Motor rotation principle

About current, magnetic field and force

First of all, in order to facilitate the follow-up explanation of the principle of motor, let's review the basic laws / rules of current, magnetic field and force. Although there is a sense of nostalgia, it is easy to forget this knowledge if you don't often use magnetic components.

Rotation principle of motor

Now let's introduce the rotation principle of the motor. Let's illustrate with pictures and formulas - when the wire frame is rectangular, the force acting on the current should be considered.

The force F acting on the side a and C is

Generate torque with the central axis as the spindle.

For example, when considering that the rotation angle is only θ The force acting at right angles to B and D is sin θ， Therefore, the torque TA of part a is expressed by the following formula:

Considering Part C in the same way, the torque is doubled and the torque calculated by the following formula is generated:

Because the area of the rectangle is s = H? l. Therefore, the following results can be obtained by substituting it into the above formula:

The formula is applicable not only to rectangles, but also to other common shapes such as circles. The motor uses this principle.

Key points

The rotation principle of the motor follows the laws (rules) related to current, magnetic field and force.