Reduction of Fringing-Effect in Inductors by Quasi-Distributed-Gap Method

The fringing-field phenomenon can have a significant impact on the key performance parameters of magnetic components with an air gap. The fringing magnetic flux at the air gap has an effect on a component’s inductance, power loss and temperature distribution in copper windings. The induced excess eddy currents in the windings due to the fringing effect cause localized heating and reduce the overall efficiency of power conversion. This effect can be analysed by infra-red thermography to demonstrate the potential hazards of designing magnetic components with an air gap. Design engineers are frequently forced to design around the problem by employing a number of available techniques. The quasi-distributed-gap technique combats the issue at the origin as it essentially constrains the fringing magnetic flux at the downsized air gaps to their immediate vicinity. The selection of the length of the individual air gaps as well as their placement is not straightforward, as the phenomenon is a function of the air gap length and geometry. The resulting inductance of the component has to be the same or at least comparable to the original value in order to maintain the operating conditions of the application which the component is part of. This paper examines the effects of splitting a discrete air gap on the electromagnetic and thermal properties of inductors and presents a method to aid the design of quasi-distributed-gap inductors based on finite-element simulations as well as measurements. An analytic expression, which closely approximates the required length of quasi-distributed gaps, is developed.

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Opracowanie rekordu w ramach umowy 509/P-DUN/2018 ze środków MNiSW przeznaczonych na działalność upowszechniającą naukę (2019).