Detailed thermal dynamics of high-power IGBT modules are important information for the reliability analysis and thermal design of power electronic systems. However, the existing thermal models have their limits to correctly predict these complicated thermal behavior in the IGBTs: The typically used thermal model based on one-dimensional RC lumps have limits to provide temperature distributions inside the device; moreover, some variable factors in the real-field applications like the cooling and heating conditions of the converter cannot be adapted. On the other hand, the more advanced three-dimensional (3-D) thermal models based on finite-element method (FEM) need massive computations, which make the long-term thermal dynamics difficult to calculate. In this paper, a new lumped 3-D thermal model is proposed, which can be easily characterized from FEM simulations and can acquire the critical thermal distribution under long-term studies. Meanwhile, the boundary conditions for the thermal analysis are modeled and included, which can be adapted to different real-field applications of power electronic converters. Finally, the accuracy of the proposed thermal model is verified by FEM simulations and experimental results show a good agreement.

Thermal loading of power devices are closely related to the reliability performance of the whole converter system. The electrical loading and device rating are both important factors that determine the loss and thermal behaviors of power semiconductor devices. In the existing loss and thermal models, only the electrical loadings are focused and treated as design variables, while the device rating is normally predefined by experience with limited design flexibility. Consequently, a more complete loss and thermal model is proposed in this paper, which takes into account not only the electrical loading but also the device rating as input variables. The quantified correlation between the power loss, thermal impedance, and silicon area of insulated gate bipolar transistor (IGBT) is mathematically established. By this new modeling approach, all factors that have impacts to the loss and thermal profiles of the power devices can accurately be mapped, enabling more design freedom to optimize the efficiency and thermal loading of the power converter. The proposed model can be further improved by experimental tests, and it is well agreed by both circuit and finite element method (FEM) simulation results.

The reliability analysis and lifetime prediction for SiC-based power modules is crucial in order to fulfill the design specification for next-generation power converters. This paper presents a fast mission-profile-based simulation strategy for a commercial 1.2 kV all-SiC power module used in a photovoltaic (PV) inverter topology. The approach relies on a fast condition-mapping simulation structure and the detailed electro-thermal modeling of the module topology and devices. Both parasitic electrical elements and thermal impedance network are extracted from the finite-element analysis of the module geometry. The use of operating conditions mapping and look-up tables enables the simulation of very long timescales in only a few minutes, preserving at the same time the accuracy of circuit-based simulations. The accumulated damage related to thermo-mechanical stress on the module is determined analytically and a simple consumed lifetime calculation is performed for two different mission profiles and compared in different operating conditions.

Thermal loading of Insulated Gate Bipolar Transistor (IGBT) modules is important for the reliability performance of power electronic systems, thus the thermal information of critical points inside module like junction temperature must be accurately modeled and predicted. Usually in the existing thermal models, only the self-heating effects of the chips are taken into account, while the thermal coupling effects among chips are less considered. This could result in inaccurate temperature estimation, especially in the high power IGBT modules where the chips are allocated closely to each other with large amount of heat generated. In this paper, both the self-heating and heat-coupling effects in the of IGBT module are investigated based on Finite Element Method (FEM) simulation, a new thermal impedance model is thereby proposed to better describe the temperature distribution inside IGBT modules. It is concluded that the heat coupling between IGBT and diode chips strongly influence the temperature distribution inside IGBT module, and this effect can be properly modeled/predicted by the proposed thermal impedance model.

One way to achieve the best in class reliability is the implementation of a Design for Reliability methodology into the design process in order to estimate the lifetime of each individual critical component, based on proper reliability models for failure modes. The main drawback of above-mentioned approach is that it is relying on handbook-based reliability models, which usually are accurate only for particular components. This fact causes a necessity to develop a testing procedure for SiC power MOSFET, to determine its reliability model parameters. Such model could be further implemented in the Design for Reliability methodology for high performance power supplies design process. In this paper, a cost effective and industrial friendly laboratory setup for Active Power Cycling of SiC power MOSFETs in SOT-227b housing is presented. By this example, various control strategies for accelerated lifetime testing, degradation indicators for wear out condition monitoring and junction temperature estimation methods are compared on their impact on test results and complexity in either laboratory setup and its maintenance procedure. Technical issues related to start up of Active Power Cycling test and failure detection algorithm are discussed. At last, test results for SiC power MOSFETs subjected to over 63355 power cycles are presented.

In this letter, a compact SiC power module featuring low stray inductance and balanced thermal resistance is proposed. To make full utilization of SiC devices in high-frequency and high-power-density applications, the laminated busbar and double-sided cooling heatsinks are directly packed as parts of SiC power module. To balance the mechanical and thermal stress on the chips, a press-pack-like package technology is adopted. The electrical and thermal experiments of the prototype are evaluated to validate the design of low inductance and balanced thermal distribution.