Get to know brushless DC motor stators and rotors in one minute

　　 Brushless motor stator and rotor These are parts of a motor. The two parts can cooperate with each other through the action of the magnetic coil to convert electromagnetic energy information into mechanical energy.

　　In simple terms, the stator and rotor of a brushless motor are the rotating parts of the motor. Brushless DC motors use semiconductor switching devices to achieve electronic commutation, that is, electronic switching devices replace traditional contact commutators and brushes. It has the advantages of high reliability, no commutation sparks, and low mechanical noise, and is widely used in high-end tape recorders, video recorders, electronic instruments, and automated office equipment.

　　A brushless DC motor consists of a permanent magnet rotor, a multi-pole winding stator, and a position sensor. The position sensor detects the change in the rotor position and switches the current of the stator windings in a certain order (that is, it detects the position of the rotor magnetic pole relative to the stator windings, and generates a position sensing signal at a certain position, which is processed by the signal conversion circuit to control the power switching circuit, and switches the winding current according to a certain logical relationship). The working voltage of the stator winding is provided by the electronic switching circuit controlled by the position sensor output.

　　There are three types of brushless motor stator and rotor position sensors: photoelectric, magnetoresistive, and electromagnetic.

　　In a brushless DC motor using a magnetoresistive position sensor, the magnetoresistive sensor (such as a Hall element, magnetoresistive diode, magnetoresistive triode, magnetoresistive resistor, or special integrated circuit) is mounted on the stator assembly to detect the change in the magnetic field generated when the permanent magnet rotor rotates.

　　In a brushless DC motor with a photoelectric position sensor, a photoelectric sensing device is installed at a certain position on the stator assembly, and a light-shielding plate is installed on the rotor. The light source is a light-emitting diode or a small bulb. When the rotor rotates, the photosensitive element on the stator will intermittently generate a pulse signal of a certain frequency due to the action of the light-shielding plate. In a brushless DC motor using an electromagnetic position sensor, an electromagnetic sensor component is installed on the stator assembly. When the position of the permanent magnet rotor changes, the electromagnetic effect will cause the electromagnetic sensor to generate a high-frequency modulated signal (its amplitude changes with the change of the rotor position).