US3270307A - Laminated magnetic core joint structure - Google Patents

Laminated magnetic core joint structure Download PDF

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Publication number
US3270307A
US3270307A US323168A US32316863A US3270307A US 3270307 A US3270307 A US 3270307A US 323168 A US323168 A US 323168A US 32316863 A US32316863 A US 32316863A US 3270307 A US3270307 A US 3270307A
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Prior art keywords
joint
branches
joints
sheets
staircase
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Expired - Lifetime
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US323168A
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English (en)
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Jean Maxime Louis Emile
Jean Michel Marcel
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Individual
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/24—Magnetic cores
    • H01F27/245—Magnetic cores made from sheets, e.g. grain-oriented

Definitions

  • the present invention relates to the field of laminated magnetic circuits for electrical apparatus such as transformers or machines, and more particularly to transformers comprising at least one rectangular core element aving two legs designed to received transformer windings and yokes or cross-members joining the winding legs together at their extremities.
  • Such magnetic circuits are generally constructed by the stacking of sheets which have been suitably cut for the purpose of assembling them in successive layers. At present one preferably uses sheets which are said to have oriented grains which present in a preferential direction, corresponding to the direction of their lamination, a permeability which is greater than the permeability presented in any other direction, and which sheets will have losses, expressed in Watts per unit volume or unit weight, which will be at -a minimum when their magnetization is oriented in this preferential direction.
  • an embodiment in which elements in the form of an L were assembled by joining a winding leg layer and a yoke layer by welding along a joint having an oblique direction with respect to the optimum flux direction of each layer, the joint being occasionally formed by having the abutting edges of the two pieces in the form of a sawtooth in order to improve the strength of the weld.
  • the magnetic circuit is produced, in this case, by the simple joining of two stacks of such L-shaped elements.
  • the present invention is aimed at avoiding these inconveniences by offering the advantage of causing the cutting and assembling ofthe sheets to be simpler and more economical, and especially by presenting the possibility of rendering almost negligible the undesirable effects of the disturbances in the corners of the magnetic circuits.
  • a laminated magnetic circuit according to this invention is essentially characterized by the fact that in each of its corner zones, corresponding to the meeting of any pair of its branches, the abutting joint of each and every component sheet follows a staircase pattern composed of steps having sides which are oriented to follow substantially the longitudinal directions of the pair of branches under consideration.
  • FIGURE 1 is a vertical cross-sectional vview of the magnetic circuit of a single phase transformer
  • FIGURE 2 is a detail view to a larger scale of one corner region of the unit of FIGURE 1;
  • FIGURE 3 is a view, similar to that of FIGURE l, showing a variation of the basic unit
  • FIGURE 4 shows a three phase magnetic circuit
  • FIGURE 5 shows an example of a magnetic circuit having widened yokes
  • FIGURE 6 is a detail view case joint
  • FIGURE 7 is a partially cross-sectional view of one example of an experimental embodiment of the magnetic circuit of a single phase transformer
  • FIGURE 8 is a cross-sectional view taken along the plane VIII-VIII of FIGURE 7;
  • FIGURE 9 is a graph showing the relative losses in a transformer whose core is constructed according to FIGURES 7 and 8.
  • the concept of the present invention is applied to the construction of the magnetic circuit of a single phase transformer of a generally rectangular shape having two cores, or winding legs, 11 and 12, adapted to receive several windings (not shown), and two yokes, 13 and 14; each of the four branches, 11-14, is constructed from a stack of sheets cut in bands from a sheet of grain oriented material so that there is thus presented a preferential direction of the flux lines which is indicated by the arrows P.
  • the yoke 13 If one, considers, for example, the yoke 13, one sees that it iscomposed of sheets, such as ABCD, of a genof a variation of the stairerally trapezoidal form, with a large base AD along the exterior side, a small base BC along the inner side, and two latenal sides AB and CD, the latter being cut in a staircase pattern with the treads and the risers being of practically equal length parallel to and perpendicular to the preferential direction P.
  • sheets such as ABCD
  • a genof a variation of the stairerally trapezoidal form
  • each sheet of the yoke thus constructed there is attached a winding leg sheet 12 which is cut out along A1-B1-C1-D1 and a winding leg sheet 11 which is cut out along A3-B3-C3-D3, while another yoke sheet 14 is inserted at A2-B2-C2-D2.
  • every point of the staircase joint A-D3- -B-C3 is found to be above the diagonal A-C3, while every point of the joint A1-D -Bl-C is found to be below the diagonal Al-C, and so forth.
  • each of the legs, or branches, of the magnetic circuit consists of a simple stacking of similar sheets according to FIGURE l; the different branches thus formed are then fitted together, the joints of each of the layers being in alignment with the corresponding joints -of all of the other layers of the circuit.
  • This form of construction obviously :constitutes a considerable simplification in the construction and, should the need arise, in the repair or modiication of the device, especially with regard to adding or replacing the windings. In this case the overlapping of joints is entirely done away with.
  • the staircase shape of the joints leads to a surprising reduction in losses, as will appear from the performances of certain experimental embodiments, the results of which will be set forth further along in the specification.
  • FIGURE 2 where there has been drawn, to one side of the diagonal A-C3, a line M-M which is parallel to the diagonal and whi-ch divides the staircase joint into two equal parts, one can consider that the portions where large losses occur will be found to be reduced to the shaded areas which extend between the line M-M and the steps of the staircase joint.
  • each leg of the circuit will be constructed by placing side by side a certain number of prismatic blocks of various lengths for example parallelepipeds, with their long dimensions arranged in echelons, or steps, in order of increasing length; each of these blocks itself being formed by the stacking of a desired number of rectangular strips.
  • FIGURE 3 layers which alternate between the arrangement shown in FIGURE 1, land that shown in FIGURE 3, the latter arrangement being obtainable either by a turning over or by a simple translation in a lengthwise direction of all of the sheets in one or several layers of the structure of FIGURE l.
  • FIGURE 3 where the joints of the layers constructed according to FIGURE 1 are shown in dotted lines at each corner, the entire staircase joint of each layer will appear on one side or the other of its diagonal, with the side on which it appears alternating from layer'to layer or from group of layers to the next group.
  • FIGURE 4 shows one modification of this invention which can be used to construct the magnetic circuit of a three phase transformer.
  • the exterior winding legs 21 and 22 of this circuit meet the yokes 23 and Z4 along joints which are similar to those which have already been described in connection with FIGURES 1 and 2, the nature of any eventual overlapping being indicated by dotted lines.
  • the central winding leg 25 is composed of layers, cut in the form indicated, which are fit into corresponding layers of the yokes to form the staircase joints, these joints being formed alternately in each successive layer, on alternating sides of the diagonal-s EF, GF, H] and KJ of corner zones like E-El-F-Fl, F-Gl-G-Fl, etc.
  • FIGURE 5 shows a modiication of the single-phase core having two cores, or winding legs 31 and 32 and two yokes 33 and 34, which differs from those shown in FIGURES l and 2 in that lthe width of the yoke layers exceeds that of the winding leg sheets by a given amount L.
  • the joints are laid out to one side of 45 diagonals, such as QP1 extending from the inside corners of the circuit, of the square zones such as Q-P1-P-Q1 which squares are derived by ignoring the added width L Iof the yokes.
  • the second orientation of elements is obtainable lby a lengthwise shifting of the Winding leg sheets and a rotation of of the yoke sheets about an axis which is parallel to the length of the winding legs and which lies lin the plane of the ligure.
  • this invention is not limited to such a form, but encompasses in particular the possibility of establishing, on one side or the other of base lines, such as the diagonal P-QZ of FIGURES 5 and 6, staircase joints, each edge of which has a length proportional to the cosine of the angle which it forms with its respective diagonal or base line (cf. FIGURE 6).
  • base lines such as the diagonal P-QZ of FIGURES 5 and 6, staircase joints, each edge of which has a length proportional to the cosine of the angle which it forms with its respective diagonal or base line (cf. FIGURE 6).
  • FIGURES 7 and 8 show in a detailed manner, and with the dimensions shown in millimeters, the precise form of the magnetic circuit for a single phase transformer which was constructed from sheets of ARMCO grainoriented steel having a thickness of 0.35 mm. (0.014 inch) with ends which have been cut according to a staircase pattern, each edge of which has a length of 10 mm. (0.4 inch). 'Ihe circuit was square in shape, with each exterior edge having a length of 465 mm. (18.3 inches).
  • T the curve of the inherent losses in a solid untreated sheet of the material used in the manufacture of these circuits, as indicated by the manufacturer of the sheets, expressed in watts/kg. vs. fiux density (B) in gauss;
  • the graph shows that, 15000 gauss for example, the increased losses due to the presence of joints equals 1.80 w./kg. for the reference construction, decreases to 1.45 w./kg. for the device made with staircase joints without overlapping, as in construction II, and diminishes still further to 1.19 W./kg. for construction III, the model utilising the staircase j-oints and overlapping suggested by FIGURE III, while the minimum possible losses for this material have been determined by the manufacturer to be equal to 1.13 at this fiux density.
  • the joints of a typical prior art construction caused the magnetic circuit losses to increase by more than 59% while the joints of the present invention caused losses to increase by only 28% in the simpler embodiment of FIGURE 1 and by only 5% for the embodiment of FIGURE 3.
  • a laminated magnetic circuit for electrical devices comprising at least one polygonal frame member having a plurality of branches each defining one side of said member, each of said branches being composed of a plurality of stacked sheets, each having a short inner longitudinal edge, a long outer longitudinal edge, and two lateral edges, with each said sheet in each said branch being coplanar with a corresponding sheet in every other one of said branches, and with each lateral edge of each said sheet abutting against the adjacent lateral edge of the corresponding sheet in a respective adjacent one of said branches to form a joint, each said lateral edge defining said joint having a staircase configuration defined by a plurality of successive straight edge sections, with every other one of said sections extending parallel to the longitudinal dimension of one of the sheets whose lateral edge defines said joint and the remaining ones of said sections extending parallel to the longitudinal dimension of the other one of said sheets Whose lateral edge defines said joint.
  • each of said joints is disposed along, and to one side of a diagonal of the rectangular region enclosing said joint and defined by the outer longitudinal edges and the extensions of the inner longitudinal edges of said sheets forming said joint.
  • each of said rectangular regions are square in shape, so that said diagonal forms a 45 angle wit-h the longitudinal direction of each of the adjacent branches.
  • a magnetic circuit as recited in claim 2 wherein the staircase joints in all but two adjacent corners of said frame member are disposed alternately, from one layer of sheets to the next on opposite sides of their diagonal in such a way that the joints in one layer of sheets are displaced with respect to, and overlap, those of the adjacent layers.
  • a laminated magnetic circuit comprising a series of rectangular layers, each comprising four branches of generally trapezoidal configuration, the boundaries of each said branch being constituted by a long base, a short base, and a pair of oblique ends, each of said ends being cut in the form of a staircase comprising a series of steps the component edges of which are alternately perpendicular to and parallel to the bases of said branches, with all of said parallel edges being of equal length and all of said perpendicular edges being of equal length, eac-h of said branches being joined at its ends to corresponding ends of its adjacent branches by the imbricating of the steps of each pair of abutting ends to form a staircase joint at ea-ch corner of each of said rectangular layers.
  • a magnetic circuit as recited in claim 9 wherein, at each corner of said circuit, the staircase joints of successive layers lie on alternate sides of said base line.
  • a laminated magnetic circuit comprising two yoke branches, two external leg branches and at least one intermediate leg branch parallel to said external leg branches, each of said branches being made-up by the stacking of a succession of layer-forming sheets; said yoke and external leg branches being assembled at four corner zones into an outer closed frame of generally rectangular shape, this assembling being made along corner base lines extending from each corner point of the inner contour of said frame to the outer contour, whereas said intermediate leg extends at each end within the adjacent yoke branch along two intermediate base lines dening an ⁇ isosceles triangle with that portion of the inner side of said adjacent yoke branch which is intercepted by the two longitudinal sides of said intermediate leg; each butt joint between any two adjacent sheets of any given layer being in the shape of a staircase pattern built upon and to one side of a respective one of said base lines; wherein, an observer following a closed path along the four sides of said outer frame will meet each joint in succession with each joint being disposed on a same side relatively to its respective base line.
  • each said staircase joint associated with a given base line is disposed on alternate sides thereof in successive layers of said circuit, all of said staircase joints associated with each base line of said one yoke branch being disposed to the same side of their associated base line.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing Cores, Coils, And Magnets (AREA)
  • Coils Or Transformers For Communication (AREA)
US323168A 1962-11-10 1963-11-12 Laminated magnetic core joint structure Expired - Lifetime US3270307A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR915006A FR1418765A (fr) 1962-11-10 1962-11-10 Procédé pour obtenir une meilleure utilisation des tôles magnétiques à cristaux orientés dans les transformateurs statiques

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CH (1) CH392682A (fr)
FR (1) FR1418765A (fr)
GB (1) GB1070784A (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2658665A1 (de) * 1976-12-23 1978-06-29 Philberth Karl Dr Phys Kernblech fuer mantelkerne, vorzugsweise fuer transformatoren
US20060226946A1 (en) * 2005-03-30 2006-10-12 Abb Technology Ag Transformer having a stacked core with a cruciform leg and a method of making the same
US20060226947A1 (en) * 2005-03-30 2006-10-12 Abb Technology Ag Transformer having a stacked core with a split leg and a method of making the same
US20090149848A1 (en) * 2007-12-10 2009-06-11 Werneth Randell L RF Energy Delivery System and Method
EP2207187A3 (fr) * 2009-01-09 2015-04-29 Hitachi Industrial Equipment Systems Co., Ltd. Transformateur
US9576709B2 (en) 2010-04-22 2017-02-21 Abb Schweiz Ag Transformer having a stacked core
CN112753082A (zh) * 2018-04-23 2021-05-04 西门子股份公司 高效率且高防腐蚀性能的变压器芯及其组装方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2393038A (en) * 1942-07-15 1946-01-15 Westinghouse Electric Corp Magnetic core structure
US2407626A (en) * 1942-12-30 1946-09-17 Gen Electric Magnetic core
GB735228A (en) * 1951-04-18 1955-08-17 Siemens Ag Improvements in or relating to laminated cores for electric transformers, inductances and the like
CH337271A (de) * 1954-12-21 1959-03-31 Smit & Willem & Co Nv Magnetischer Kreis aus ferromagnetischem Material

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2393038A (en) * 1942-07-15 1946-01-15 Westinghouse Electric Corp Magnetic core structure
US2407626A (en) * 1942-12-30 1946-09-17 Gen Electric Magnetic core
GB735228A (en) * 1951-04-18 1955-08-17 Siemens Ag Improvements in or relating to laminated cores for electric transformers, inductances and the like
CH337271A (de) * 1954-12-21 1959-03-31 Smit & Willem & Co Nv Magnetischer Kreis aus ferromagnetischem Material

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2658665A1 (de) * 1976-12-23 1978-06-29 Philberth Karl Dr Phys Kernblech fuer mantelkerne, vorzugsweise fuer transformatoren
US4149136A (en) * 1976-12-23 1979-04-10 Karl Philberth Core lamination for shell-type cores, preferably for transformers
US7877861B2 (en) 2005-03-30 2011-02-01 Abb Technology Ag Method of making a transformer having a stacked core with a split leg
US7882615B2 (en) 2005-03-30 2011-02-08 Abb Technology Ag Method of making a transformer having a stacked core with a cruciform leg
US20070033797A1 (en) * 2005-03-30 2007-02-15 Abb Technology Ag Method of making a transformer having a stacked core with a split leg
US7199696B2 (en) * 2005-03-30 2007-04-03 Abb Technology Ag Transformer having a stacked core with a split leg and a method of making the same
US7256677B2 (en) 2005-03-30 2007-08-14 Abb Technology Ag Transformer having a stacked core with a cruciform leg and a method of making the same
US20080010813A1 (en) * 2005-03-30 2008-01-17 Abb Technology Ag Method of making a transformer having a stacked core with a cruciform leg
US20060226947A1 (en) * 2005-03-30 2006-10-12 Abb Technology Ag Transformer having a stacked core with a split leg and a method of making the same
US20060226946A1 (en) * 2005-03-30 2006-10-12 Abb Technology Ag Transformer having a stacked core with a cruciform leg and a method of making the same
WO2009076461A1 (fr) * 2007-12-10 2009-06-18 Ablation Frontiers, Inc. Système et procédé de délivrance d'énergie rf
US20090149848A1 (en) * 2007-12-10 2009-06-11 Werneth Randell L RF Energy Delivery System and Method
US8475449B2 (en) 2007-12-10 2013-07-02 Medtronic Ablation Frontiers Llc RF energy delivery system and method
US8849367B2 (en) 2007-12-10 2014-09-30 Medtronic Ablation Frontiers Llc RF energy delivery system and method
US9364286B2 (en) 2007-12-10 2016-06-14 Medtronic Ablation Frontiers Llc RF energy delivery system and method
US9757194B2 (en) 2007-12-10 2017-09-12 Medtronic Ablation Frontiers Llc RF energy delivery system and method
EP2207187A3 (fr) * 2009-01-09 2015-04-29 Hitachi Industrial Equipment Systems Co., Ltd. Transformateur
US9576709B2 (en) 2010-04-22 2017-02-21 Abb Schweiz Ag Transformer having a stacked core
CN112753082A (zh) * 2018-04-23 2021-05-04 西门子股份公司 高效率且高防腐蚀性能的变压器芯及其组装方法
US11282627B2 (en) * 2018-04-23 2022-03-22 Siemens Energy Global GmbH & Co. KG Transformer cores and assembly methods thereof for high efficiency and high anti-corrosion performance

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Publication number Publication date
FR1418765A (fr) 1965-11-26
GB1070784A (en) 1967-06-01
CH392682A (fr) 1965-05-31

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