Research On Bidirectional DC/DC Converters Based On GaN Devices

With the development of energy Internet and distributed power grid,the future power grid is rapidly developing towards AC/DC hybrid power network with the goal of integrating renewable energy,energy storage and modern intelligent load.The power system architecture using power electronics can reduce the number of power converters,improve system efficiency and power quality,and increase system control flexibility.As an important interface in the DC microgrid and a core device in the energy storage system,the bidirectional DC/DC converter should have higher power density and conversion efficiency,which enables the microgrid to operate better and improve the overall efficiency of the microgrid.And it's important to improve its reliability.Therefore,research on bidirectional DC/DC converters is of great significance.In this dissertation,a bidirectional DC/DC converter system based on GaN device is designed,which combines the third generation power semiconductor device GaN with bidirectional DC/DC converter.It can improve the power density and transmission efficiency of energy storage converter system.In this dissertation,the characteristics of GaN power devices are studied,including the effects of static characteristics,dynamic characteristics and parasitic parameters on GaN devices.The characteristics of GS66508B and TPH series GaN are compared,based on this,a drive system suitable for GaN power devices is designed.Based on the dual active bridge topology and the application of GaN devices,an efficient bidirectional DC/DC converter is designed.The working principle of the system is introduced in detail,and the small signal model is deduced and established for the bidirectional DC/DC converter.The control algorithm is studied,and the working process and power characteristics of single phase shift control and triple phase shift control are compared and analyzed.This dissertation designs the hardware and software of the system,builds the simulation circuit model of bidirectional DC/DC converter,the characteristics of GaN power device are analyzed.The simulation is carried out on the LTspice software simulation platform.Finally,a power of 900W is designed.The experimental results show that the designed bidirectional DC/DC converter based on GaN device can realize bidirectional flow of power and improve system transmission efficiency.