Low permeability composite magnetic core transformer with high coupling coefficient and its application to PFM controlled quasi-resonant mode flyback-type DC-DC converter

Abstract

We describe a low permeability composite magnetic core transformer with a high coupling coefficient and its application to a PFM controlled quasi-resonant mode flyback-type DC-DC converter. To increase the coupling coefficient between primary and secondary windings embedded in a carbonyl-iron powder/epoxy composite magnetic core with a relative permeability of 6, three types of winding layouts were investigated by using a 2D-FEA numerical simulation and the characteristics were confirmed experimentally. The primary and secondary windings that were laid out adjacent to each other were the best choice as it had the highest coupling coefficient at over 0.99. By applying the composite magnetic core transformer with this coupling coefficient to a 48 V input/12 V output PFM controlled quasi-resonant mode flyback-type DC-DC converter, the maximum efficiency was 92.5% at an output power of around 28 W, and an efficiency of 90.0% was obtained at an output power of 60 W.

Fabrication and evaluation of dispersed-Ag nanoparticles-in-polyimide thin films

“…Therefore, the RF circuits and devices must be smaller and thinner. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] RF circuits are generally differential input=output circuits that need the common-mode filter (CMF) in order to reduce the common-mode noise generated by unbalance signals. 1,25) The CMF is a common chip device, 26) and its miniaturization is also important in the future.…”