Research On Bidirectional DC/DC Converter And Control Of New Energy Vehicle Based On SiC

With the depletion of energy and global warming,electric vehicles have become one of the best ways to solve this problem.In recent years,the rapid development of on-board bidirectional DC/DC converter as a bridge connecting electric vehicle power battery and motor drive module,its conversion efficiency and power density requirements continue to improve.At present,power electronics technology is developing towards high frequency,high reliability and high energy density.Compared with traditional silicon devices,high efficiency power device SiC has the advantages of high switching frequency,low switching loss and fast switching speed,which can significantly improve the power density of onboard bidirectional DC/DC converters.Firstly,this paper introduces the structure and components of electric vehicle powertrain and the characteristics of on-board DC/DC converter.CLLC was chosen as the main circuit topology after comparing various topologies.The SiC power device is selected as the power switching device of DC/DC converter.Compared with traditional SiMOSFET,SiC MOSFET’s gate threshold voltage is low,the gate opening voltage range is narrow,and the driving circuit will have a large voltage spike when working at high frequency.The influence of SiC MOSFET’s switching principle,switching characteristics,static characteristics and parasitic parameters on the driving circuit of SiC MOSFET is analyzed.Combined with the characteristics of the converter topology,a SiC MOSFET driver circuit is designed.Secondly,analyzes the bidirectional CLLC resonant full bridge converter topology structure and working principle of steady-state modeling analysis with the method of fundamental analysis,comparative analysis the parameters determination of different effect on the performance of resonant converter,and on the basis of converter at full load within the scope of opening the zero voltage(ZVS)constraints,reliable parameter design scheme is put forward.Against the traditional control strategy of dynamic performance,voltage steady-state value is slow,the shortcomings of switch by the load disturbance is larger,this paper proposes a ADRC to CLLC resonant converter control strategy,in does not need to CLLC resonant converter under the condition of precise modeling,build extended state observer and PD controller is designed,to improve the dynamic response performance,reduce the overshoot,The purpose of reducing overshoot time and harmonic content.The key components of the converter design and selection,complete the hardware circuit and software program design.Finally,the resonant converter is simulated and verified by Simulink,and an experimental prototype is built to carry out forward and reverse experiments of the converter under multiple working modes.The results verify the rationality of the parameter design of the bidirectional full-bridge CLLC resonant converter,and the soft switching of the switching device can be realized in both forward and reverse operation,which has good efficiency and meets the requirements of the converter for wide range voltage regulation.