Controllable Built-in Leakage Inductance for A Novel Matrix Integrated Transformer

Integrated transformer with built-in leakage inductors is a good approach for simplifying the whole system, as it integrates leakage inductors into the transformer with printed circuit board (PCB) windings for CLLC resonant converter. A novel matrix integrated transformer with adjustable built-in leakage inductance is proposed in this paper. The built-in leakage inductance can be controlled by adjusting the winding arrangement of primary and secondary windings or adjusting the reluctance of each core leg, which changes the coupling between primary and secondary windings. Inductance measurements of integrated transformers with different winding arrangements and air gaps of cores are implemented to verify the proposed two methods. The novel matrix integrated transformer was demonstrated on a 500kHz 11kW single-phase CLLC resonant converter for onboard charger application with 0.14% efficiency improvement at full load compared with the original design.