A Multi-Frequency PWM Scheme for Multi-Level Five-Phase Open-End Winding Drives

This paper presents a multi-frequency pulse width modulation (PWM) scheme for a multi-level five-phase open-end winding drive using the unified modulation technique. The openend winding machine is supplied via a two-level voltage source inverter from each side of the windings. One inverter operates in ten-step mode while the other is operated under PWM. The multi-frequency PWM scheme is aimed to control the magnitude of the fundamental output and to cancel low-order harmonics produced by the inverter operating in ten-step mode. Simulation results show excellent performance resulting in multi-level output voltages with a low THD. Implementation of the scheme is straightforward, compared with the space-vector modulation based approach, since space vector transformation, sector identification, and look up tables are not required.