An improved capacitor voltage balance control for cascaded H-bridge rectifier

The cascaded H-bridge rectifier (CHBR) is widely used in high voltage and high power applications. Due to switch in/out of H-bridge module frequently, the problem of traditional CHBR is the high switch frequency and great switch power loss of semiconductor devices. In this paper, an improved capacitor voltage control strategy for CHBR is proposed. Through setting up capacitor voltage limit interval, the H-bridge modules in the voltage interval keep the last switch in/out status. Thus switch times of switch devices is reduced in a period. The validity and feasibility of proposed control strategy is verified through simulation and experiment results.