Working principle of brushless motor

In brushless motor, the commutation is completed by the control circuit of the controller (usually Hall sensor controller, and the more advanced technology is magnetic encoder).


Brushless motor adopts electronic commutation, coil does not move, and magnetic pole rotates. Brushless motor is to use a set of electronic equipment to sense the position of permanent magnet pole through Hall element SS2712. According to this perception, the electronic circuit is used to switch the direction of current in coil in time to ensure that the magnetic force in the correct direction can be generated to drive the motor. The shortcomings of brushing motor are eliminated.


These circuits are motor controllers. The controller of brushless motor can also realize some functions that can not be realized by brushless motor, such as adjusting the switching angle of power supply, braking motor, turning the motor upside down, locking the motor, using braking signal, stopping supplying power to the motor. Now the electronic alarm lock of battery car makes full use of these functions.


Brushless DC motor is composed of motor body and driver, which is a typical mechatronics product. Because the brushless DC motor is operated by automatic control, it will not add the starting winding on the rotor like the synchronous motor with heavy load start under frequency conversion speed regulation, nor will it produce oscillation and out of step when the load is abrupt.


The difference of Speed Regulation between Brushless Motor and Brushless Motor


In fact, the control of the two kinds of motor is voltage regulation, only because brushless DC adopts electronic commutation, so digital control can be realized, while brush DC can be controlled by carbon brush, using thyristor and other traditional analog circuits, which is relatively simple.


1. The speed regulation process of the brush motor is to adjust the power supply voltage of the motor. The regulated voltage current is converted by a commutator and a brush, so that the intensity of the magnetic field generated by the electrode is changed, and the purpose of changing the rotating speed is achieved. This process is called a pressure-varying speed regulation.


2. The speed regulation process of the brushless motor is that the voltage of the power supply power supply of the motor is unchanged, the control signal of the electric adjustment is changed, and the switching speed of the high-power MOS tube is changed by the microprocessor to realize the change of the rotating speed. This process is called variable frequency speed regulation.