Brushless Electric Motor for Passage Gate and Its Advantages Oct 06, 2020

1. Definition of brushless electric motor

Brushless electric motors, also called brushless DC motors, use semiconductor switching devices to achieve electronic commutation, that is, electronic switching devices are used to replace traditional contact commutators and brushes. It has the advantages of high reliability, no reversing sparks, low mechanical noise, etc., and is widely used in high-end audio jacks, video recorders, electronic instruments and automated office equipment.

2. Analysis of Brushless electric motor structure

In terms of structure, brushless motors and brushed motors have similarities. They both have rotors and stators, but the structure is opposite to that of brushed motors; the rotor of brushed motors is a coil winding connected to the power output shaft, and the stator is the permanent magnet steel; The rotor of the brushless motor is permanent magnet steel, which is connected with the output shaft together with the casing. The stator is a winding coil. The commutation brush used by the brush motor to alternately transform the electromagnetic field is removed, so it is called a brushless motor. Now there is a problem: without the transformation of the electromagnetic field, how to make the brushless motor rotate?

3. Operating principle of brushless motor

Simply put, by changing the alternating frequency and waveform of the current wave input to the stator coil of the brushless motor, a magnetic field is formed around the winding coil to rotate around the geometric axis of the motor. When the magnetic field drives the permanent magnet on the rotor to rotate, the motor starts to rotate. The performance of the motor is related to the number of magnets, the magnetic flux intensity of the magnets, and the input voltage of the motor. It also has a lot to do with the control performance of the brushless motor, because the input is direct current, and the current needs electronics. The governor turns it into a 3-phase alternating current. It also needs to receive a control signal from the remote control receiver to control the speed of the motor to meet the needs of the model. In general, the structure of the brushless motor is relatively simple, and the real decision of its performance is the brushless electronic speed controller. A good electronic speed controller requires the process of single-chip control program design, circuit design, and complex processing technology. so the price is much higher than the brush motor.

4. Comparison of advantages and disadvantages of brushless motor and brush motor

Disadvantages of brush motors

1) Large friction and large loss

Old model friends have encountered this problem when playing with brushed motors before. After using the motor for a period of time, the motor needs to be opened to clean the carbon brushes of the motor, which is time-consuming and laborious, and the maintenance intensity is no less than a home cleaning.

2) Large heat and short life

Due to the structure of the brush motor, the contact resistance between the brush and the commutator is very large, which causes the overall resistance of the motor to be large and easy to generate heat. The permanent magnet is a thermal element. If the temperature is too high, the magnetic steel will demagnetize, making the performance of the motor reduced, and the life of the brushed motor affected.

3) Low efficiency and low output power

The heating problem of the brushed motor mentioned above is largely due to the fact that the current is done on the internal resistance of the motor, so the electrical energy is largely converted into heat energy, so the output power of the brushed motor is not high and the efficiency is not high.

Brushless motor advantages

1) No brush, low interference

The brushless motor removes the brush, and the most direct change is that there is no electric spark generated when the brush motor is running, which greatly reduces the interference of the electric spark to the remote control radio equipment.

2) Low noise and smooth operation

The brushless motor has no brush, the friction is greatly reduced during operation, the operation is smooth, and the noise is much lower. This advantage is a huge support for the stability of the model.

3) Long life and low maintenance cost

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, you only need to do some dust removal maintenance.