TAF PUBLISHING

The proposed transformer was designed with flexible spirals, similar to the Archimedes spiral design, to achieve a thin transformer structure. Soft layered magnetic materials were produced by stacking two or more sets of spiral coils on a plane at a short distance from each other and using suitable spacer materials between these coil sets. Accordingly, an innovative, thin, flat, and flexible transformer was created, and its functionality was ensured. The specifications of the spiral coils were as follows: wire diameter = 20 mil, the gap between turns = 20 mil, number of turns = 40, and thickness = 1 OZ. The transformer was designed with a one-layer or two-layer structure for conducting experiments. Coils were stacked directly to change the coil ratio of the transformer. The substrate material was polyimide, which is flexible and can generate a sound when interacting with magnets. The performance of the developed transformer was examined under two coil ratios: 1:1 and 1:2. Different magnetic materials were used between the coil sets to examine the effects of these materials on the transformer performance. Five settings (A–E) were adopted in this study, and the optimal experimental results were obtained in Setting E, and the second-best results were obtained in Setting C. A silicon steel/primary coil/secondary coil/silicon steel structure was used in Setting E. The output voltage and current were 0.22 V and 12.6 mA, respectively, at a coil ratio of 1:1, as well as 0.49 V and 8.7 mA, respectively, at a coil ratio of 1:2. In Setting C, a magnet/primary coil/secondary coil/magnet structure was used, and the output voltage and current were 0.20 V and 9.27 mA, respectively, at a coil ratio of 1:1 as well as 0.46 V and 7.45 mA, respectively, at a coil ratio of 1:2. The experimental results revealed that the performance of a flat transformer is mainly affected by the spacing between the primary and secondary coils and not by the magnetic material between two coil sets. The secondary coils generate the maximum voltage and current when the primary and secondary coils tightly fit together without any spacer material.