Primary-Side Regulated Active-Clamp Forward Converter by Controlling Clamp Capacitor Voltage

This paper proposes a novel primary-side regulation (PSR) technique for an active-clamp forward converter (ACFW) by controlling the clamp capacitor voltage. The reference voltage of the clamp capacitor is expressed as a polynomial of input power and input voltage derived by the high-precision simulation including the parasitic components such as leakage and magnetic inductance of a transformer, on-state resistance of a transistor, and forward voltage drop of a diode. The proposed PSR method is robust enough, i.e., the output voltage regulated by the proposed method varies little, though the characteristics of these components vary by temperature fluctuation or aging. The small-signal model of the proposed PSR method is verified and utilized to design compensator and sensing circuits. The effectiveness of the proposed method is experimentally verified using a 100-kHz, 200-W prototype ACFW…