Optimization of Single-Phase Induction Motors—Part II: Magnetic and Torque Performance Under Optimal Control

The magnetic and torque performance of a capacitor-run single-phase induction motor operated at constant torque under the optimal efficiency control, as presented in Part I, is analyzed. The magnetic field analysis demonstrates that magnetic saturation is considerably decreased with optimal efficiency control. Although triac-based optimal voltage controller introduces voltage and current harmonics, torque pulsations and acoustic noise are reduced due to magnetic flux weakening. The reduction of torque pulsations and acoustic noise is considerable in the low torque region where significant energy savings are also achieved. Selected calculated and experimental results are presented to validate the theoretical considerations and the resulting improvements.