Current control strategy for parallel-connected inverters to drive an smpmsm with small sharing inductors

Abstract

This paper presents a distributed current control strategy for parallel-connected inverters driving a surface-mounted permanent-magnet synchronous machine with small sharing inductors. In this configuration, when each inverter regulates its own current, uncontrollable differential-mode circulating current (DMCC) is inevitably induced, whose frequency may exceed the control bandwidth and make the system unstable. Detailed stability analysis reveals that simultaneously achieving both effective DMCC mitigation and fast performance using conventional decoupling proportional-integral control is difficult. This paper proposes a feed-forward compensation-based current control strategy that utilizes a compensator for rapid response to overcome this limitation. This approach effectively decouples the rapid reference tracking from the DMCC. Furthermore, because the accuracy of feed-forward compensation relies on model parameters, a simple online parameter estimation algorithm is integrated to mitigate performance degradation caused by parameter errors. The effectiveness and feasibility of the proposed method are verified through experimental results. The proposed control strategy not only effectively reduces the DMCC but also enables the output current to follow its reference rapidly.