How does motor work?

Why the motor will rotate as long as it is powered on, why there are magnets and coils in the motor. This video visually explains the transformation relationship between electricity and magnetism, and how to drive the motor to rotate through the connection between electromagnetism:

Motor is a kind of electromagnetic device based on the law of electromagnetic induction to achieve power conversion. In the circuit with the letter M, its main function is to generate driving torque, can be used as a power source of electrical equipment.

The motor mainly consists of an electromagnet winding or a distributed stator winding for generating magnetic field, a rotating armature or rotor and other accessories. Under the action of the rotating magnetic field of the stator winding, there is a current passing through the armature squirrel cage aluminum frame, which is rotated by the magnetic field.

Stator (stationary part)

Stator core: part of the magnetic circuit of a motor on which the stator winding is placed.
Stator winding: it is the circuit part of the motor, which is connected with three-phase alternating current to generate rotating magnetic field.
Frame: fix the stator core and the front and rear end covers to support the rotor, and play the role of protection and heat dissipation.

Rotor (rotating part)

Rotor core: as a part of the magnetic circuit of the motor, the rotor winding is placed in the core slot.
Rotor winding: cutting the rotating magnetic field of stator to produce induced electromotive force and current, and form electromagnetic torque to make the motor rotate.

DC motor

DC motor is a kind of motor that converts DC electric energy into mechanical energy.

In the figure above, there is a magnet in the fixed part, which is called the main magnetic pole; there is a brush in the fixed part. The rotating part has a ring-shaped core and a winding wound on the ring-shaped core (two small circles are set to conveniently indicate the direction of the conductor potential or current at the position).

Stepping motor

Stepping motor is an open-loop control unit which converts electric pulse signal into angular displacement or linear displacement. In the case of non overload, the speed and stop position of the motor only depend on the frequency and pulse number of the pulse signal, and are not affected by the load change. When the stepper driver receives a pulse signal, it drives the stepper motor to rotate a fixed angle according to the set direction. The angular displacement can be controlled by controlling the number of pulses, so as to achieve the purpose of accurate positioning; at the same time, the motor speed and acceleration can be controlled by controlling the pulse frequency, so as to achieve the purpose of speed regulation.

Working principle of stepping motor:

When the current flows through the stator winding, the stator winding generates a vector magnetic field. The magnetic field will drive the rotor to rotate an angle, so that the direction of a pair of magnetic fields of the rotor is consistent with that of the stator. When the vector magnetic field of the stator rotates an angle, the rotor also rotates an angle with the magnetic field. Each time an electric pulse is input, the motor rotates an angle to advance one step. The output angular displacement is proportional to the number of input pulses, and the rotational speed is proportional to the pulse frequency. Change the sequence of winding power, the motor will reverse. Therefore, the number and frequency of pulses and the power on sequence of each phase winding of the motor can be controlled to control the rotation of the stepping motor.

Unidirectional asynchronous motor

Induction motor is a kind of AC motor which generates electromagnetic torque by the interaction of air gap rotating magnetic field and rotor winding induced current, so as to realize the conversion of electrical energy into mechanical energy.

Working principle of single phase asynchronous motor

In the AC motor, when the stator winding passes through the AC current, the armature magnetomotive force is established, which has a great influence on the energy conversion and operation performance of the motor. The pulsating magnetomotive force (MMF) generated by single-phase AC winding is decomposed into the sum of two rotating MMFs with equal amplitude and opposite speed, so as to establish the sum of forward and reverse magnetic fields in the air gap. The two rotating magnetic fields cut the rotor conductor and generate induced electromotive force and induced current in the rotor conductor respectively.

The current interacts with the magnetic field to produce positive and negative electromagnetic torque. The forward electromagnetic torque attempts to make the rotor rotate forward; the reverse electromagnetic torque attempts to make the rotor rotate backward. The sum of these two torques is the resultant torque that drives the motor to rotate.

Permanent magnet motor

Permanent magnet motor is a kind of motor which uses permanent magnet to provide magnetic field. There are two conditions for motor to do work, one is the existence of magnetic field, the other is the existence of moving current in magnetic field.