What is the difference between synchronous motor and asynchronous motor using variable frequency speed regulation?

Many users do not know what is the difference between synchronous motor and asynchronous motor in frequency conversion speed regulation. Today, JINJIU Motor will take you to learn it, hoping to help friends in need.

1. Frequency control of synchronous motor

(1) The rotor of the synchronous frequency conversion speed regulating motor has the same DC poles as the stator winding poles. After the motor is started, the motor is transferred to normal operation, and the stator rotating magnetic field drives the rotor to perform synchronous operation. At this time, the motor speed is based on The number of poles of the motor and the input power frequency of the motor form a strict correspondence, and the speed is not affected by the load and other factors.

(2) Due to the strict correspondence between the speed of the motor and the power frequency, the speed accuracy of the motor mainly depends on the accuracy of the output power frequency of the inverter, and the control system is simple. The rotation speed is consistent, and no expensive optical encoder is needed for closed-loop control.

(3) An independent forced cooling fan is added to the synchronous frequency conversion speed regulation motor to adapt to the efficient heat dissipation of the motor at low speed and reduce the wind friction of the motor at high speed.

2. Frequency control of asynchronous motor

(1) Asynchronous frequency conversion motor is derived from ordinary asynchronous motor. Due to adapting to the characteristics of the output power of the inverter, the motor has made great changes in the rotor slot shape, insulation process, electromagnetic design check, etc., especially Ventilation and heat dissipation of the motor. In general, an independent forced cooling fan is added to adapt to the efficient heat dissipation of the motor at low speed and reduce the wind friction of the motor at high speed.

(2) The output of the inverter generally shows the output frequency of the power supply, and the speed output is displayed as the calculated number of poles of the motor and the output frequency of the power supply, which is very different from the actual speed of the asynchronous motor.

(3) Since the slip rate of the asynchronous motor is determined by the manufacturing process of the motor, its dispersion is very large, and the load change directly affects the speed of the motor. To accurately control the speed of the motor, only a photoelectric encoder can be used for closed-loop control When the single machine is controlled, the accuracy of the speed is determined by the number of pulses of the encoder. When controlled by multiple machines, the speed of multiple motors cannot be strictly synchronized, which is determined by the asynchronous motor.