Pulse-Width Modulation for Five-Phase Converters Based on Device Turn-on Times

High power, high reliability electric motor drives in such applications as electric ship propulsions, electric locomotives and hybrid electric vehicles require the use of high order phase electric machines run with multi-phase converters. Presently, five and asymmetrical six-phase machines with their associated converters are emerging industry standards. This paper presents a novel carrier-based pulse-width modulation technique for the five phase converters, which in applications is required to generate five phase fundamental frequency voltages with or without a third harmonic (of the fundamental frequency) component voltages. The modulation waveforms required to switch the devices in the converter legs are obtained by summing the turn-on times of the switching devices, which are calculated using the space vector representations of the converter switching states. The determination of the carrier-based modulation waveforms which with a high frequency sine-triangle generate the switching functions for the converter is set forth explicitly. The resulting carrier-based PWM modulation scheme is experimentally implemented with a TMS DSP for converter operation in the linear and over-modulation regions. Experimental results are presented to confirm theory