Structural characteristics of DC motors

DC motor is a rotating electric machine that converts DC electric energy into mechanical energy (DC motor) or converts mechanical energy into DC electric energy (DC generator). DC motors can be divided into permanent magnet DC motors and winding excitation motors. Generally, the former is used for low power and the latter for high power. The latter will be discussed below.

Structural characteristics of DC motors

(1) DC motor structure

DC motor: A rotating electric machine that converts DC electrical energy into mechanical energy (DC motor) or converts mechanical energy into DC electrical energy (DC generator).

The structure of the DC motor should be composed of two parts: the stator and the rotor. The static part of the DC motor is called the stator. The main function of the stator is to generate a magnetic field, which is composed of the frame, the main magnetic pole, the commutating pole, the end cover, the bearing and the brush device. The part that rotates during operation is called the rotor. Its main function is to generate electromagnetic torque and induced electromotive force. It is the hub of DC motor energy conversion, so it is usually called armature. It consists of rotating shaft, armature core, armature winding, and Composed of a fan and a fan.

Brushed DC motors are widely used in occasions that require adjustable speed, good speed regulation performance, and frequent starting, braking and reverse rotation.

(2) Features of DC motor

DC motors have the following advantages: simple structure; excellent electromagnetic torque control characteristics, can achieve constant torque below the base speed, constant power above the base speed, and can meet the requirements of low-speed, high-torque, high-speed, and low-torque power sources. Requirements; can be started, braked and reversed frequently and quickly; speed regulation is smooth, stepless, precise, convenient, and has a wide range; strong anti-overload ability, able to withstand frequent impact loads; simple control method, only need to use voltage control, no Need to detect the magnetic pole position.

But it also has the following shortcomings: equipped with brushes and commutator, the surface of the commutator is easy to produce electric sparks during high-speed and heavy-load operation. At the same time, the commutator is difficult to maintain, and it is difficult to develop to large capacity and high speed. In addition, electric sparks Will produce electromagnetic interference; not suitable for use in dusty, humid, flammable and explosive environments; high price, large size and quality. Among them, the electromagnetic interference generated by electric sparks will be fatal to highly electronic electric vehicles. With the development of electronic power technology and control theory, compared with other drive systems, the application of DC motors in electric vehicles has been at a disadvantage and has been gradually eliminated.

(3) DC motor control system

The DC motor control system is mainly composed of a chopper and a central controller. According to the output torque of the DC motor, the input voltage and current of the motor are controlled by the chopper to control and drive the operation of the DC motor.