Single-stage, single-switch, islolated power-supply technique with input- current shaping and fast output-voltage regulation

摘要

A new single-stage, single-switch, input-current-shaping technique which combines the boost-like input-current shaper with a continuous- conduction-mode dc/dc output stage is described. 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. One winding appears in series with the boost inductor during the on time, whereas the other winding appears in series with the same inductor during the off time. By connecting the windings so that the voltages across them when they conduct the inductor current are in opposition to the input voltage, the volt-second balance of the boost-inductor core is achieved at a substantially lower voltage of the energy-storage capacitor compared to the other known approaches. In addition, for the forward-converter- type single-stage, single-switch input-current shapers, a direct transfer of a part of the input energy is achieved by the winding which appears in series with the boost inductor during the on time, while for the flyback implementation a direct transfer of a part of the input energy is achieved by the winding which appears in series with the boost inductor during the off time.