The advantage of a DC motor is that it is relatively simple in speed control. It only needs to control the voltage to control the speed. However, this type of motor is not suitable for operation in high temperature, flammable and other environments, and because the motor needs to use carbon brushes as a Commutator components (brush motors), so it is necessary to regularly clean up the dirt generated by carbon brush friction. A brushless motor is called a brushless motor. Compared with a brush, a brushless motor is less power-saving and quieter because of the less friction between the carbon brush and the shaft. The production is more difficult and the price is higher. AC Motor can operate in high temperature, flammable and other environments, and does not need to clean carbon brush dirt regularly, but it is difficult to control the speed, because controlling the speed of the AC motor requires controlling the frequency of the AC (or using induction For the motor, the internal resistance is increased, and the motor speed is reduced at the same AC frequency. Controlling its voltage will only affect the torque of the motor. Generally, the voltage of civil motors is 110V and 220V. In industrial applications, there are also 380V or 440V.

Working principle

The principle of rotation of the motor is based on John Ambrose Fleming’s left-hand rule. When a wire is placed in a magnetic field, if the wire is energized, the wire will cut the magnetic field line and move the wire. The electric current enters the coil to generate a magnetic field, and the magnetic effect of the electric current is used to make the electromagnet continuously rotate in the fixed magnet, which can convert electrical energy into mechanical energy. It interacts with a permanent magnet or a magnetic field generated by another set of coils to generate power. The principle of a DC motor is that the stator does not move, and the rotor moves in the direction of the force generated by the interaction. An AC motor generates a rotating magnetic field through the stator winding coils. The rotating magnetic field attracts the rotor to rotate together. The basic structure of a DC motor includes "armature", "field magnet", "snumeric ring", and "brush".

Armature: A soft iron core that can rotate around an axis is wound with multiple coils. Field magnet: A powerful permanent magnet or electromagnet that generates a magnetic field. Slip ring: The coil is connected to two semi-circular slip rings at about both ends, which can be used to change the direction of the current as the coil rotates. Every half a turn (180 degrees), the direction of the current on the coil changes. Brush: Usually made of carbon, the collector ring contacts the brush at a fixed position to connect to the power source.