Second, the introduction of brushless DC motor
The "BL" in the BLDC motor means "brushless", that is, the "brush" in the DC motor (brushed motor) is gone.
The brushless DC motor (BLDC) replaces the mechanical commutator with an electronic commutator, so the brushless DC motor has the characteristics of good speed regulation performance of the DC motor, and has the simple structure of the AC motor, no commutating spark, and reliable operation. And easy to maintain and other advantages.
The brushless DC motor is mainly composed of a rotor made of a permanent magnet material, a stator with coil windings, and a position sensor (with or without). It can be seen that it has much in common with DC motors. The structure of the stator and rotor is similar (the original stator becomes the rotor, the rotor becomes the stator), and the windings are basically the same. However, there is a significant difference in the structure: brushless DC motors do not have commutators and brushes in DC motors, but instead are position sensors. In this way, the motor structure is relatively simple, reducing the manufacturing and maintenance costs of the motor, but the brushless DC motor cannot be automatically commutated (phase), at the expense of the cost of the motor controller (such as the same three-phase DC motor, there are The drive axle of the brush DC motor requires 4 power tubes, while the drive axle of the brushless DC motor requires 6 power tubes).
Figure 1 shows one of the low-power three-phase, star-connected, single-pair magnetic-pair brushless DC motors with the stator inside and the rotor outside. Another brushless DC motor has the same structure as this, except that its stator is outside and the rotor is inside, that is, the stator is a frame composed of coil windings, and the rotor is made of a permanent magnet material.
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