Zero Sequence Circulating Current Reduction of Paralleled Converters With Interleaved Discontinuous PWM

Zero sequence circulating current (ZSCC) generated by common mode voltage differences in paralleled converters leads to current quality deterioation and additional power losses. In this paper, detailed effects of space vector selection on ZSCC and line current harmonic performance are discussed. A three-dimensional voltage space vector is introduced considering both the grid current and ZSCC for two paralleled converters. A novel method to reduce ZSCC in paralleled converters with interleaved discontinuous pulse width modulation is proposed. Only voltage vectors with zero or small common-mode voltage differences are applied in this strategy. The proposed method is implemented by a simple carrier-based algorithm. Simulation and experimental results are presented to verify theoretical analysis.