矩阵变换器电流方向换流策略的改进

Commutation Strategy Improvement for Matrix Converter Current Direction

由于矩阵变换器电路没有续流路径,它的换流过程与交-直-交变换器相比更为复杂,换流问题是阻碍其工业应用的主要原因之一。为了解决传统四步换流策略中因换流步长固定而导致波形失真的问题,提出一种新的检测负载电流方向的方法和变步长四步换流策略。改进策略包括通过检测管压降来判断电流方向,根据不同电流情况下元件的开关时间采用变换流时间的四步换流策略。最后设计了基于数字信号处理技术和复杂可编程逻辑器件的控制系统。实验结果表明:改进的换流策略提高了换流的可靠性,同时缩短了换流时间。

Compared to AC-DC-AC converter,the absent follow current path in matrix converter circuit complicates the commutation process which obstructs its industrial application. In order to solve waveform distortion incurred by the fixed step of traditional four-step commutation strategy,a new method to detect the load current direction and the variable-step four-step communication strategy were proposed. Improvement strategy includes deciding current direction according to detector tube＇s voltage drop,and the four-step commutation strategy of changing conversion time according to the element＇s switching time under various currents. Both DSP and CPLD-based control system was designed. The experimental result demonstrates that the improved commutation strategy can enhance commutation availability and reduce commutation time meanwhile.