1、 The working principle of brushless DC motor is composed of the main body and driver of the brushless DC motor. The brushless DC motor is a typical electromechanical integrated product. The stator windings of DC brushless motors are mostly made into three-phase symmetrical star connections, which are very similar to three-phase asynchronous DC brushless motors. The rotor of a DC brushless motor is adhered with a magnetized permanent magnet. In order to detect the polarity of the rotor of the DC brushless motor, a position sensor is installed inside the motor. The driver is composed of power electronic devices and integrated circuits, and its function is to receive the start, stop, and brake signals of the DC brushless motor to control the start, stop, and brake of the DC brushless motor; Receive position sensor signals and forward and reverse signals to control the on/off of each power transistor in the inverter bridge, generating continuous torque; Receive speed commands and speed feedback signals to control and adjust the speed; Provide protection and display, etc. DC motors have fast response, large starting torque, and the ability to provide rated torque from zero speed to rated speed. However, the advantages of DC motors are also their drawbacks, as in order to generate constant torque under rated load, the armature and rotor magnetic fields must be maintained at a constant angle of 90 °, which requires the use of carbon brushes and commutators. Carbon brushes and commutators generate sparks and toner when the motor rotates, which not only causes component damage but also limits their usage. AC motors do not have carbon brushes or commutators, which are maintenance free, sturdy, and widely used. However, in order to achieve the performance equivalent to DC motors in terms of characteristics, complex control techniques are required. Nowadays, with the rapid development of semiconductors, the switching frequency of power components is much faster, improving the performance of driving motors. The speed of microprocessors is also increasing, which can achieve the control of AC motors in a rotating two axis Cartesian coordinate system, and appropriately control the current components of AC motors on both axes, achieving similar performance to DC motor control and comparable to DC motors.

2、 DC brushless motor structure: DC brushless motor is a type of synchronous motor, which means that the speed of the motor rotor is affected by the speed of the motor stator rotating magnetic field and the number of rotor poles (p): n=60. f/p. When the number of rotor poles in a DC brushless motor is fixed, changing the frequency of the stator rotating magnetic field can change the rotor speed. A DC brushless motor is a synchronous motor that is equipped with an electronic control (driver) to control the frequency of the stator rotating magnetic field and feedback the speed of the motor rotor to the control center for repeated correction, in order to achieve characteristics close to that of a DC motor. That is to say, DC brushless motors can still control the motor rotor to maintain a certain speed when the load changes within the rated load range. The DC brushless driver includes a power supply unit and a control unit: the power supply unit provides three-phase power to the motor, and the control unit converts the input power frequency according to the demand. The power supply unit can directly input DC (usually 24V) or AC (110V/220V). If the input is AC, it must first be converted into DC through a converter. Whether it is DC or AC input, the DC voltage must be converted from the inverter to a 3-phase voltage to drive the motor before being transferred into the motor coil. The inverter is generally composed of six power transistors (q1-q6) divided into upper arm (q1, q3, q5) and lower arm (q2, q4, q6) connected to the motor as a switch to control the flow through the motor coil. The control unit provides PWM (pulse width modulation) to determine the switching frequency of the power transistor and the timing of inverter commutation. DC brushless motors generally hope to use speed control that can stabilize the speed at the set value without too much change when the load changes. Therefore, DC brushless motors are equipped with Hall sensors that can sense magnetic fields as a closed loop control for speed and as a basis for phase sequence control. But this is only used as speed control and cannot be used as positioning control.

3、 Features of DC brushless motor: 1. DC brushless motor can replace DC motor speed regulation, frequency converter+variable frequency motor speed regulation, asynchronous motor+reducer speed regulation; 2. Brushless DC motors have the advantages of traditional DC motors, while eliminating carbon brush and slip ring structures; 3. The DC brushless motor can operate at low speed and high power, eliminating the need for the gearbox to directly drive large loads; 4. DC brushless motor has small volume, light weight, and high output; 5. The DC brushless motor has excellent torque characteristics, good torque performance at medium and low speeds, high starting torque, and low starting current; 6. DC brushless motor with stepless speed regulation, wide speed range, and strong overload capacity; 7. The DC brushless motor has good soft start/stop and braking characteristics, eliminating the need for existing mechanical or electromagnetic braking devices; 8. The DC brushless motor has high efficiency, and there is no excitation loss or carbon brush loss in the motor itself, eliminating multi-level deceleration loss. The comprehensive power saving rate can reach 20%~60%. 9. DC brushless motor has high reliability, good stability, strong adaptability, and simple maintenance and repair; 10. DC brushless motor is resistant to bumps and vibrations, with low noise, low vibration, smooth operation, and long service life; 11. DC brushless motors do not generate sparks and are particularly suitable for explosive locations, with explosion-proof types; 12. DC brushless motor can be selected as trapezoidal wave magnetic field motor or sine wave magnetic field motor according to needs.