Nouns Explained:
Motor (English: Electric machinery, commonly known as "motor") refers to the law of electromagnetic induction based on the realization of the conversion of electrical energy or transmission of an electromagnetic device. In the circuit with the letter M (old standard with D). Its main function is to generate driving torque, as the power source of electrical appliances or various machinery. Generator is represented by the letter G in the circuit. Its main role is to use mechanical energy into electrical energy, the most commonly used at present, the use of heat, water, etc. to drive the generator rotor to generate electricity.
Basic structure
I. The structure of a three-phase asynchronous motor, consisting of a stator, rotor and other accessories.
(I) stator (stationary part)
1, stator core
role: part of the magnetic circuit of the motor and on which the stator windings are placed.
Construction: stator core is generally 0.35 ~ 0.5 mm thick surface with an insulating layer of silicon steel sheet punching, stacking and become, in the core of the inner circle of the punch has a uniform distribution of grooves for embedded stator windings.
Stator core groove type has the following kinds:
Semi-closed-end type groove: motor efficiency and power factor is higher, but the winding embedded wire and insulation are more difficult. Generally used in small low-voltage motors. Half-open type slot: can be embedded in molded windings, generally used in large, medium-sized low-voltage motors. The so-called molding winding that the winding can be insulated beforehand and then put into the slot.
Open slot: used for embedding molded windings, insulation method is convenient, mainly used in high-voltage motors.
2, stator winding
Role: is the circuit part of the motor, into the three-phase alternating current, generating a rotating magnetic field.
Construction: by three in the space between 120 ° electrical angle, team symmetry arrangement of the structure of the same winding connected to these windings, the coils of these windings according to a certain law were embedded in the stator slots.
The stator windings of the main insulation projects are the following three: (to ensure that the conductive part of the winding and the core of the core between the reliable insulation as well as the winding itself between the reliable insulation).
1) Insulation to ground: insulation between the stator winding as a whole and the stator core.
2) Phase-to-phase insulation: insulation between the stator windings of each phase.
3) turn-to-turn insulation: insulation between the turns of each phase of the stator winding.
Motor junction box wiring:
Motor junction box have a junction board, three-phase winding six wire header rows into two rows up and down, and the provisions of the upper row of the three junction stakes arranged from left to right, numbered 1 (U1), 2 (V1), 3 (W1), three rows of the three junction stakes arranged from left to right, numbered 6 (W2), 4 (U2), 5 (V2). Connect the three-phase windings into star connection or triangle connection. All manufacturing and maintenance should be arranged according to this serial number.
3, the seat
Role: fixed stator core and front and rear end caps to support the rotor, and play a protective, heat dissipation and other roles.
Construction: the seat is usually cast iron, large asynchronous motor seat is generally welded with steel plate, miniature motor seat using cast aluminum. Closed motor chassis outside the heat rib to increase the heat dissipation area, protective motor chassis end caps at both ends of the ventilation holes, so that the air inside and outside the motor can be directly convection, in order to facilitate heat dissipation.
(2) rotor (rotating part)
1, three-phase asynchronous motor rotor core:
Role: as a part of the motor magnetic circuit as well as in the core groove placed in the rotor winding.
Construction: the material used and the same stator, by 0.5 mm thick silicon steel sheet punching, stacking and become, silicon steel sheet outer circle punching a uniform distribution of holes, used to place the rotor winding. Usually with the stator core punched behind the silicon steel sheet to punch the inner circle of the rotor core. General small asynchronous motor rotor core directly mounted on the rotor shaft, large and medium-sized asynchronous motor (rotor diameter of 300 ~ 400 mm or more) rotor core with the help of the rotor bracket pressed on the rotor shaft.
2, three-phase asynchronous motor rotor winding
Role: cutting the stator rotating magnetic field to generate induced electromotive force and current, and the formation of electromagnetic torque to make the motor rotate.
Construction: squirrel cage rotor and wire-wound rotor.
1) squirrel cage rotor: the rotor winding consists of a number of guide bars inserted into the rotor groove and two end rings of the ring. If you remove the rotor core, the shape of the entire winding like a squirrel cage, so it is called cage winding. Small cage motor using cast aluminum rotor winding, for more than 100KW motor using copper bars and copper end rings welded together.
2) wire-wound rotor: wire-wound rotor winding and stator winding is similar, is also a symmetrical three-phase winding, generally connected to the star, the three outgoing head to the rotor shaft of the three collector ring, and then through the brushes and the external circuit connection.
Features: the structure is more complex, so the application of wire-wound motors is not as widespread as squirrel-cage motors. But through the collector ring and brush in the rotor winding circuit into the additional resistance and other components to improve the asynchronous motor starting, braking performance and speed performance, so in the requirements of a certain range of smooth speed regulation of equipment, such as cranes, elevators, air compressors, etc. Above the use.
(C) three-phase asynchronous motor other accessories
1, end cover: support.
2, bearing: connecting the rotating part and the immobile part.
3. Bearing end cover: to protect the bearing.
4, fan: cooling motor.
Two, dc motor with octagonal full laminated structure, not only high space utilization, but also when the static rectifier power supply, can withstand pulsating current and rapid changes in load current. DC motors generally do not have series excitation winding, applicable to the need for positive and negative motor rotation in automatic control technology. According to the needs of users can also be made with series-excited winding. The motors with center height of 100～280mm have no compensation winding, but the motors with center height of 250mm and 280mm can be made into motors with compensation winding according to the specific conditions and needs, and the motors with center height of 315～450mm have compensation winding. The motor with a center height of 500-710mm has an external mounting dimension and technical requirements in accordance with the IEC international standard, and the tolerance of the motor's mechanical dimensions is in accordance with the ISO international standard.
Main applications
1, servo motors
Servo motors are widely used in a variety of control systems, which can convert the input voltage signal into the mechanical output on the motor shaft, dragging the controlled components, so as to achieve the purpose of control.
Servo motor has a DC and AC points, the earliest servo motor is a general DC motor, in the case of control precision is not high, before the use of general DC motor as a servo motor. The current DC servo motor is structurally speaking, is a small power DC motor, its excitation more armature control and magnetic field control, but usually use armature control.
2, stepper motor
Stepper motor is mainly used in the field of CNC machine tool manufacturing, due to the stepper motor does not require A/D conversion, can be directly converted to digital pulse signals into an angular displacement, so it has been regarded as the ideal CNC machine tool actuating elements.
In addition to their use in CNC machine tools, stepper motors can also be used in other machinery, such as as motors in automatic feeders, as motors in general-purpose floppy disk drives, and in printers and plotters.
3, torque motor
The torque motor is characterized by low speed and large torque. Generally in the textile industry often use AC torque motor, its working principle and structure and single-phase asynchronous motor of the same.
4, switched reluctance motor
Switched reluctance motor is a new type of speed motor, the structure is extremely simple and strong, low cost, excellent speed performance, is a strong competitor of the traditional control motor, has a strong market potential.
5, brushless DC motor
Brushless DC motor mechanical characteristics and regulating characteristics of good linearity, wide speed range, long life, easy maintenance and low noise, there is no brush caused by a series of problems, so this motor in the control system has great applications.
6, DC motor
Direct current motor has good speed performance, easy to start, able to load the advantages of starting, so the current DC motor is still widely used, especially after the emergence of silicon controlled DC power supply.
7, asynchronous motor
Asynchronous motor has a simple structure, manufacturing, easy to use and maintenance, reliable operation and smaller quality, lower cost and other advantages. Asynchronous motor is widely used to drive machine tools, pumps, blowers, compressors, lifting and winching equipment, mining machinery, light industrial machinery, agricultural and sideline product processing machinery and most of the industrial and agricultural production machinery, as well as household appliances and medical equipment.
There are more applications in household appliances, such as fans, refrigerators, air conditioners, vacuum cleaners and so on.
8, synchronous motor
Synchronous motor is mainly used for large machinery, such as blowers, pumps, ball mills, compressors, rolling mills, and small, micro-instrumentation or as a control element. Three-phase synchronous motor is the main body. In addition, it can also be used as a regulator to deliver inductive or capacitive reactive power to the grid.