An Extended DPWM Method for Switching Loss Reduction With Dual Induction Motors Fed by Five-Leg Inverter

This paper proposes an extended discontinuous PWM (DPWM) method for the five-leg inverter (FLI) driving dual induction motors (IMs). Conventionally, a rotation carrier-based DPWM (RCB-DPWM) method has been proposed to increase the efficiency of FLI. This method reduces the switching loss of both motors similarly under the same conditions of speed and torque. However, RCB-DPWM method does not minimize the switching loss when the conditions differ. Therefore, this paper utilized the absolute value of the output currents to minimize the switching loss under different speed and torque conditions. Since the switching loss proportional to the magnitude of the output current, the offset voltage is calculated based on the current value. The offset voltage is added to the reference voltage and the modified reference voltage is clamped to 0.5V_dc or −0.5V_dc. As a result, the switching loss is minimized compared to the RCB-DPWM method under variable conditions, thereby maximizing the efficiency of the system by applying the proposed method. The performance of the proposed method is verified through the experimental results.