11 Key Points About Motor (Note to Engineers)

A motor refers to an electromagnetic device that realizes the conversion or transmission of electric energy according to the law of electromagnetic induction.

Division:

1. .Divided according to the type of working power supply: it can be divided into DC motors and AC motors.

2. According to the structure and working principle, it can be divided into DC motors, asynchronous motors, and synchronous motors.

3. According to the starting and operation mode, it can be divided into capacitor-starting single-phase asynchronous motor, capacitor-operating single-phase asynchronous motor, capacitor-starting single-phase asynchronous motor and split-phase single-phase asynchronous motor.

4. According to the purpose, it can be divided into drive motor and control motor.

5. According to the structure of the rotor, it can be divided into cage induction motor and wound rotor induction motor.

6.According to the operating speed, it can be divided into high-speed motors, low-speed motors, constant-speed motors, and speed-regulating motors. Low-speed motors are divided into gear reduction motors, electromagnetic reduction motors, torque motors, and claw-pole synchronous motors.

In addition to stepped constant-speed motors, step-less constant-speed motors stepped variable speed motors and step-less variable speed motors, speed regulating motors can also be divided into electromagnetic speed regulating motors, DC speed regulating motors, variable frequency speed regulating motors, and switches Reluctance speed motor.

The rotor speed of the synchronous motor has nothing to do with the size of the load and always maintains the synchronous speed.

DC Type:

The working principle of the DC generator is to convert the alternating electromotive force induced in the armature coil into a DC electromotive force when it is drawn from the brush end by the commutator and the commutation action of the brush.

The direction of the induced electromotive force is determined according to the right-hand rule.

Working Principle:

The direction of the conductor's force is determined by the left-hand rule. This pair of electromagnetic forces form a moment that acts on the armature. This moment is called electromagnetic torque in a rotating electric machine. The direction of the torque is counterclockwise in an attempt to make the armature rotate counterclockwise. If the electromagnetic torque can overcome the resistive torque on the armature, the armature can rotate in a counterclockwise direction.

Electromagnetic:

Electromagnetic DC motor is composed of stator poles, rotor, commutator, brushes, housing, bearings, etc. The stator pole of the electromagnetic DC motor is composed of iron core and field winding. According to the different excitation methods, it can be divided into series-excited DC motors, shunt-excited DC motors, separately-excited DC motors, and compound-excited DC motors. Due to different excitation methods, the laws of stator magnetic pole flux are also different.

DC:

The excitation method of the DC motor refers to the problem of how to supply power to the excitation winding and generate the magnetomotive force of the excitation to establish the main magnetic field. According to different excitation methods, DC motors can be divided into the following types.

Permanent Magnet Type:

Permanent magnet DC motors are also composed of stator poles, rotors, brushes, shells, etc. The stator poles use permanent magnets, including ferrite, AlNiCo, NdFeB, and other materials. According to its structure, it can be divided into cylinder type and tile type. Most of the electricity used in VCRs are cylindrical magnets, while most of the motors used in electric tools and automotive electrical appliances use special block magnets.

Asynchronous Motor:

Synchronous Motor:

A synchronous motor is a common AC motor like an induction motor. The characteristic is: during steady-state operation, there is a constant relationship between the rotor speed and the grid frequency n=ns=60f/p, and ns becomes the synchronous speed. If the frequency of the power grid does not change, the speed of the synchronous motor in the steady-state is constant regardless of the size of the load. Synchronous motors are divided into synchronous generators and synchronous motors. The AC machines in modern power plants are mainly synchronous motors.

Geared Motor:

The geared motor refers to the integrated body of the reducer and the motor. This kind of integrated body can also be commonly referred to as a gear motor or a gear motor. Usually integrated and assembled by a professional reducer manufacturer, it is supplied as a complete set. Geared motors are widely used in the steel industry, machinery industry, etc. The advantage of using a geared motor is to simplify the design and saves space.

Inverter Motor:

The frequency conversion technology actually uses the principle of motor control to control the motor through the so-called frequency converter. The motor used for this type of control is called a variable frequency motor.

Common variable frequency motors include: three-phase asynchronous motors, DC brushless motors, AC brushless motors, and switched reluctance motors.

Linear Motor:

The traditional "rotating motor + ball screw" feed transmission method on the machine tool is limited by its structure, and it is difficult to achieve breakthrough improvements in feed speed, acceleration, rapid positioning accuracy, etc., which can no longer meet the requirements of ultra-high-speed cutting. , Ultra-precision machining places higher requirements on the servo performance of the machine tool feed system. The linear motor directly converts electrical energy into linear motion mechanical energy without any intermediate conversion mechanism transmission device. It has the advantages of large starting thrust, high transmission rigidity, fast dynamic response, high positioning accuracy, and unlimited stroke length. In the machine tool feed system, the biggest difference between the direct drive of the linear motor and the original rotary motor is that the mechanical transmission link from the motor to the worktable is eliminated, and the length of the machine tool’s feed transmission chain is shortened to zero. The transmission method is also called "zero transmission". It is precise because of this "zero transmission" method that brings performance indicators and advantages that cannot be achieved by the original rotating motor drive method.

The Main Purpose:

1. Servo motor

Servo motors are widely used in various control systems. They can convert the input voltage signal into a mechanical output on the motor shaft and drag the controlled components to achieve the purpose of control.

Servo motors are divided into direct current and alternating current. The earliest servo motors are general direct current motors. When the control accuracy is not high, general direct current motors are used as servo motors. Structurally speaking, a DC servo motor is a low-power DC motor, and its excitation mostly adopts armature control and magnetic field control, but armature control is usually adopted.

2. Stepping motor

Stepping motors are mainly used in the field of CNC machine tool manufacturing. Because stepping motors do not require A/D conversion and can directly convert digital pulse signals into angular displacements, they have always been considered as the most ideal CNC machine tool actuators.

In addition to the application on CNC machine tools, the stepper motor can also be used in other machinery, such as the motor in the automatic feeder, as the motor of the general floppy disk drive, and can also be used in printers and plotters.

3. Torque motor

Torque motors have the characteristics of low speed and high torque. Generally, AC torque motors are often used in the textile industry, and their working principle and structure are the same as those of single-phase asynchronous motors.

4. Switched reluctance motor

Switched reluctance motor is a new type of speed regulating motor with an extremely simple and sturdy structure, low cost, and excellent speed regulation performance. It is a strong competitor of traditional control motors and has strong market potential.

5. Brushless DC motor

The brushless DC motor has good mechanical characteristics and adjustment characteristics linearity, wide speed range, long life, easy maintenance, low noise, and there is no series of problems caused by brushes, so this kind of motor has a lot of control in the control system. Big application.

6. DC motor

DC motors have the advantages of good speed regulation performance, easy starting, and the ability to start under load. Therefore, DC motors are still widely used, especially after the emergence of thyristor DC power supplies.

7. Induction motor

The asynchronous motor has the advantages of simple structure, convenient manufacture, use and maintenance, reliable operation, small quality, and low cost. Asynchronous motors are widely used to drive machine tools, water pumps, blowers, compressors, hoisting equipment, mining machinery, light industry machinery, agricultural and sideline products processing machinery, and most industrial and agricultural production machinery, household appliances, and medical equipment.

There are many applications in household appliances, such as electric fans, refrigerators, air conditioners, vacuum cleaners, etc.

8. Synchronous motor

Synchronous motors are mainly used in large machineries, such as blowers, water pumps, ball mills, compressors, rolling mills, and small and micro-instruments or as control components. Among them, the three-phase synchronous motor is its main body. In addition, it can also be used as a tuning camera to deliver inductive or capacitive reactive power to the grid.