IGBT Online Junction Temperature Detection Method Based On Gate Charge Of IGBT

In recent years,with the increasing use of high-power IGBT in the industrial field,especially in the fields of HVDC transmission and wind power generation,the reliability of power semiconductor devices has become more demanding.The reliability of power semiconductor devices has increasingly become the focus of people.The current research results have found that IGBT junction temperature is closely related to its reliability.Accurate online measurement of the junction temperature of IGBT modules is a prerequisite for rapid module over-temperature protection and performance evaluation,and of course it is also an important method to improve its high power density.Therefore,how to realize the easy integration,rapidity and high precision of online extraction of IGBT junction temperature has become one of the focuses of attention in the industry and academia in recent years.At present,the two main measurement methods include the sensor based on the negative temperature coefficient in the package and the thermosensitive electrical parameter(TSEP)method.Although the NTC-based method in the package is a typical choice for power device manufacturers and is cost-effective and easy to implement,its industrial application has been limited due to its slow dynamic response and low accuracy.Compared with the previous category.The method based on thermally sensitive electrical parameters is more suitable for IGBT junction temperature detection,because it uses the device itself as a temperature sensor,which has relatively high accuracy and response speed.Therefore,this article studies the on-line detection method of IGBT junction temperature from the perspective of thermally sensitive electrical parameters.This article first discusses the internal structure,working principle and switching transient process of the IGBT from the theoretical aspect.Then the distribution of parasitic capacitance inside the IGBT and the turn-off transient gate charge behavior are analyzed in detail and a mathematical model is established for electrical parameters such as gate current,turn-off delay time and gate charge.From the mathematical model,the corresponding relationship between the turn-off delay time and the junction temperature is found,and the turn-off delay time will inevitably affect the gate current,so the relationship between the junction temperature and the turn-off transient gate charge is determined.Then the principle of double pulse test was introduced,and a double pulse test platform was built.In order to obtain the turn-off transient gate charge,a gate charge collection circuit is designed and the components of the circuit in detail is introduced.After experimental tests,the gate charge is positively correlated with the junction temperature,that is,the gate charge increases with the rise of the junction temperature.Subsequently,the influence of other parameters on the gate charge was also experimentally analyzed.Such as gate drive voltage and load current.The results showed that the gate charge increased with the increase of the gate drive voltage and load current.The experimental data proved that this method is effective and feasible.There are 55 figures,4 tables and 88 references in this thesis.