EP0542445B1 - Flacher Transformator - Google Patents

Flacher Transformator Download PDF

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Publication number
EP0542445B1
EP0542445B1 EP19920309786 EP92309786A EP0542445B1 EP 0542445 B1 EP0542445 B1 EP 0542445B1 EP 19920309786 EP19920309786 EP 19920309786 EP 92309786 A EP92309786 A EP 92309786A EP 0542445 B1 EP0542445 B1 EP 0542445B1
Authority
EP
European Patent Office
Prior art keywords
windings
flat
box
transformer
figures
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19920309786
Other languages
English (en)
French (fr)
Other versions
EP0542445A1 (de
Inventor
Ian David Duff
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Electrotech Instruments Ltd
Original Assignee
Electrotech Instruments Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Electrotech Instruments Ltd filed Critical Electrotech Instruments Ltd
Publication of EP0542445A1 publication Critical patent/EP0542445A1/de
Application granted granted Critical
Publication of EP0542445B1 publication Critical patent/EP0542445B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • H01F27/28—Coils; Windings; Conductive connections
    • H01F27/32—Insulating of coils, windings, or parts thereof
    • H01F27/324—Insulation between coil and core, between different winding sections, around the coil; Other insulation structures
    • 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
    • H01F27/28—Coils; Windings; Conductive connections
    • H01F27/2847—Sheets; Strips
    • H01F2027/2861—Coil formed by folding a blank

Definitions

  • This invention relates to a flat transformer, i.e. to a transformer in which each winding is generally planar, for example of spiral shape.
  • Such transformers are particularly useful in electrical power conditioning equipment, particularly for switched mode power supplies.
  • the purpose of the invention is to provide sufficient insulation between the primary and secondary windings of a flat transformer to satisfy the requirements of the major International Safety Bodies, while maintaining simplicity of construction of the transformer.
  • the invention provides a flat transformer comprising planar windings each formed on a lamina of which at least one is contained in an otherwise hollow, air-filled, electrically-insulating, thin, flat box sealed everywhere except at the points that lead-out wires from the winding exit from the box.
  • Two such boxes may be provided for respective windings. While such a box could be used to enclose the secondary windings, in the preferred example the or each box is used to contain only a respective primary winding. This is because the transformer cores, which should be considered as electrical conductors, have in effect become "primary components" and electrical insulation is now needed between these cores and the output circuits or metal work of the power supply.
  • the electrically-insulating flat box is conveniently made from a plastics material.
  • the invention is particularly advantageous because it represents a simple solution to the problem of electrical insulation in a flat transformer, and it still enables the transformer to be assembled from modular flat components in a very simple manner.
  • a typical conventional electrical transformer consists of a number of windings wound onto a former. Insulation materials are commonly used between windings in order to provide electrical isolation. A magnetic core is used, to complete the magnetic circuit. This type of construction is shown in Figure 1a and Figure 1b, where the magnetic material is in the shape of two "E" pieces 11. There are two windings 13, 15 separated by insulation 14 and wound on formers 12. Electrical connection to the windings 13, 15 is made by means of lead-out wires 16 and 17.
  • transformers can become very complex, particularly if they are to be used as isolating components in high frequency switched mode power supplies. In such applications it is usually required to minimise the leakage inductance or to maximise the coupling between the windings, further complicating the windings, and further complicating the design and manufacturing aspects.
  • each winding consists of a disc or spiral of wire as illustrated in Figure 2.
  • An inner core 21 slots into an outer core 25, holding between them first 22 and second 24 windings separated by insulation or electrical screens 23. It is most convenient if each disc of wire is self supporting and, at the present moment, probably the best method of construction for multiple turn windings is to use double-sided flexible printed circuit materials, placing half the turns on one side and the remainder on the other side. In this manner this windings are "printed” onto a base material and electrical insulation may be applied over the printed pattern.
  • a transformer may be assembled very easily by slotting an appropriate combination of these windings onto a pair of cores such as cores 21 and 25.
  • This flat transformer is designed around two "E" cores 31, of which one is shown in Figures 3a and 3b.
  • Many different core shapes could however be used as alternatives, ranging from circular ones of the type shown in Figure 2 to rectangular ones, of which the core shown in Figure 3 is an example, so long as they are substantially flat.
  • the two sets of primary windings are contained inside two identical moulded plastics boxes 41 and 42, as shown in Figure 4c .
  • the construction of one such box is shown in Figures 4a and 4b.
  • the primary winding 491, 492 itself consists of an etched double-sided copper-polyester-copper laminate joined from one side to the other and folded as described below with reference to Figure 5.
  • Two further windings are associated with the primary winding: a power back winding 481, 482, described below with reference to Figure 6, and radio frequency interference screens 471, 472, described below with reference to Figure 7.
  • These windings are folded one inside the other, together with a single insulator 40 in the centre, this "primary build-up" being shown in Figure 4d.
  • Each primary box 41 or 42 is moulded in two parts: a flat lid and a hollow "lunch-box" style container.
  • the primary stack of windings, as shown in Figure 4d, is placed into the "lunch-box" half, and the lid is then welded in place.
  • any method of welding could be used, or the two halves could be bonded by adhesive; the preferred method is ultrasonic welding.
  • the plastics box 41 has a central elongate aperture for receiving part of the core; otherwise, the box is generally an elongate rectangle with three rounded corners, the fourth corner allowing the lead-out wires to exit.
  • Elongate rectangular ribs 45 and 46 project normally from the major surfaces of the box 41 at the fourth corner: as can be seen in Figures 4c and 10b, these ribs are intended to be staggered so as to interlock when identical boxes are placed adjacent one another in the stack. The ribs increase the length of the electrical creepage path between primary and secondary conductors in the vicinity of the primary winding lead-outs.
  • the box 41 is thin in relation to its width and length, and that the walls of the box are also very thin.
  • the overall length of the box may be 94mm, the overall width 27mm, the overall thickness 3.2mm and the air space between the major walls 1.6mm, with the walls themselves being 0.8mm thick.
  • the material thickness must not be less than 0.5mm at all points including any weld lines; there are no rivets.
  • the primary winding 491, 492 is shown in Figures 5a and 5b.
  • Copper tracks 53 and 54, with terminals 531 and 541, are provided on one side of the plastics lamina 51, and a corresponding copper track 55 is provided on the opposite side of the same lamina 51.
  • Copper track 53 is connected electrically to copper track 55 through the plastics lamina 51 at the point indicated "x" in the drawing, by the technique described below as an embodiment of the second invention.
  • copper track 54 is bonded through the lamina 51 to copper track 55, at the point shown as " ⁇ " in the drawing.
  • the double-sided laminate is folded along the F1-F1, to assume the position shown in Figure 4d for assembly into the plastics box 41.
  • the power back winding 481, 482 of Figure 4d comprises a single-sided laminate having a plastics lamina 61 on which copper tracks 62 and 63 are printed.
  • the power back winding is folded along the line F1-F1 to adopt the configuration shown schematically in Figure 4d.
  • the radio frequency interference screen layer 471, 472 of Figure 4d is constituted by a single-sided plastics-copper laminate with a copper "winding" 72 on a plastics lamina 71; the laminate is folded about the line F1-F1.
  • the secondary windings consist of a single turn high current winding 81 with terminals 86 and 87, as shown in Figures 8a to 8e, plus up to four auxiliary windings of the type shown in Figures 9a and 9b.
  • the high current winding 81 is formed from a planar copper element cut as shown in Figure 8a, having mounting holes 84, 85 as shown.
  • the element 81 is generally U-shaped, with relatively long 82 and relatively short 83 end pieces.
  • the end pieces 82, 83 are folded through 90° about the line F1-F1 to assume the position shown in Figure 8b, and then the longer end piece 82 is folded about the line F2-F2 through 180° so as to lie adjacent the shorter end element 83.
  • the ends of these pieces 82, 83 are formed into cylindrical terminals 86, 87, as shown in Figures 8c, 8d and 8e.
  • auxiliary secondary windings 90 is shown in Figures 9a and 9b, in the form of a double-sided copper-polyester-copper laminate. Copper tracks 91 and 92 are formed on one side of the laminate, and are connected electrically through the plastics intermediate layer at respective points "x" and " ⁇ " to different ends of a spiral copper track 93 on the other side.
  • each primary stack is assembled into its plastics box 101, two such boxes being provided in this example.
  • the secondary windings consisting of the high current winding and four auxiliary windings, are assembled as at 102 between the plastics boxes 101.
  • the leadout wires 105 and 106 from the respective primary windings emerge at one end of the transformer, while the leadout wires 104 from the auxiliary secondary windings, and the leadout wires 103 from the high current secondary winding, are located at the opposite end, for maximum electrical isolation.

Claims (4)

  1. Flacher Transformator, der primäre und sekundäre planare Wicklungen (40, 471, 472, 481, 482, 491, 492) aufweist, die jeweils auf einer entsprechenden Folie gebildet werden, und von denen mindestens eine in einem anderweitig hohlen, luftgefüllten, elektrisch isolierenden, dünnen, flachen Gehäuse (41, 42) enthalten ist, das überall mit Ausnahme der Stellen abgedichtet ist, wo die wegführenden Drähte (104, 105, 106) von der Wicklung aus dem Gehäuse austreten; wobei die Wicklungen um einen gemeinsamen, elektrisch leitfähigen Magnetkern herum gebildet werden.
  2. Flacher Transformator nach Anspruch 1, bei dem mindestens zwei derartige flache Gehäuse (41, 42) für die entsprechenden Wicklungen vorhanden sind.
  3. Flacher Transformator nach Anspruch 1, bei dem das oder jedes flache Gehäuse (41, 42) benutzt wird, um nur eine entsprechende primäre Wicklung (491, 492) aufzunehmen.
  4. Flacher Transformator nach Anspruch 1, bei dem das oder jedes flache Gehäuse aus einem Kunststoff besteht.
EP19920309786 1991-11-14 1992-10-26 Flacher Transformator Expired - Lifetime EP0542445B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB919124228A GB9124228D0 (en) 1991-11-14 1991-11-14 Flat transformer,and method and apparatus for electrically connecting metal layers across an intermediate plastics layer
GB9124228 1991-11-14

Publications (2)

Publication Number Publication Date
EP0542445A1 EP0542445A1 (de) 1993-05-19
EP0542445B1 true EP0542445B1 (de) 1996-09-25

Family

ID=10704644

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19920309786 Expired - Lifetime EP0542445B1 (de) 1991-11-14 1992-10-26 Flacher Transformator

Country Status (4)

Country Link
EP (1) EP0542445B1 (de)
JP (1) JPH05217769A (de)
DE (1) DE69214094T2 (de)
GB (1) GB9124228D0 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6778060B2 (en) 2001-11-23 2004-08-17 Abb T&D Technologies Ltd. Winding for a transformer or a coil and method for producing the winding

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9424349D0 (en) 1994-12-02 1995-01-18 Measurement Tech Ltd Transformers

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB845530A (en) * 1956-11-28 1960-08-24 British Thomson Houston Co Ltd Improvements relating to the insulation of electrical components
GB954795A (en) * 1959-05-05 1964-04-08 Philips Electrical Ind Ltd Improvements in or relating to electrical coils and methods of manufacturing them
FR2086527A5 (de) * 1970-04-01 1971-12-31 Clausin Pierre
US3868766A (en) * 1973-08-31 1975-03-04 Ford Motor Co Method of forming an insulated coil for a dynamoelectric machine
US3964009A (en) * 1975-11-03 1976-06-15 Bel Fuse Inc. Ac radiation choke insulator

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6778060B2 (en) 2001-11-23 2004-08-17 Abb T&D Technologies Ltd. Winding for a transformer or a coil and method for producing the winding

Also Published As

Publication number Publication date
EP0542445A1 (de) 1993-05-19
JPH05217769A (ja) 1993-08-27
DE69214094T2 (de) 1997-02-27
DE69214094D1 (de) 1996-10-31
GB9124228D0 (en) 1992-01-08

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