Impact of Mechanical Deformations of Transformer Corners on Core Losses

Penin, Rémi; Parent, Guillaume; Lecointe, Jean‐Philippe; Brudny, J.F.; Belgrand, Thierry

doi:10.1109/tmag.2014.2363057

Cited by 6 publications

(3 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It means that transformer cores represent 3D magnetization objects with very complex flux distribution, as recently found in [7]. The strain depends strongly on the induction and the clamping, as described in details in [8,9]. However, on one hand side, the induction within a transformer core tends to show variations of more than 10% [10], and on the other hand the clamping is not uniform [8].…”

Section: Introductionmentioning

confidence: 90%

Printed detector bands for measurements of strain in core interior of transformers

Shilyashki

Pfützner

Windischhofer

et al. 2018

Journal of Electrical Engineering

View full text Add to dashboard Cite

In the recent years, the reducing of audible noise of laminated machine cores has become great importance, due to high relevance given to environmental awareness. The strain caused by magnetostriction and magnetostatic forces is recognized as one of the main sources of noise. Especially for transformers, strain in the core interior tends to be different from that on the surface, due to differences of clamping, variation of in-plane fluxes and pronounced off-plane (normal) fluxes. For the first time, local measurements of strain in the core interior are presented by means of a novel printed detector band. First results tend to be very promising, exhibiting very high sensitivity and resolution. So far, the relevance of measurements is restricted to comparisons of different core regions.

show abstract

Section: Introductionmentioning

confidence: 90%

Printed detector bands for measurements of strain in core interior of transformers

Shilyashki

Pfützner

Windischhofer

et al. 2018

Journal of Electrical Engineering

View full text Add to dashboard Cite

show abstract

“…However, during the core assembly, the core experiences different mechanical constraints, which are required to ensure its integrity. This impacts the magnetic properties [53] and changes the core structure near the air gaps. In many cases, these changes are difficult to determine, especially once the core is assembled.…”

Section: Mft Vsc1 Vsc2mentioning

confidence: 99%

Effective Permeability of Multi Air Gap Ferrite Core 3-Phase Medium Frequency Transformer in Isolated DC-DC Converters

et al. 2020

View full text Add to dashboard Cite

The magnetizing inductance of the medium frequency transformer (MFT) impacts the performance of the isolated dc-dc power converters. The ferrite material is considered for high power transformers but it requires an assembly of type “I” cores resulting in a multi air gap structure of the magnetic core. The authors claim that the multiple air gaps are randomly distributed and that the average air gap length is unpredictable at the industrial design stage. As a consequence, the required effective magnetic permeability and the magnetizing inductance are difficult to achieve within reasonable error margins. This article presents the measurements of the equivalent B(H) and the equivalent magnetic permeability of two three-phase MFT prototypes. The measured equivalent B(H) is used in an FEM simulation and compared against a no load test of a 100 kW isolated dc-dc converter showing a good fit within a 10% error. Further analysis leads to the demonstration that the equivalent magnetic permeability and the average air gap length are nonlinear functions of the number of air gaps. The proposed exponential scaling function enables rapid estimation of the magnetizing inductance based on the ferrite material datasheet only.

show abstract

“…It is now admitted that this noise founds its origin into two magnetic phenomena: the Maxwell's forces and the magnetostriction [1][2][3][4][5]. In both cases, the most critical areas are the corner joints where the magnetic flux distribution presents a high degree of heterogeneity [6,7]. It is the consequence of various parameters such as the geometry of the magnetic core [8], the anisotropy level of the electrical steel [9] and a critical induction B C [4,10,11].…”

Section: Introductionmentioning

confidence: 99%

A new approach to the critical induction in transformer cores

Parent

Penin

Lecointe

et al. 2016

JAE

Self Cite

View full text Add to dashboard Cite

The most critical areas in power transformers are their corner joints where the magnetic flux distribution presents a very high heterogeneity. This heterogeneity results from several parameters such as the geometry of the magnetic core, the anisotropy level of the electrical steel laminations and a critical induction. This paper is focused on the magnetic steel grades influence on the critical induction, adding a new parameter to those classically considered, such as the number of steps in a multiple step lap stack. Due to the difficulty to perform local measurements inside a real transformer corner, the study is performed both experimentally and by Finite Element analyses on a simplified magnetic core structure. The paper highlights that, in a corner of a core, it exists a critical induction level which depends on the magnetic steel grades and that, in a lamination, the magnetic flux density value along the Transverse Direction can be of the same order that it has along the Rolling Direction.

show abstract

Impact of Mechanical Deformations of Transformer Corners on Core Losses

Cited by 6 publications

References 11 publications

Printed detector bands for measurements of strain in core interior of transformers

Printed detector bands for measurements of strain in core interior of transformers

Effective Permeability of Multi Air Gap Ferrite Core 3-Phase Medium Frequency Transformer in Isolated DC-DC Converters

A new approach to the critical induction in transformer cores

Contact Info

Product

Resources

About