Lifetime extension through Tj equalisation by use of intelligent gate driver with multi-chip power module

Abstract

Typical high-current power modules used in traction and wind generation contain several dies in parallel. Non-ideal geometries and electrical parameter variations cause an unequal aging of each die which limits the effectiveness of using parallel devices. This paper presents an intelligent power module with a TSEP-based junction temperature measurement and internal temperature equalisation for extending its operational lifetime. As the magnitude and number of junction temperature cycles strongly dictate the power module lifetime, this paper focuses on the quantification of the lifetime gain via the application of common automotive drive cycles. Thus, a general thermal model is first deduced from the experimental results. The lifetime is then estimated using a stress-counting rainflow algorithm, a pre-determined damage law and a linear damage accumulation rule. Finally, in order to illustrate the lifetime extension, 160 drive cycles, including the legislatives drive cycles, are simulated. A lifetime gain of up to two times can be expected with the temperature equalisation method. Therefore, the initial investment on the developed intelligent power module is justified by the benefit of the large gain in lifetime and of the end-of life indication functions.