A Feedforward-Based Harmonic Current Minimization Method for Six-Phase Permanent Magnet Synchronous Machine Drives

This paper presents a feedforward voltage injection-based current harmonics minimization method for Wide Bandgap (WBG) device-based six-phase Permanent Magnet Synchronous Machine (PMSM) drives. PMSMs with a low number of slots and a high number of poles commonly have lower-order voltage harmonics in the back EMF. Lower-order back-EMF harmonics generate harmonic currents that increase losses and generate torque ripples. The harmonic currents are significantly high in the case of low inductance PMSMs. A feedforward-based harmonics voltage injection method is proposed for reducing the lower-order current harmonics of six-phase PMSMs. The feedforward voltages are determined from offline harmonic flux linkage measurement and motor speed. The proposed harmonic current minimization method is experimentally verified using a GaN-based three-level (3L) Active Neutral Point Clamped (ANPC) inverter-driven 8-pole six-phase PMSM at 6750 RPM (450Hz).