级联H桥逆变器漏电流分析与抑制

摘要

Aimed at the leakage current issue of the transformerless cascaded H-bridge inverter, this paper first establishes the equivalent common-mode circuit of the inverter with the parasitic capacitance, and analyzes the characteristics of leakage current in the symmetrical and asymmetrical inductance circuit respectively. The analysis shows that the leakage current can be eliminated through optimizing the modulation methods in the symmetrical circuit, but in the asymmetrical circuit the leakage current issue cannot be solved through modulation strategies. For this reason a new modulation strategy for the symmetrical circuit based on the multicarrier pulse width modulation is proposed which can eliminate the leakage current effectively with simple implementation. Finally, the validity and effectiveness of the proposed method is verified by the simulation and experiment.%针对非隔离型级联H桥逆变器的漏电流问题,首先建立带有寄生电容参数的逆变器共模等效模型,分别分析单电感电路与对称电感电路中漏电流的特点及其影响因素,指出在对称电感电路中通过优化调制策略可以有效抑制系统漏电流,而在单电感电路中调制手段无法解决漏电流问题.为此针对对称电感电路提出一种改进型载波层叠多电平调制策略,能够有效地抑制系统漏电流,而且实现简单、运算量小.最后仿真与实验结果验证了该方法的有效性与正确性.