Single-stage, single-switch, isolated power supply technique with input-current shaping and fast output-voltage regulation for universal input-voltage-range applications

A new single-stage, single-switch, input-current shaping (S/sup 4/ICS) technique which combines the boost-like input-current shaper with a continuous-conduction-mode DC/DC output stage is described. In this technique, the boost inductor can operate in both the discontinuous and continuous conduction modes. Due to the ability to keep a relatively low voltage (<450 Vdc) on the energy-storage capacitor, this technique is suitable for the universal line voltage applications. The voltage on the energy-storage capacitor is kept within the desirable range by the addition of two transformer windings. The principle of operation of the S/sup 4/ICS circuit with forward DC/DC converter is presented. Experimental results obtained on a 100-W (5-V/20-A) prototype circuit are also given.