Bench test

I tested the motor + drive system last night, and overall it was a success. I ran the motor up to 7500 rpm with no problems. The cooling fan sounds like a jet taking off at that speed, though. It's nice to have a lot of cooling air, though. Unloaded, the motor consumes about 750 watts at top speed, which seems reasonable. I can run the motor down to about 30 rpm, where it uses about 50 watts. It would have been nice to get an idea of torque output, but I don't have an easy way of loading the motor.

The motor controller has two modes: V/f and sensorless vector. At its simplest, V/f mode makes the voltage to the motor linear with frequency, so for example, to run the motor at 30 rpm, the drive would supply 10 Volts at 1 Hz, and at 7500 rpm it would supply 230 Volts at 250 Hz. This is fine for constant load applications, but if the load increases too much, the motor can stall. In sensorless vector mode, the drive uses a mathematical model of the motor to calculate the torque applied at any time. It can then change the voltage and frequency to match a requested torque or speed. This is much better for an electric car, because motorists are used to an accelerator pedal that requests more torque from the motor. Because the motor's rated capacity is much smaller than the drive's (5 HP vs 30 HP) the drive was unable to model the motor, so sensorless vector mode is not working. I will see if I can input parameters specific to the motor and get it working. Otherwise, I will probably need a bigger motor eventually. In the meantime, I can set the acceleration and deceleration times for the drive to be long enough so that everything works. This just means that the drive will take the car's inertia into account a little better, and won't ask the motor to turn at 7000 rpm when the car's speed is telling the motor it must turn at 500 rpm.

Now to get rid of that pesky gas engine so I can start putting things in the car...