Brief Introduction Of DC Brushless Motor

Ordinary DC motors have the same working principle and application characteristics, but their composition is different. In addition to the motor itself, the former also has an additional commutation circuit, and the motor itself and the commutation circuit are closely integrated. The motor itself of many low-power motors is integrated with the commutation circuit. From the appearance, the brushless DC motor is the same as the DC motor.

The motor itself of the DC brushless motor is an electromechanical energy conversion part. In addition to the motor armature and permanent magnet excitation, it also has sensors. The motor itself is the core of the brushless DC motor. It is not only related to performance indicators, noise and vibration, reliability and service life, but also involves manufacturing costs and product costs. Due to the permanent magnetic field, the DC brushless motor gets rid of the traditional design and structure of the ordinary DC motor, meets the requirements of various application markets, and develops towards the direction of saving copper and materials and cumbersome manufacturing. The development of the permanent magnetic field is closely related to the application of permanent magnet materials. The application of the third generation of permanent magnet materials promotes the development of brushless DC motors in the direction of high efficiency, miniaturization and energy saving.

In order to complete the electronic commutation, there must be a position signal to control the circuit. In the early days, electromechanical position sensors were used to obtain position signals, and now electronic position sensors or other methods are gradually used to obtain position signals. The cumbersome method is to use the potential signal of the armature winding as the position signal.

To complete the control of the motor speed, a speed signal is necessary. The speed signal is obtained by the similar method of obtaining the position signal. The simple speed sensor is a frequency measuring type tachogenerator separated from the electronic circuit.
The commutation circuit of the DC brushless motor is composed of two parts: drive and control. These two parts are not easy to separate. Especially for low-power circuits, the two are often integrated into a single application-specific integrated circuit.

In a motor with a higher power, the drive circuit and the control circuit can each be integrated. The drive circuit outputs electric power, drives the armature winding of the motor, and is controlled by the control circuit. The drive circuit has changed from a linear amplification state to a pulse width modulation switching state, and the corresponding circuit composition has also changed from a transistor discrete circuit to a modular integrated circuit. Modular integrated circuits are composed of power bipolar transistors, power field effect transistors and isolation gate field effect bipolar transistors. Of course, the isolation gate field effect bipolar transistor is more expensive, but from the perspective of reliability, safety and performance, it is still more suitable to choose.

The control circuit is used to control the speed, steering, current (or torque) of the motor and maintain the overcurrent, overvoltage, overheating, etc. of the motor. The above parameters are easily converted into analog signals, which is relatively simple to control, but from the perspective of development, the parameters of the motor should be converted into digital quantities, and the motor is controlled through a digital control circuit. At present, the control circuit has three kinds of composition methods: application-specific integrated circuit, microprocessor and digital signal processor. In places where the requirements for motor control are not high, it is a simple and practical way to form a control circuit with an ASIC. The use of digital signal processors to form control circuits is the future development direction, and the relevant digital signal processors will be introduced in the following AC synchronous servo motors.

In the small power range, the DC brushless motor is a new type of motor that develops rapidly. Since each application field requires its own unique DC brushless motor, there are many types of DC brushless motors. Generally, there are flat non-dead center motor structures for computer external memory, VCD, DVD, and CD spindle drives, external rotor motor structures for small fans, multi-pole magnetic field structures and built-in structures for home appliances, and multi-pole and external rotors for electric bicycles. structure and so on. The motor itself and the circuit of the above-mentioned DC brushless motor are integrated, which is very convenient to use, and its output is also very large. In order to meet the market demand of large quantities and low cost, the production of brushless DC motors must form economies of scale. Therefore, DC brushless motor is a high-input, high-output industry. At the same time, we should take into account that the market is also constantly developing, such as the motor for household air conditioners is changing from 3A to 3D.

The above is a brief understanding of the brushless motor we introduced to you. Welcome to consult us for performance testing and customized services for your samples.