The working principle of AC motor frequency conversion and speed regulation

AC braking motor There are many AC and speed control methods for practical applications.

　　AC braking motor There are many AC and speed control methods for practical applications. Here are a few commonly used methods:

 

　　1. Speed control

 

　　This speed control method is only used for specially produced multi-stage multi-speed asynchronous motors. By using different combinations of winding connection methods, you can obtain 2, 3, and 4 speeds. The speed changes of this speed control method are different, and it is only suitable for some special applications, and can only achieve the purpose of large-scale coarse adjustment. This introduces the speed control of a two-speed AC braking motor; other similar multi-stage multi-speed AC braking motor speed control circuits are similar to this.

 

　　2. AC braking motor rotor series resistance speed control

       

　　This speed control method is only applicable to wound rotor asynchronous motors. It changes the slip of the motor by changing the resistance value connected to the rotor circuit, thereby achieving the purpose of speed regulation. Because the resistance value of the external series resistance can be changed in multiple stages, speed regulation of multiple speeds can be achieved. In principle, it can also achieve stepless speed regulation. However, due to the power consumption of the connected resistance, the efficiency is low, so the mechanical characteristics of this speed regulation method are relatively soft, and it is only suitable for occasions with low speed regulation requirements.

 

　　3. AC braking motor cascade speed control

 

　　This speed control method is only applicable to wound rotor asynchronous motors. It feeds the slip power back to the grid through certain electronic devices and uses it. It is more widely used in fan and pump transmission systems.

 

　　4. AC braking motor voltage regulation speed control

 

　　It connects thyristors in reverse parallel to form a communication speed regulation circuit. By adjusting the trigger angle of the thyristor, the terminal voltage of the asynchronous motor is changed to control the speed. This method also changes the slip. The slip power is consumed in the rotor circuit, the efficiency is low, and it is more suitable for special rotor motors (such as deep-groove motors) and other high-slip motors. Usually, this speed control method should constitute a speed or voltage closed loop for practical application.

 

　　5. Electromagnetic speed control asynchronous motor.

 

　　This system transmits mechanical power through electromagnetic coupling. Through the electromagnetic coupler between the asynchronous motor and the load, the magnitude of the slip can be adjusted to achieve the purpose of speed regulation. The AC braking motor speed regulation system has a simple structure and low price, and is suitable for simple adjustment systems, but its slip power is consumed on the coupler, and the efficiency is low.

 

　　6. AC braking motor frequency conversion speed control

 

　　Changing the power frequency can enable the asynchronous motor to obtain different synchronous speeds. The method of using a frequency converter for asynchronous motor speed regulation is rarely used, and currently used is a static frequency converter power supply. Semiconductor devices. Currently, this speed control method has become the mainstream of AC speed control development.

 

　　The above is an overview of " AC braking motor Frequency conversion speed regulation working principle", please take a look.