Indented Core to Reduce and Desensitize Inductor’s Fringing Losses without Increasing Volume

There is a constant push towards more compact and efficient power electronic converters. However, the fringing losses of gapped magnetic components inhibit size reduction by requiring extra space to keep the winding away from the gaps. Concurrent high efficiency and high power density cannot thus be achieved with conventional gapping approaches. A core structure that reduces the fringing and overall losses without requiring additional space is presented here, simultaneously enabling higher efficiency and power density. The geometry also reduces the sensitivity of the winding to its position in the winding window compared to the conventional discrete gapping approach. The idea is verified in a planar inductor design, decreasing the power loss of a soft-switched unloaded buck converter by more than 32%.