Junction Temperature Estimation And Thermoelectric Performance Optimization Control Of Si IGBT/SiC MOSFET Hybrid Switch

The emergence of Si IGBT/SiC MOSFET hybrid switch has broken the predicament of silicon carbide(SiC)based devices,strongly promoted the development and application of SiC based devices,and provided a new way for the development of the power electronical technology.However,the development time of the hybrid switch is relatively short,and so most of the current research on the hybrid switch focus on the comparative verification of and preliminary performance optimization of device.It is well known that junction temperature is an important factor affecting the reliability and life of the power semiconductor devices,but there has not yet been a simple and effective method for estimating the junction temperature of the hybrid switch.Then,the hybrid switch is composed of two devices of different materials connected in parallel,and this parallel structure usually has an unbalanced junction temperature of the device,which results in a device that cannot exert its performance advantages.In addition,the problem of conflict between junction temperature optimization and performance optimization is prone to occur in the actual application of the hybrid switch.Therefore,it is necessary to carry out theoretical analysis and experimental research on these urgently needed problems to find suitable solutions,so as to further optimize the thermoelectric performance of the hybrid switch and enhance their practical value.On the basis of previous research,this paper has carried out a number of researches around the Si IGBT/SiC MOSFET hybrid switch.The main work content is as follows:1.As a new technology,the hybrid switch has very different characteristics compared with traditional power semiconductor devices.Therefore,exploring the characteristics of the hybrid switch is the basis of subsequent research.This paper elaborates the selection requirements of the hybrid switch and determines the hybrid switch design scheme.And then,the static characteristics if the hybrid switch are tested and analyzed in detail through instruments.Finally,a dynamic characteristics test circuit is designed to explore the dynamic characteristics of the hybrid switch.2.Aiming at the problems of loss calculation and junction temperature estimation of hybrid switch,a loss model which can accurately calculate the loss of hybrid devices is established based on the conduction and switching characteristics of hybrid devices.The loss model reflects the shunting of Si IGBT and SiC MOSFET after the conduction of the hybrid switch,and also describes the influence of turn-on and turn-off delay time on the switching characteristics of the hybrid switch.Subsequently,this paper established a thermal impedance network suitable for the hybrid switch based on the heat conduction path.Finally,the loss model and thermal impedance network are used to estimate the junction temperature of the hybrid switch.3.In order to solve the problem that the hybrid switch cannot achieve the ultimate performance in the actual operation of the converter due to using the improper driving modes.This paper designs an active junction temperature control and a multi-objective optimization control for hybrid switch.And then this two types thermoelectric performance optimization control strategy of the hybrid switch presented in this paper is verified experimentally.Through the above research work,it is found that the hybrid switch combines the advantages of two different materials devices,and demonstrates higher cost performance,flexibility,and reliability.The loss model and junction temperature estimation method proposed in this paper make the junction temperature estimation of hybrid switch more concise and convenient,and provide new ideas for solving the problem of junction temperature estimation of hybrid switch.While the operating temperature of the hybrid switch with the performance optimization control strategy is optimized,the working performance is also improved,which plays a positive role in the promotion and application of the hybrid switch.