Transversely Isotropic Model of the Stacked Iron Core and its Application in the Design of the Low-Noise Power Transformers

No-load noise, mainly comes from the magnetostriction of the grain-oriented silicon steel, is one of the main noise sources of transformers. The noise level can be amplified when natural frequencies of the core get close to the frequency of magnetostriction. Therefore, modelling the stacked grain-oriented (GRO) silicon steel is valuable for designing low-noise transformers. This paper firstly conducts vibration tests of silicon steel sheets to obtain the variation law of the natural frequency of stacked silicon steel sheets. Secondly, an equivalent method is proposed to establish the transversely isotropic model of the stacked iron core. Then, the influence of such as the length of the yoke, the height of the core column and the thickness of the core on the natural frequencies are discussed. Lastly, an appropriate size range of the core to avoid noise amplification is obtained. The conclusion provides the basis for the optimal design of the low-noise transformer.