Bidirectional GaN-Based Semiconductor Galvanic Isolation (SGI) Converter for Energy Storage Application

This paper presents a bidirectional GaN-based transformerless Semiconductor Galvanic Isolation (SGI) converter designed for energy storage applications. The SGI converter enables differential-mode (DM) power transfer between switching cells while blocking common-mode (CM) voltages through the use of bidirectional switches. Compared to traditional solutions, the SGI converter simplifies circuit topology, reduces the number of magnetic components, improves manufacturability, and increases power density. The paper introduces the fundamental principles, relevant safety standards, circuit topology derivation, and design guidelines for the SGI converter. A 2.5-kW 3-cell SGI converter prototype is developed using advanced bidirectional GaN devices, achieving a peak efficiency of 97.5% and a power density of 6.8 kW/L.