Analysis and design of asymmetrical half bridge flyback converter

The detailed circuit behaviour of the asymmetrical half bridge flyback converter is analysed. The specific relationships between the duty cycle and the different types of energy in the energy storage elements are thoroughly investigated. From the analytical results, the maximum duty cycle is not bounded by 50%, whch means that the converter can now be optimally used for the different applications. The zero voltage switching (ZVS) conditions of the power switches are derived. Mathematical equations and design considerations are also given. According to the presented design guidelines, the ZVS operations of the power switches can be maintained from noload to full-load conditions. A 5 VI20 A prototype has been built to verify the analytical results under real life conditions.