Shanghai Peaks, who is specialized in DC brushless motors, will introduce you the basic knowledge about motors. In the process of industrial development, the emergence of motor can be said to be a revolutionary achievement, because the drive of motor is the basis of industrial development, and DC motor is one of the most frequently used ones. DC motor refers to the transmission of DC power to DC motor and the conversion of electrical energy of DC motor into mechanical energy.
In DC motors, according to the different connection modes of excitation winding, they can be divided into four types of motors: separately excited, parallel excited, series excited and compound excited. In speed control systems, separately excited motors are used more frequently.
In recent years, the industry of small and medium-sized motors and micro and special motors in China has developed rapidly, among which the brushless DC motor has gradually replaced the brushless motor with its low noise characteristics and become a new star in the industry application. This is more prominent in China's leading outsourcing service platform, Fast Pack. It is reported that the brushless motor almost monopolizes the platform motor control task demand with 78% of the fast pack 100+motor control tasks.
Knowledge point 1
DC motors can be classified into several categories: compound excitation DC motors, series excitation DC motors, parallel excitation DC motors, and separate excitation DC motors.
Knowledge point 2
The applied brushless DC motor is developed on the basis of the DC motor. The permanent magnet brushless DC motor developed on the basis of the traditional DC motor is basically the same in structure. The difference is that the armature winding of the permanent magnet brushless DC motor is placed on the stator, which is similar to the winding of the AC motor. At the same time, it is generally in the form of multi-phase. At present, three-phase application is more common; The rotor is a permanent magnet and adopts electronic commutation. The interaction between the stator magnetic field and the rotor permanent magnetic field generates electromagnetic torque. According to the shape and magnetic circuit structure of permanent magnet, the air-gap magnetic field waveform of permanent magnet brushless DC motor includes square wave, trapezoid wave and sine wave, and the waveform of back EMF is the same.
Knowledge point 3
The difference between DC brushless motor and stepping motor. Stepping motor is an open-loop control element stepping motor that converts electric pulse signal into angular displacement or linear displacement. In the case of non-overloading, the speed and stop position of the motor only depend on the frequency and number of pulses of the pulse signal, and are not affected by the load change. Brushless DC motor is a high-performance motor. Its characteristics are the external characteristics of the DC motor and the mechanical contact structure composed of no brush. It uses a permanent magnet rotor without excitation loss. The heated armature winding is installed on the external stator, and the heat dissipation capacity is easy.
The differences between the two are as follows:
1. Different control accuracy
Based on the different driving principles, the general DC brushless motor is used where the control accuracy is not high, and the stepper motor is used where the control accuracy is high.
2. Different driving principles
The driving principle of DC brushless motor is different from that of stepping motor. The induction DC brushless motor is controlled by the alternating power supply provided by the Hall element positioning. The stepper motor is directly driven by a single pulse voltage and does not need Hall element positioning. It can precisely locate the rotation angle by controlling the number of pulses added to the motor;
3. Different speed
The speed of DC brushless motor is higher than that of stepping motor.
These are the relevant knowledge points about DC brushless motor shared by Shanghai Peaks.
