Gallium Nitride (GaN) Based Topology Comparison for Low Power Battery Charging Applications

This paper presents the design and implementation of a GaN-based Power Converter for low-power battery chargers. It compares the performance of the Asymmetrical Half Bridge Flyback (AHB-FB) with 2-Switch Flyback (2SW-FB) and resonant LCC topologies, all using the same 600V/150mΩ GaN Half Bridge (HB) System in Package (SiP). High Voltage (HV) GaN High Electron Mobility Transistors (HEMT) SiP technology enables a simpler implementation and smaller form factor compared to standard, discrete silicon solutions. Additionally, GaN-SiP facilitates soft switching over a wider operational range with minimal circulating current, enhancing system efficiency.The AHB-FB, LCC, and 2SW-FB converters use dedicated analog controllers to achieve Zero Voltage Switching (ZVS) for the AHB and LCC, and Quasi-Resonant (QR) Operation for the 2SW-FB.The paper outlines the experimental results for a battery charger designed around these three topologies: AHB-FB, LCC, and 2SW-FB. Key factors for comparison include efficiency for performance, Bill Of Materials (BOM) for cost, and size for power density. The analysis highlights the advantages of Flyback topologies, particularly in terms of reduced components and cost. The findings emphasize the benefits of GaN-based Flyback configurations in these power applications.