Design and implementation of a universal input flyback converter

Due to rapid increase in use of mobile devices, development of power supply for these devices has become a challenge. There is demand for smaller size adapter with high efficiency, power density etc. Instead of having a selector switch for different supply voltages in the adapter, the approach is to design a converter which takes universal input voltage and provides constant output voltage. Performance of converter has to be efficient for different load conditions too. Meeting these requirements will require efficient design, proper selection of discrete components, optimal topology, thermal considerations etc. In this paper, approach carried out to develop an adapter circuit for a laptop is discussed. A flyback converter with switching frequency 65 kHz is designed to provide a DC output of 19V for universal ac input (90V to 250V). Considering nature of the load, converter is designed to operate in discontinuous conduction mode (DCM). Design carried out to find the optimal values of the discrete components is elaborated. Closed loop operation of the designed converter is simulated in NI Multisim 13.0 and analysed. After simulation results were satisfactory, for study purpose, with available resources, an effort was made to develop a module of the converter without any industrial assistance. The simulation results, challenges encountered during hardware development, open loop hardware module results are also discussed in the paper.