The difference between brushless DC motor and brushed DC motor

The difference in working principle:

The brushed motor adopts mechanical commutation, the magnetic pole does not move, and the coil rotates. The main structure of the brushed motor is the stator + rotor + brushes, and the rotational torque is obtained through the rotating magnetic field, thereby outputting kinetic energy. The brushes and the commutator are in constant contact and friction and play the role of conduction and commutation during rotation.

The brushless motor adopts electronic commutation, the coil does not move, and the magnetic pole rotates. The brushless DC motor is composed of a motor body and a driver and is a typical mechatronic product. The brushless motor senses the position of the poles of the permanent magnet through the Hall element. According to this perception, the electronic circuit is used to switch the direction of the current in the coil in a timely manner to ensure that the magnetic force in the correct direction is generated to drive the motor.

The difference in performance:

The brushed DC motor technology is more mature, the starting response speed is faster, the starting torque is larger, the operation is smoother, and the control accuracy is higher. The DC brushed motor has a simple mechanism and is easy to produce and process. It was widely used in the 19th century, and its technology development is relatively mature. However, brushless DC motors have only been put into commercial operation in the past ten years, and the technology is relatively immature. DC brushed motors have fast starting response speed, large starting torque, and smooth speed change, while brushless motors have large starting resistance (inductive reactance) and relatively small starting torque. The DC brushed motor has higher output power and higher control precision, which can reach 0.01mm, which can make the moving parts stop almost anywhere you want. All precision machine tools use DC motors to control precision.

Brushless DC motors have less disturbance, less noise, longer life and lower maintenance costs. Compared with brushed DC motors, brushless DC motors have removed the brushes. The most direct change is that there is no electric spark generated when the brushed motor is running, which greatly reduces the interference of electric sparks on remote control radio equipment. There are no brushes in the brushless motor, the friction force is greatly reduced during operation, the operation is smooth, and the noise will be much lower. This advantage is a huge support for the stability of the model operation. Without the brush, the wear of the brushless motor is mainly on the bearing. From a mechanical point of view, the brushless motor is almost a maintenance-free motor. When necessary, only some dust removal maintenance is required.

The difference in speed regulation:

In fact, the control of the two motors is voltage regulation, but because the brushless DC uses electronic commutation, it can only be realized with digital control, while the brushed DC is commutated through carbon brushes, using silicon controlled rectifiers, etc. Traditional analog circuits can be controlled and are relatively simple.