Design Of Urban Rail Charger System Based On PWM Rectifier

In recent years,with the continuous advancement of urbanization,urban rail construction has become more intensive and transportation resources have developed rapidly,which has greatly improved the efficiency of people’s travel and effectively alleviated the problem of traffic congestion within the city.During the operation of urban rail trains,the charger serves as the source of DC voltage for the auxiliary power supply converter system of the train,mainly for the low-voltage DC load of the train and the battery.The battery can also be used as an emergency power supply for the train when necessary.In general,conventional chargers often use diode uncontrolled or three-phase half-controlled rectifier circuits,which will not only cause grid-side voltage distortion,but also generate harmonic pollution.Therefore,this paper aims at the problems of the above urban rail transit,builds a city rail charger system with battery based on the topology structure of PWM rectifier,and simulates the battery charging and discharging and experimentally verifies the feasibility of the system.This paper first expounds the basic structure and topological principle of the PWM rectifier,and divides the entire charger system into a hardware system and a software system for design.The hardware structure of the main circuit of the charger system is designed according to the topology of the three-phase VSR,and the main circuit of the system is parameterized according to the parameter design method of the PWM rectifier.Several common charging characteristic curves of the battery are compared and the cost is determined.The charging method of the battery of the charger is designed according to the parameters of the Alstom power module for the sampling hardware circuit and the sampling protection circuit.Finally,other control boards such as the main control board and PWM board of the control system are explained accordingly.After analyzing the PWM rectifier,the topology of the PWM rectifier is converted by coordinate transformation to obtain the dq mathematical model in the corresponding rotating coordinate system,and the double closed-loop control and decoupling design of the PWM rectifier are performed.On this basis,an improved double closed-loop control strategy suitable for battery charging is proposed to achieve constant current and voltage charging of the battery.It also modularizes the design of other parts of the control system,including phase-locked loop logic,battery charging logic,auxiliary inverter logic,precharging,and sampling and protection logic.This paper uses Matlab/Simulink to connect the charger system with battery to the three-phase AC voltage side for simulation to verify the feasibility of its own control system.Secondly,it is connected to the auxiliary inverter output side for simulation to verify that it can Unit power factor control is achieved,and the harmonic content on the grid side can be kept at a low level.Build a simulation of the charger system when the battery is discharged,the system can play the role of emergency power supply.Finally,based on the charger system platform built by the power module running on Beijing Metro Line 15,the control mode of combining FPGA and DSP has further verified the excellent characteristics of this system with good power factor and stable system.This paper contains 73 figures,4 tables,and 49 references.