Mitigating Circulating Currents of Parallel Three-Phase Vienna Rectifiers with Unbalanced Filter Inductors

Parallel connections of three-phase Vienna rectifiers have been widely utilized to increase power ratings of charging stations. However, paralleled operations will introduce a path for the zero sequence circulating current (ZSCC) circulations. This problem will become worse especially for these rectifiers are operated under interleaved modes with unbalanced filter inductors. To mitigate these circulating currents, an integrated control scheme is proposed by mitigating the low frequency component of the ZSCC by PIR control in the inner-loop control and the high frequency component of the ZSCC by discontinuous PWM. Both numerical simulations and hardware experiments are performed to validate the effectiveness of the proposed control scheme.