Performance improvement of capacitor-run single-phase induction motors by non-orthogonal armature windings

In a traditional capacitor-run motor, two armature windings are orthogonal and supplied by a single-phase source. Rotating air-gap MMF contains both forward and backward components, where the backward component leads to loss and noise. This paper presents a method to effectively weaken the backward component around the rated load while the forward component is kept constant, which improves the performance of the motor. The proposed method uses non-orthogonal armature windings. A complete technique is presented to calculate the shift angle between the stator windings and series capacitance for elimination of the backward rotating air-gap MMF at a specified load. Afterwards, a series of simulations are done to find the optimal shift angle and series capacitance.