Output Current-Ripple Analysis of Five-Phase PWM Inverters

An output current-ripple analysis of five-phase pulsewidth-modulated (PWM) inverters under sinusoidal and nonsinusoidal operations is presented in this paper. A general expression of output current ripple of five-phase PWM inverters under nonsinusoidal operation is first derived. Under sinusoidal operation, it is found that the optimum reference signal that results in minimum output current ripple is a sinusoidal reference signal. Under nonsinusoidal operation, however, it is found that fifth harmonic injection can be used to reduce the output current ripple. Moreover, fifth harmonic injection is useful to increase the maximum modulation index of five-phase PWM inverter. Simulation and experimental results are included to show the validity of the derived expressions.