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Speed control method of AC motor

Speed control method of AC motor

Answer:

The characteristics of various speed regulating devices:(1) change pole speed regulation;Advantage:No additional slip loss, high efficiency;Control circuit is simple, easy maintenance, low price;The smooth speed regulation with higher efficiency can be obtained by matching with the stator voltage regulating or electromagnetic slip clutch.Shortcoming:Stepless speed regulation without stepless speed regulation. Due to the limitation of the motor structure and manufacturing process, only 2~3 kinds of pole to rail speed regulation are usually achieved, and the speed range is quite limited.
The specific AC speed regulating device has:Efficient speed regulation includes:Changing pole logarithmic speed regulation -- squirrel cage motorSquirrel cage type motor controlled by frequency conversionCascade speed control - winding motorSynchronous motor of commutator motorInefficient speed control methods include:Stator voltage regulating speed governing squirrel cage motorSpeed control of electromagnetic slip clutch -- squirrel cage motorSpeed control of rotor series resistance winding motor
From the point of view of energy saving, the speed regulating device of AC motor can be divided into two categories: efficient speed regulating device and low speed governing device. The characteristics of an efficient speed regulating device are that the rated speed is maintained basically at the speed regulation, no slip loss is increased, or the differential feedback is fed back to the power grid. The low speed regulating device is characterized by changing the speed change and increasing the slip loss during speed regulation.
The AC motor speed regulating method is just the opposite to the direct current motor speed regulation method. The motor has the advantages of simple structure, little inertia, convenient maintenance, operation in harsh environment, easy realization of large capacity, high voltage, high speed, and low price.

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