Asynchronous motors and synchronous motors are two common types of rotating motors, which differ in their operating principles and performance characteristics.
1. Operating Principle: Asynchronous motors rotate based on the relative motion between the rotating magnetic field generated in the windings and the magnetic field; synchronous motors, on the other hand, need to synchronise the magnetic field generated in the windings with the external magnetic field.
2. Starting method: asynchronous motors usually use starting capacitors, starting resistors, motor exciters and other auxiliary equipment to start; while synchronous motors generally need to be externally provided with starting torque.
3. speed control: asynchronous motor speed is generally controlled by the voltage change, can be achieved by frequency conversion and other ways; synchronous motor speed is limited by the frequency of the power supply, usually need to use a mechanical speed changer to achieve speed control.
4. power factor: asynchronous motor in the load change, its power factor is usually variable, in the light load or no load situation power factor is low; synchronous motor in part of the load power factor is high, and can be adjusted through the reactive power compensation power factor.
5. Overload characteristics: asynchronous motors have better overload capacity, can withstand a large load impact in a short period of time; synchronous motors have poorer overload capacity, and are prone to stall for overload conditions.Because synchronous motors need to be synchronised with an external power source, they usually require a more complex control system for implementation; whereas asynchronous motors have a relatively simple control system because they do not need to be synchronised with an external source.