载波移相SPWM并联变流器及其环流问题的研究

针对模块并联中的线路级并联，提出正弦脉宽调制的载波移相技术，使并联系统在原有开关频率基础上获得一个加倍的等效开关频率。通过对载波移相中每个模块的开关状态分析，得出载波移相导致模块之间形成环流，且各相的环流相互独立。公共直流母线条件下，环流包含零序和非零序成分。采用独立直流母线，能有效抑制环流中的零序分量。仿真结果验证了上述结论。

The Research on Carrier Phase-shift SPWM and Circulating Currents in Parallel Converters

According to the circuit level parallel in modules parallel technology, a new method of carrier phase-shift SPWM was proposed, which makes the parallel system obtain a higher equivalent switch frequency based on the original frequency. By the analysis of the switch ing-status of the modules, derived that carrier phase-shift SPWM produces circulating currents among modules and each phase is independent. At the condition of common DC-bus the circulating current contains zero sequence component and no-zero sequence component. To adopt independent DC bus can suppress the zero sequence component. The simulation validated these conclutions.