Working principle and fan speed of cooling fan

Fans can be divided into DC cooling fans and AC cooling fans according to the power supply type.

Operating principle of fixed fan

According to the right-hand ampere's law, when a conductor passes through an electric current, a magnetic field will be generated around it. If the guide device is placed in another constant magnetic field, it will generate suction or repulsion, causing the object to move. A magnetic rubber magnet is connected to the inside of the DC fan blade. Around the silicon steel sheet, the shaft part is wound by two groups of coils, and the Hall inductance element is used as a synchronous detection device to control the circuit group, so that the two groups of coils wound around the shaft work in turn. Silicon steel sheet produces various magnetic poles, which generate attraction and repulsion through rubber magnet. When the suction and repulsion force is greater than the friction force of the static fan blade, the fan blade rotates naturally. Because the Hall sensor module provides a synchronization signal, the fan blades can operate continuously.

Working principle of AC fan

The difference between an AC fan and a DC fan. Different from the fixed fan, the fixed fan has a constant power supply voltage, which depends on the circuit control to make the two coils work in turn to produce different magnetic fields. As the power frequency of AC fan is constant, the change speed of magnetic pole generated by silicon steel sheet is determined by the power frequency. The higher the frequency is, the faster the switching speed of the magnetic field is theoretically, just as the more poles of the fixed fan, the faster the speed is. However, the frequency should not be too fast, which will make activation difficult.

Fan speed refers to the number of revolutions per minute of fan blades, in revolutions. Usually measured externally by the instrument.

DC fan, EC fan, CPU heat sink