US Patent 8098123 Power inductor with reduced DC current saturation

A power inductor includes a first magnetic core having a first end and a second end, an inner surface and an outer surface, and an inner cavity defined by the inner surface. A slotted air gap in the first magnetic core extends from i) the first end to the second end and ii) from the inner surface to the outer surface. A second magnetic core is located inside the slotted air gap between opposing inner walls of the slotted air gap. The second magnetic core i) extends from the inner surface to the outer surface of the first magnetic core inside the slotted air gap and ii) has a shape configured to lock the second magnetic core between the opposing inner walls of the slotted air gap.