Working principle of motor:
From the structure of the stator winding, the single-phase motor has the starting winding, which is combined with the main winding to form a rotating magnetic field. After starting, the starting winding is broken or the operation is involved. A single-phase motor with positive and negative operation is required. The main winding and the starting winding are exactly the same. Otherwise, the starting winding is smaller, and the starting winding will be cut off after the motor starts.
The three winding of a three-phase motor is symmetrical in the stator. The three phase power supply is integrated into the three phase power supply, which generates the rotating magnetic field automatically, and induces the induced current in the rotor cage. When the conducting conductor is subjected to electromagnetic force in the magnetic field, it will generate motion. Thus the electric energy is converted into mechanical energy.
The three-phase motor is similar to the single-phase motor in principle. It is through the 220V alternating current in the stator winding, so that the coil generates magnetic field. According to the left hand rule, the rotor rotates in the magnetic field. But there are differences between the single-phase motor into the AC 220V way, therefore cannot produce a rotating magnetic field and rotor stress the same direction, in order to make the rotor turn up, certain measures must be taken, if there are two coil motor, in which a coil in series capacitor so, the two coil generates a moment in time off, so the motor can turn up. The three-phase motor is a three - way 220V alternating current, so that a rotating magnetic field can be formed, without other measures, the motor can be turned.
The positive and reverse of the single-phase motor only needs to change the connection direction of the capacitor and the coil and the power supply, and the rotation direction can be changed. The three phase motor can change the direction of rotation only by changing the connection between any two roads.
According to the above principle, the three-phase motor is generally used in the industry which needs large torque. The single-phase motor is generally used for civil, torque, and small power occasions.