Abstract

Partial power converters (PPCs) have emerged as an attractive solution for improving efficiency in DC–DC conversion systems by processing only a fraction of the total power. However, this high efficiency is typically limited to a reduced range around the nominal operating point, leading to performance degradation under light-load conditions. This paper proposes a hybrid modulation strategy for a step-down full-bridge-based PPC that extends the high-efficiency operating range. The proposed strategy combines phase-shift modulation (PSM), ensuring partial power operation and high efficiency near nominal load, and a pulse-width modulation (PWM) where the converter operates as a full-power converter (FPC) to improve efficiency under low output power operation. An analytical model of the converter under both modulation strategies is presented, along with an analysis of the transition between operating modes. The proposed strategy is validated experimentally on a laboratory prototype, demonstrating efficiency improvements above 97\% at light load and a peak efficiency of 97.4\%. The results confirm that the proposed hybrid modulation effectively enhances efficiency across a wide range of operating conditions without requiring hardware modifications.