
    Dave G

     

    Vote -1 Vote +1

    Dave G
     Says

     

    Sep 14th, 2007 (8:46 pm)

    Actually, the Rippel article says:
    “My conclusion is that DC brushless drives will likely continue to dominate in the hybrid and coming plug-in hybrid markets, and that induction drives will likely maintain dominance for the high-performance pure electrics.”


  9. 9
    AES

     

    Vote -1 Vote +1

    AES
     Says

     

    Sep 14th, 2007 (10:26 pm)

    The PHEV’s that Rippel is referring to are likely ones with lower pure electric power needs – e.g. Prius conversions that retain the stock 67hp motor, AND have an ICE assist. In other words, the electric motor isn’t doing all the mechanical work.

    The EV1 had a 137 horsepower motor, and the Volt is planned for a 160hp motor. So with that higher power requirement – only 88hp shy of the Tesla – I guess the Volt still qualifies as a high performance electric, and thus also necessitates an AC induction motor.


  10. 10
    Tim

     

    Vote -1 Vote +1

    Tim
     Says

     

    Sep 15th, 2007 (10:03 am)

    Well, what they showed at the Detroit Auto Show was a DC brushless motor. I wish that GM, like Tesla, would talk more about the technology they intend to use and give as idea of what kind of vehicle performance we can expect from the Volt.


  11. 11
    Tim

     

    Vote -1 Vote +1

    Tim
     Says

     

    Sep 15th, 2007 (5:21 pm)

    Good, the AC power will be easier to use as a whole house back-up.


  12. 12
    Dave G

     

    Vote -1 Vote +1

    Dave G
     Says

     

    Sep 15th, 2007 (7:53 pm)

    Tim – I’m pretty sure the AC induction motor in the Volt isn’t powered by the same kind of electricity that is in your home.

    In fact, it appears that they just use pulsating DC from the batteries to drive the induction motor. As I understand it, these DC pulses are preceisly controlled by special software algorithms that optimize for power and efficiency.

    So, if you want a whole house backup system, you’ll probably still need to spring $2K-$4K for a real sinusoidal DC to AC house type inverter, and then figure out some way to tap into the 300 volt DC batteries.


  13. 13
    greg

     

    Vote -1 Vote +1

    greg
     Says

     

    Sep 24th, 2007 (7:58 pm)

    cars are nice but in my neck of the woods we drive full size trucks. Mine has a diesel with 4 wheel drive. Lots of room for plugin eletric drive with diesel assist. Please!!!


  14. 14
    Jim

    +2

     

    Vote -1 Vote +1

    Jim
     Says

     

    Oct 11th, 2008 (1:43 am)

    There three possible traction motor for electrci or hybred vehicles, Switched Reluctance , PM AC synchronous (known as brushless) and AC induction. Most of the comments on this blog are quite incorrect due to the lack of techncal knowledge of electrci motors.

    The highest power density and best performing traction motot with the highest efficiencies at all speeds including high speeds is the axial flux PM AC synchronous motor. Second is the radial flux PM AC synchronous motor. Third is the Switched Reluctance DC motor without slip rings, brushes, without magnets and without windings on the rotor. The 4th and poorest performing motor of them all is the AC induction motor. However the two best ones are the most expensive even though every hybred car on production on earth uses the PM AC radial flux Synchronous electric motor. This is because they are much more efficient than the AC induction motor, they weigh less and they do not require as much cooling (The ac induction motor has a very hot rotor that cannpot be easily cooled).

    The reason high performance cars like Tesla use AC induction motors is because for the power they need they can buy almost off the shelf AC motors and inverters from several sources for their low volumes. A PM AC machine must be designed from scratch.

    If Tesla is successful to the point their volume goes to 50,000 cars per year they will have to switch to PM AC Synchronous to be competive or the competition will kill them.

    The first GM electric vehicle the EV1 had a production run of 135 cars all leased. The traction motor was a modified version of a standard GE/AO Smith AC induction motor. The inverter was made by GM’s HUGHES division which was a flux vector AC drive. All production hybred vehicles made by GM currently us a permanent magnet synchronous brushless motor driven by a similar flux vector drive. They do not use an AC induction motor. The new Chevy VOLT will also have the same PM sychronous brushless motor.
    One or two Chrysler care use this same PM brushless motor. This motor is made by REMY a former division of GM. The second generation Chevy Volt is reported to use a greatly enhanced PM sychronous brushless motor. (Probably two rather than one) There are no plans to use AC Induction motors in any production vehicles except the Tesla.