The cooling fan can be divided into a DC cooling fan and an AC cooling fan according to the power supply type.

DC fan working principle

According to Ampere's right-hand rule, when a conductor passes a current, a magnetic field will be generated around it. If this conductor is placed in another fixed magnetic field, suction or repulsion will occur, causing the object to move. Inside the fan blades of the DC fan, a rubber magnet previously filled with magnets is attached. Around the silicon steel plate, the axis part winds two sets of coils, and uses a Hall sensor assembly as a synchronous detection device to control a set of circuits. This circuit makes two sets of coils winding the shaft work in turn. The silicon steel sheet produces different magnetic poles that generate a repulsive force with the rubber magnet. When the repulsive force is greater than the static friction force of the fan, the fan blade naturally rotates. Since the Hall sensor assembly provides the synchronizing signal, the fan blade can thus continue to operate, and its direction of rotation can be determined according to Fleming's right-hand rule.

AC fan working principle

The difference between AC fan and DC fan. The former power supply is AC, and the power supply voltage will alternate positively and negatively. Unlike DC fan power supply voltage, it must rely on circuit control, so that the two sets of coils work in rotation to produce different magnetic fields. Because the frequency of the AC fan is fixed, the speed of the magnetic pole change produced by the silicon steel sheet is determined by the power supply frequency. The higher the frequency is, the faster the magnetic field switching speed is, and the faster the speed will theoretically be, just as the more the number of DC fan poles, the faster the speed. same. However, the frequency should not be too fast, too fast will cause activation difficulties.

The fan speed refers to the number of times the fan blade rotates per minute. The unit is the RPM and is usually measured externally by the instrument.