The speed regulation of frequency converter is to realize the speed adjustment of AC asynchronous motor by changing the frequency of motor power supply. The speed adjustment is balanced. The load characteristics of motor do not change with the speed change. It is suitable for load adjustment and constant moment adjustment. Good performance, but high cost.

The electronic governor changes the supply voltage of the motor by controlling the conduction angle of the thyristor, and makes the characteristic curve of the motor move down to change the speed of the asynchronous motor. Its characteristics are: the motor speed adjustment range is small, the motor load capacity is poor at low speed, when the speed is reduced, the motor torque will be reduced, not suitable for constant torque load, when the speed is low, it is easy to have locked rotor phenomenon; generally only suitable for fan load.