IGBT Junction Temperature Measurement Based On Short Based On Short Circuit Current Via Combined Method Circuit Current Via

Power semiconductor devices,as one of the core components of energy conversion interface,are widely used in the fields of hybrid electric vehicles,renewable new energy and aerospace and so on.The failure of power electronic equipment or system may result in abnormal operation,shutdown,breakdown and so on.There may be great threats to personnel security and great economic losses.For the power semiconductor devices,the failure modes can be divided into package level failure and chip level failure.Package level failure is mainly caused by material fatigue failure.There are mainly bond wire fatigue and bond foot cracking,solder layer void and cracking,aluminum metal reconstruction and so on.Chip level failures are related to semiconductor physics.There are mainly due to thermal breakdown caused by short circuit and open circuit,latch effect,electron migration and so on.These failure modes have an important relationship with the junction temperature of the device.Especially for wind power system,energy is transmitted through the converter,but because of the instability of wind energy,the power of wind power generation fluctuates greatly,therefore,the junction temperature of IGBT?Insulated Gate Bipolar Transistor-IGBT?fluctuates greatly.Meanwhile,because IGBT material thermal expansion coefficient is inconsistent,after a period of time,it's easy to make IGBT bond wire off and solder layer fatigue.Industrial experience indicates that power semiconductor devices account for more than 31%of the failure in converter systems.However,the temperature factor accounts for 61%of the device failure.Therefore,the temperature control and thermal management become more of a concern.Experience with power transformer suggests that temperature monitoring will be a valuable way to improve operational reliability and reduce maintenance cost of the system.This paper proposes a combined method using short-circuit current to measure the junction temperature of IGBT.On normal bus voltage,two short-circuit current values of IGBT module can be measured to mathematically eliminate the influence of ageing on two specific gate driving voltages.Therefore,the new TSEP can be obtained without considering the effect of ageing.Thus the junction temperature of IGBT is measured accurately.The main work of this paper is as follows:Firstly,the structure of IGBT module is introduced.The possibility of reflecting device temperature by electrical parameters and the effect of IGBT module aging on the short circuit current are analyzed.Meanwhile,the influence of various factors on short circuit current is analyzed.Therefore,a method of IGBT module junction measurement is proposed to eliminate the influence of aging.Secondly,based on the short circuit current formula,the derivation of characteristic parameter V₀ based on short circuit current via combined method is introduced in detail,and the relationship between the characteristic parameter V₀ and IGBT module aging is explained theoretically.In order to realize the online monitoring of characteristic parameter V₀,the parameter selection of characteristic parameter V₀ is analyzed,and the measurement method of characteristic parameter V₀ in practice is introduced.In order to realize the application in the converter,taking single-phase inverter and three-phase inverter as examples,how to conduct shortcircuit test in normal operation of converter is introduced,and the influence of short circuit test on single phase inverter is also explained.Meanwhile,the IGBT module aging was simulated by cutting off bond wire,and the short circuit test platform is built.Finally,whether characteristic parameter V₀ is affected by the aging is confirmed.The adjustable drive circuit of IGBT module is designed to make the short circuit test of IGBT module at the specific gate driving voltage can be implemented.By cutting off bond wire,short circuit current at different temperature is measured under different aging condition,and the effect of various factors on short circuit current and the validity of the method proposed in this paper are verified.In the operation of single-phase converter,short circuit test is carried out once per cycle,and it is verified that the output performance of converter is not affected by short circuit test.Meanwhile,the characteristic parameter V₀ as temperature sensitive electrical parameter is analyzed,and characteristic parameter V₀ is compared with the existing temperature sensitive electrical parameters in terms of temperature sensitivity,temperature sensitivity ratio,the effect of aging and online monitoring.