Dual Resonant Tank Single-Stage LLC Converter with Variable DC-Link Voltage and Wide-Output Voltage Range for EV Fast Charging Stations

This paper introduces a single-stage LLC converter architecture featuring a dual resonant tank with a single bridge and two separate rectifiers operating in a series-parallel configuration. The proposed dual resonant tank single-stage LLC converter (2RTSS-LLC) design addresses the challenges of operating with variable input DC-link voltage, while achieving wide output voltage range, making it specifically suited for both nominal 400 V and 800 V electric vehicle (EV) battery fast-charging stations. By optimizing the input-tooutput voltage ratio, the 2RTSS-LLC delivers enhanced efficiency across a wide range of charging power levels. The design supports output voltage variations from 200 V to 1000 V and input voltage ranges between 650 V and 850 V using a flexible series-parallel configuration. Additionally, the LLC converter operates with zero-voltage zero-current switching (ZVZCS) at power levels up to 25 kW, ensuring high operational efficiency. The proposed solution provides a robust and adaptable approach to meet the technical requirements of modern EV fast charging stations, offering a highly efficient, adaptable, and reliable approach under wide power and voltage conditions.