1. DC motor-a motor that uses DC current to rotate is called a DC motor. Due to the different ways of connecting the magnetic field circuit and the armature circuit, it can be divided into series motors, split motors, and reexcited motors.

2. AC motor-a motor that rotates with AC current is called an AC motor. More types, mainly:

① AC and DC dual-purpose motor-make the series-excited DC motor for AC electric use, that is, this kind of motor, because the AC power is in the magnetic field and armature circuit, and turns at the same time, so the torque and steering remain unchanged, so it can rotate non-stop. This kind of motor can use both AC and DC, so it is also called "universal motor". Vacuum cleaners, sewing machines and other household appliances, such as multi-use motor.

② Synchronous motor-a motor in which the armature turns from one pole to the second pole, just in the same cycle as the steering of the current. This kind of motor can not start by itself, must use another motor or special auxiliary winding to reach the appropriate frequency, can be connected to the alternating current. If the load changes and the speed changes, the speed is inconsistent with the AC frequency, enough to make its pace disorder, tend to stop or cause damage. Due to many restrictions, it is not widely used.

③Induction motor-a device that puts the rotor in a rotating magnetic field and makes the rotor rotate due to the action of eddy current. The rotating magnetic field is not caused by mechanical methods, but by alternating current through several pairs of electromagnets, so that the nature of the magnetic poles can be changed cyclically, which can be regarded as a rotating magnetic field. Three-phase induction motors (with three pairs of magnetic poles) are usually used. The movement of a DC motor is just the opposite of a DC generator. In a generator, the induced current is formed by the induced electromotive force, so they are in the same direction.

The current in the motor is supplied by the external power source in the direction of the induced electromotive force and the direction of the armature current I. The induction motor in the AC motor has a strong induced current (eddy current) generated in the rotating magnetic field. The copper bar on the rotor continuously cuts the magnetic field lines. According to Lenz's law, this induced current has the effect of resisting the relative movement of the magnetic field and the rotor. Therefore, the rotor rotates with the magnetic field. However, the rotor rotation speed is not as high as the magnetic field transformation speed, otherwise the stator pole (main pole) of the electromagnetic DC motor is composed of the iron core and the excitation winding. According to its excitation (the old standard is called excitation), it can be divided into series-excited DC motors, shunt-excited DC motors, separately-excited DC motors and compound-excited DC motors. Due to different excitation methods, the law of the stator magnetic pole flux (generated by the excitation coil of the stator magnetic pole) is also different.