Working principle of single-phase motor Characteristics of single-phase motor

A single-phase motor is an electric motor that only needs a single-phase power supply to operate. It is a type of motor. According to different working principles and structures, single-phase motors can be divided into many types such as single-phase asynchronous motors, single-phase induction motors, single-phase capacitor motors, etc.

The working principle of a single-phase motor is mainly based on the rotating magnetic field generated by single-phase alternating current acting on the rotor in the motor, allowing the rotor to rotate. Specifically, there is only one set of coils in the stator winding of a single-phase motor. The coils divide the alternating current into two paths through a shunt, forming two currents with a phase difference of 90 degrees. These two currents form two rotating magnetic fields in the stator winding. Since the magnetic flux of the two rotating magnetic fields is different in size and direction, they will alternately act on the rotor in the motor, generating a rotational torque, thereby driving the rotor to rotate.

In single-phase motors, auxiliary starting devices are usually used to help the motor start. For example, single-phase induction motors are usually equipped with starting capacitors. When starting, the starting capacitor changes the current phase difference in the circuit, thereby starting the motor. It should be noted that since single-phase motors are only powered by a single phase, their torque fluctuations are large, and they do not run as smoothly as three-phase motors. They also have relatively small power and are usually used in low-power and light-load situations.

Single-phase motors have the following characteristics:

Simple structure and low cost: Since single-phase motors only require single-phase power supply, their structure is relatively simple and the manufacturing cost is relatively low.

Easy to use: Single-phase motors can be powered by ordinary household electricity and are easy to use.

Auxiliary devices are required for starting: Since single-phase motors are powered by only one phase, auxiliary devices (such as starting capacitors) are required during starting to change the phase difference in the circuit and help the motor start.

Large torque fluctuations: Since single-phase motors are powered by only a single phase, their torque fluctuations are large and their operation is not as smooth as that of three-phase motors.

Suitable for low power and light load: Single-phase motors have relatively small power and are suitable for applications with low power and light load, such as household appliances, light industrial equipment, etc.

Compared with three-phase motors, single-phase motors have the advantages of simple structure, easy use, and low cost, and are widely used in household, commercial and light industrial fields, such as water pumps, fans, compressors, machine tools, etc. It should be noted that single-phase motors have large fluctuations in torque due to only a single phase of power supply, and their operation is not as stable as that of three-phase motors. They also have relatively small power and are usually used in low-power and light-load situations.