A Solid State Transformer-based Charging Station for Catering Heavy/Medium and Light Electric Vehicles

Incorporating solid-state transformers into EV charging stations can greatly improve their power density, reliability, efficiency, etc. This paper presents an solid state transformer (SST)-based EV charging station that can cater to three different types of vehicles according to the charging power requirement; heavy, medium, and light electric vehicles. Also, the proposed charging station provides both AC on-board charging and DC off-board charging ports. A MATLAB model of the proposed system was developed and simulated to validate the feasibility. The simulation results verifies that the proposed 10 kV, 1 MVA charging station is capable of charging the all categories of electric vehicles from 20% state of charge (SoC) to 80% SoC within 17.8 mins using constant current charging strategy. Furthermore, one heavy duty electric vehicle which is 30% of the charging station capacity is disconnected to demonstrate a sudden EV demand drop and the total harmonic distortion (THD) of grid current is observed to be laid below 2.6% before and after the event of disconnecting ensuring the stability of the proposed system.