Generally, 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 motors of many low-power motors are integrated with the commutation circuit. From the appearance, the DC brushless motors are exactly the same as the DC motors.
The motor of the DC brushless motor is the 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 DC brushless 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 can get rid of the traditional design and structure of the general DC motor, meet the requirements of various application markets, and develop towards the direction of saving copper, saving materials and simple manufacturing. The development of permanent magnet 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 achieve 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 electronic position sensors or other methods have been gradually used to obtain position signals. The easiest way is to use the potential signal of the armature winding as the position signal.
To realize the control of the motor speed, there must be a speed signal. The speed signal is obtained by the similar method of obtaining the position signal. The simplest speed sensor is a combination of a frequency-measuring tachogenerator and an electronic circuit.