Sep 27, 2020
1、 According to the working principle of the brushless DC motor and the brushless motor.
DC brush motor is composed of commutator, magnetic pole and coil. Mechanical commutator is used for commutation. The stator composed of magnetic pole does not move and the rotor composed of coil is rotating. When the motor works, the rotor and the commutator rotate, the stator and carbon brush do not rotate, and the alternating change of the rotor current direction is completed by the commutator and the electric brush.
The working process of DC brush motor: the two coil ends of each group of coils on the rotor form a closed loop in turn. The coils and coils are separated by insulating materials and matched with silicon steel sheet to form a cylinder. The motor shaft passes through the middle to form the rotor together. The power supply is pressed from two specific fixed positions by two carbon brushes under the action of spring pressure On the commutator. Each coil is electrified by commutator in turn, and the rotor rotates in a certain direction under the action of magnetic force of stator magnetic field.
The commutator will rub the carbon brush in the process of rotation, causing loss, so it is necessary to replace the carbon brush regularly; the electric spark occurs alternately between the carbon brush and the commutator, which produces electromagnetic breakdown and interferes with electronic equipment, which is the disadvantage of brush motor.
The working principle of brushless motor is different. It adopts electronic commutation, the coil does not move and the magnetic pole rotates. Through the brushless controller, the coil is electrified according to a certain law to generate an alternating magnetic field. Under the action of the alternating magnetic field force, the magnetic pole rotates. At the same time, the position of the rotor is judged by the hall element, which is fed back to the brushless controller. The magnetic direction is adjusted by the brushless controller to drive the rotor to rotate. The disadvantages caused by the carbon brush commutation of brush motor are completely solved.
Our company combined with practical experience, developed different power brushless motor controllers of dc10-48dpw15bl and dc10-48dpw30bl. Through the control of the brushless motor controller, we can achieve some functions that the brush motor can not achieve, such as adjusting the power supply switching angle, braking the motor, making the motor reverse, locking the motor, and stopping the motor quickly through the brake function.
2、 Speed control principle to distinguish.
Although the control mode of the two motors is voltage regulation, the brushless DC motor adopts electronic commutation, so it should work with the brushless controller. However, the brush DC motor is commutating by carbon brush, which can be controlled by traditional analog circuits such as pulse width modulation and silicon controlled rectifier modulation.
The PWM, SCR series DC motor driver developed by our company is a speed regulating product developed and produced on the basis of absorbing the previous successful experience and combining with modern advanced technology. This series of products have reached the requirements of international standards and are exported to many countries. The driver is based on SCR chopping principle and unique trigger mode. It can achieve high speed regulation ratio without speed feedback, and its control is more accurate and reliable.
Its excellent performance, reliable quality and high cost performance make it a leader in the field of DC motor drive. It is widely used in plastic machinery, food machinery, cable equipment, mechanical processing, paper printing, test equipment, laboratory equipment, mixing equipment and other fields.
3、 Performance difference:
1. Brush motor has simple structure, long development time and mature technology. Due to its simple mechanism, easy production and processing, convenient maintenance and easy control, DC motor also has fast response, large starting torque, and can provide rated torque from zero speed to rated speed, so it has been widely used.
2. DC brush motor has the advantages of fast response, large torque, stable speed change, almost no vibration from zero to maximum speed, and it can drive more load when starting. The starting resistance of brushless motor is large (inductive reactance), so the power factor is small, the starting torque is relatively small, there is a buzzing sound when starting, accompanied by strong vibration, and the driving load is small when starting.
3. DC brush motor runs smoothly and has good starting and braking effect. The speed of brush motor is regulated by voltage regulation, so the starting and braking are stable, and the operation at constant speed is also stable. Brushless motor is usually controlled by digital frequency conversion, which changes AC into DC, DC and then AC. the speed is controlled by frequency change. Therefore, the brushless motor runs unsteadily and vibrates heavily when starting and braking, and it will be stable only when the speed is constant.
4. DC brush motor has low cost and convenient maintenance. The technology of brushless motor is immature and its price is high. 5. Brushless motor without brush, low interference, low noise, smooth operation, long life, low maintenance cost.