Comparison and design of three coupled inductor structures

A new coupled-inductor structure that achieves zero current ripple without need for turns ratio adjustment is presented. Its residual ripple performance is as good as conventional structures, it is easier to design and has much less radiated noise. Three different gap arrangements of practical interest are considered and closed-form design equations are given for each of them. As a practical example, coupled inductor design for a 50 W Cuk converter is performed with all three gap arrangements and relative circuit performance is compared.