Model predictive control for circulating current suppression in parallel-connected PMSM drive

The parallel three-phase voltage source inverters have been widely used to raise system power rating. However, the zero-sequence circulating current can be generated according to switching method in the direct connection scheme. Zero-sequence circulating current not only distorts current but also reduces system reliability and efficiency. In this paper, model predictive control scheme is proposed for the parallel three-phase voltage inverters-fed interior permanent magnet synchronous motor with the zero-sequence circulating current suppression. The voltage vectors of the parallel inverter are derived for accurate prediction and control of the torque and stator flux components. In addition, the circulating current is suppressed by adding a zero-sequence circulating current suppression term consisting of the voltages of the output inductor to the cost function without additional current sensors and high impedance inductors. Simulation results illustrate the validity of the analytical approach and the efficiency of the proposed method.