Design and Validation of a High-Power Radiation-Hardened DC/DC Converter Based on Bidirectional Magnetic Isolation

Abstract

This article proposes a bidirectional magnetically isolated feedback technique for isolated regulation. By using an isolation transformer to transfer feedback/control information bidirectionally via magnetic coupling, it enables a fully isolated closed-loop regulation and, at the mechanism level, avoids regulation drift and failure risks caused by optocoupler current transfer ratio (CTR) degradation under ionizing radiation. Based on this technique, a 150-W isolated DC/DC converter is designed and implemented for cost-sensitive low-Earth-orbit (LEO) platforms. The converter adopts thick-film hybrid integrated circuit (HIC) technology and a single-ended forward power stage, with the magnetic feedback link driven by radiation-tolerant analog components. The prototype delivers a regulated 28-V output over a 16–50 V input range, achieves a power density of 100 W/in³ in a $63.5\times 38.3\times 10.16$ mm³ hermetic package, and maintains $\ge 85$ % full-load efficiency at room temperature. To validate the reliability of this technical route, single-event effect (SEE) and total ionizing dose (TID) tests were conducted: the initial SEE campaign at the Heavy Ion Research Facility in Lanzhou (HIRFL) identified single-event-induced overstress risks in the auxiliary supply and secondary feedback circuitry, and targeted hardening measures were implemented accordingly; after hardening, no catastrophic failures were observed. TID testing up to 100 krad(Si) shows strong dose-rate dependence, with more pronounced degradation at 0.01 rad(Si)/s, consistent with enhanced low-dose-rate sensitivity (ELDRS).