Experimental Verification of Current Ripple Amplitude in Five-Phase PWM VSIs

Multiphase systems are nowadays considered a viable solution for various industrial applications. Numerous PWM schemes for multiphase voltage source inverters with sinusoidal outputs have been developed, but no detailed analysis of the impact of these modulation schemes on the output peak-to-peak current ripple amplitude has been reported. Determination of the current ripple in multiphase PWM voltage source inverters is interesting from the theoretical point of view and, in some cases, is useful for both design and control purposes. This paper gives the complete analysis of the peak-to-peak current ripple distribution over a fundamental period with experimental verification in the case of five-phase voltage source inverters. In particular, peak-to-peak current ripple amplitude is analytically determined as a function of the modulation index with a symmetrical centered PWM, being the most simple and effective solution to maximize the dc bus utilization, leading to a nearly-optimal modulation to minimize the rms of the current ripple. However, the analysis could be easily extended to either discontinuous or asymmetrical modulation, both carrier-based and space vector PWM.