A PWM strategy for suppressing zero-sequence circulating current of an open-winding induction motor system

In an open-winding induction motor system fed by parallel-connected inverters, there is a well-known issue of zero-sequence circulating current. To tackle this problem, this paper proposes a modulation strategy that can suppress zero-sequence current. The proposed strategy treats two inverters as a whole, selecting six voltage vectors with zero common-mode voltage from 64 voltage vectors as basic vectors for synthesizing reference voltage. In addition, to further improve the suppression effect of zero-sequence current, the distribution of zero vectors is readjusted accordingly. The effectiveness of the proposed method is fully verified by a 2.2 kW induction motor experimental system.