Detailed description of the difference between brush motor and brushless motor
First, the difference between the speed control method
In fact, the control of the two motors is voltage regulation, only because the brushless DC uses electronic commutation, so digital control can be achieved, while brushed DC is commutated by carbon brush, using thyristor, etc. Traditional analog circuits can be controlled and are relatively simple.
1. The brush motor speed regulation process is to adjust the voltage of the motor power supply voltage. The adjusted voltage and current are converted by the commutator and the brush to change the strength of the magnetic field generated by the electrode to achieve the purpose of changing the rotational speed. This process is called variable voltage speed regulation.
2. The brushless motor speed regulation process is that the voltage of the power supply of the motor is constant, the control signal of the ESC is changed, and the switching speed of the high-power MOS tube is changed by the microprocessor to realize the change of the rotation speed. This process is called variable frequency speed regulation.
Second, the performance difference
1. The brush motor has a simple structure, long development time and mature technology.
When the motor was born in the 19th century, the practical motor produced was the brushless form, that is, the AC squirrel-cage asynchronous motor, which was widely used after the generation of AC power. However, asynchronous motors have many insurmountable defects, resulting in slow development of motor technology. In particular, DC brushless motors have been unable to be put into commercial operation. With the rapid development of electronic technology, it has only been slowly put into commercial operation in recent years. In essence, it still belongs to the category of AC motors.
Shortly after the birth of the brushless motor, people invented the DC brush motor. Because the DC brush motor mechanism is simple, the production process is easy, the maintenance is convenient, and the control is easy; the DC motor also has a fast response, a large starting torque, and a performance capable of providing rated torque from zero speed to a rated speed, so that once it is released It has been widely used.
2. DC brush motor has fast response speed and large starting torque
The DC brush motor has a fast starting response speed, a large starting torque, a stable shifting speed, almost no vibration from zero to maximum, and a larger load at the start. The brushless motor has a large starting resistance (inductive reactance), so the power factor is small, the starting torque is relatively small, there is a click when starting, and accompanied by strong vibration, the load is small when starting.
3. The DC brush motor runs smoothly, and the starting and braking effects are good.
The brush motor is regulated by voltage regulation, so the starting and braking are stable, and it is stable even at constant speed. The brushless motor is usually digital frequency conversion control. First, the alternating current is converted into direct current, and the direct current becomes alternating current. The speed is controlled by the frequency change. Therefore, the brushless motor runs unevenly during starting and braking, and the vibration is large, only when the speed is constant. Will be smooth.
4, DC brush motor control accuracy is high
The DC brush motor is usually used together with the reduction gear box and the decoder to make the motor have higher output power, higher control precision, and control precision of 0.01 mm, which can almost move the moving parts to any desired place. All precision machine tools use DC motor control accuracy. Since the brushless motor is not stable during starting and braking, the moving parts are stopped at different positions each time, and must be stopped by the positioning pin or the stopper to the desired position.
5, DC brush motor is low in cost and easy to maintain. Because the DC brush motor has a simple structure, low production cost, many manufacturers, and mature technology, it is also widely used, such as factories, machine tools, precision instruments, etc. If the motor is faulty, just replace the carbon brush, each The carbon brush only costs a few yuan and is very cheap. The brushless motor technology is immature, the price is high, and the application range is limited. It should be mainly on constant speed equipment, such as inverter air conditioners, refrigerators, etc. The brushless motor can only be replaced.
6, no brush, low interference
The brushless motor removes the brush, and the most direct change is that there is no spark generated when the brush motor is running, which greatly reduces the interference of the spark to the remote control radio.
7, low noise, 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 great support for the stability of the model operation.
8, long life, low maintenance costs
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 need to do some dust removal maintenance.
