Maximum Torque-per-Current Waveform Design for Induction Motors via Semidefinite Programming

N. Moehle and S. Boyd

Proceedings IEEE Conference on Decision and Control, pages 1920-1925, December 2016.

We present a method for finding current waveforms for induction motors that minimize resistive loss while achieving a desired average torque output. Our method is not based on reference-frame theory, and therefore directly handles induction motors with asymmetric winding patterns, nonsinusoidally distributed windings, and a general winding connection. We do not explicitly handle torque ripple or voltage constraints, although we discuss heuristics for handling the latter. Our method is based on converting the torque control problem to a nonconvex linear-quadratic control problem, which can be solved by using a (tight) semidefinite programming relaxation.