A novel 3D thermal impedance model for high power modules considering multi-layer thermal coupling and different heating/cooling conditions

Abstract

Thermal management of power electronic devices is essential for reliable performance especially at high power levels. One of the most important activities in the thermal management and reliability improvement is acquiring the temperature information in critical points of the power module. However accurate temperature estimation either vertically or horizontally inside the power devices is still hard to identify. This paper investigates the thermal behavior of high power module in various operating conditions by means of Finite Element Method (FEM). A novel 3D thermal impedance network considering the multi-layer thermal coupling among chips is proposed. The impacts to the thermal impedance by various cooling and heating conditions are also studied. It is concluded that the heating and cooling conditions will have influence on the junction to case thermal impedances and need to be carefully considered in the thermal modelling. The proposed 3D thermal impedance network and the extraction procedure are verified in a circuit simulator and shows to be much faster with the same accuracy compared to FEM simulation. This network can be used for life-time estimation of IGBT module considering the whole converter system and more realistic loading conditions of the device.

A 3-D-Lumped Thermal Network Model for Long-Term Load Profiles Analysis in High-Power IGBT Modules

“…It is widely shared that the ambient temperature does not affect the thermal behavior of power devices, so the IGBT module is assumed to be adiabatic from top and lateral sides. In addition, it has been proven in [39] that the loading conditions affect the accuracy of the thermal model which is due to the variation of thermal conductivities of materials in different temperatures. On the other hand, cooling conditions may affect the parameters of the thermal network.…”

“…So, the temperature difference between the junction and case and consequently the thermal resistance will be increased respectively. More discussion regarding boundary conditions effects on thermal impedance is presented in [39].…”

A Physical RC Network Model for Electrothermal Analysis of a Multichip SiC Power Module

“…Then the compact RC network model consisting of 115 R and C parameters to predict the transient junction temperatures of the 6 MOSFETS has further been developed, where cross-heating effects between the MOSFETs are represented with lateral thermal resistors. Such a compact RC network model represents the real structure and heat-flow paths within the module much better than those RC network models reported in the existing literature [15][16][17][18][19][20][21], but there is no existing method to effectively determine the R and C parameters.…”

“…Compact thermal models expressed as thermal resistorcapacitor (RC) networks were more widely employed to rapidly predict junction temperatures or the temperatures at a few critical locations in the power modules for electro-thermal design, thermal management, reliability and lifetime prediction [15][16][17][18][19][20][21][22][23][24]. In the simplified cases, individual power device might be considered and one dimensional heat conduction was assumed to predict the junction temperatures [23][24][25].…”

“…Generally speaking, the Foster networks were used as behavior models to calculate the transient junction temperatures, while the R and C parameters in the Cauer networks were taken to have true physical meanings. In most cases, multiple power devices with both self-heating and crossheating effects were considered [15][16][17][18][19][20][21]. In these models, no matter whether it is self-heating or cross-heating, the heating contribution from each power device was described using a Foster network.…”