Isolated Converters as LED Drivers

In this study, comparative analyses of performance of isolated flyback and forward DC-DC converters for output voltage and current of 12V and 300mA, respectively, are reported, based on solutions of the governing ordinary differential equations. Results of simulations using MATLAB / Simulink are presented. The importance of selecting a proper step size is shown. For simulations, the LED is considered as a resistive load and its current and voltage characteristics are studied under loaded conditions. The modeling is based on ‘Commonly Used Blocks’ and hence the dependence on SimPower System tool box is reduced. Closed-loop analyses of the converters are carried out using a PI controller. The simulations show that flyback converter is better suited than forward converter as the response time was better. Further, the flyback converter shows lesser value of filter inductance, lesser duty cycle and hence reduced conduction losses.