An 800-V High-Density Traction Inverter—Electro-Thermal Characterization and Low-Inductance PCB Bussing Design

The need to increase the power density of traction inverters for the electrified transportation systems offers an opportunity to adopt silicon carbide (SiC) devices. To ensure the system reliability, it is critical to select a SiC power module that can dissipate a sufficient amount of power to avoid operating beyond the maximum allowed junction temperature. In this work, a comprehensive electro-thermal characterization procedure based on the virtual junction temperature concept is proposed to characterize the module’s maximum power dissipation as a function of coolant temperature. Using the characterization results, it is feasible to determine the module’s safe operating area for a traction application in terms of the switching frequency and the coolant temperature. The proposed characterization method is demonstrated on a custom 1200-V SiC module to validate its feasibility for an 800-V, 150-kVA traction inverter system. In addition, the design approach for a low-inductance bussing structure using heavy copper printed circuit board (PCB) is presented in this work, which leads to a snubberless, compact, and low-cost system design. Measurements and experimental studies have been performed to validate the effectiveness of PCB bussing design. The overall volume of the inverter system is around 1.75 L, which leads to a volumetric power density of 86 kVA/L.