It seems there is a standard way that industrial manufacturer's of PMSM follow when aligning incremental encoders on motors. They align the encoder module to the motor so that the index pulse and U-hall falling edge aligns with the U-W phase back EMF going negative to positive through 0V. This positions the index pulse (and U-hall falling edge) at an InstaSpin electrical angle that is not zero.
For example, when you align the motor to its U pole as done in the Labs (U+ and V-), and equate this to electrical zero, what I see is you have to rotate the motor 210° electrical to get the index pulse.
After aligning the motor I would like to use the index pulse as a check that the alignment was successful. So if I know the index pulse should always occur at 210° electrical and it doesn’t then there is a problem.
My question is based on the method I described for positioning increment encoders on PMS motors, what is the theoretical angle at the index and why?
Iv'e empirically measured 210° electrical and theoretically think that the 210° electrical is because encoder alignment (aligned to UW back emf going negative to positive) is shifted 300° from U-phase alignment, minus the back emf vector shift from d-azis rotor flux alignment of 90°, equals 210°.