| The on-board charger module is the only device on the passe nger train that provides DC power supply to the battery,lighting,control and other systems,and plays a vital role in the safety and stability of the passenger train’s power supply.With the rapid development of my country’s rail transit industry,new re quirements have been put forward for the stability and performance of on-board chargers.On request,the 25 K passenger car was modified and the 160 km/h Fuxing EMU train to be launched was put into use.This paper studies and designs a set of soft-switching technology and digital control that can switch between cons tant voltage and constant current charging methods.Charging and real-time monitoring of various performance indicators of the charger,and can realize various independent protection functions,a nd a high-performance intelligent charger system that communi cates with the upper computer in real time,thus realizing the miniaturization,efficiency and intelligence of the on-board charger system It is of great significance to ensure the safety and stable power supply of passenger buses.In order to solve the problems of low efficiency,short lifespan,bloated volume and single function of traditional on-board auxiliary power supply,according to the technical requirements of the charger,a full-bridge soft-switching DC conversion circuit is used as the realization method of the charger,and the switch is selected on the secondary side.Full-wave rectifier circuit with less loss.The loss of switching devices is reduced,and the efficiency of the charger is improved.At the same time,the working principle and working mode of the zero-voltage switching phase-shifted full-bridge main circuit topology are analyzed and related calculations.And according to the proposed technical requirements,the selection and design of the main circuit components are carried out.Designed and explained hardware circuits such as sampling circuit,isolation drive circuit,communication circuit,etc.for the control system of the charger;based on the small signal model of the Buck circuit,small signal modeling of the zero-voltage switching phase-shifted full-bridge topology,and related transmission Function calculation.At the same time,in order to reduce the impact of the delay in the digital control on the control system and improve the dynamic performance of the system,the predictive deadbeat current control is introduced;finally,the control strategy of using the outer loop voltage PI control and the inner loop predictive deadbeat current control is determined.A Matlab/Simlink simulation model was built,and the design scheme was preliminarily verified through the simulation waveform.At the same time,the comparison and analysis of the single closed-loop control and the voltage-current double closed-loop control system under the two charging modes of constant voltage and constant current are carried out.The software design of the charger control system is carried out using the STM32 chip,and the realization scheme of the software system is briefly introduced.Finally,a prototype of the charger was made in accordance with the technical requirements.Through experiments on the prototype,the realization of the zero-voltage switch,the ripple and noise of the output voltage,the constant voltage and constant current output mode,and the realization of the protection function of t he experimental prototype were verified by experiments.The results show that the prototype has good control performance and Higher efficiency meets system design indicators and technical requirements. |
