Variable time step control with synchronous PWM in flux weakening region of PMSM

In the flux weakening region of Permanent-Magnet Synchronous Machine, the six-step operation maximizes the voltage utilization and widens the possible operating area. However, since the rotor speed is relatively high compared to the sampling frequency in the flux weakening region, the low frequency current ripple can be incurred in the fixed sampling system. Also, the magnitude of the modulated voltage should be adjustable for fast torque control. In this paper, the variable time step controller with synchronous PWM is proposed for six-step operation in flux weakening region. From the comparative experiments, the effectiveness of the proposed method is verified.