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Changzhou High-Efficiency Motors Co., Ltd.
Changzhou High-Efficiency Motors Co., Ltd.

Application of Brushless DC Motor in Automotive Industry

Ⅰ. Understand the brushless DC motor


Brushless DC motors, as the name implies, do not use brushes. Instead of utilizing a commutator to regulate the current inside the coils, a brushless DC motor uses an electronic commutator to pass current, which generates an AC signal that causes the motor to drive. Brushless DC motors work similarly to brushed DC motors. Lorentz's law of force states that whenever a current-carrying conductor is placed in a magnetic field, it experiences a force. Due to the reaction force, the magnets will experience equal and opposite forces.


Ⅱ. The role of brushless DC motors in automobiles


1. Brushless DC motor for automobile wheel drive. At present, the types of motors used to drive vehicle wheels can be roughly divided into four categories: DC brush motors, AC induction motors, brushless DC motors, reluctance motors, etc. After practice, it is believed that brushless DC motors have obvious advantages. The four electric vehicles are directly driven by four independent wheel motors. The inverter is used for electronic commutation, and the mechanical commutator and brushes are eliminated. This structure is convenient for high-speed operation and does not affect the motor body when changing tires, which is very simple and convenient.


2. Brushless DC motors for automotive air conditioners. The development of low-voltage and high-current brushless DC motors for automotive air conditioners can solve the shortcomings of brushed DC motors, such as high noise, short life and difficult maintenance, and improve the performance of the motor. Its rated voltage is 2V. Due to the limited structure, it adds difficulties to the design of the brushless DC motor. The stator punching is a 2-slot structure. Since it is a low-voltage and high-current type, in order to ensure that the current density will not be too high, double wires are wound in parallel to reduce the wire diameter; the rotor is a 4-pole structure with permanent magnets pasted on the surface. The rare earth permanent magnet material NdFeB is selected. Since the remanence and coercive force of NdFeB are high and the magnetization direction is short, the permanent magnet adopts radial tile type.


3. Brushless DC motors for car purifiers. Car purifiers mostly use brushless DC motors to drive centrifugal fan blades to discharge dirty air. The brushless DC motor body is determined according to the motor circuit scheme, and a two-phase bridge commutation drive circuit is commonly used. The inner stator winding can be more conveniently wound on the core teeth. The brushless DC motor is made into an outer rotor structure, and the stator and stator windings are placed inside the rotor. The commutation drive circuit adopts an application-specific integrated circuit (ASIC), which is simple and has control and protection functions.