Armature: The core component of the motor
The armature is a key component in the motor or generator. It is responsible for converting electrical energy into mechanical energy, or converting mechanical energy into electrical energy. The armature is widely used in DC motors, synchronous motors and asynchronous motors. Although its structure and working principle are different in different motor types, it always plays a core role in the conversion of electrical energy and mechanical energy. This article will introduce the structure, classification, working principle and application field of the armature in detail.
Definition and function of armature
The armature refers to the rotating part in DC motors and AC synchronous motors, usually composed of winding coils, iron cores and commutators. The main function of the armature is to generate or induce electromagnetic fields, thereby realizing the conversion between mechanical energy and electrical energy.
- In the motor: the armature is the rotating part, and the magnetic field generated by the current interacts with the stator magnetic field to generate torque and drive the motor to rotate.
- In the generator: the armature cuts the magnetic lines of force by rotation, generates induced electromotive force, and outputs electrical energy.
Armature structure
The armature usually consists of the following parts:
Armature core:
Armature winding:
Commutator (DC motor only):
Brush:
Classification of armatures
According to different motor types, armatures can be divided into the following categories:DC motor armature:
AC motor armature:
Generator armature:
How the armature works in an electric motor
1.Current flows through the armature winding
2.Generation of electromagnetic force (Ampere's law)
3.Generation of torque
4.The role of the commutator (DC motor)
How the armature works in a generator
The role of the generator is to convert mechanical energy into electrical energy, and the armature is the main source of electrical energy in this process.
1.Armature winding cuts magnetic lines of force
2.Electromagnetic induction (Faraday's law of electromagnetic induction)
3.Generation of induced current
Detailed explanation of the electromagnetic induction process of the armature
Whether in a motor or a generator, the working principle of the armature is based on the principle of electromagnetic induction. When explaining in detail, Faraday's law and Ampere's law are usually used:
Faraday's law of electromagnetic induction
Wherein, Φ is the magnetic flux, which indicates the number of magnetic lines of force of the magnetic field passing through the armature winding, and t is the time. The armature changes the magnetic flux by rotating, inducing an electromotive force.
Ampere's law (torque principle in motors)
Application fields of armature
Motor
Generator
Electromagnetic brakes and clutches
Losses and effects of armatures
Copper loss
Iron loss
Iron loss includes hysteresis loss and eddy current loss, which mainly occurs in the armature core. Hysteresis loss is the loss caused by repeated magnetization reversal of the core material during magnetization, while eddy current loss is caused by the induced current in the core flowing inside the core.
Mechanical loss
Troubleshooting for armature
During use, if you encounter armature failure, you can use the following methods to troubleshoot and solve it:
The motor does not rotate or the speed is low:
Reason: winding open circuit, poor commutator contact, carbon brush wear, bearing damage, etc.
Solution:
- Check whether the winding is open circuit or short circuit, repair or replace the winding.
- Check the contact between the commutator and the carbon brush, clean or replace the severely worn parts.
- Check whether the bearing is damaged, and replace new bearings if necessary.
Motor overheating:
Solution:
- Check whether the winding is short circuit, repair or replace the winding.
- Clean the dust inside the motor and ensure good ventilation.
- Check whether the load exceeds the rated value and reduce the load appropriately.
The motor is noisy:
Solution:
- Check whether the bearing is damaged, and replace new bearings if necessary.
- Check whether the winding is loose, re-fix or replace the winding.
- Check the wear of the commutator, clean or replace the seriously worn parts.
Motor vibrates loudly:
Solutions:
- Check the bearing for damage, and replace new bearings if necessary.
- Check the rotor for balance, and rebalance the rotor.
- Check the installation of the motor to ensure firmness and stability.
About armature maintenance and care
Cleaning:
Clean the dust and dirt on the surface of the armature regularly to prevent dust accumulation from affecting the heat dissipation performance.
Check the winding:
Check whether the winding is burnt, broken or damaged in insulation.
Check the commutator:
Check whether the commutator copper sheet is worn, dented or oxidized.
Lubrication:
Check the carbon brushes:
Check the wear of the carbon brushes and ensure that their length is within the allowable range.
Conclusion
As a key component of motors and generators, the performance of the armature has a direct impact on the efficiency, reliability and life of the equipment. By understanding the structure, working principle and loss mechanism of the armature, we can better design, use and maintain motors and generators.
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FAQ:
What is an armature and what does it do?
The armature is a core component in motors and generators, used to convert electrical energy into mechanical energy in motors and mechanical energy into electrical energy in generators. The armature coil winding rotates in a magnetic field, generating current or torque through electromagnetic induction.
What is the difference between an armature and a rotor?
In a DC motor, the armature is usually the rotating part (rotor), but in an AC motor, the armature may be the fixed part (stator), mainly depending on the design of the motor. The armature is the part that generates electromotive force and current, while the rotor or stator is just its physical location.
How does an armature work?
The armature rotates in a magnetic field, and electromagnetic induction generates current. In a generator, mechanical energy drives the armature to rotate and generate electromotive force, while in a motor, the armature coil is subjected to force in the magnetic field through the energized armature coil, generating torque to drive the rotor to rotate.
What materials does the armature consist of?
The armature usually consists of an iron core made of soft iron or silicon steel laminations, conductive copper wire windings, and a commutator (for DC motors). The iron core helps to concentrate the magnetic field, while the copper wire windings are responsible for conducting electricity and generating electromotive force.
What is the difference between the role of the armature in DC motors and AC motors?
In DC motors, the armature is the rotating part that commutates the current through the commutator and brushes. In AC motors, the armature is usually the stator, which is used to generate a rotating magnetic field and interacts with the rotor through inductive coupling.
What are the common manifestations of armature failure?
Common armature failures include short circuits, open circuits, or excessive brush wear. These failures usually cause the motor to overheat, vibrate, reduce efficiency, or fail to start.
How to check if the armature is damaged?
You can determine whether the armature is damaged by measuring the winding resistance with a multimeter, testing the winding insulation with a megohmmeter, or checking the contact between the commutator and the brushes. In addition, excessive sparking may also indicate that the armature is faulty.
How does the armature work with the commutator in the motor?
In DC motors, the windings of the armature are connected to the commutator, which changes the direction of the current as the armature rotates to ensure that the motor produces continuous rotation torque.
How to maintain and service the armature?
When maintaining the armature, you should regularly check the contact between the brush and the commutator, clean the commutator surface to reduce sparks, check the insulation and resistance of the windings, and ensure that the armature runs smoothly without abnormalities.
What impact does the armature have on the performance of the motor?
The design and performance of the armature directly affect the power, efficiency, speed and torque output of the motor. The number of turns of the armature winding, the thickness of the wire and the quality of the material will affect the performance of the motor.