+Understand the basic structure of DC motors

2021-09-07

The basic structure of a DC motor:

Two parts of stator and rotor

Stator function: Generate the main magnetic field and mechanically support the motor.

Stator composition: main magnetic pole, commutation pole, frame, end cover, bearing, etc.

The main structure is a DC motor


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1. Main magnetic pole


The main magnetic pole includes the main magnetic pole iron core and the magnetic field winding sleeve on it, and its main task is to generate the main magnetic field. The enlarged part under the magnetic pole is called the pole palm, and its function is to make the magnetic flux distribution in the passing air suitable, so that the field winding can be firmly fixed on the iron core. The magnetic pole is a part of the magnetic circuit and is made of laminated steel plate of 1.0-1.5 mm. The field winding is wound with insulated copper wire.


2. Reversing pole


The commutation pole is to improve the commutation performance of the armature current. It also consists of an iron core and windings, which are fixed between the two main magnetic poles of the stator with screws.


3. Base


The frame is used to fix the main magnetic poles, commutation poles and end caps on the one hand, and on the other hand as the support of the entire motor. The motor is fixed on the foundation with anchor screws. On the other hand, it is also a part of the magnetic circuit of the motor, so it is made of cast steel or steel plate. Pressed into.


4. Armature core


The armature core is part of the main magnetic pole. It is made of silicon steel sheet and has a cylindrical shape. The surface is slotted, and the discharge pivot winding is embedded in the slot. In order to strengthen the cooling of the iron core, axial ventilation holes are provided on the armature iron core.


5. Armature winding


The armature winding is the key component for DC motor to generate induced electric potential and electromagnetic torque to realize energy conversion. The winding is generally made of copper wire, wrapped with insulating material, and embedded in the slot of the armature core. In order to prevent the centrifugal force from throwing the winding out of the slot, the winding conductor is wedged into the slot with a slot wedge.


6. Brush device


The brush holder device includes a brush holder and a brush holder fixed on the stator, and the brush holder maintains sliding contact with the commutator, thereby connecting the armature winding and the external current.


7. Commutator


The function of the generator commutator is to convert the AC electromotive force induced by the armature winding into the DC electromotive force between the brushes. For the motor, it converts the applied DC current into the AC DC of the armature winding, and ensures that the current direction of the armature conductor under each magnetic pole does not change, and a constant electromagnetic torque is generated. The commutator is composed of many copper sheets isolated from each other. These copper sheets are called commutator segments, and each commutator segment is connected to the armature winding. The structure diagram of the commutator is shown in the figure. The commutator is a structural feature of the DC motor and is easy to identify.


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