DC Capacitor Voltage Balance Control Method for High-Power Single-Phase Cascaded H-Bridge Rectifier to Extend the Regulation Range

Single-phase cascaded H-bridge rectifier (CHBR) plays an important role in high-speed trains. The dc capacitor voltage balance control is essential for a single-phase CHBR. However, existing dc capacitor voltage balance control methods suffer from lacking regulation range. To tackle this issue, a balance control method for dc capacitor voltage to extend the regulation range that is readily implemented is proposed in this article, whose regulation range is the widest. The steady-state operating region (SOR) of a single-phase CHBR is analyzed, and the operation loci of different methods in SOR are derived. According to the geometric relationship of operation loci, a simple method to evaluate the regulation range of different balance methods is introduced. Meanwhile, regulation ranges of different balance methods are compared based on this method, from which it can be known that the proposed dc capacitor voltage balance control method has the widest regulation range. Finally, experimental results verify the effectiveness and superiority of the proposed method.