Peter C. Wallace wrote: > Also you mentioned that you had some cogging. Is the resonance something that > happens statically or only when moving at certain velocities? Is it possible > that you have some non-linearity or even hysteresis in you drive - torque > curve? > The first large motor I tried this on has probably been dropped, or is just a horribly-built motor. This motor works MUCH better, and after a little tuneup of the commutation encoder it runs with very little vibration. > To get our 3 phase driver to work well, we first had to first fix the VQ -> IQ > nonlinearitys as best we could before closing the current loop. It was really > lumpy at first... This motor runs quite well, there is just a slight hum at one narrow speed band. I assume that is when the 6-step commutation frequency matches the motor's natural frequency. It is never "lumpy" at all. I still would like to get more P gain without instability, but I suspect it is impossible without solving the current vs. voltage drive question. Getting the absolute current out of the power stage isn't so hard, as it already has current sense resistors for limit purposes. But, turning that current into a SIGNED value indicating the correct sign of power flow is tougher.
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