Working principle of traction motor of electric locomotive traction motor is an important part of locomotive, which is used for the mutual conversion of mechanical energy and electrical energy. The main circuit consists of two inverter units, which make the wheelset rotate and drive the locomotive to run, with good speed regulation performance. The working principle of electric locomotive traction motor is analyzed below.
Working principle of traction motor of 1 electric locomotive I. Basic working principle
Straight electric locomotive is usually called DC electric locomotive, which is the simplest one of modern electric locomotives. Adopt DC power supply and DC series excitation traction motor. At present, some industrial and mining electric locomotives, subway emus and urban trolleybuses still use this type.
Second, the characteristics of DC electric locomotive
By analyzing the working principle of DC electric locomotive, it can be concluded that DC electric locomotive has the following characteristics:
(1) The locomotive has simple structure, low cost and good economy.
(2) DC series motors suitable for traction are adopted, with good traction performance and convenient speed regulation.
(3) Simple control and reliable operation.
(4) Low power supply efficiency. Due to the limitation of the terminal voltage of traction motor, the voltage of catenary is generally1500 ~ 3000 V. When a certain power is delivered, the current is large, the power consumption of catenary wires is large, and the power supply efficiency is low.
(5) Large investment in infrastructure. In order to reduce the voltage drop on the catenary, there are many traction substations in the electrified section, and the capital investment is large.
(6) Step speed regulation. Because the early locomotives used voltage regulating resistor to start speed regulation, there was energy loss in the regulation process, which made the efficiency very low and it was difficult to realize continuous and smooth regulation. With the development of power electronics technology, the application of DC chopper technology to speed regulation can continuously and smoothly adjust the terminal voltage of traction motor, thus realizing stepless speed regulation.
To sum up, DC electric locomotive is limited by the terminal voltage of traction motor, and the network voltage cannot be too high, which limits the further improvement of locomotive power. With the development of modern railway transportation, DC electric locomotives have obviously not adapted to the requirements of high power of trunk lines. Generally used in industrial and mining and urban transportation.
Working principle of traction motor for electric locomotive. Traction motor is the main motor to drive the power shaft of the vehicle, which is used for acceleration and braking of the vehicle.
The stator winding of traction motor is connected with three-phase alternating current, which will produce rotating magnetic field in stator space. The rotor winding will produce induction motor and induction current in the rotating magnetic field, which will make the rotor rotate under the action of electromagnetic force.
There are many types of traction motors, such as DC traction motor, pulse traction motor, single-phase commutator traction motor, AC rotary induction (asynchronous) traction motor, AC synchronous traction motor and linear traction motor.
Traction motor is one of the important parts of electric locomotive, which is installed on the bogie under the car body. When the electric locomotive is in traction state, the traction motor converts electric energy into mechanical energy, which makes the wheelset rotate and drives the locomotive to run.
form
Traction motor is mainly composed of stator and rotor.
Stator includes stator core, stator winding and frame. The stator core is made of silicon steel sheet, which is used to place the stator winding and form the magnetic circuit of the motor; The stator winding is made of copper wire to form the circuit of the motor; The frame is generally made of cast iron or cast steel and is the support of the motor.
The rotor also includes an iron core and a rotating shaft. The rotor core is similar to the stator core, and is also made of silicon steel sheet, which is a part of the middle magnetic circuit of the motor. The iron core is provided with a slot for placing or pouring windings, which is installed on the rotating shaft. When working, it rotates with the rotating shaft. Winding is divided into cage and winding. Cage rotor winding is composed of cast aluminum conductor bars or copper bars, and the ends are short-circuited by short-circuit rings. The wound rotor winding is similar to the stator winding. The rotating shaft is made of medium carbon steel, and both ends are supported by bearings to output torque.
In order to ensure the normal operation of traction motor, there is an air gap between stator and rotor, and the size of the air gap has a great influence on the performance of the motor. When the air gap is large, the reluctance is large and the excitation current provided by the power supply is large, which makes the motor run with low power factor; However, the air gap is too small, which will make the assembly difficult, and it is easy to cause the collision of stator and rotor cores in operation.
ask
(1) should have sufficient starting traction and strong overload capacity.
(2) It has good speed regulation performance. Ensure that the EMU has a wide speed range under different driving conditions, and give full play to the power of the traction motor within the speed range. When running forward and backward, its characteristics are as same as possible.
(3) The commutation of 3)DC traction motor is reliable. When operating under the conditions of high current, high voltage, high speed and weak magnetic field, the commutation spark should not exceed the specified spark grade.
(4) All components should have sufficient mechanical strength to ensure the reliable operation of the motor under the worst conditions.
(5) The insulation of the traction motor must have high electrical strength and good moisture-proof and heat-resistant performance, so as to ensure that the motor has sufficient overload capacity and works reliably in its service life.
(6) The structure of traction motor should fully meet the needs of electric train operation and maintenance. For example, the transmission and suspension of the motor should minimize the dynamic effect between the train and the track; Good dust-proof, moisture-proof, rain and snow invasion ability; Easy to repair and replace brushes, etc.
(7) The unit power weight of traction motor must be reduced as much as possible to make full use of electromagnetic materials and structural materials.
Working principle of traction motor of electric locomotive 3 In the case of electric locomotive, electric energy is converted into mechanical energy, and traction is generated through friction between wheels and tracks.
The acting direction of the force is the same as the moving direction of the vehicle, and the magnitude of the force depends on the power of the prime mover and the moving speed of the vehicle, which can be controlled by the vehicle user as required. Often called F-pull, as opposed to resistance.
According to the force transmission process, the actual locomotive traction can be divided into several types. The tangential external force produced by the force acting on the wheel circumference of a moving wheel is called wheel circumference traction; Coupler traction (or drawbar traction) refers to the traction used by the locomotive to pull the train, which is equal to the traction around the wheel MINUS the total running resistance of the locomotive.
Calculation of traction force:
The calculation of traction force is especially common in railway rolling stock, and it is one of the important performance indexes. According to the force transmission process, the actual locomotive traction can be divided into several types. The tangential external force generated by the peripheral force of a moving wheel is called peripheral traction.
Coupler traction (or drawbar traction) refers to the traction used by the locomotive to pull the train, which is equal to the traction around the wheel MINUS the total running resistance of the locomotive. According to the working state of the vehicle, the traction can be divided into starting traction, continuous traction and maximum traction.
Starting traction refers to the traction that the vehicle can emit when it starts from a static state, and its exertion is limited by adhesion; The maximum traction refers to the maximum traction that a vehicle can produce without damaging its own machinery, and its value is usually the same as the starting traction.