Research On High-Temperature Characteristics Of High-Power SiC MOSFET Half-Bridge Module And Its Application In Converter

SiC materials have the advantages of large forbidden band width,strong critical breakdown electric field,and high thermal conductivity.They have great potential in the field of high-temperature high-power switching devices.Compared with Si IGBT devices at the same grade,SiC MOSFET,as a new wide-bandgap high-temperature device,has higher voltage resistance,higher junction temperature and higher operating frequency.It can be used in high-temperature fields such as petroleum exploration,multi-electric aircraft and electric vehicles,where Si IGBT is incapable.Therefore,it is necessary and valuable to study the high-temperature characteristics and application of high-power SiC MOSFET half-bridge modules.First,based on the study of the basic structure and working principle of SiC MOSFET power devices,this article builds a test platform to study the high temperature static,switching,and short-circuit characteristics of high-power SiC MOSFET half-bridge modules.The analysis of output characteristics,on-resistance and transient electrical stress of the module has verified that it has excellent high temperature characteristics,and provides a test basis for long-term operation research of building a high-temperature converter.Second,aiming at the problem that the switching speed of SiC MOSFET half-bridge modules is too fast,which reduces the reliability of the device at high temperature,a high temperature deceleration analysis is carried out.At the same power,voltage level and switching frequency,increase the driving resistance to reduces the switching speed of the SiC MOSFET to the same as that of the Si IGBT.The switching loss is theoretically calculated and experimentally verified and compared with Si IGBT.The results show that when the speed of the SiC MOSFET half-bridge module is reduced to the same as that of the Si IGBT,the switching loss is still smaller than that of the Si IGBT,which verifies that the SiC MOSFET half-bridge module has the possibility of speed reduction application.It provides experimental basis for the subsequent research on building a high-temperature converter for long-term speed reduction.Third,based on the characteristics of SiC MOSFET half-bridge modules which have excellent high-temperature characteristics and high-temperature speed reduction applications,research on the application of SiC MOSFETs in high-temperature high-power converters has been carried out.First,based on the static and dynamic test results of the high-power SiC MOSFET half-bridge module at high temperature in Chapter 2.a comparative analysis of the loss of a 100-kilowatt DC/AC converter using SiC MOSFET and Si IGBT at different temperatures was performed,indicating that the high-power SiC MOSFET half-bridge module can meet the application requirements of high-temperature converters.Subsequently,for cost and safety considerations,high-power SiC MOSFET half-bridge module was tested for thermal resistance at 180? and thermal equivalent power operation test before constructing high-temperature converters,which provides a feasible basis for the subsequent construction of high-temperature converter for long-term operation test.Finally,a test method for estimating the junction temperature using the measured thermal resistance,loss,and case temperature was used to build a 100kW high-temperature converter for a junction temperature 180? power operation test study.The test shows that the converter can run stably for a long time at a junction temperature of 185.5? and meet the needs of high-temperature high-power engineering applications.