逆变器并联系统直流环流产生原因及其检测与抑制方法

对于无输出隔离变压器的逆变器并联系统，各模块输出电压直流分量不一致会在模块间产生较大的直流环流。该文分析了逆变器输出电压产生直流分量的原因，介绍了逆变器并联系统直流环流检测和抑制方法。通过对逆变器基准正弦波直流分量的高精度数字调节，相应调节逆变器输出电压直流分量以抑制直流环流。在由两台3kVA逆变器组成的并联系统上进行的试验结果证明，该文介绍的直流环流检测与抑制方法对逆变器并联系统直流环流有较好的抑制效果。

REASONS AND METHODS FOR DETECTING AND RESTRAINING DC CIRCULATING CURRENT IN PARALLEL INVERTER SYSTEM

For a parallel inverter system without output isolating transformers, discrepancy in DC biases contained in the output voltage of each module can cause large DC circulating current among inverters. The reasons producing DC bias in inverter output voltage are analyzed, and the methods for detecting and restraining DC circulating current in parallel inverter system are also well stecdied in this paper. By digital adjustment with high precision on the DC bias of reference sine wave, the DC bias contained in inverter output voltage can be adjusted to restrain DC circulating current. Experimental results in a parallel system consists of two 3kVA inverters prove that the DC circulating current detecting and restraining methods proposed in this paper have a good performance on restraining DC circulating current.