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How does an electric motor work physics

How does an electric motor work physics

The role of the motor is to convert electrical energy into mechanical energy. Motors are divided into two major categories: AC motors and DC motors.
(1) AC motor and its control
AC motors are classified into asynchronous motors and synchronous motors. How does an electric motor work physicsAsynchronous motors are classified into single-phase asynchronous motors, two-phase asynchronous motors and three-phase asynchronous motors according to the number of stator phases. The three-phase asynchronous motor has the advantages of simple structure, reliable operation and low cost, and is widely used in industrial and agricultural production.

How does an electric motor work physics
1. The basic structure of a three-phase asynchronous motor
The construction of a three-phase asynchronous motor is also divided into two parts: the stator and the rotor.
(1) Stator:
The stator is a fixed part of the motor and is used to generate a rotating magnetic field. It is mainly composed of a stator core, a stator winding and a base.
(2) Rotor:
The rotor is the key part of the rotor.How does an electric motor work physics There are two types of rotors, squirrel-cage and winding. Master their respective characteristics and differences. The squirrel cage is used for small and medium power (100k or less) motors. It has a simple structure, reliable operation and convenient maintenance. The winding type can improve the starting performance and adjust the speed. The air gap between the stator and the rotor will affect the performance of the motor. The thickness of the air gap is generally between 0.2 and 1.5 mm.
Master the wiring method of the stator windings.How does an electric motor work physics
2. The working principle of three-phase asynchronous motor
Master the formulas n1=60f/P, S=(n1-n)/n1, n=(1-S)60f/P, and understand their meaning (very important), and be able to use these formulas flexibly to calculate. Also keep in mind that usually the slip SN of the motor at rated load is approximately 0.01-0.06. The examples in the book should be focused on.

How does an electric motor work physics
3.How does an electric motor work physics. Data on the nameplate of the three-phase asynchronous motor
(1) Model: Master the example on the book.
(2) Rating: Generally understand, master the rated frequency and rated speed, the frequency of our country is 50 Hz.
(3) Connection method: There are Y type and angle type.
(4) Insulation class and temperature rise: Master the definition of allowable temperature rise.
(5) Working methods: generally understand.
4. Mechanical characteristics of three-phase asynchronous motor
Master the relationship between rated torque, maximum torque and starting torque. The formulas in the book should be mastered and used flexibly for calculation. Also remember the following:
(1) When rotating at constant speed, the torque of the motor must be balanced with the resistance torque.
(2) When the load torque increases, the torque T(3) of the initial moment of the motor is generally 1.8-2.2.
(4) When the motor is started, n=0, s=1.

How does an electric motor work physics
5. How does an electric motor work physics. Starting of three-phase asynchronous motor
(1) Direct start
The slip rate at start-up is 1, the induced electromotive force in the rotor is large, and the rotor current is also large. When the motor is started at rated voltage, it is called direct start, and the direct start current is about 5-7 times of the rated current. In general, a small-capacity asynchronous motor with a rated power of 7.5 kW or less can be started directly.
The electrical appliances used in the direct start control circuit include combination switches, buttons, AC contactor intermediate relays, thermal relays and fuses. Master their respective characteristics and master the calculation of the rated current of the fuse.
How does an electric motor work physics. Direct start control circuit: master its control principle.
(2) Buck start of squirrel cage asynchronous motor.
Master the working principle of star-angle starter and autotransformer step-down start
(3) Starting of wound three-phase asynchronous motor
Generally understand.
6. Forward and reverse control of three-phase asynchronous motor
General understanding
7. Three-phase asynchronous motor speed regulation
This part is more important and you need to understand the formula. How does an electric motor work physics. There are three possibilities for changing the speed of the motor, ie changing the frequency, changing the number of pole pairs of the winding or changing the slip.
8. Synchronous motor
(1) Construction of synchronous motor
To be compared with asynchronous motors. (objective question)
(2) Working principle of synchronous motor
Know that the speed of the synchronous motor is constant and does not change with load. The speed of the synchronous motor cannot be adjusted.

How does an electric motor work physics

The principle of the motor refers to the action of the magnetic field on the current, which causes the motor to rotate. It is a machine that converts electrical energy into mechanical energy.How does an electric motor work physics.

1 dual phase motor principle
          The energized coil is forced to rotate in the magnetic field.

         That is to say, the energized coil generates magnetism and repels the original magnetic field, thereby effectively rotating it.

         The direction in which the energized conductor is forced to move in the magnetic field is related to the direction of the current and the direction of the magnetic induction line (the direction of the magnetic field). The working principle of the motor is magnetic field to electricity

         The flow is forced to rotate the motor.How does an electric motor work physics.  It is a machine that converts electrical energy into mechanical energy.

         The motor uses the principle of magnetic effect of current, and the motor is divided into a DC motor and an AC motor according to the power source used.

2 How does an electric motor work physics. DC motor principle
        The DC coil can only be rotated half a turn in the magnetic field. To make a turn, the commutator is required to turn the balance position to automatically change the current direction.

 

3 Principle of Rotor Rotation of Three-Phase AC Asynchronous Motor
 
When the magnetic pole rotates in the clockwise direction, the magnetic flux of the magnetic pole cuts the rotor bar, and an electromotive force is induced in the bar. The direction of the electromotive force is determined by the right hand rule. Because the motion is relative, if the pole is not moving and the rotor bar rotates in the counterclockwise direction, the electromotive force can also be induced in the bar. Under the action of the electromotive force, a current is generated in the closed bar. How does an electric motor work physics. This current interacts with the magnetic field of the rotating magnetic pole, and the rotor bar is subjected to the electromagnetic force F, and the direction of the electromagnetic force can be determined by the left hand rule. The electromagnetic force generates electromagnetic torque and the rotor rotates.

 

With Best Regards,
 
Lee ( Sales Department; Miss. )         
NER GROUP CO.,LIMITED    
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