Why permanent magnet motors are becoming increasingly popular

In recent years, the most high-profile electric motor industry is undoubtedly the permanent magnet motor, which is becoming increasingly popular. The reason for such a sensational effect lies not only in the driving force of energy-saving and environmentally friendly economic development models, but also in the inherent characteristics of permanent magnet motors.

The latest achievements in high-energy permanent magnet materials, strong magnetic materials, and power electronics technology have greatly promoted the application fields of permanent magnet motors, such as robots, aerospace, electric tools, generators, new energy, various medical equipment, and electric or hybrid vehicles. Permanent magnet motors are everywhere, and without exception, it declares the fact that permanent magnet motors have advantages that surpass brushless commutation DC motors There are many advantages to traditional motors such as synchronous motors and induction motors.

(1) The copper loss of the rotor is zero, resulting in higher natural efficiency;

(2) High driving torque and output power per unit volume make compact design solutions possible;

(3) Eliminating slip rings, phase converters, carbon brushes, etc. simplifies motor structure and maintenance;

(4) The air gap magnetic flux density is relatively high compared to traditional motors, resulting in better dynamic performance;

(5) Can operate at high power factor;

(6) A simple six phase switching voltage source can achieve precise torque, speed, and position control.

The permanent magnet synchronous motor is mainly composed of various components such as the rotor, end cover, and stator. The stator structure of permanent magnet synchronous motors is very similar to that of ordinary induction motors. The biggest difference between the rotor structure and asynchronous motors is that high-quality permanent magnet poles are placed on the rotor. Depending on the position of the permanent magnet on the rotor, permanent magnet synchronous electric motors are usually divided into surface rotor structure and built-in rotor structure.

The placement of permanent magnets has a significant impact on the performance of electric motors. Surface type rotor structure - The permanent magnet is located on the outer surface of the rotor core. This type of rotor structure is simple, but produces very small asynchronous torque, which is only suitable for situations with low starting requirements and is rarely used. Built in rotor structure - The permanent magnet is located in the iron core between the squirrel cage guide bar and the shaft, with good starting performance. The vast majority of permanent magnet synchronous motors adopt this structure.

The starting and operation of a permanent magnet synchronous motor is formed by the interaction of the magnetic field generated by the stator winding, rotor squirrel cage winding, and permanent magnet. When the motor is stationary, a three-phase symmetrical current is applied to the stator winding, generating a stator rotating magnetic field. The stator rotating magnetic field generates current in the cage winding relative to the rotor rotation, forming a rotor rotating magnetic field. The asynchronous torque generated by the interaction between the stator rotating magnetic field and the rotor rotating magnetic field causes the rotor to accelerate from stationary. During this process, the speed of the rotor permanent magnetic field and the stator rotating magnetic field are different, resulting in alternating torque.

When the rotor accelerates to a speed close to synchronous speed, the speed of the rotor permanent magnetic field and the stator rotating magnetic field are close to equal. The speed of the stator rotating magnetic field is slightly higher than that of the rotor permanent magnetic field, and their interaction generates torque to pull the rotor into synchronous operation. In synchronous operation, no current is generated in the rotor winding. At this time, only the permanent magnet on the rotor generates a magnetic field, which interacts with the rotating magnetic field of the stator to generate driving torque. It can be inferred that the permanent magnet synchronous motor is started by the asynchronous torque of the rotor winding. After startup, the rotor winding is no longer functional, and the driving torque is generated by the interaction of the magnetic field generated by the permanent magnet and stator winding.

To do a good job in permanent magnet motors, a key accessory is indispensable: permanent magnet materials, neodymium iron boron permanent magnets. Dongguan Xinyuan Magnetic Products Co., Ltd. has a self built neodymium iron boron raw material sintering factory, engaged in the production and processing of neodymium iron boron permanent magnets for more than 30 years, and has rich experience in the production of motor magnetic steel. Our technical research and development team can cooperate and support customers, participate in product supporting research and development, and provide corresponding technical support to achieve faster and better research and development.