考虑不同调制策略的间接矩阵变换器输入电流谐波特性分析

Harmonic Analysis on the Input Current of Indirect Matrix Converter under Different Modulation Strategies

为明确间接矩阵变换器(IMC)的输入电流谐波特性,进而抑制其输入谐波以改善网侧电能质量,利用变换器传递函数建立输入电流数学模型,确定其谐波组成,同时通过引入脉冲重心思想,综合考虑不同脉宽调制策略下脉冲幅值、宽度以及分布位置等特征,进一步分析明确输入电流谐波的主要频率成分及其含量。此外,在理论分析过程中发现了降低谐波频率成分的脉宽分布规律,即输出电压矢量脉宽比例对称分布。仿真和实验结果表明,根据所发现的脉宽比例对称分布原则,在采用双空间矢量调制(SVM)策略和两段式脉宽调制(PWM)策略时,输入电流中均主要含有输入频率的6n±1倍次谐波,而与输出频率无关。仿真和实验中测得的各次谐波含量符合理论分析结果,且随频率提高而衰减,证明了理论分析的有效性和正确性。

The mathematical model based on the transfer function of the indirect matrix converter（IMC） is established for ascertaining harmonic components, to clarify the characteristics of input current harmonics and further suppress harmonics for improving power grid quality. Furthermore, the pulse barycenter concept, in which the amplitude, width and distribution position of a pulse are all considered, is introduced to analyze and determine the frequencies and magnitudes of main harmonic components. In addition, the principle of the output voltage vector pulse proportional symmetric distribution, which is able to attenuate input current harmonics, is discovered in the process of theoretical analysis and utilized under different modulation strategies. Simulation and experimental results show that, by using either dual space vector modulation（SVM） or two-stage pulse-width-modulation（PWM） with the pulse proportional symmetric distribution, the input currents mainly contain（6 n±1）th low order harmonics, which are irrelevant to the output frequency, and the harmonic contents decrease as the frequency increases. Simulation and experimental results coincide with the theoretical results, which demonstrate the validity of the theoretical analysis.