I. Motor Classification
1. According to the type of power supply: motors can be divided into DC motors and AC motors.
1) DC motors can be classified into brushless DC motors and brushed DC motors according to their structure and working principle.
Brushed DC motors can be classified into two types: permanent magnet DC motors and electromagnetic DC motors.
Electromagnetic DC motors can be classified into: series-wound DC motors, shunt-wound DC motors, separately excited DC motors, and compound-wound DC motors.
Permanent magnet DC motors can be classified into three types: rare earth permanent magnet DC motors, ferrite permanent magnet DC motors, and AlNiCo permanent magnet DC motors.
2) AC motors can be further divided into single-phase motors and three-phase motors.
2. According to structure and working principle, motors can be divided into DC motors, asynchronous motors, and synchronous motors.
1) Synchronous motors can be classified as: permanent magnet synchronous motors, reluctance synchronous motors, and hysteresis synchronous motors.
2) Asynchronous motors can be divided into: induction motors and AC commutator motors.
Induction motors can be classified as: three-phase asynchronous motors, single-phase asynchronous motors, and shaded-pole asynchronous motors, etc.
AC commutator motors can be classified as: single-phase series motors, AC/DC universal motors, and repulsion motors.
3. According to the starting and running methods, single-phase asynchronous motors can be divided into: capacitor-start single-phase asynchronous motors, capacitor-run single-phase asynchronous motors, capacitor-start-run single-phase asynchronous motors, and split-phase single-phase asynchronous motors.
II. Carbon Brush Motor
Motor carbon brushes are a general term for carbon brushes in electric motors and generators. They resemble pencil erasers, with wires leading out from the top, and come in various sizes.
In an electric motor, carbon brushes function to change the direction of current. Motors are classified as either direct current (DC) or alternating current (AC). In a DC motor, carbon brushes change the direction of current through the rotor's conductive coils, thereby altering the rotor's magnetic poles and ultimately changing the motor's motion. Carbon brushes are used on the commutator or slip rings of the motor as sliding contacts that conduct current. They possess good electrical conductivity, thermal conductivity, and lubrication properties, and also have a certain degree of mechanical strength and the ability to generate commutation sparks. Almost all brushed motors use carbon brushes; they are a crucial component of brushed motors.
Motor carbon brushes are suitable for various electric motors, generators, and wheel axle machines. They have good commutation performance and a long service life. Motor carbon brushes are used on the commutator or slip rings of motors as sliding contacts that conduct and guide current. They have good electrical conductivity, thermal conductivity, and lubrication properties, and possess a certain degree of mechanical strength and the ability to generate commutation sparks. Almost all motors use carbon brushes; they are an important component of motors. They are widely used in various AC/DC generators, synchronous motors, battery-powered DC motors, crane motor slip rings, various types of welding machines, etc. With the development of science and technology, the types of motors and their operating conditions are becoming increasingly diverse, thus requiring various grades of brushes to meet these requirements. Therefore, the types of brushes are also increasing along with the development of the motor industry.
The functions of a carbon brush motor include:
1. External current (excitation current) is applied to the rotating rotor through carbon brushes (input current);
2. The static charge on the main shaft is introduced to the ground through a carbon brush (grounding carbon brush) (output current);
3. Changing the direction of current (in commutator motors, brushes also play a commutation role);
4. Connect the main shaft (ground) to the protection device for rotor grounding protection and to measure the positive and negative voltages of the rotor to ground.
A commutator consists of brushes and commutator rings; carbon brushes are a type of brush. Due to the rotor's rotation, the brushes constantly rub against the commutator rings, and electrical sparks are generated at the moment of commutation, causing erosion. Therefore, brushes are vulnerable components in DC motors. To improve the lifespan, operational stability, and reduce noise and electromagnetic interference of DC motors, brushless DC motors are gradually replacing brushed motors. Generally, AC motors do not use a constant magnetic field, so they do not need a commutator and therefore do not require brushes; however, AC motors are generally larger. Household appliances typically use AC motors, such as fans, washing machines, refrigerators, and air conditioners, which do not have carbon brushes. However, some DC motors, such as many electric shavers, small kitchen appliances, and electric bicycles, do have carbon brushes; these are present in DC motors (excluding brushless ones). Motors that use dry cell batteries are DC motors.
