电网扰动时矩阵变换器的电流闭环控制及稳定性分析

Current closed-loop control and stability analysis of matrix converter under grid disturbance

矩阵变换器作为一种交-交直接变换电路拓扑,由于没有中间储能环节,当电网电压不平衡或非正弦时将直接影响其输出特性。以提高矩阵变换器的输出电流品质为控制目标,基于空间矢量调制技术,同时结合PI调制对输出电流进行闭环控制。通过控制输出电流空间矢量幅值维持恒定,在电网存在扰动时都能使得输出电流波形正弦且平衡。基于开环传递函数,运用对数频率稳定判据对系统进行了稳定性分析。在此基础上采用Matlab软件对该控制策略在3种不同工作条件下进行了仿真分析,结果表明输出电流幅值和频率都能很好地跟随给定,动态响应快,且不受电网低次谐波和负序分量的影响,同时器件的开关频率恒定,验证了控制策略的可行性和有效性。

As the MC（Matrix Converter） performs direct energy transfer from input to output, the distortion and unbalance of input voltage directly affects its output, for which, a current closed-loop control based on SVM（Space Vector Modulation） and PI regulation is presented. The magnitude of output current space vector is kept constant to ensure the output currents of MC sinusoidal and balanced under grid disturbance. Based on open-loop transfer function, the system stability is analyzed with logarithm frequency criterion. The control strategy is simulated with Matlab under three conditions. Results show that, the output current rapidly follows the reference in magnitude and frequency, free of the influences of low order harmonics and negative component, while the switching frequency of the converter is kept constant, which verities its feasibility and effectiveness.