AC motors generally use a three-phase system because three-phase AC motors have obvious advantages over single-phase motors in terms of performance indicators, raw material utilization, and price. Three-phase motors of the same power are smaller, lighter and cheaper than single-phase motors. Three-phase motors have self-starting capabilities. Single-phase motors have no starting torque, and some special measures need to be taken to solve the starting problem. The torque of a single-phase motor is pulsating and the noise is relatively large, but the required power supply is relatively simple, especially in the home is very convenient to use. Therefore, small household motors and instrument motors mostly use single-phase motors.
