This digest proposes an output voltage estimator for primary side regulation of active-clamp forward converter (ACFW) to regulate its output voltage tightly. The proposed method is simple to implement as it does not require signal isolation or additional winding of the transformer. The proposed method estimates the output voltage by a polynomial function of input voltage, clamp capacitor voltage, and input current considering the various parasitic components of the converter. A closed-loop control compares this estimated value and the reference to determine the duty ratio. The effectiveness of the proposed method is verified experimentally with a 100-kHz 200-W prototype ACFW.
