Nowadays, residential energy storage systems have become increasingly indispensable, functioning as flexible energy sources capable of storing renewable energy and ensuring peak power supply during high-demand periods. These applications are generally configured based on an AC-coupled microgrid architecture, which interconnects the utility grid, distributed energy resources, and residential loads. Power electronic converters are typically studied for power exchange between distributed energy sources—including solar panels, storage batteries, and EV batteries—and the common AC bus. Specifically, this paper focuses on the AC Battery, which includes a storage battery and a power converter capable of bidirectional energy transfer. Fig. 1 summarizes the characteristics of commercial products from manufacturers such as Tesla, Franklin, SunPower, Enphase, LG, Sonnen, and Delta... The classification criteria include: a wide input DC voltage range for compatibility with various second-lifetime battery standards, flexible connectivity with multiple power grid topologies, and the operational power rating. Normally, each product is only designed for a specific application. In this study, a versatile power converter, namely the Universal Battery Converter (UBC), is proposed to fulfill all the aforementioned functions of the AC Battery application. The proposed structure employs a two-stage topology: a DC/DC converter connected to the battery and a DC/AC converter connected to the common AC bus.