A Thermal Estimation Method for IGBT Module Adaptable to Operating Conditions

Abstract

This letter proposes a novel junction temperature estimation method for the IGBT module to adapt to various operating conditions and improve the computing efficiency. By using the superposition theorem and odd/even mode analysis, the input power loss is decomposed into the even and odd mode loss. Further, the thermal model considering the thermal coupling between the upper and lower arms is equivalently decomposed into the even and odd mode thermal model according to the structure symmetry. The odd mode power loss is the cause of the thermal coupling between the upper and lower arms, and the odd mode junction temperature variation is used as an indicator to measure the thermal coupling. Based on the frequency domain analysis, the dividing line for operating condition with weak thermal coupling and strong thermal coupling can be obtained. Finally, experimental results verify the validity of the theoretical analysis and the accuracy of the proposed thermal estimation method.