High Frequency Planar Transformer (HFPT) for Universal Contact-Less Battery Charging Platform

High frequency planar transformer (HFPT) is an up-and-coming technology which can be used for designing a contact-less battery charging platform. In this paper, fractal-based high frequency planar transformers are presented with two different structures: 4-to-1 and 16-to-4 turn ratio. Because they are PCB-based transformers, two cases of 0.8 mm and 1.6 mm thickness were investigated. A finite-element method has been used to calculate the magnetic field. LLC resonant converter has been designed to improve the conversion efficiency. The voltage ratio has been measured with and without a capacitor at the primary side. The winding with a capacitor can increase the efficiency without any distortion and harmonics.