ABSTRACT This paper proposes a hybrid modulation strategy based on variable frequency and variable dead time for the LLC resonant converter in a PV energy storage grid‐forming system, aiming to achieve high‐efficiency and stable operation across a wide input voltage range under a single enhanced pulse width modulation (ePWM) module. Conventional pulse frequency modulation (PFM) under a single ePWM module faces challenges in gain regulation when the input voltage exceeds the rated value, while burst mode operation increases output voltage ripple and input current stress, thereby compromising system coordination. The proposed method integrates PFM with variable dead‐time modulation (VDM) to achieve full‐range control within a single ePWM module, extending the gain regulation capability under high input voltage conditions while simultaneously reducing ripple and input current stress. A 1‐kW experimental prototype for a PV energy storage grid‐forming system is developed, with an input voltage range of 28–60 V. The switching frequency is adjustable across a range of 110 to 160 kHz. Experimental results demonstrate that, under a single ePWM architecture, the hybrid modulation strategy enables efficient and stable operation over a wide input voltage range, achieving a peak efficiency of 97.1%.
Xu et al. (Fri,) studied this question.