Finite element analysis of copper loss in 1-10 MHz transformers

Issues related to the copper loss in 1-10 MHz power transformers are discussed. The relationship between current distribution and transformer structure is investigated using finite-element analysis, to understand how to minimize copper loss caused by proximity effects. It is concluded that a slotted transformer design should be used if the magnetizing current is relatively large. A concentrated-gap and a distributed-gap structure give comparable results, although the distributed-gap design relies strongly on the exact permeability of the material and could suffer from higher core losses because all of the energy is stored in the magnetic material. In either case, the depth of the slot should be about 40% of its width.<>