Basic structure and working principle of brushless DC motor

As the market has increasingly higher requirements for energy saving and quiet operation of motors, brushless DC (BLDC) motors are widely used in various occasions. First, the structure of the brushless DC motor is introduced, and then the basic principle and working principle of the linear stepper motor, as well as its advantages and applications are introduced.

Brief introduction of brushless DC motor:

Brushless DC motor (BLDC) is a type of permanent magnet synchronous motor, rather than a real DC motor, referred to as BLDC in English. Different from the brushed DC motor, the brushless DC motor does not use a mechanical brush device. It adopts a square wave self-control permanent magnet synchronous motor, replaces the carbon brush commutator with a Hall sensor, and uses neodymium iron boron as the permanent magnet material of the rotor , Compared with the general traditional DC motor in performance, it has great advantages.

Brushless DC motor structure diagram:

Brushless DC motors are the most ideal speed-regulating motors today.

Basic principle of brushless DC motor:

The brushless DC motor is composed of a motor body and a driver, and is a typical mechatronic product. The stator windings of motors are mostly made into three-phase symmetrical star connection, which is very similar to three-phase asynchronous motors. Magnetized permanent magnets are glued to the rotor of the motor. In order to detect the polarity of the motor rotor, a position sensor is installed in the motor. The driver is composed of power electronics and integrated circuits. Its function is to receive the start, stop, and brake signals of the motor to control the start, stop and brake of the motor; to receive the position sensor signal and the forward and reverse signals to control the reverse The on and off of each power tube of the variable bridge produces continuous torque; accepts speed commands and speed feedback signals to control and adjust the speed; provide protection and display, etc. Because the brushless DC motor runs in a self-control mode, it will not add a start winding to the rotor like a synchronous motor that is started under heavy load under variable frequency speed regulation, nor will it oscillate and lose step when the load changes suddenly.

The advantages of brushless DC motors:

① The advantage of the brushless DC motor is that no spark is generated during the commutation process of the brushless DC motor, while a small amount of sparks are generated during the commutation process of the ordinary brush motor;

② The life of brushless DC motors is generally between tens of thousands of hours, while the life of ordinary brushless motors is generally between 1000-2000 hours;

③No oscillation and loss of synchronization will occur when the load changes suddenly.

Application areas of brushless DC motors:

Winding machine, treadmill. Some machines on medical centrifuges, jet dryers, and textile machinery are all brushless. Brushless DC motors are widely used, such as automobiles, tools, industrial control, automation, and aerospace. In general, brushless DC motors can be divided into the following three main uses: ① continuous load applications; ② variable load applications; ③ positioning applications.