V/f control technique for mitigating pulsating torque based on active and reactive power sharing in single-phase induction motors

Abstract

Single-phase induction motors (SPIMs) have main and auxiliary windings on the stator, which is an asymmetrical circuit for the starting torque. Owing to an asymmetrical stator circuit, the torque pulsation is inevitably generated along with noise and loss. This paper proposes the open-loop V/f control method for reducing the torque pulsation in SPIMs. The proposed method uses a three-leg inverter and power sharing controllers without the start capacitor. The line-to-line voltages of a three-leg inverter correspond to two stator winding voltages. Therefore, the active power sharing of two stator windings can be adjusted by the voltage ratio, while reactive power sharing can be adjusted by the phase angle difference. In addition, the modified modulation strategy is used to apply the proposed method, which is suitable for the V/f control with SPIMs driven by a three-leg inverter. With the proposed method including the power sharing controllers and the modified modulation strategy, the torque pulsation and currents are reduced in SPIMs because of power balancing of stator windings. The effectiveness of the proposed method is validated by simulation and experimental results.