As the growth in electric vehicle (EV) chargers continues to push research towards compact and efficient power converters, high-frequency magnetic design becomes pivotal. The use of PCB winding planar transformers addresses high-frequency design challenges by offering good heat dissipation, low losses, and controlled parasitics. Therefore, this paper presents a planar transformer design using PCB windings with novel interleaving and design aspects to minimise the losses and parasitics of the high-frequency transformer. It aims to achieve an optimal balance between the trade-offs whilst ensuring compatibility with the target converter's requirements and cooling system. The proposed anti-symmetrical interleaving achieves a drastic reduction in interwinding capacitance compared to a conventional design combined with low winding losses. The paper provides extensive comparisons of different interleaving types, supported by thorough finite element simulations. The resulting design approach is applied to a 3.3 kW isolated dc-dc converter for level-1 EV charging. Finally, different prototypes are built and extensively characterised and validated for implementation in the EV charger.
