A 10-level GaN-based Flying Capacitor Multilevel Boost Converter for Radiation-Hardened Operation in Space Applications

Recent work has shown the high efficiency and high power density of multilevel converters in terrestrial applications. This work applies the advantages of multilevel converters to space applications by investigating a 10-level flying capacitor multilevel boost converter for compact and efficient high-voltage generation. The converter exploits the low on-state resistance and reduced parasitic capacitance, as well as radiation hardened qualities of GaN power semiconductor switches to achieve high efficiency and power density. Practical challenges such as driving a large number of high-side switches while maintaining high-voltage creepage and clearance requirements are addressed through innovative cascaded bootstrap techniques for gate driver power, and a new commutation loop design with reduced parasitic inductance. The performance benefits of these techniques are demonstrated in a 1 kW, 100 V to 500 V step-up dc-dc hardware prototype, achieving 99.1% efficiency and a power density of 24 kW/kg.