DC Inductor Design, Using Gapped Cores

The buck regulator filter circuit has three current probes. Current probe A monitors the power MOSFET, Q1, switching current. Current probe B monitors the commutating current through CR1. Current probe C monitors the current through the output inductor, L1. Designers have routinely tended to specify Molypermalloy powder materials for filter inductors used in high-frequency, power converters and pulse-width-modulators switched regulators, because of the availability of manufacturers’ literature containing tables, graphs, and examples that simplify the design task. There are significant advantages to be gained by the use of iron alloys and ferrites in the design of power inductors, despite certain disadvantages, such as the need for banding and gapping materials, banding tools, mounting brackets, and winding mandrels. Inductors that carry direct current are used frequently in a wide variety of ground, air, and space applications. Selection of the best magnetic core for an inductor frequently involves a trial-and-error type of calculation.