Design and Assessment of SiC Multi-Chip Power Module with Kelvin Source

Silicon carbide (SiC) power module with paralleled multi chips is driven by the demand for compact size and high-power density in some emerging applications, especially electric vehicles. Compared with Si counterparts, SiC MOSFET presents some inherent advantages, including faster switching speed. Therefore, the larger di/dt induced by faster switching transient, along with the source parasitic inductance in the power loop, results in the reduction of the switching speed and increase of the switching loss of the power module. To mitigate this challenge, a new layout of the power module with the Kelvin source is designed and assessed in this paper. Focusing on the influence of the Kelvin source, the mechanism and equivalent circuit are both modeled and analyzed. Besides, parasitic parameters of the power module with and without Kelvin source are both extracted by Q3D and imported into the LTspice model for electrical performance evaluation. Based on the simulation results, the switching loss is decreased by 14.3% while the turn-off voltage overshooting of the drain-source voltage is increased by 3.3% after introducing the Kelvin source. Besides, the imbalance degree of transient current reduces from 16% to about 1%, which proves the feasibility and competence of the designed SiC power module with the Kelvin source.