What brakes the ICE? Calling Patrick, Bob & other experts

Hello Vincent,

Many thanks for that link. Yes, I see I was a bit loose with the physics there. In fact, to avoid having the ICE rotate, MG1 would have to be precisely controlled (accelerated or decelerated as appropriate), as the vehicle speed changes, and the more rapidly the speed changes, the greater the need to drive MG1. Otherwise, the inertia of MG1 is going to present a torque reaction to the PSD, which will be reflected to the ICE crankshaft, and cause it to rotate.

It would almost seem simpler and easier to have a brake on the ICE crankshaft, as I originally pondered. Then, one could (also) use MG1 to accelerate from low speed, and regen down to low speed. But maybe they worked out that the economics just did not justify it. But, seems to me, since you're going to have to control power to or from MG1, you might as well do a little more, and drive the car or charge the battery, and just let MG1 freewheel until the speed gets up a bit.

I guess the argument is that the losses through the PSD are slightly higher if going that way, so it's better to waste a little electrical energy on simply keeping MG1 at the right speed (and no load on the PSD gears), than it would be to lose a (more or less fixed) percentage of the motor output power by running it through the PSD.

 

Correct!!! Wires crossed, for sure. Fixed for the benefit of those who follow.