Ac motor speed control method
You can change the frequency, you can change the logarithm of the magnetic pole, and you can change the difference in three ways
Disadvantages: During the process of speed adjustment, the transfer loss is increased, which makes the rotor hot and less efficient. The range of speed adjustment is small; It is required to adopt high torque motor, such as special design torque motor, so the characteristic is softer, and a section is suitable for asynchronous motors under 55kW. (6) the electromagnetic variation clutch speed adjustment Advantages: The structure is simple, the control device is small and the value is cheap. Reliable operation and easy maintenance. No harmonic interference.
Disadvantages: The maximum speed of the output shaft is 80% ~ 90% of the synchronous speed of the motor. The transition difference power of the speed adjustment process is converted into thermal energy and low efficiency. (7) the rotor resistance speed adjustment Advantages: The technical requirements are low and easy to master; The cost of equipment is low; No electromagnetic harmonic interference.
Disadvantages: A series of cast-iron resistance can only be adjusted for the stage. If the liquid resistance is used for stepless speed adjustment, the maintenance and maintenance requirements are higher. The addition of the transfer power in the speed adjustment process is converted into the loss of the series resistance heat, and the efficiency is low. The range of speed regulation is not big. To sum up, the most ideal speed regulating method of communication should be to change the frequency of electric power supply of the motor, which is the variable frequency speed adjustment. With the rapid development of electric power electronic technology, the performance index of variable frequency speed adjustment can meet even more than dc motor speed regulating system.
The most common method is to add a matching frequency converter You can also use a gearbox
