AC 모터 개요: 구조, 도시 철도 운송 분야의 응용 & 시민 메트로 케이스

Overview of AC motors

DC traction motors have excellent traction and braking performance. 단자 전압과 여자를 조정하여, 속도 조절이 편리하게 수행될 수 있습니다.. 하지만, the commutator structure of DC traction motors still has a series of disadvantages: motor commutation is difficult and potential conditions are deteriorating, the structure is complex, the working reliability is poor, the manufacturing cost is high, and the maintenance is troublesome. Especially at high voltage and high power, the commutator becomes difficult, the potential conditions deteriorate, and the working reliability of the motor is reduced. AC motors do not have commutators. As traction motors, a series of problems caused by this are eliminated. 게다가, they have a series of advantages such as simple structure, convenient maintenance, small size, light weight, high speed, high power, and automatic anti-skid. 그러므로, they are a relatively ideal traction motor and are rapidly replacing DC traction motors in the field of urban rail transit. Let me take the three-phase asynchronous motor of Nanjing Metro as an example to talk about the application of AC motors in urban rail transit.

1.Structure of AC motors

AC motors are composed of stators and rotors. In the model, the stator is the stationary part, the rotor is the rotating part, and there is a certain air gap between the stator and the rotor. The stator consists of three parts: the core, the winding and the base. The rotor consists of an iron core and a winding. The rotor winding can be a squirrel cage type or a wire wound type. The squirrel cage rotor is made by inserting copper bars into the rotor core slots and then welding the two ends of all the copper bars to two copper end rings. The wire wound rotor winding is the same as the stator winding, which consists of coils placed in the rotor core slots. Although the structures of squirrel-cage and wire-wound motors are different, their working principles are the same.

2.Application examples of AC motors in urban rail transit

(1) Working principle of 1C4M for urban rail transit AC motors
1C4M refers to a method in which a VVVF inverter supplies power to four asynchronous motors connected in parallel on the same vehicle, also known as the “vehicle control” method. 예를 들어, the Guangzhou Metro adopts the vehicle control power supply method. There is also a configuration in which an inverter supplies power to two parallel traction motors on the same bogie, called the “frame control” method, namely “1C2M”, such as the Tianjin Binhai Metro. The choice of power supply method depends on the traction and braking characteristics requirements, as well as the capacity of the inverter and motor. If an inverter only supplies power to one traction motor, it is called “axle control”, i.e., “1ClM”. In urban rail EMUs, since the power of traction motors is relatively small, there is no need to use the axle control method. The function of the VVF inverter is to convert DC power into AC power with adjustable voltage and frequency to supply the traction motor under traction conditions. Under electric braking conditions, the inverter feeds back the power to the grid (회생 제동) or consumes it on the resistor (resistance braking) in a rectified manner

(2) Circuit principle of the “two motors and one trailer (2M1T)” unit vehicle
The grid supplies power to the inverter through the high-speed switches of the two EMUs after the pantograph. A main traction inverter controls each EMU to control the four AC traction motors of the two bogies. The four AC traction motors are operated in parallel; the pantograph powers the auxiliary inverter on the trailer after receiving current through the isolation diode.

(3) Case analysis of the main traction system of Guangzhou Metro Line 1
Adtranz of Germany provides the traction and electric braking system of the Guangzhou Metro Line 1. It is the first metro vehicle project in China to adopt AC transmission and distributed power control technology. The whole system consists of the pantograph, a high-speed circuit breaker HSCB, a VVVF traction inverter, a DCU/UNAS (traction control unit), a traction motor, a brake resistor, 등.
The train pantograph receives current from the contact network, and after passing through the high-speed circuit breaker, it sends the DC1500V voltage to the VVVF traction inverter. The VVVF traction inverter adopts PWM mode to invert the DC1500V into three-phase AC with adjustable frequency and voltage, and supplies it to the four AC cage asynchronous traction motors of the vehicle in parallel, regulating the speed of the motors and realizing the traction and braking functions of the train.

A speed sensor and two output channels are installed on the shaft of each traction motor. Each channel has a square wave with a phase difference of 90°, and the direction is determined by judging the phase difference. Each traction control unit is connected to 3 speed sensors. Under normal circumstances, this value is directly sent to the traction control unit for traction control. When measuring speed, if the speed values ​​are not equal (예를 들어, when idling/coasting), even in extreme cases, the speed information of one motor is sufficient for traction control.

The motor is controlled by space vector control. The parameters of the inverter output voltage, phase current and motor speed can approximate the magnitude and direction of the motor flux (space vector). The current in the winding and the motor voltage are related to the flux as space vectors. This decoupling process can realize the separate control of flux and torque (field-oriented control)
The generation of motor torque current depends on the interaction between the excitation magnetic field and the rotor magnetic field. In the case of asynchronous motors, the excitation magnetic field and the rotor magnetic field are both generated by the stator current. At high speed, the motor reaches the control limit. The motor transitions to the field weakening mode, in which the pulse control takes precedence over the input control of the inverter set torque.

공급자

뤄양포뇨중공업(Luoyang Fonyo Heavy Industries), 주식회사,1998년에 설립된 캐스트 철도 부품 제조업체입니다. 저희 공장 부지는 72,600㎡입니다., 이상으로 300 직원, 32 기술자, 포함 5 수석 엔지니어, 11 보조 엔지니어, 그리고 16 기술자. 우리의 생산 능력은 30,000 연간 톤. 현재, 우리는 주로 주조물을 생산하고 있습니다, 가공, 기관차 조립 및 조립,철도 차량,고속 열차, 광산 장비,풍력,etc.Our 제품은 러시아에 수출되었습니다, 미국, 독일, 아르헨티나, 일본, 프랑스, 남아프리카,이탈리아 및 기타 국가.
연락하다: 스텔라 리우
이메일:[email protected]
이동하는:+8615515351287