Research on Zero-sequence Circulating Current Suppression Method of Multiple Paralleled Bidirectional Power Converters

With the improvement of the power level of low-voltage AC/DC hybrid microgrid, a single bidirectional power converter (BPC) is not suitable. So the redundant configuration of BPCs is adopted to increase power transmission of the AC/DC hybrid microgrid, but the application of multiple paralleled BPCs will produce zero-sequence circulating current (ZSCC). For the problem of ZSCC, this paper analyzes the principle of ZSCC under the condition of ensuring the autonomous operation of BPCs. The average equivalent model of the ZSCC of multiple inverters in paralleled is derived. And a single-module zero-axis current loop design method is proposed based on the average equivalent model. By comparing the influence of control parameters on the results, better control parameters are chosen. At last the results of simulation and experiment verify the correctness and effectiveness of the method.