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Old 12-16-2015, 05:06 PM   #2482 (permalink)
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Originally Posted by e*clipse View Post
Paul, thingstodo -

These are some great videos and data of the debugging process - thank you very much for posting all of it.

I'm a bit confused about the regen mode, could you clarify some things?

Is the DC motor driving the rotation of both motors?
Yes. The motors are coupled together with a joy coupler

It seems that when the rotation gets to zero, it then reverses - is this true?
Yes. The negative torque command (throttle or potentiometer) slows down rotation using the AC motor, then the direction reverses and the AC motor continues to 'accelerate' in the negative direction

Is the net current between the AC motor and the battery pack flowing into the battery at all times during regen? If not, it's more of "reverse torque" than pure regen - does it switch modes?
In the first part of the test, the 24V pack is putting power into the DC motor, which drives both motors. Using the throttle, I command negative torque on the AC controller, which is done by lowering the frequency put out by the AC motor. That puts the motor into a 'generator' mode. That energy output from the generator flows back into the AC controller, becomes DC, charges up the capacitors to a higher voltags, and supplies the power used by the electronics on the AC controller. Since the voltage is now above the voltage of the battery pack, the surplus power flows back into the high voltage pack.

When the 24V pack is turned off and the inertia of the motors turning is overcome by the negative torque on the AC controller .. there is no more energy to feed 'back' into the AC controller. The DC bus voltage drops back to the battery pack voltage. The AC controller starts to consume energy from the battery pack again.

That likely does not make much sense .. but that's how I understand it.

If so, (if it does reverse) what happens with the current near 0 rpm?
The DC current into the battery pack drops until it is near zero, then the battery pack starts to supply current to the AC controller.

I don't have a way to correlate at what rpm that happens ... I suspect somewhere around 300 rpm but that's just a wild guess.

Perhaps I can rig up some cameras to synchronize measurements for the next test so that everyone can see what is going on.
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e*clipse (12-16-2015), MPaulHolmes (12-16-2015)