Study Of Novel High Efficiency Single-phase Induction Motor

Due to the simple structure, low manufacturing cost and other advantages, the single-phase induction motors are widely used in industry, agriculture, daily life, and etc. In comparison with three-phase induction motors, the single-phase induction motors have lower efficiency, larger volume and consume large amounts of energy. Therefore, improving the efficiency of single-phase induction motors is significant.For the advantages of three-phase induction motors, many studies have been done about the operation of three-phase induction motor supplied by the single-phase power, and some effective connection methods have been put forward. SemihexTM connection can enable three-phase induction motor operate symmetrically from single-phase supply, which has higher efficiency and high power factor than single-phase induction motor. But the single-phase motor with SemihexTM connection mainly is suitable for the fan and pump load since its complex starting circuit and low starting torque.Based on three-phase induction motor, this paper presents a novel high efficiency single-phase induction motor with three windings in the stator and two capacitors. By using capacitors as its phase-shifting component, the motor can operate approximately symmetrically from single-phase supply. Following studies have been carried out:(1)The symmetrical operation condition of the proposed motor is analyzed by the symmetrical components method; the formula for calculating the phase-shifting capacitor is derived. The steady equivalent circuit is established and the steady performances of the proposed motor are studied. On the basis of the foregoing, the starting circuit with one start-up capacitor is proposed.(2)The transient mathematic model of the proposed motor is established and the transient simulation model is built in MATLAB, which is used to analyze the starting and running characteristics of the proposed motor.(3)To verify the superiority of the novel high efficiency single-phase induction motor, a prototype is designed. The static and dynamic tests on the prototype and a three-phase induction motor are carried out.