Research On High Power Density FSBB Converter Based On SiC MOSFET

With the continuous development of aerospace,new energy vehicles and clean energy power generation technologies,the performance requirements for power electronic devices are also increasing.The performance indicators of the entire power electronic device are inextricably linked with power electronic devices.Compared with traditional Si semiconductor power devices,emerging SiC power devices have the advantages of high blocking voltage,high-temperature operation,and fast switching speed,which can better meet the market demand for future power electronics technology.The material properties of SiC semiconductors are quite different from those of conventional Si semiconductors.In order to ensure the correct use of SiC power devices and give full play to their performance advantages,and to improve the performance and power density of power electronic converters,the electrical characteristics of SiC devices need to be improved.And parameters,especially static and dynamic characteristics,are studied and analyzed in depth.In this paper,a simple and accurate SiC MOSFET static and dynamic characteristics,temperature characteristics model,the use of nonlinear capacitance averaging method to establish the loss model of the device,laid the theoretical foundation for the loss analysis of the follow-up converter.A four-switch Buck-Boost(FSBB)topology is used as the main circuit topology of a high power density DC/DC converter.First,the topology,working principle,and gain characteristics of the FSBB are analyzed in detail.The FSBB converter is established.The loss model and the performance comparison of the SiC MOSFET and the conventional Si MOSFET are calculated to show that the SiC MOSFET improves the converter's performance.Based on the improvement of the efficiency of FSBB converter,several soft-switching and hard-switching modulation modes of FSBB converter are analyzed.The loss modeling method is used to determine the optimal three-mode control strategy for achieving the efficiency of FSBB converter over a wide input range.The optimal switching frequency of the FSBB converter is determined by a quantitative calculation method,and the Saber software is used to simulate the circuit under the three modes to verify the correctness of the hardware parameter design.Finally,a FSBB converter experimental platform using SiC MOSFETs is built.The input voltage of the converter is 50V-400 V and the output is 200V/2A.The basic function verification,three-mode verification,different switching frequency verification,and efficiency test of the FSBB converter were performed under a wide input range toverify the correctness of the theoretical analysis and design of this paper.