Research on Zero Sequence Circulating Current Suppression of Parallel Inverter System with Common AC and DC Bus

Abstract

The parallel inverter system with common AC and DC bus has the advantages of small size, low cost and high reliability. However, due to the inconsistency of switch status and main circuit parameters, zero sequence circulating current will be generated between inverters, which will cause serious distortion of grid-connected current, increase of system loss, and decrease of efficiency. This paper focuses on the research on zero-sequence circulating current suppression of parallel inverter systems with common AC and DC bus. First, the zero-sequence circulating current model of parallel inverters is analyzed, and the reasons for the generation of zero-sequence circulating current are analyzed. The circulation suppression method with zero-sequence component feedforward based on traditional PI control is proposed. Finally, the effectiveness of the proposed control method is verified by simulation and experiment.