Torque Improvement of Six-Phase Permanent-Magnet Synchronous Machine Drive with Fifth-Harmonic Current Injection for Electric Vehicles

This paper proposes a method to improve the output torque of six-phase permanent-magnet synchronous machine (PMSM) within same current peak limit through fifth-harmonic injection into each phase stator. Compared fifth + seventh-harmonic current-injection used PMSM, control system can be stably controlled, and controller design complexity decreased. is because harmonic component was converted direct (DC) controlled by proportional-integral (PI) instead method, which converts an alternating (AC) controls it with resonance controller. The appropriate ratio for maximum selected optimization using values analyzed via fast Fourier transform (FFT) stator terms caused inverter nonlinearity motor errors. Therefore, possible optimize injected without requiring modeling physical properties motor. experimental results were obtained under rated condition PMSM in laboratory, average increase about 5% compared injection.