Input current shaper using Cuk converter

The Cuk converter with integrated magnetics when used for input current shaping exhibits advantages over other topologies. When the ´ripple steering´ mechanism is employed, essentially zero input and output current ripples are obtained for all operating conditions, and the size of the magnetics can be significantly reduced. The discontinuous inductor current mode (DICM) with no current feedback loop is analyzed. Current shaping takes place automatically by keeping the duty cycle and switching frequency constant when the converter operates in DICM. The high input power factor and high overall conversion efficiency suggest operation in DICM for low-power applications. Experimental results obtained on a 200-W prototype are presented.