Publication: Solid-state transformers for electric vehicle extreme fast charging
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Date
2024-08
Authors
Ngun, Meng Ze
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Abstract
The rising adoption of electric vehicles (EVs) in developed countries stems from heightened environmental awareness and the cost-effectiveness of recharging
compared to traditional petrol-refuelling methods. Despite the availability of levels 1 and 2 EV charging options, their time-consuming nature, often taking more than 8 hours to charge a vehicle fully, and limited suitability for long-distance journeys have spurred the evolution of level 3 DC extreme fast charging (XFC) stations at 300kW power rating. However, conventional XFC systems employing line frequency transformers (LFTs) encounter challenges such as large physical dimensions and significant power losses, leading to complexities and elevated installation costs. Solid state transformer (SST) XFC systems have been proposed in this FYP project to address these issues. The objective of this project is to design a power electronic architecture for a DC level 3 extreme fast charging station (XFC) using solid-state transformers (SSTs) that can charge a few classes of EV batteries with different voltage and power levels. The proposed architecture is verified by measuring the state of charge (SoC) of the EV batteries through simulation in MATLAB/Simulink. A SST based XFC system is successfully designed with an output power at 320kW. The simulation results verify that the proposed power electronic architecture can charge different voltage and power levels of electric vehicles from 0% state of charge (SoC) to 100% SoC within 16.67 minutes for a heavy-duty EV battery and 6.17 minutes for a battery of light-duty EV. In conclusion, the study addresses the limitations of conventional XFC systems and proposes a more versatile solution utilizing SSTs.