The basic working principle of brushless DC motors

    Brushless DC motor refers to an electric motor without carbon brushes and commutators. Its rotor is made of permanent magnet steel, and the coil winding is wound on the stator; Brushless DC motors have various shapes, but their basic structures are the same, all composed of a casing, shaft, bearings, stator winding coils, rotor magnetic steel, Hall elements, etc. As shown in the following figure.

    Hall element is a magnetic induction sensor that can detect the polarity of a magnetic field, convert the polarity of the magnetic field into an electrical signal, and send it to the control pole of the corresponding transistor. The excitation current in the stator winding is switched based on the signal of the Hall element, which can form a rotating magnetic field and drive the rotor to rotate.

    The Hall element is connected to the DC power supply through a current limiting resistor, and a bias current flows through it, causing the transistor to cut off or conduct in the corresponding direction. As shown in the figure below, in the stator W1 coil and stator w2 stator coil, it changes due to the signal detected by the Hall element change, forming a rotational motion.

    Generally, Hall elements are installed near the rotor magnetic poles in brushless DC motors.

    Hall elements are used to detect the position of the rotor magnetic poles, collect position signals at any time, and send them to electronic circuits. The chip emits corresponding control voltage, which is fed back to the motor to change the direction and phase of the current in the stator winding coil and drive the rotor to rotate. As shown in the following figure.

    The basic working principle of a brushless DC motor is that the stator winding coil of the motor must switch the current direction according to the magnetic pole orientation of the rotor in order to make the rotor rotate continuously. Therefore, a sensor for the position of the rotor magnetic pole is installed in the brushless DC motor, which uses Hall elements.

    The Hall element is installed near the rotor magnetic pole in a brushless DC motor, and the output terminals are respectively added to the base poles of two crystal transistors to output voltage with opposite polarity. It controls the conductor and cutoff of the crystal transistor, thereby controlling the current in the winding coil, generating a magnetic field in the winding coil, and attracting the rotor to operate continuously. Please refer to the prompts in the detailed diagram;

    Simply put, as semiconductor technology continues to mature, brushless DC motors have adopted SPWM and SVPWM technologies to replace the traditional commutator of permanent magnet brushless DC motors. The other working principles are exactly the same.