Novel concepts for high frequency high efficiency transformer design

This paper provides a thorough study of transformer design for high-frequency applications. Several novel concepts are proposed to reveal the fundamentals of the transformer design. The minimum electric and magnetic energy theorem is presented to optimize the transformer design. With the utilization of the minimum electric and magnetic energy theorem, the current distribution among high-frequency parallel windings can be identified. Optimal winding structures are proposed to achieve low power losses, and leakage inductance controllability is studied for soft-switching applications. The proposed concepts and theoretical analysis are verified in an LLC resonant dc-dc converter prototype.