H桥级联型整流器直流电压平衡控制改进算法

直流母线电压平衡控制是H桥级联型整流器（CHBR）主要的研究问题。为此在建立CHBR的数学模型基础上,分析了一种基于比例-积分（PI）调节器的CHBR直流电压平衡控制算法,并针对其不能空载运行的问题展开研究,利用相量图法揭示了该方法在空载时失控的内在机理;同时根据分析的结果提出了改进算法。改进算法的主要特点是通过使各功率单元的交流侧电压基波相位保持相同来实现空载条件下的电压控制,它不仅适用于直流电压给定值相同或者不相同的CHBR控制,同时也易于扩展到多单元的CHBR。对所提的算法进行了仿真研究,并搭建两单元CHBR的实验样机,对文中提到的改进算法进行了实验验证。实验结果表明了改进算法的有效性,同时也验证了改进算法和原算法在空载运行特性上的差异。

Improved DC-link Voltage Balancing Method for Cascaded H-bridge Rectifier

It is a challenge to balance the DC-link voltages of cascaded H-bridge rectifier(CHBR).We put forward an improved PI-based control method.Firstly,we establish a mathematics model of CHBR and introduce a PI-based DC-voltages balancing method.Then,we adopt the phasorial diagram method to discover and analyze the intrinsic reason that CHBR can not work on no-load condition with this control scheme.Based on the analysis results,measures are taken in control scheme to make the phases of all the cells’ AC side voltage equal,which guarantees stability of system when the CHBR works on the no-load condition.The improved method can regulate the cell’s voltages well,either the reference voltages are the same or different.Furthermore,it can easily extend to the CHBR with more cells,and is testified by a 4-cell CHBR simulation results.A 2-cell CHBR prototype is built in the laboratory.Accordingly,comparison experiments by the referred control method are done.The experimental results indicate the feasibility of the presented method and good performance on the no-load condition with the improved control scheme.