Reliability-Oriented IGBT Selection for High Power Converters
The critical nature of grid applications in power engineering demands the utmost levels of apparatus reliability as well as high availability and low maintenance. The latter additionally implies a high lifetime for all components used. Power electronics, now a mature technology, is currently employed in critical applications such as commercial aviation, and is being increasingly introduced in grid applications to improve the controllability and efficiency of power flow within power grids. The design of power converters at medium voltage and high voltage levels nonetheless still represents an immense challenge in terms of reliability. As a critical step in the Reliability-Oriented Design (ROD) of power converters, the IGBT selection should be conducted in a reliability-oriented manner. Detailed procedures of Reliability-Oriented IGBT selection are presented in this paper.
The conventional approach to deciding the current rating of IGBTs for a power converter design is basically to guarantee that the junction temperature of the IGBT will not exceed its maximum allowable value in all ranges of operating conditions. However, the lowest junction temperature does not necessarily indicate the highest reliability or the longest lifetime, which are instead related to the chip and packaging technologies from different manufacturers. Therefore, this paper mainly focuses on the impact of chip and packaging technologies on reliability performance. Comprehensive comparisons are made to determine the final IGBT selection in order to achieve the highest reliability.