Medium voltage extreme fast charger based on novel medium voltage SiC power devices

Sen, Soumik, Ph. D.
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With an increased number of electric vehicles on the roads, there is a need for adequate charging infrastructure to serve these vehicles. Extreme fast charging technology has the potential to add 200 miles charge to electric vehicles in less than 10 minutes to provide a refueling experience comparable to gasoline vehicles. Having access to these fast charging stations can help alleviate the “range anxiety” commonly cited as a reason for consumer’s hesitation to buy an electric vehicle. This thesis presents the design and implementation of a 4.16kVac/800Vdc three phase 150kW fast charger which uses a modular single-phase single-stage isolated ac/dc power converter in each phase. Novel 7.2kV/60A SiC Austin SuperMOS devices are used as the medium voltage power electronic switches and soft-switching over the entire range of grid voltage has been ensured by a novel variable switching frequency double phase shift modulation technique. Experimental results validate the simulation results and show a high efficiency of 98%. A novel and improved 4.5kV SiC Austin SuperMOS half-bridge module with double-sided cooling and ultra-low stray inductance has been developed which can be used to realize a 500kW extreme fast charger. Device characterization tests on the module demonstrate satisfactory static and dynamic performance.