Do you know how the motor works?

Nearly half of the world's electricity consumption is consumed by electric motors, so the high efficiency of electric motors is known as the most effective measure to solve the world's energy problems. This article briefly introduces the basic knowledge of the principle of motor rotation.

Motor type

Generally speaking, the force generated by the current flowing in the magnetic field is converted into rotational motion, and linear motion is also included in a wide range.

According to the type of motor drive power supply, it can be divided into DC motor and AC motor.

According to the principle of motor rotation, it can be roughly divided into the following categories.

(Except special motors)

One DC motor and one AC motor

1) The motor rotates through magnets and magnets

Around the permanent magnet with a rotating shaft, ① rotating magnet (generating a rotating magnetic field), ② according to the principle that the N pole and the S pole attract and repel each other at the same level, ③ the magnet with a rotating shaft will rotate.

This is the basic principle of motor rotation.

The basic principle of motor rotation

A current flows through the wire, causing a rotating magnetic field (magnetic force) around the wire to rotate the magnet, which is actually the same state of action.

Current passes through the wire to create a magnetic field

In addition, when the wire is wound into a coil shape, the magnetic force synthesis forms a large magnetic field flux (magnetic flux), resulting in the N pole and the S pole.

Furthermore, by inserting the iron core into the coil-like conductor, the magnetic field lines can be easily passed through and a stronger magnetic force can be generated.

When inserting an iron core, the magnetic field becomes stronger, producing a stronger magnetic force

2) Actual rotating motor

Here, as a practical method of rotating electrical machines, a method of manufacturing rotating magnetic fields using three-phase alternating current and coils is introduced.

(Three-phase AC is an AC signal separated by 120 phases)

The synthetic magnetic field in the above ① state corresponds to the following ①.

The synthetic magnetic field of the above ② state corresponds to the following ②.

The composite magnetic field of the above state ③ corresponds to the following figure ③.

As mentioned above, the coils wound on the iron core are divided into three phases, U-phase coils, V-phase coils and W-phase coils are arranged at 120 ° intervals. Coils with high voltage generate N poles, and coils with low voltage generate S poles.

Each phase changes in a sine wave, so the polarity (N pole, S pole) and magnetic field (magnetic force) of each coil will change.

At this time, only look at the n-pole coil, and change from the u-phase coil to the v-phase coil to the w-phase coil to the u-phase coil in turn, thereby rotating.