Voltage-Balanced Control for a Cascaded 3H-Bridge Rectifier

This paper studies the CHBR (Cascaded H-Bridge Rectifier)’s DC side capacitor voltage balance control algorithm, introduces single-phase DQ coordinate transformation, deduces the mathematical model in this coordinate. This uses feed-forward decoupled control strategy to keep voltage and current of AC side in the same phase, puts forward an improved algorithm to balance DC capacitor voltage even if the loads of CHBR are imbalanced. Finally, establishes a simulation model of three cells’ CHBR. The simulation results indicate that this improved algorithm can reduce the switching frequency effectively, and balance the DC voltage of every module much better.