On 06/15/2016 10:04 AM, D. Hugh Redelmeier via talk wrote:

| From: Lennart Sorensen via talk <talk@gtalug.org>

| Well I am quite sure they are running AC motors, so they would be taking
| the DC and inverting it to AC and making it whatever voltage they need
| at the time for the motors.

Most people think 60Hz when they think AC.  But I would guess that in
a motor AC is timed to the rotation so that commutators (I think
that's what they are called) can be eliminated.

Would that AC be 60Hz or would it be variable, matching some function
of the motor's current speed?

With AC motors you can vary the speed by changing the drive frequency.
Most motors you will see tend to be designed for fixed frequency operation (think older furnace fan or pump or AC unit) and they will have start circuits that expect the design frequency.
But vehicle motors are going to be multiphase and the input voltage can vary from DC to a very large number of Hz.

Take a look at: https://en.wikipedia.org/wiki/Variable-frequency_drive

VFD controlled pool pumps are all the rage now to try and cut down on power consumption.

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