A modified flux weakening direct torque control for open winding PMSM system fed by hybrid inverter

To extend the constant power range and enlarge the output power of permanent magnet synchronous motor (PMSM) system fed by a single power source, an improved direct torque control (DTC) strategy is proposed for the open winding PMSM (OW-PMSM) system fed by hybrid inverter. The hybrid inverter system is composed of a main inverter powered by a DC voltage power source and a compensation inverter powered by a floating capacitor. A modified strategy using the main inverter voltage as the feedback is proposed to maintain the maximum voltage of main inverter and modify the stator flux linkage reference for the flux weakening operation. Moreover, the voltage references for two inverters are distributed appropriately to extend the constant power range and enlarge the output power of the OW-PMSM. Simulation results verify the effectiveness and superiorities of the proposed strategy.