US3559136A - Magnetic core structure - Google Patents

Magnetic core structure Download PDF

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Publication number
US3559136A
US3559136A US834998A US3559136DA US3559136A US 3559136 A US3559136 A US 3559136A US 834998 A US834998 A US 834998A US 3559136D A US3559136D A US 3559136DA US 3559136 A US3559136 A US 3559136A
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Prior art keywords
laminations
lamination
inner leg
layer
yoke
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Expired - Lifetime
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US834998A
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English (en)
Inventor
Theodore R Specht
Angelo A De Laurentis
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Westinghouse Electric Corp
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Westinghouse Electric Corp
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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
    • 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
    • H01F27/33—Arrangements for noise damping
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/4902—Electromagnet, transformer or inductor
    • Y10T29/49075—Electromagnet, transformer or inductor including permanent magnet or core
    • Y10T29/49078—Laminated

Definitions

  • the invention relates in general to magnetic core structures for electrical inductive apparatus, such as transformers and reactors, and more specifically to magnetic core structures of the stacked type.
  • the stepped-lap joint was found to substantially improve the performance of the magnetic core, compared with magnetic cores which utilize the conventional butt-lap type joint, lowering the core losses, lowering the exciting volt-ampere requirements, and lowering the sound level of the magnetic core.
  • the present invention is a new and improved magnetic core of the stacked stepped-lap type, having a plurality of layers of magnetic, metallic laminations.
  • Each layer of laminations includes outer leg laminations, at least one inner leg lamination, and yoke laminations which "ice join the ends of the leg laminations to complete the desired magnetic circuits.
  • the inner leg lamination in one embodiment of the invention, has the same configuration and dimensions in each of the layers, with the ends of the inner leg lamination having the configuration of a truncated isosceles triangle.
  • the stepped-lap joint between the inner leg and the adjoining yoke laminations is formed in this embodiment by incrementally offsetting the inner leg lamination from layer to layer along the longitudinal axis of the inner leg laminations.
  • the truncated isosceles triangular configuration of the ends of the inner leg lamination substantially reduces the scrap generated, compared with prior art structures which utilize a V-shaped inner leg lamination.
  • the core losses and sound level of the magnetic core constructed according to the teachings of the invention are substantially the same as a similarly rated stepped-lap magnetic core of the prior art utilizing the V-shaped triangular inner leg laminations, which produces about 4% scrap.
  • FIG. 1 is an elevational view of a polyphase magnetic core-winding assembly of the core-form type, having a magnetic core constructed according to the teachings of the invention
  • FIGS. 2, 3 and 4 are elevational views of difierent layers of laminations of the magnetic core structure shown in FIG. 1;
  • FIG. 5 is a plan view of magnetic strip material illustrating the pattern for cutting the yoke laminations for the magnetic core structure shown in FIG. 1;
  • FIG. 6 is a plan view of magnetic strip material, illus trating the pattern for cutting the inner leg laminations for the magnetic core structure shown in FIG. 1;
  • FIG. 7 is a plan view of magnetic strip material illustrating the pattern for cutting the outer leg laminations for the magnetic core structure shown in FIG. 1.
  • FIG. 1 there is shown an elevational view of a magnetic corewinding assembly 10 of the core-form type, having a magnetic core 12 constructed according to the teachings of the invention.
  • the windings which are shown in phantom, may be for a transformer, or a reactor, as desired.
  • magnetic core 12 includes first and second outer leg portions 14 and 16, respectively, an inner leg portion 18, and upper and lower yoke portions 20 and 22, respectively.
  • Magnetic core 12 is of the stacked type, with each of the leg and yoke portions being constructed of a stack of metallic, magnetic laminations, such as grain oriented silicon steel.
  • Magnetic core 12 thus has a plurality of layers of laminations, with the ends of the various laminations of each layer being butted together to provide closed magnetic loops about openings or windows 24 and 26, through which the windings pass.
  • the magnetic core-Winding assembly 10 includes phase winding assembly 28, 3t and 32 disposed about leg portions 14, 18 and 16, respectively, with the phase winding assemblies including the high and low voltage windings of a transformer, or reactor windings, depending upon the specific application.
  • Magnetic core 12 is of the stepped-lap type, with the joints between the leg and yoke portions of the magnetic core being incrementally otTset from layer to layer in a predetermined pattern.
  • the joints between the outer leg portions 14 and 16 and the yoke portions 20 and 22 are mitered, preferably at an angle of 45 with respect to the sides of the laminations, with the mitered joints being offset from layer to layer in a predetermined stepped-lap pattern.
  • the pattern may step incrementally in one direction only, and then return to the starting point to repeat the pattern, or it may incrementally step in both directions, as desired.
  • FIG. 1 illustrates three layers of laminations, with the outer two layers illustrating the maximum limits of the stepped pattern, and with the inner of the three layers corresponding to the central layer of a pattern which steps incrementally in only one direction, returning to the starting point to repeat the pattern.
  • steps in one direction may be utilized as desired.
  • the stepped-lap pattern may utilize as few as three steps in one direction, it has been found that better results are obtained, from the standpoint of efliciency and noise, when using more than three steps. For example, seven steps in one direction when using a step increment of of an inch, has been found to be about optimum. Smaller magnetic cores may utilize a step increment of A; of an inch, while the larger cores may utilize a step increment as great as one-quarter of an inch. Therefore, the three layers of laminations shown in FIG. 1 may correspond to the first, fourth and seventh layers of a seven step pattern. These three layers are shown in FIGS. 2, 3 and 4 with the reference numerals 34, 36 and 38, respectively.
  • each of the ends of each inner leg lamination have the configuration of an isoceles triangle. Then, in order to provide a stepped-lap joint between the inner leg and the yoke portion of the core, the V-shaped ends of the inner leg 1amination are incrementally shifted transverse to the length dimension of the lamination, in order to provide a steppedlap joint without narrowing the yoke portion of the core.
  • the penetration of the inner leg lamination into the yoke is maintained constantly by shifting the V-shaped end of the inner leg lamination in a direction parallel with the longitudinal dimension of the yoke portions of the core.
  • This construction requires a large plurality of different lamination configurations for the inner leg portion of the core, and it produces about 4% scrap.
  • This invention discloses a new and improved magnetic core structure which substantially reduces the amount of scrap generated, while still obtaining a stepped-lap joint at the inner leg portion of the core which has substantially the same efiiciency and sound level as magnetic cores having stepped-lap joints of the prior art configurations. Further, these results have been obtained while utilizing an inner leg constructed of only one lamination size, and the incremental shifting of the inner leg lamination to achieve the stepped-lap pattern does not unduly narrow the yoke portion of the core.
  • the inner leg portion 18 has a plurality of like dimensioned laminations, offset from one another along the longitudinal axis 40 of the inner leg laminations, to step the ends of the laminations from layer-to-layer in a predetermined steppedlap pattern.
  • the configuration of each end of each inner lag lamination is that of a truncated isosceles triangle.
  • the apex of the normal triangular point is cut-off by a plane which passes through the mitered r angularly proceeding edges in a direction perpendicular to the major sides of the laminations.
  • the new and improved magnetic core structures 12 may be better understood by examining the layers 34, 36 and 38 of laminations shown in FIGS. 2, 3 and 4, respectively.
  • layers 34 and 38 represent the two extreme positions of the stepped pattern, and layer 36 an intermediate position.
  • the first layer 34 shown in FIG. 2, includes first and second outer leg laminations 42 and 44, respectively, an inner leg lamination 46, upper yoke laminations 48 and 50, and lower yoke laminations 52 and 54.
  • the yoke portions 20 and 22 are illustrated as being divided, as it is felt that the magnetic core may be more easily assembled using this construction, especially on the larger magnetic core ratings.
  • the upper and lower yoke portions may each have a single lamination per layer if desired, since the maximum penetration of the inner leg lamination into the core is substantially less than the overall width of the yoke laminations.
  • the inner leg lamination has first and second ends 56 and 58, the edges of which define the longitudinal dimension L, and first and second sides 60 and 62, respectively, the edges of which define the width dimension W of the lamination.
  • Each end of the lamination 46 has a composite cut which includes first and second mitered edges, and an extreme end which is perpendicular to the sides of the lamination, with the extreme end having a dimension less than the width dimension W.
  • the first end 56 of lamination 46 has first and second mitered edges 64 and 66 which angle inwardly from the sides 60 and 62 at angles 61 and 63, respectively, ending at the extreme ends 68 of the lamination.
  • the extreme end 68 of the lamination is perpendicular to imaginary extensions on the sides 60 and 62 of the lamination.
  • the second end 58 is of like configuration.
  • mitered edges 64 and 66 have a like length dimension and make like angles with the parallel sides of the lamination
  • the configuration of the ends of the inner leg lamination is that of a truncated isosceles triangle. While the magniture of angles 61 and 63 is preferably 45, other angles may be chosen if desired.
  • All of the like positioned laminations of the various layers have exactly the same dimensions in magnetic core 12, except for the two yoke laminations 50 and 54.
  • the outer leg laminations 42 and 44 are trapezoidal in configuration, and each have the same dimensions in each layer, and their dimensions remain the same from layer to layer.
  • the inner leg laminations 46 has the same dimensions from layer to layer.
  • the upper and lower yoke laminations 48 and 52 are trapezoidal in configuration, and have the same dimensions as one another, and the same dimensions from layer to layer.
  • the remaining yoke laminations 50 and 54 are substantially parallelogram in configuration, but each is modified with a composite cut to accommodate the truncated ends of the inner leg laminations.
  • the composite cut is of minimum size in lamination 50 and of maximum size in lamination 54 in the first layer of the pattern, and the sizes of the incremental cuts change until reaching the last layer 38 of the pattern, where the cut is of maximum size in lamination 50 of minimum size in lamination 54.
  • the composite cuts are of equal size in the intermediate layer 36 shown in FIG. 3.
  • lamination 50 has first and second parallel sides 70 and 72, respectively, which define the width dimension W of the lamination, and first and second parallel edges 74 and 76 which intersect the sides 70 and 72 with predetermined angles, such as a 45 angle.
  • the corner of lamination 50 defined by sides 72 and 74 is modified to have the same configuration as the extreme end 68 and mitered edge 66 of the first end 56 of the inner leg lamination 46, by utilizing a composite out having first and second portions or edges 78 and 80, respectively.
  • the second edge 80 angles inwardly from side 72, towards the apex of the corner defined by sides 72 and 74, until the width dimension W is narrowed by the specific predetermined penetration of the inner leg lamination into the yoke lamination for the specified layer, and then the composite cut is completed by edge 78 which is parallel with sides 70 and 72 and which extends to edge 74 of the lamination.
  • a similar composite cut is made in yoke lamination 54'.
  • layer 36 is the intermediate layer of the pattern, the volume of material removed from lamination 50' and from lamination 54' by the composite cuts is identical.
  • the composite cut in yoke lamination 50 removes less material than the composite cut in yoke lamination 54, while in the last layer 38 the composite cut in yoke lamination 50" removes more material than the composite cut in yoke lamination 54".
  • the stepped-lap joints at the other corners of the core, and between the yoke and inner leg laminations is achieved by incrementally moving the laminations which make up the outside core loop, in a counterclockwise direction, which incrementally moves the inner leg into the upper yoke portion 20 and out of the lower yoke portion 22.
  • the pattern may start all over again with layer 34, or the outer laminations which make up the outer core loop may all be incrementally moved clockwise to move the inner leg incrementally back into yoke portion 22 and out of yoke portion 20, until reaching the layer 34 configuration.
  • FIGS. 1, 2, 3 and 4 While the embodiment of the invention shown in FIGS. 1, 2, 3 and 4 is preferred because all of the inner leg laminations have the same dimensions in all of the layers, it would also be suitable to change the length of each inner leg lamination from layer to layer, while maintaining the same configurations on their ends.
  • the inner leg laminations would not be incrementally moved along their longitudinal axis from layer to layer, but would all have their axes, which intersect the geometrical center of the lamination perpendicular to the major plane of the lamination, in alignment.
  • the upper and lower yoke laminations 50 and 54 would both have the same configuration in each layer, but their configurations would change from layer to layer.
  • FIG. 5 is a plan view which illustrates how the yoke laminations may be cut from a strip of magnetic material.
  • FIG. 6 is a plan view which illustrates how the inner leg laminations may be cut from a strip of magnetic material, and
  • FIG. 7 is a plan view which illustrates how the outer leg laminations may be cut from a strip of magnetic material.
  • FIG. 5 illustrates a strip 90 of magnetic metallic material having a width dimension W.
  • An oscillating shear may cut the strip diagonally along lines 92, 94, 96, 98 and 100, to form yoke laminations 48, 50, 54 and 52, while dies are indexed at an angle of 45 to the strip direction indicated by arrow 102, to provide the composite cuts in laminations 50 and 54.
  • a first composite cut 104 would be made in lamination 50, and then the similar lamination for the next layer would be out after the die is indexed in the direction of arrow 110.
  • the composite cut for the intermediate layer of the pattern is shown at 106, and the composite cut for the layer at the extreme end of the pattern limit is shown at 108.
  • the first composite cut would be the cut of maximum penetration, which is given the reference numeral 112, and then the die is indexed in the direction of arrow 114, also at an angle of 45 with respect to the sides of the lamination, with the composite cut for the intermediate layer of the pattern being shown at 116, and the composite cut for the layer at the extreme end of the pattern being shown at 118. Indexing the dies at an angle of 45 to the sides of the strip, or parallel with the cut 94, is essential in order to keep the dimension of the portion of the composite out which will butt against the extreme end of the inner leg laminations constant.
  • FIG. 6 illustrates a strip of metallic magnetic material, illustrating how the inner leg lamination 46 may be cut from the strip.
  • Dies may cut the V-shaped notches 132 and 134 at like locations on opposite sides of the strip 130 to a predetermined depth, determined by the desired dimension of the extreme end of the inner leg lamination. Then, an oscillating shear may make a cut 136 between the apexes of the triangular cuts 132 and 134 to complete the truncated isosceles triangular configuration of the end of the lamination.
  • the only scrap is the small triangular portion removed from each side of the strip by the dies. It will be noted that if the inner legs were to have a V-shaped point, instead of a truncated isosceles triangular end, the scrap generated would be substantially increased.
  • FIG. 7 is a plan view of a strip 140 of magnetic metallic material, illustrating how the outer leg laminations may be cut.
  • An oscillating shear may be used to make diagonal cuts 142, 144 and 146, to produce outer leg laminations 42 and 44 without scrap.
  • the stepped-lap pattern at the corners may be formed with other configurations.
  • the stepped-lap pattern may be formed as taught in the hereinbefore mentioned U.S. Pat. 3,153,215, wherein the stepped joints are located on only one side of each of the corners; or, as taught by copending application Ser. No. 774,941, filed Nov. 12, 1968, which is assigned to the same assignee as the present application, the stepped-lap joints may be formed in a manner which eliminates voids at the inner and outer corners of the core.
  • a magnetic core comprising: a plurality of stacked layers of metallic laminations, each of said layers including first and second outer laminations, an inner leg lamination having first and second ends, and yoke laminations, said yoke laminations connecting the ends of said leg laminations with predetermined joint configurations, each end of each inner leg lamination having a similarly dimensioned configuration of a truncated isosceles triangle, including first and second mitered edges which angle inwardly from the sides of the lamination to an extreme end, the surface of which is substantially perpendicular to the sides of the lamination,
  • ends of said inner leg lamination being incrementally otfset from layer to layer in a predetermined stepped-lap pattern, which progresses at least three steps in one direction before repeating.
  • the inner leg laminations may step incrementally in the direction of the longitudinal axis of the inner leg laminations, without penetrating too deeply into the yoke portions of the core.
  • each layer of laminations includes first, second, third and fourth yoke laminations, with the first and second yoke laminations being part of a first yoke portion of the core, and the third and fourth laminations being part of a second yoke portion of the core.
  • first and third yoke laminations of each layer have trapezoidal configurations, with one of the mitered edges of each of these laminations contacting the first mitered edge at the first and second ends, respectively, of the inner leg lamination.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing Cores, Coils, And Magnets (AREA)
  • Soft Magnetic Materials (AREA)
US834998A 1969-06-20 1969-06-20 Magnetic core structure Expired - Lifetime US3559136A (en)

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US83499869A 1969-06-20 1969-06-20

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US (1) US3559136A (enrdf_load_stackoverflow)
JP (1) JPS4922607B1 (enrdf_load_stackoverflow)
BE (1) BE752299A (enrdf_load_stackoverflow)
FR (1) FR2049200B1 (enrdf_load_stackoverflow)
GB (1) GB1302419A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4140987A (en) * 1975-12-12 1979-02-20 Hitachi, Ltd. Core of a core-type transformer
US4200854A (en) * 1979-01-04 1980-04-29 Westinghouse Electric Corp. Core with step-lap joints
US4201966A (en) * 1979-01-04 1980-05-06 Westinghouse Electric Corp. Magnetic core structure
US4482880A (en) * 1981-09-10 1984-11-13 Mitsubishi Denki Kabushiki Kaisha Iron core for three-phase electromagnetic induction machine
US7249546B1 (en) 1991-05-13 2007-07-31 Franklin Electric Co., Ltd. Die-shaping apparatus and process and product formed thereby
US11488759B2 (en) * 2016-12-20 2022-11-01 Hyosung Heavy Industries Corporation Transformer iron core

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL93030C (enrdf_load_stackoverflow) * 1900-01-01
FR1241331A (fr) * 1958-10-15 1960-09-16 Westinghouse Electric Corp Construction de noyau magnétique
FR1256000A (fr) * 1960-02-01 1961-03-17 Westinghouse Electric Corp Structure de noyau magnétique
GB923276A (en) * 1960-02-09 1963-04-10 Ferranti Ltd Improvements relating to electrical transformers
FR1324664A (fr) * 1962-06-07 1963-04-19 éléments de tôle pour circuits magnétiques

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4140987A (en) * 1975-12-12 1979-02-20 Hitachi, Ltd. Core of a core-type transformer
US4200854A (en) * 1979-01-04 1980-04-29 Westinghouse Electric Corp. Core with step-lap joints
US4201966A (en) * 1979-01-04 1980-05-06 Westinghouse Electric Corp. Magnetic core structure
US4482880A (en) * 1981-09-10 1984-11-13 Mitsubishi Denki Kabushiki Kaisha Iron core for three-phase electromagnetic induction machine
US7249546B1 (en) 1991-05-13 2007-07-31 Franklin Electric Co., Ltd. Die-shaping apparatus and process and product formed thereby
US11488759B2 (en) * 2016-12-20 2022-11-01 Hyosung Heavy Industries Corporation Transformer iron core

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Publication number Publication date
BE752299A (fr) 1970-12-01
GB1302419A (enrdf_load_stackoverflow) 1973-01-10
FR2049200B1 (enrdf_load_stackoverflow) 1975-02-21
JPS4922607B1 (enrdf_load_stackoverflow) 1974-06-10
FR2049200A1 (enrdf_load_stackoverflow) 1971-03-26

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