三相逆变器不平衡抑制研究

三相逆变器的一个重要性能是输出电压的对称性，输出电压不对称主要由不平衡负载引起，文中基于对称分量法和叠加原理分析了输出基波电压对称性畸变机理，指出了输出电压正、负、零序分量不同的补偿特性，表明输出电压对称性控制不仅与控制器性能有关，还取决于逆变器电路结构的固有特性，并提出了改善逆变器输出对称性的方法。仿真和基于DSP控制的35kW逆变器样机实验均验证了理论分析结论。

RESEARCH ON THREE-PHASE INVERTER WITH UNBALANCED LOAD

One of important performances of three-phase inverter is output voltage symmetry. Unsymmetrical output voltage is caused mainly by unbalanced load. The mechanism distorting output voltage fundamental waveform of an inverter under unbalanced load is analyzed based on symmetrical component decomposing and superimpose theory. It is presented that positive-, negative- and zero-sequence components of output voltage show different effect of compensation. This problem is related to not only controller characteristic but also the inherent nature of the inverter circuit. The method to improve the output voltage symmetry of inverter is proposed in this paper. Theoretical analysis is confirmed well through both simulation and experimental results on a 35kW DSP-controlled three-phase inverter.