Single-switch flyback power-factor-corrected AC/DC converter with loosely regulated intermediate storage capacitor voltage

Single-stage power-factor-corrected AC/DC converters (SSPFC) usually bear high voltage stress on the intermediate storage capacitor due to the lack of control of this voltage. The storage capacitor voltage varies largely with line voltage and load current and is usually higher than the peak line voltage. This paper presents a new single-switch SSPFC based on flyback topology for which the storage capacitor voltage is loosely regulated by the output voltage, reducing the range of storage capacitor voltage fluctuation against change of input voltage and load current. Moreover, the maximum storage capacitor voltage can be smaller than the peak line voltage at high line condition. Without the addition of power switches to increase the control dimension, the proposed converter utilizes a flyback transformer with multiple-output structure to achieve the control purpose. Experimental results verifying the operation of SSPFC are also reported.