The Experimental Study of Bi-directional Buck-Boost Converter Based on GaN-FETs for Satellite Energy Systems

This study presents the design and experimental validation of a bi-directional, non-inverting Buck–Boost DC–DC converter based on Gallium Nitride (GaN) field-effect transistors for satellite power management and distribution systems. The symmetrical topology enables fully bi-directional power flow, supporting charging and discharging operations in distributed spacecraft power architectures. GaN devices enable high-frequency operation up to 500 kHz, reducing switching losses and allowing a compact, high–power-density implementation. The converter is designed in alignment with key ECSS-E-ST-20C guidelines adopted by the European Space Agency (ESA), including component derating, protection strategies, and thermal margin considerations, while full ECSS qualification and ESA acceptance testing are beyond the scope of this work. Active current and voltage protection mechanisms are incorporated to ensure safe operation under wide input-voltage variations and dynamic load conditions. Experimental results demonstrate a rated output power of 90 W, a maximum output power of 135 W, a peak efficiency of 95.2%, a power density of 375 W/cm³, and a maximum device temperature below 73 °C at full load under ambient laboratory conditions. The results indicate that the proposed GaN-based converter is a promising candidate architecture for future ESA-aligned, ECSS-compliant satellite power processing units.