A novel control strategy of circulating currents in paralleled single-phase boost converters for micro-grid applications

In this paper, analysis of circulating currents of paralleled single-phase boost converter systems is presented. The DC loop and AC loop circulating currents are clearly explained. In order to eliminate the DC loop circulating currents and reduce switching losses, a simplified PWM strategy is adopted in a paralleled single-phase boost converter. Based on the analysis of circulating currents, common mode circulating current (CMCC) and differential mode circulating current (DMCC) are defined. Then, CMCC and DMCC compensator in a centralized control scheme are proposed to reduce the common-mode and differential-mode circulating currents in the parallel system operated in both rectifier mode and inverter mode for micro-grid applications. Some simulation results are carried out to verify the validity of the proposed control scheme. In addition, a prototype system is constructed to facilitate the theoretical results as verification. From simulation and experimental results, the proposed control scheme can indeed reduce the circulating currents under equal and/or different power rating condition in the parallel system.