Permanent Magnet Brushless Motor Magnet
Brushless motor is a typical mechatronics product, which is composed of motor body and driver. Since the brushless DC motor operates in a self-control mode, it will not add a starting winding on the rotor like the synchronous motor started under heavy load under variable frequency speed regulation, nor will it produce oscillation and out of step when the load changes suddenly.
Introduction
Brushless motor is a typical mechatronics product, which is composed of motor body and driver. Since the brushless DC motor operates in a self-control mode, it will not add a starting winding on the rotor like the synchronous motor started under heavy load under variable frequency speed regulation, nor will it produce oscillation and out of step when the load changes suddenly. The permanent magnets of small and medium-sized brushless DC motors now mostly use rare earth neodymium iron boron (Nd-Fe-B) materials with high magnetic energy level. Therefore, the volume of rare earth permanent magnet brushless motor is one frame number smaller than that of three-phase asynchronous motor with the same capacity.
Working principle
Permanent magnets are used in the rotor of brushless motor, which are mostly neodymium magnet blocks and neodymium magnet tiles. The stator is an excitation coil, but the structure of the permanent magnet inside is also different, which is often divided into surface mount type and embedded type.
The difference is:
The surface mount direct quadrature axis inductors Ld and Lq are the same, with large air gap, small magnetic weakening ability and limited speed expansion ability.
Embedded AC-DC axis inductance: Lq > Ld, small air gap and good magnetic weakening ability.
performance requirements
The brushless motor mainly uses high-performance rare earth neodymium magnet, because the power of the motor is closely related to the performance of the magnet. It can be understood that the Volume and Grade of neodymium magnet determine the maximum power of the motor.
Common shape
The shape of brushless motor magnet mainly includes Square magnet, Tile (Arc) magnet, Ring magnet and Bread magnet.
Advantages of Square magnet: simple processing and relatively cheap price
Advantages of Tile/Arc magnet: arc can ensure that the air gap between magnet and silicon steel sheet is consistent, and it is superior to square magnet in power and efficiency.
Advantages of Bread shaped magnet: according to professionals, they think this kind of magnet has better effect than arc magnet.
Advantages of Ring magnet: convenient installation, superior performance, high-end generally use ring.
Requirements for the number of magnet poles
The less the pole, the higher the speed.
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