Principle of single-phase AC motor:
Description with single-phase capacitor motor: Single-phase motor has two windings, namely start winding and running winding. The two windings differ in space by 90 degrees. A capacitor with a larger capacity is connected in series with the starting winding. When the running winding and the starting winding pass single-phase alternating current, the current in the starting winding is ahead of the current of the running winding by a 90-degree angle in time due to the action of the capacitor. value. Two identical pulsed magnetic fields are formed in time and space, so that a rotating magnetic field is generated in the air gap between the stator and the rotor. Under the action of the rotating magnetic field, an induced current is generated in the motor rotor, and the current and the rotating magnetic field interact The torque of the electromagnetic field rotates the motor.
1. The split-phase starting type, as shown in Figure 1, is assisted by the auxiliary starting winding, and its starting torque is not large. The running speed remains roughly constant. Mainly used in electric fans, air conditioner fan motors, washing machines and other motors.
2. The centrifugal switch is turned on when the motor is at rest, and the starting capacitor participates in the starting work after power is supplied. When the rotor speed reaches 70% to 80% of the rated value, the centrifugal switch will automatically trip, the starting capacitor completes the task and is disconnected open. The starting winding does not participate in the running work, and the motor continues to operate with the running winding coil.
3. The centrifugal switch is turned on when the motor is at rest. After power is supplied, the starting capacitor participates in the starting work. When the rotor speed reaches 70% to 80% of the rated value, the centrifugal switch will automatically trip, the starting capacitor completes the task and is disconnected. open. The running capacitor is connected in series to the starting winding to participate in the running work. This connection method is generally used in places with large and unstable loads such as air compressors, cutting machines, and woodworking machines.