Peak Current Mode Controlled Active Clamp Forward Converter with Magnetic Feedback

Abstract

Active clamp forward converter is used extensively in medium power applications due to galvanic isolation between input and output. The feedback loop is realized using either optocoupler or magnetic feedback for isolating the control loop. Optocoupler feedback uses a combination of optocoupler and an operational amplifier for realizing the control loop. The variation of current transfer ratio and aging effect of the optocoupler limits the usage to commercial applications where temperature variation is minimal. Magnetic feedback withstands high operating temperature compared to optocoupler feedback. It uses the transformer to isolate the feedback and hence used in military and space applications. The operation and analysis of a 48W magnetic feedback isolated peak current mode controlled active clamp forward converter was presented with PSPICE simulation results. In PSPICE simulation, vendor model of all the discrete components has been used such that the PCB can be made directly from the schematic.