Cooling fans can be divided into two types based on voltage: AC fans and DC fans. Apart from the difference in voltage, what are the differences in their internal structures?

Firstly, the internal structure of the AC fan consists of two coil windings (starting winding and running winding) connected in series, creating three crossing points. The series connection point is the common terminal. The AC motor requires a starting capacitor with a small capacity and a voltage resistance of generally 250V. This capacitor has no positive or negative poles and only two interfaces, one connected to the end of the starting winding and the other to the end of the running winding, forming a triangle. One end of the power cord is connected to the end of the running winding, the other end is connected to the common terminal, and the bottom line is connected to the motor housing. The difference between DC fans and AC fans is that DC fans have three windings, which are wound around the rotor and magnetic blocks are installed on the stator to surround the rotor. They do not require starting capacitors and require carbon brushes. Simply change the positive and negative poles of the power supply to reverse the fan.