Virtual-Balanced-Systems-Based Modeling and Control for Dual Three-Phase PMSM Under Unbalanced Power Sharing Operation

This study proposes a new modeling and control scheme for dual three-phase permanent-magnet synchronous machine with harmonic current regulation requirements. Compared with existing schemes, the proposed scheme further considers the situation where two sub-three-phase winding sets of the machine are in an unbalanced power sharing state. In such case, classical vector space decomposition (VSD) will no longer be able to decouple the fundamental and main harmonic (5th and 7th) currents into the fundamental and harmonic subspaces, respectively. Consequently, both subspaces need more filters to separate the fundamental and harmonic current components, thereby affecting control performance. For this reason, this article first analyzes the specific coupling mechanism of fundamental and harmonic currents in VSD model under unbalanced power sharing. Subsequently, based on common-mode and differential-mode concept, two virtual balanced systems are proposed to decouple the coupling of fundamental and harmonics caused by power unbalance. Owing to the natural decoupling features of the proposed scheme, the dynamic and steady-state performance of current regulation under unbalanced power sharing can be improved. Finally, the effectiveness and advantages of the proposed scheme are verified by experiments.