Design And Implementation Of Soft-switching Bi-direction DC-DC Converter

Bi-directional DC-DC Converters can regulate Bi-directional energy transmission according to different situation.With the development of science and technology,it’s becoming urgent to apply Bi-directional DC-DC converters to many fields like UPS,Space Power Systems,Hybrid Electric Vehicle.The application of Soft-Switching technology can reduce the energy losses in switching process and enhance the efficiency,making it possible to reduce converters’ volume and weight.Based on the design of the 5KW lithium battery Bi-directional DC-DC converter in the DC micro grid,this dissertation mainly study the main circuit and control method of Bi-directional full-bridge DC-DC converter,the control algorithm design,the application of Soft-Switching technology,digital control system design.The main contents of this dissertation are as follows:Based on the technical specifications,the main circuit design scheme was voltage and current isolated full-bridge.In order to enhance the efficiency,some improvement of the main circuit and the control methods is needed.A kind of soft start-up scheme and fly-back transformer are combined to realize soft start-up successfully.The active clamp technique is adopted to restrain the peak of power switch voltage.Building the small signal model according to the State Averaging method and making the simulation in MATLAB.Based on the simulation,designing the PID control method.Then design the overall program of digital controller software,including software requirements analysis and the main program design.PWM module,A/D data acquisition module,serial and CAN communication and control systems software have been designed.Finally,the converter was built and some tests were made about it.The test results show that the active clamp technique reduces the output ripple,active clamp soft-switching technology to improve the conversion efficiency of the converter.The protection mechanism was also built to coordinate with other converters on the grid.The test results show that the conversion efficiency of this converter is higher than traditional converters.It can contribute to the improvement of efficiency.