A Thermal Model Considering the Effective Heat Conduction Path in IGBT Module

Abstract High-power insulated-gate bipolar transistor (IGBT) play a crucial role in diverse fields, including offshore photovoltaic systems, energy storage systems, and electric traction systems. The temperature information at the key positions of the IGBT module serves as a crucial indicator for its safe operation. Currently, the thermal model is extensively employed as an efficient and concise instrument for assessing the junction temperature of the IGBT module. Nevertheless, it still exhibits certain limitations in precisely forecasting the junction temperature of the IGBT module, particularly when considering the change of effective heat conduction path (EHCP) resulting from the aging of the solder layer within the IGBT module. Therefore, this paper proposes a thermal model considering the change of EHCP of the IGBT module. The change of EHCP is manifested by the increase in the non-uniformity of the temperature distribution on the baseplate. The RC parameters of the IGBT module are computed using multi-point heat flux density information, thereby eliminating the influence of the change of the EHCP on the junction temperature calculation. Finally, the validity of the proposed thermal model was verified through experimental results. The research findings suggest that, in comparison with conventional thermal models, the model proposed in this paper exhibits greater accuracy in calculating junction temperature. This improvement enhances the precision of junction temperature calculation for high-power IGBT modules and offers theoretical and technical support for the reliable operation of offshore photovoltaic inverters.