A Modified PSPWM for a Five-Level Hybrid-Clamped Inverter to Reduce Flying Capacitor Size

In order to reduce the size of high-voltage flying capacitors in a five-level hybrid-clamped inverter, a modified phase-shifted pulsewidth modulation (PWM) method is proposed in this paper. The four carrier waves are redistributed and the charge/discharge time of the high-voltage capacitor can be reduced. The only disadvantage of this PWM method is that the harmonic characteristic will become worse. However, no low-order harmonics is imported and most of the harmonics are around carrier frequency and multitimes the carrier frequency, which are very easy to be filtered. Simulation and experimental results are presented to demonstrate the effectiveness of this method.