级联H桥整流器电容电压平衡控制改进算法

摘要

直流侧电容电压平衡的问题是级联H桥整流器CHBR(cascaded H-bridge rectifier)目前研究的热点问题.分析并推导了CHBR的电路模型;然后引入单相dq变换,建立了CHBR在此坐标系下的数学模型;分析了一种基于能量交换的CHBR直流母线电压平衡的算法;针对其开关频率高且在负载不平衡时无法正常运行的问题,提出了一种适用于负载不平衡条件下的算法.最后通过Matlab搭建了2级级联的系统仿真.结果表明,该算法可以在负载达到一定不平衡度的范围内较好地平衡各模块的直流电容电压,并且有效地控制系统的有功和无功,实现网侧电压电流同相位运行.%DC capacitor voltage balanced-control is the hot issue of CHBR's (cascaded H-bridge rectifier) research at present,its circuit model is analyzed and deduced,and a single-phase dq transformation is introduced,furthermore CHBR's mathematical model in this coordinate system is built.An algorithm based on the energy exchange for CHBR DC links to balance voltage is analyzed.In order to solve the problems that switch frequency is high and the load is unbalance,a new algorithm that is suitable for the load unbalance condition is proposed.Through the simulation,it is proved that the algorithm can balance the DC capacitor voltage of each module when the load is unbalanced,and control the active and reactive power of the system effectively,it can realize the grid side voltage and current in the same phase.