Improving of Heat Spreading in a SiC Propulsion Inverter using Graphene Assembled Films

Journal article, 2021

The focus of this work is first to establish the effect of the chip temperature and thermal feedback on the determination of the power loss in a three-phase propulsion inverter, then to demonstrate the possibility of achieving an improved heat spreading through the different layers inside a SiC power module by using graphene assembled films in the packaging of the power module. The power loss analysis has been carried out for two Silicon Carbide (SiC) modules in a vehicle inverter, incorporating the MOSFET’s reverse conduction as well as including the impact of blanking time on the inverter on-state losses. This data for calculating the losses is determined at an operationg situation below the filed weakening speed with a high torque for a PMSM machine The operating point is found to be the worst operating condition point when looking at the power loss point. First, it can be noted that not accounting for the thermal feed-back, the power loss is considerably underrated, i.e.,11-15% on the on-state converter. Following, the analysis of utilizing the graphene layer in the SiC module reveals a reduction of 10°C per SiC chips in the junction temperature of the SiC MOSFET is achievable. The reduction is calculated based on an applied power loss per SiC chips in steady-state simulation. Furthermore, up to 15°C decrease in the transient computation over the Worldwide Harmonized Light Vehicles Test Cycle (WLTC) per SiC chip is noticed. Moreover, a reduction up to 50% for the junction to case thermal resistance (Rth,JC) is observed by adding the graphene layer in the power module.