The Estimation Of MOSFET Junction Temperature

In recent years,the government had paid more and more attention to energy saving and environmental protection problem,however,on one hand,the use of the conventional cars has caused continuous consumption of non-renewable energy,on the other hand,environmental pollution which caused by the conventional cars has become more and more serious.Therefore,the research and development of new energy vehicles has been widely recognized by the country and society.As the core of new energy vehicles,the motor controller plays a decisive role in the vehicle performance.The motor controller needs to flow a large current during operation,so the temperature will rise inevitably.As we know,the influence of temperature on the semiconductor device is very huge,so the temperature monitoring during the operation of the controller requires more attention.Currently,the mainstream of three-phase inverter core devices have two options,namely IGBT and MOSFET.In the area of low-voltage controllers,based on the cost and the actual demand,MOSFET is generally preferred.As the core of power output device,the temperature rise of MOSFET in the work is inevitable,so the estimation of MOSFET junction temperature has become a hot topic in current research.In this paper,the low-voltage motor controller will be the experimental platform to achieve the MOSFET junction temperature evaluation.First of all,the selection of the MOSFET and the characteristics of the MOSFET working will be discussed,using the controller as the experimental object,the power consumption of MOSFET will be calculated based on the theory.Secondly,the influence of temperature on MOSFET life span will be discussed,and the theoretical modeling of MOSFET junction temperature estimation will be carried out by using the theory of thermoelectric analogy and experiment.Thirdly,on the basis of the model,the controller temperature protection system with MOSFET junction temperature as the monitoring temperature is proposed,which will protect the controller from damage caused by excessive temperature rise.Finally,the paper summarizes the issues and points out the shortcomings of the project,and make a prospect of the follow-up experiment.