Evaluation on Current Sharing of Power Module Affected by Kelvin Connection

High capacity power module with multiple chips in parallel is a key element for renewable energy integration and electrified transportation applications. Imbalance electro-thermal stress in a multi-chip power module challenges the high power capacity applications. Advanced packaging is considered as a promising solution toward next-generation power electronics. In this paper, based on a commercial power module packaging, to enhance the current sharing in the multi-chip power module, the capability of auxiliary Kelvin connection to limit the transient imbalance current among parallel chips was comparatively surveyed. Taking parasitics into account, electric circuit and finite element analysis were proposed to illustrate the influences of Kelvin connection. Based on customized power modules and a test rig, simulation and experimental results were presented to comprehensively demonstrate the current sharing of parallel chips affected by Kelvin connection. It reveals the capability to eliminate imbalance current by using Kelvin connection is limited. Optimized direct bonded copper (DBC) layout to eliminate the asymmetric loops is needed for multi-chip modules. © 2019 Chin. Soc. for Elec. Eng.