Research And Design Of Phase Shifted Full Bridge Low Voltage High Current Converter

With the rapid development of China’s rail transit industry,subway has become one of the important means of transportation in people’s daily life.The metro traction power supply system mostly adopts DC power supply mode.Among them,the low-voltage DC circuit breaker is the only breaking element in the metro traction power supply system,which plays a key role in protecting the power supply system and other equipment.Regular trip test of low-voltage DC circuit breaker is an effective way to ensure the safe operation of Metro.The trip test needs to input more than ten times the rated current of the circuit breaker in a short time to simulate the short circuit condition of rail transit,and verify its performance by collecting the trip time of the circuit breaker breaking.The tripping test has higher requirements on the power supply capacity and output current rise rate characteristics.This paper combines the development trend of high frequency,miniaturization and digitalization of power supply.A 5000A/5V single module full bridge converter prototype is developed based on the phase-shift full bridge converter and DSP28335 controller.In this paper,the process of parameter calculation,device selection and hardware and software design are given in detail.The experimental results show that the prototype can meet the requirements of power supply for the trip test of low-voltage DC circuit breaker.On this basis,this paper analyzes the soft switch technology,puts forward the method of improving the performance of the experimental prototype by ZVS technology,analyzes the working state of the phase-shifting full bridge ZVS converter in detail and designs the parameters,realizes ZVS in the Simulink software simulation,and verifies the rationality of the parameter design.Aiming at the shortage of traditional PID controllers that can not meet the dynamic characteristics of non-linear time-varying converters,a fractional PI~λD~μcontroller is used to improve the output performance of the converter.In this experiment,the controller parameters were self-tuned by an adaptive genetic algorithm,and achieved better results than a PID controller with manual adjustment.In order to achieve the technical index of the trip test,the influence of the selection of the internal parameters of the phase-shifting full bridge ZVS converter on the rise rate of the output current is analyzed,which has certain guiding significance for the design of the trip test power supply of the DC circuit breaker in the rail transit industry.