An improved Active Clamp Forward Converter with Integrated Magnetics

The large output ripple current impaired the performance of Active clamp forward (ACF) converter. By the ac flux positive coupling of the inductor and transformer, the output ripple current can be reduced. The improved ACF converter with integrated magnetics is proposed in this paper. The operation principle of the proposed converter is analyzed in detail. By setting D=0.5 as the zero ripple current point, the minimized output ripple current and minimized voltage stress of primary switches are achieved simultaneously. The design consideration for the integrated magnetics is discussed along with the effect on the ripple currents. Two 100 W ACF prototype converters, with integrated magnetics and without, are built to verify the operation principle. Experimental results also proved that the proposed ACF converter has higher efficiency compared with conventional one.