Virginia Polytechnic Institute and State University
This work presents the design and optimization of a PCB-based matrix transformer with integrated controllable leakage inductance for an 11 kW, 250 kHz bidirectional DC/DC CLLC resonant converter. To improve modeling, non-air-gapped core legs are incorporated into the reluctance model, and an x-direction extension parameter is introduced to enable reluctance variation limiting peak flux density. At 11kW, a 2EI-core matrix design is shown to achieve superior flux distribution and lower losses than a 3EI-core design at the same footprint. Furthermore, a novel Circular Orthogonal Parallel (C.O.P) airgap structure is proposed, positioning airgaps above PCB traces to mitigate the current crowding found in Traditional Parallel (T.P) structures. Experimental validation on an SiC prototype shows a peak efficiency of 98.3% for the C.O.P structure versus 97.9% for T.P, with both meeting all gain requirements and confirming the C.O.P design's advantage for high-density matrix transformers.
