Peter C. Wallace wrote: > > > Permanent magnet servo motor. Its possible to get very good performance > without a current loop at least for small motors, you may need to add a phase > lead feed forward term for very high drive speeds. Of course it is closed > loop > in the sense that drive voltage is controlled by the normal position PID loop. > Not really much different than straight PWM control of a DC brush motor > > Some (mod) math is required to generate the reference angle from the > encoder count of course. > > OK, so you want to run it without commutation signals. The problem is getting the motor to the index position. All sorts of sensorless schemes were worked out 20 years ago to get motors from an unknown position to index without causing runaways or other jerky behavior. I would think you'd need to disable the regular servo loop and have the controller try different commutation angles until the motor starts to move, and then keep it moving until you get the index pulse.
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