Problem solving

What is a brushless DC motor?
Release Date : 2020-08-07 17:51:24
Brushed DC motors have many advantages, such as high efficiency, the potential for downsizing, the ability to run on electricity, and lower manufacturing costs. However, these motors have many disadvantages, such as noise due to brush friction, generation of sparks and electrical noise, and limited life due to brush wear. The development of brushless DC motors has solved all these problems. Introduction of brushless motor, brush motor, servo motor, stepper motor, reducer
 
In a brushless DC motor, the rotor made of permanent magnets is driven by the magnetic force of the stator winding circuit.
Brushed DC motors use brushes and commutators for current switching, while brushless DC motors use sensors and electronic circuits for current switching.

 


The development of this motor is possible due to the development of semiconductor and peripheral equipment technology. The motor has the advantageous characteristics of a DC motor (current and voltage are proportional to torque and speed respectively) and an AC motor (brushless structure). Brushless DC motors are characterized by small size, high output power, long life, and no sparks and noise, and are widely used in various applications from PCs to household appliances.
 
 
Brushless DC motor structure
Brushless DC motors use permanent magnets in the rotor of a three-phase motor. In addition, inside the stator, a Hall-effect IC (magnetic sensor) is built-in to detect the change in the magnetic field of the permanent magnet and compare the feedback signal of the motor Hall-effect IC with the set speed. It is controlled by the controller and continuously adjusts the motor speed.


 


The characteristic of the brushless DC motor is that there is a three-phase (U, V and W three-phase) star-shaped (Y-shaped) star-shaped coil in the stator, and the rotor is made of magnets with multi-pole configuration.
Inside the stator, three Hall ICs are arranged as magnetic elements, so the phase difference of the output signal of each Hall IC will be 120 degrees apart as the rotor rotates.
 
The brushless DC motor actually flips from the inside out, eliminating the need to use brushes to flip the electromagnetic field. In a brushless DC motor, the permanent magnet is located on the rotor and the electromagnet is located on the stator. The computer then charges the electromagnet in the stator to rotate the rotor 360 degrees.

 
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