1. Home
  2. Knowhow

Types of variable frequency motors

Date:2023-11-28   Author:XINDA MOTOR

Types of variable frequency motors 

Variable frequency motor refers to the general term for motors driven by frequency converters. Variable frequency speed regulation is currently replacing traditional mechanical speed regulation at a very fast speed due to its advantages such as high efficiency, wide speed range, high precision, smooth speed regulation, and stepless speed change. speed and DC speed regulation scheme.

Common variable frequency motors include: three-phase asynchronous motors, DC brushless motors, AC brushless motors and switched reluctance motors, etc.

1. Three-phase asynchronous motor  

In a three-phase AC motor, the three-phase alternating current in the stator winding generates a rotating magnetic field on the circumference of the stator gap. The speed of this rotating magnetic field is called the synchronous speed, recorded as n. The actual motor speed n is lower than the synchronous speed, so it is generally called this Three-phase asynchronous motor. In principle, we can know that the rotation speed of a three-phase asynchronous motor is directly proportional to the stator power frequency. Frequency conversion speed regulation is a speed regulation method that changes the frequency of the motor stator power supply, thereby changing its synchronous speed.

With the rapid development of electronic technology, the application of variable frequency speed-regulated three-phase AC asynchronous motors is becoming more and more widespread. It has gradually replaced various other speed-regulated motors. The variable frequency speed-regulated three-phase asynchronous motors are simple in structure and easy to manufacture. , easy to maintain, good performance, reliable operation and other advantages, it is widely used in the industrial field.

2. Brushless DC motor

Brushless DC motors use semiconductor switching devices to achieve electronic commutation, that is, electronic switching devices are used to replace traditional contact commutators and brushes. It has the advantages of high reliability, no commutation sparks, and low mechanical noise. It is widely used in high-end audio recorders, video recorders, electronic instruments and automated office equipment. The brushless DC motor is composed of a permanent magnet rotor, a multi-pole winding stator, and a position sensor. Position sensing commutates the current of the stator winding in a certain order according to the change of the rotor position. The operating voltage for the stator windings is provided by an electronic switching circuit controlled by the position sensor output.

3. Switched reluctance motor

The switched reluctance motor is a new type of stepless speed regulation motor that emerged with the development of modern power electronics technology, control technology and digital computer technology. It is a typical electromechanical integration product. Because it utilizes the principle of minimum reluctance, it is called a reluctance motor. And because the coil current is turned on and off and the magnetic flux state is directly controlled by the switch, it is called a switched reluctance motor.

Switched reluctance speed regulating motor has good speed regulating performance and high-speed operation characteristics, and has the advantages of DC drive and ordinary AC drive. It is gradually used in household appliances, general industry, servo and speed control systems, traction motors, high-speed motors, etc. In the fields of aerospace equipment and automotive auxiliary equipment, it has become a strong competitor in AC motor speed control systems, DC motor speed control systems and brushless DC motor speed control systems.