Variable DC-Link Voltage for an LLC Converter with Wide Input and Output Voltage Range

This paper introduces an LLC converter with a variable input DC-link voltage, aimed to address the challenges of single stage DC-DC converter with wide output voltage range associated with electric vehicle (EV) fast chargers. The proposed design optimizes the input/output voltage ratio to enhance efficiency across a wide range of charging operating power values. The analysis highlights the converter's ability to accommodate the output voltage range from 200 V to 500 V with input voltage variations from 650 V to 850 V, while operating at frequencies between 73 kHz and 114 kHz for power levels up to 25 kW. With efficiency range from 97.5 % to 98.5 %, this design offers a highly efficient and adaptable solution for EV fast chargers, aligned with the technical requirements and performance expectations of modern EV charging infrastructures.