This innovation integrates transformer and resonant inductors into a single nanocrystalline three-core planar structure for high-frequency CLLC resonant converters. By eliminating discrete magnetics and enabling precise inductance control with reduced losses, it delivers high power density, compact form factor, and exceptional efficiency for next-generation EV chargers, aircraft power electronics, and grid-scale energy storage systems.
Background: High-frequency AC-DC resonant converters offer compact, efficient energy transfer, but planar magnetics based on ferrite suffer from low saturation flux, high fringing losses, and the need for separate inductors and transformers. Large air gaps used to achieve soft-switching inductance cause heat buildup and reduce efficiency, while multiple magnetic components increase size, cost, and thermal management complexity. A solution is required that enables independent control of primary and secondary inductances, minimizes losses at high frequency, and supports bidirectional operation without adding manufacturing difficulty or compromising converter performance.
Technology Overview: The invention uses three nanocrystalline subcores—left, central, and right—each incorporating distributed air gaps and independent flux paths. The primary winding surrounds the left and central subcores to generate primary-side resonant and magnetizing inductances, while the secondary winding surrounds the right and central subcores to establish secondary resonant inductance. Distributed air gaps and decoupled flux paths allow precise inductance tuning, reduced fringing and eddy-current losses, and full integration of transformer and inductor functions into a compact planar architecture. Operating efficiently at high frequencies, this structure provides a scalable, manufacturable approach for soft-switched, bidirectional power converters.
Advantages: • Integrates resonant inductors and transformer into one planar module, reducing part count and footprint • Independent primary and secondary flux control improves inductance tuning and converter precision • Distributed air gaps minimize fringing and eddy-current losses by up to 30% • Nanocrystalline FT-3M cores achieve 40% lower core loss and 30% higher flux density than ferrite • Multilayer PCB windings improve thermal dissipation and reduce AC/DC copper losses • Achieves higher power density and efficiency (>98%) than discrete or ferrite-based solutions • Simplifies production through standardized PCB and core-stack fabrication
Applications: • Bidirectional EV fast chargers and vehicle-to-grid (V2G) systems • Lightweight more-electric aircraft DC-DC converters • Compact power modules for renewable and stationary energy storage systems • High-density power electronics for smart grids and industrial automation • Solid-state transformers and DC microgrid interface systems
Intellectual Property Summary: • United States – 63/203,015, Provisional, filed 07/04/2021, Converted • United States – 17/810,579, Utility, filed 07/01/2022, Status: Filed
Stage of Development: Prototype
Licensing Status: This technology is available for licensing.
Licensing Potential: Information available upon request.
Additional Information: Information available upon request.
Inventors: Pritam Das, Sunil Dube, Kalyan Yenduri