Improvement of Torque Production in Single-Phase Induction Motors

Existing single phase induction motors exhibit low starting torque. Moreover, during accelerating time and at steady state, they produce a significant level of torque pulsations which gives rise to noise and vibration in the machine. As part of efforts to mitigate these problems, a performance improvement strategy using a PWM inverter to drive the existing motor is implemented in MATLAB/Simulink environment in this work. The drive supplies variable voltage and phase to the auxiliary winding with the aid of a pulse width modulation (PWM) technique and a PID controller. Simulation results show the starting torque of the motor increased by 75% under the developed drive scheme. In addition, torque pulsations reduced from 1.4 Nm peak-peak to 0.14 Nm peak-peak at steady state.  It was observed that the accelerating time reduced by 30% compared to the accelerating time under line operation. The strategy eliminates the need for series-connected capacitors thereby potentially enhancing the reliability of the motor.