Improving the Starting Characteristics of Single-Phase Induction Motors with an Auxiliary-Winding Current Control

抄録

This paper proposes a novel starting method for single-phase induction motors. Induction motors are unable to obtain sufficient starting torque with only a single-phase source. Therefore, the proposed method increases the starting torque by controlling the auxiliary-winding current with a triode for alternating current (TRIAC) and a very small microcontroller. The auxiliary winding is connected to the main windings via the TRIAC and a small capacitor. The intermittent TRIAC connections provide a pulse current series, i.e., half-cycle waveforms of the resonant current. The fundamental component of this current is sufficiently large and leads the main winding current; hence, a better two-phase current is realized. Thus, the proposed control achieves a large starting torque by utilizing only a small capacitor; it does not use any electrolytic capacitors. The effectiveness of the control is verified by theoretical and experimental methods. The proposed method obtained almost twice the starting torque of the conventional method, using the same capacitor.