An Active Power Decoupling Control Method of Single-Phase Cascaded H-Bridge Rectifier

Single-phase cascaded H-bridge rectifier(CHBR) of power electronic traction transformer(PETT) has disadvantage of secondary ripple power. To solve this problem, a CHBR with the active power decoupling(APD) topology is used, and a comprehensive control strategy is proposed, which includes dc-side capacitor voltage control and the APD control strategy based on real-time calculating conduction duty cycle. Firstly, the causes of secondary ripple power and the working mechanism of the APD circuit are analyzed. Then, based on the theoretical analysis, the control strategy of the APD of the CHBR is established to realize rectifier voltage control. Based on real-time calculating conduction duty cycle of each APD arm, the secondary ripple power during rectifier conversion can be suppressed, and the circuit works in the current intermittent mode. So that,the system reliability and power density can be improved. Finally, simulation and experiment results are carried out to verify the of correctness and effectiveness of the proposed method.