Phase-shifted pulse-width-amplitude modulation for quasi-Z-source cascade multilevel inverter-based photovoltaic power system

A phase-shifted pulse-width-amplitude modulation (PS-PWAM) is proposed for a quasi-Z-source cascade multilevel inverter (qZS-CMI)-based photovoltaic power system. The switching actions of each power device of the qZS-CMI in the PS-PWAM technique are greatly reduced when compared with that in the phase-shifted sinewave pulsewidth modulation, so the qZS-CMI's power loss is reduced when using the PS-PWAM. The PS-PWAM principle and the qZS-CMI's loss analysis are presented. The simulation and experimental results verify the proposed PS-PWAM and the resultant efficiency improvement.