Study of Five-phase Space Vector PWM Considering Third Order Harmonics

Five-phase motors are usually designed with nonpure-sinusoidal back-EMF and the 3rd order harmonics is the main harmonic. Since the 3rd order voltage can be with arbitrary phase-shift with the fundamental voltage, this paper points out that the space-vector-modulation for five-phase motor drive should consider both fundamental and 3rd order voltage, which is a double-vector combination. With SVPWM to generate both fundamental and 3rd order reference voltage, the distribution of the two different zero vectors builds the relationship between SVPWM and carrier based PWM. This paper has done a study for the SVPWM of five phase motor drive with arbitrary distributed 3rd order harmonics and proved that with different amplitude and phase shift, the modulation index of SPWM and SVPWM will change. SVPWM keeps higher modulation index than SPWM and DPWM will keep the same modulation index with SVPWM in the whole region.