Commutator is the armature component of DC motor and AC commutator motor, the following will be introduced in detail from its structure, working principle, type, role and application areas:
Structural components
Commutator: usually made of copper, is the main conductive part of the commutator, more than one commutator evenly arranged to form a cylindrical or disk-shaped structure.
Mica: used to separate the various commutator, play the role of insulation, to ensure that the current can only be conducted between the specific commutator, to prevent short-circuit.
Brush: contact with the commutator surface, generally made of graphite and other conductive and wear-resistant materials. It introduces current from an external circuit into the commutator, or passes current from the commutator output to an external circuit.
Other parts: It may also include pressure rings, fasteners, etc., which are used to fix the commutator and the mica sheet so that they become an integral structure to ensure that they remain stable during the operation of the motor.
Principle of operation
Role in DC motors: When the coil of a DC motor passes current, it is rotated by electromagnetic force under the magnetic field of a permanent magnet. When the coil turns to the position of balance with the magnet field, the original energized coil corresponding to the commutator contacts and brushes are separated, and the brushes are connected to the group of coils corresponding to the contacts that can produce propulsion, thus changing the direction of the current in the coil, so that the coil can continue to be rotated in the same direction under the action of the electromagnetic force, and so on, the DC motor will continue to rotate.
Role in DC generators: In a DC generator, the armature windings rotate in a magnetic field to cut the magnetic inductance, and the induced electromotive force generated is alternating. Through the cooperation of commutator and brush, the alternating electric potential in the armature winding is converted into DC potential output between the brushes.
Type classification
According to the manufacturing process classification: can be divided into mechanical commutator, semi-plastic commutator, full plastic commutator. Mechanical commutator structure is simple, low cost, but relatively low precision and reliability; semi-plastic commutator and full plastic commutator has better insulation properties and mechanical strength, suitable for some of the higher performance requirements of the occasion.
According to the wiring form classification: can be divided into hook type commutator, slot type commutator, plane type commutator and so on. Different wiring forms are suitable for different motor structure and connection requirements.
Classification according to mechanical strength: can be divided into ordinary type commutator and reinforced type commutator. Reinforced type commutator adopts stronger material and structure design, which can withstand greater mechanical stress and current load, and is suitable for high power and high speed motors.
Main functions
Current commutation: This is the most important role of commutator, in DC motor, it makes the direction of current in the armature winding keep alternating, so as to ensure that the direction of electromagnetic torque is always unchanged, so that the motor can run continuously and stably.
Rectifier function: in DC generator, it converts the alternating electric potential generated by the armature winding into DC electric potential output, providing stable DC power supply for the external circuit.
Application fields
Electric power field: used in DC generators and DC motors, such as DC exciter in power plants, DC speed motors in industrial production, etc., which can realize the conversion of electric energy and speed control of motors.
Transportation field: in electric vehicles, electric trains and other means of transportation, commutator is used for DC motor control, to achieve the vehicle forward, backward and speed regulation.
Industrial automation field: widely used in various automation equipment and robots, such as CNC machine tools, automated production lines, etc., to provide accurate commutation control for the motor to ensure the accurate operation of the equipment.
Household appliances field: some small appliances such as power tools, vacuum cleaners, hairdryers, etc., their DC motors will also use the commutator, so that the motor can operate normally, to achieve a variety of functions.
