6 ms·

I've always wondered what it would be like if you used a dual motor system in a car, where one motor is wound and sized for very high torque and the other motor

I've always wondered what it would be like if you used a dual motor system in a car, where one motor is wound and sized for very high torque and the other motor is wound and sized for very high speed. The dual motor versions (D) of Tesla electric vehicles (models S and X at least) use this principle. As far as I know, they have induction motors. However, I am not sure to which extent one of the motors is used primarily for high torque and the other for high speed.

vvanders 9y ago
Yup, the front motor is the cruising motor and the rear one is the accelerating one(since weight distribution means that the rear wheels get a bit more traction). They shut the rear motor down at highway speeds giving the Dual Motor cars slightly better range.
- MBCook 9y ago
  Do the single motorcars only have one of those two? If so which? Or do they have a third kind of motor which is wound to be a better balance?
  - vvanders 9y ago
    My understanding is that there's 3 configurations Single motor, non-P: 1 large motor in the rear. Dual motor, non-P: 2 small motors in front/rear with front motor geared for cruising, rear for accel. Dual motor, Performance: 1 small motor in front geared for cruising, one large motor in the rear. There's really no reason to have a front motor only. It's done in ICE cars to save cost/complexity since the engine is up front. With how the center of gravity shifts during accel you want the drive wheels to be on the rear since they have better traction. Same reason in reverse you have large disk brakes on the front wheels and drum in the rear.
    - ars 9y ago
      > you want the drive wheels to be on the rear since they have better traction. But you need a powerful motor to act as the brake (you want to avoid friction braking as much as possible). And that needs to be in the front.
      - vvanders 9y ago
        Not really, unless you're in a panic brake situation(where I want friction brakes anyway) Tesla only brakes to 60kW which is more than plenty for normal driving. You also want friction braking for cases where you've got 100% charge or the battery is cold and you can't dump energy into the pack.
    - TheSpiceIsLife 9y ago
      Maybe you want the rear wheels driving under acceleration if accelerating in a straight line is the only metric your optimising for. I'll argue front wheel drive is better / safer for most driving situations most people find themselves in, especially in slippery conditions, on wet or dirt roads.
      - vvanders 9y ago
        I'd argue that independent all wheel drive is better / safer for most people ;). That said the traction control on Tesla is responsive to < 1ms. Lots of throttle inputs that would cause traction to break free on a traditional ICE due to momentum in the drivetrain doesn't on our Tesla. Heck I can floor it in the rain and it doesn't step out at all.
- bronz 9y ago
  wow, i thought i knew something

vvanders 9y ago

Yup, the front motor is the cruising motor and the rear one is the accelerating one(since weight distribution means that the rear wheels get a bit more traction). They shut the rear motor down at highway speeds giving the Dual Motor cars slightly better range.

MBCook 9y ago
Do the single motorcars only have one of those two? If so which? Or do they have a third kind of motor which is wound to be a better balance?
- vvanders 9y ago
  My understanding is that there's 3 configurations Single motor, non-P: 1 large motor in the rear. Dual motor, non-P: 2 small motors in front/rear with front motor geared for cruising, rear for accel. Dual motor, Performance: 1 small motor in front geared for cruising, one large motor in the rear. There's really no reason to have a front motor only. It's done in ICE cars to save cost/complexity since the engine is up front. With how the center of gravity shifts during accel you want the drive wheels to be on the rear since they have better traction. Same reason in reverse you have large disk brakes on the front wheels and drum in the rear.
  - ars 9y ago
    > you want the drive wheels to be on the rear since they have better traction. But you need a powerful motor to act as the brake (you want to avoid friction braking as much as possible). And that needs to be in the front.
    - vvanders 9y ago
      Not really, unless you're in a panic brake situation(where I want friction brakes anyway) Tesla only brakes to 60kW which is more than plenty for normal driving. You also want friction braking for cases where you've got 100% charge or the battery is cold and you can't dump energy into the pack.
  - TheSpiceIsLife 9y ago
    Maybe you want the rear wheels driving under acceleration if accelerating in a straight line is the only metric your optimising for. I'll argue front wheel drive is better / safer for most driving situations most people find themselves in, especially in slippery conditions, on wet or dirt roads.
    - vvanders 9y ago
      I'd argue that independent all wheel drive is better / safer for most people ;). That said the traction control on Tesla is responsive to < 1ms. Lots of throttle inputs that would cause traction to break free on a traditional ICE due to momentum in the drivetrain doesn't on our Tesla. Heck I can floor it in the rain and it doesn't step out at all.
bronz 9y ago
wow, i thought i knew something