Design Approaches for Nonlinear Inductors with a Stepped Air-Gap

This paper presents design approaches to build a nonlinear inductor with a stepped air gap for PWM converters in CCM or BCM/DCM operation. The investigations are based on a reluctance model to derive the necessary correlations between geometry and inductance characteristics. Based on this, design approaches are developed to move from an existing conventional coil to a nonlinear one with a stepped air gap. Finally, the results are verified by comparison to numerical simulations and measurements.