Constant Frequency, Forward Converter With Resonant Transition
A single ended forward converter, operating at constant frequency and switching at zero voltage is presented. By using a secondary switch, the main transformer’s core is symmetrically reset and a part of magnetizing energy is used to discharge the parasitic capacitance of the primary switch to zero. Zero voltage switching conditions are achieved over a broad input voltage and output current range. An experimental 500 KHz converter, which delivers an output power of 200W at 5V, is presented. Operating from an input voltage of 180 to 400 Vdc, the converter exhibits efficiency greater than 88% at full load.