Acoustic noise emitted by passive components in magnetic devices and design of a low-noise industrial inductor

Purpose - The purpose of this paper is to present the original study of an industrial device. Industrial inductors are used to decrease the current variations, resulting from the use of modern power converters. To reduce these variations, the magnetic energy stored in these components is automatically used when the receptor is unconnected to the principal sources. Such storage is generally obtained by using a magnetic circuit containing air-gaps. The rigidity of this circuit, associated with the magnetic stresses which appear in these areas, causes the structure to produce mechanical vibration and to emit audible sounds.Design methodology approach - Experiments, simulations and test devices are used to determine the main physical phenomenon that generates the undesirable audible noise. The resulting knowledge is used to design a quieter device.Findings - The mechanical vibrations and emitted noises are attached to magnetic effects. Even if it is not possible to suppress all these effects, the level of sound emitted can be decreased through a suitable design of the magnetic core.Originality value - Industrial inductors are usually built and designed using methods coming from the transformer studies. A new concept for the design of the magnetic core is presented. Experimental approaches and numerical simulations are performed in order to highlight the physical behaviours of the coils and their magnetic coupling to the magnetic core. It appears that breaking the magnetic core into free parts is an original solution that decreases the emitted noise.