Flyback Converter Using Planar Magnetics

Abstract

A DC power supply is an essential part of all electronic devices. A switched mode power supply is a light weight power solution for most modern electronic equipment. The high frequency transformer is the backbone of modern switched mode power supplies. The skin effect and proximity effects are major problems in high frequency transformer design, because of induced eddy currents. These effects can result in transformers being destroyed and losing their power transferring function at high frequencies. Therefore, eddy currents are unwanted currents especially in high frequency transformers. Leakage inductance and the unbalanced magnetic flux distribution are two further obstacles for the development of high frequency transformers. In this work Flyback converter for 12 V, 5 W output is designed with 250 kHz switching frequency. In power transformers different obstacles at high frequency are thoroughly studied. Then Planar magnetic and different issues related with it are thoroughly studied. Based on this study, Planar transformer (4cm*5cm*0.82cm sized) for the SMPS is designed. Detailed simulation analysis of magnetic circuit was also done on MAGNET. The proposed Planar magnetics based SMPS has universal input range from 20 V AC to 240 V AC. The line and load regulation of the proposed SMPS are also measured and found within prescribed specification. Finally by comparing the results with conventional and planar transformer, the advantages of planar transformer have been realized.