A Novel Hybrid Modulation Method for Single‐Stage Single‐Phase DC/AC Converter

The single‐stage DC/AC converter has attracted extensive attention due to advantages such as fewer power switching devices, a wide zero‐voltage switching (ZVS) range, and high efficiency. This paper proposes a hybrid modulation strategy for a single‐stage single‐phase dual‐active‐bridge (DAB)‐based DC/AC converter. The proposed modulation strategy combines phase‐shift (PS) modulation and variable frequency (VF) control using three control variables, namely, two PS ratios and switching frequency. First, a mode‐switching control method is analyzed. The underlying idea is to switch between two modulation modes over a line‐frequency cycle to maximize the ZVS range. Then, based on the mode‐switching control method, a VF control method is developed to automatically regulate the switching frequency according to the output power, thereby improving efficiency across a wide load range. Specifically, a lower switching frequency is adopted under heavy‐loads to limit the peak current, whereas a higher switching frequency is applied under light‐loads to extend the ZVS range. Finally, a 400‐W experimental prototype is built and tested to validate the effectiveness of the proposed control strategy.