Publish Time: 2022-12-27 Origin: Site
DC motors have good starting and braking functions, and are widely used in electric drive automatic control systems, such as rolling mills and their auxiliary machinery, mine hoists and other fields. Although the DC motor has a more complex structure and inconvenient maintenance than the three-phase AC asynchronous motor, due to its better speed regulation performance and larger starting torque, the production machinery that requires higher speed regulation may require a larger starting torque. The production machinery is often driven by a DC motor.
The follow is the list
working principle
4 types of DC motors and their characteristics
Compound excitation DC motor
It is mainly composed of three major parts: magnetic pole, armature, brush and commutator (also known as commutator or converter). The two magnetic poles N and S are fixed during operation, so they are also called stators. The stator poles are used to generate a main magnetic field. In a permanent magnet DC motor (generally a low-power DC motor), the magnetic poles are made of permanent magnet materials. After magnetization, a constant magnetic field can be generated. In a separately excited DC motor, the magnetic poles are superimposed by stamping silicon steel sheets; the excitation coil is wound outside, and the magnetic field can only be generated by applying an excitation current. On the inner side of the magnetic pole there is an iron core that is rotatable on a bearing. The armature is the rotating part of the DC motor, so it is also called the rotor. It is made of silicon steel sheets and has windings (armature windings) embedded on the surface. The start and end of the winding are connected to a commutation piece that rotates coaxially with the armature core, connected to the brush fixed on the frame, and connected to the external armature power supply. When direct current is passed through the armature winding, under the action of the stator magnetic field, electromagnetic force and electromagnetic torque that drive the load to rotate will be generated, and the rotor will be driven to rotate.
1. Separately excited DC motor
There is no connection between the excitation winding and the armature winding, and the DC motor powered by other DC power sources to the excitation group is called a separately excited DC motor, and a permanent magnet DC motor can also be regarded as a separately excited DC motor.
2. Series excitation DC motor
In a series DC motor, the field is connected in series with the armature. The field is generated by the thick wire winding so that it can carry the full armature current. A feature of series motors is their high starting torque. However, its speed at no-load and full-load is also very different. Series motors cannot maintain a constant speed when the load changes. In addition, the speed of the series motor at no load may be too high and cause damage to the motor, so some load is generally added to the series motor. Series connected motors are generally not suitable for most variable speed drive applications.
3. Shunt DC motor
In a shunt motor, the field and armature windings are connected in parallel. Motors connected in parallel provide good speed regulation. The excitation source of the magnetic field coil can be separated from the excitation source of the armature winding, or can be combined. One benefit of the excitation source for the separate field coils is the ability to independently control the armature and field to provide different speeds for the motor. Motors connected in parallel can be easily reverse-controlled. Particularly beneficial for bidirectional drives, for example in electric vehicle applications.
The field and armature of a composite DC motor are connected in series, while also providing a separate source of field excitation. Fields in series provide better starting torque, while separate fields provide better speed regulation.
Hangzhou New Hengli Electric Machine MFG. Co., Ltd. (Originally Hangzhou Hengli Electric Machine MFG. Co., Ltd.) was founded in 1954. Over 68 years of manufacturing experience in kinds of DC & AC Motors built up the customer-centered product development methodology and do under the special requirements of customers.