Comparative Performance of Isolated Forward and Flyback AC-DC Converters for Low Power Applications

This paper addresses several issues concerning the modeling and application of single-phase, single switch, power factor corrected AC-DC high frequency switching converter topologies with transformer isolation. A detailed analysis, simulation and development are presented for forward buck and flyback buck-boost converters with high frequency isolation in discontinuous conduction mode (DCM) operation. To verify and investigate the design and performance at preliminary stage, simulation study of these converters is accomplished in DCM operation for input AC voltage 220V at 50 Hz and output DC voltage of 13.5V and 20.25W output power rating using PSIM6.0 platform. Simulation results show high quality steady state performance from 20% to 100% loading conditions with good power factor and efficiency. Test results on developed converters are compared with simulated results to validate the design. This work, highlighting advantages and drawbacks of both the selected topologies, facilitate designers to make a proper choice for a given application in the low power range (below 25 W).