International audienceIn this paper, a 2.5-kW 330–410-V/14-V, 250-kHz dc/dc converter prototype is developed targeted for electric ve-hicle/hybrid vehicle applications. Benefiting from numerous ad-vantages brought by the LLC resonant topology, this converter is able to perform high efficiency, high power density, and low EMI. To arrange high-output current, this paper proposes a parallel-connected LLC structure with developed novel double-loop control to realize an equal current distribution and an overall efficiency improvement. Considering the LLC cell's dimensioning, this paper establishes a more precise model by taking the secondary leak-age inductance into consideration. System amelioration and design considerations of the developed LLC are also presented in this pa-per. A special transformer is presented, and various types of power losses are quantified to improve its efficiency. This converter also implements synchronous rectification, power semiconductor mod-ule, and an air-cooling system. The power conversion performance of this prototype is measured and the developed prototype attains a peak efficiency of 95% and efficiency is higher than 94% from 500 W to 2 kW, with a power density of 1 W/cm 3 . Finally, the EMC results of this prototype are also measured and presented