EP0355298A2 - Air gap in a transformer for a switching power supply - Google Patents

Air gap in a transformer for a switching power supply Download PDF

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Publication number
EP0355298A2
EP0355298A2 EP89110974A EP89110974A EP0355298A2 EP 0355298 A2 EP0355298 A2 EP 0355298A2 EP 89110974 A EP89110974 A EP 89110974A EP 89110974 A EP89110974 A EP 89110974A EP 0355298 A2 EP0355298 A2 EP 0355298A2
Authority
EP
European Patent Office
Prior art keywords
air gap
transformer
switching power
power supply
ferrite core
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.)
Withdrawn
Application number
EP89110974A
Other languages
German (de)
French (fr)
Other versions
EP0355298A3 (en
Inventor
Günter GRUNDIG E.M.V. Elek. Mech. Luber
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.)
Grundig EMV Elektromechanische Versuchsanstalt Max Grundig GmbH
Original Assignee
Grundig EMV Elektromechanische Versuchsanstalt Max Grundig GmbH
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 Grundig EMV Elektromechanische Versuchsanstalt Max Grundig GmbH filed Critical Grundig EMV Elektromechanische Versuchsanstalt Max Grundig GmbH
Publication of EP0355298A2 publication Critical patent/EP0355298A2/en
Publication of EP0355298A3 publication Critical patent/EP0355298A3/en
Withdrawn legal-status Critical Current

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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
    • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
    • H01F27/346—Preventing or reducing leakage fields
    • 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
    • H01F27/255—Magnetic cores made from particles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F3/00—Cores, Yokes, or armatures
    • H01F3/10—Composite arrangements of magnetic circuits
    • H01F3/14—Constrictions; Gaps, e.g. air-gaps

Definitions

  • the invention relates to the special configuration of an air gap in a transformer with a ferrite core, the stray magnetic field being spatially restricted.
  • the transformer according to the invention is particularly suitable for switching power supplies in television receivers.
  • the object of the invention is to design the air gap in a transformer for a switching power supply in such a way that a particularly low magnetic leakage flux is achieved.
  • transformers for switched-mode power supplies according to FIG. 1, it is necessary to provide one or more air gaps in the associated ferrite core 1, firstly in order to establish certain coupling ratios between the windings and secondly to avoid the magnetization of the ferrite core by saturation.
  • the air gap is therefore divided into a plurality of partial air gaps 5 between the core legs 2, 3 of the ferrite core in order to limit the magnetic stray field by inserting ferrite disks 4 which correspond to the material and cross section of the ferrite core, such that the addition of the lengths of the partial air gaps Length of the total required air gap corresponds.
  • the stray magnetic field is considerably restricted in space, and the eddy current losses in the adjacent windings are avoided.
  • a comb-shaped plastic part 6 according to FIG.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • Coils Or Transformers For Communication (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
  • Regulation Of General Use Transformers (AREA)

Abstract

The air gap of the ferrite core in a transformer for a switching power supply generates a magnetic stray field which can lead to eddy-current losses in adjacent copper windings. By inserting ferrite plates into the air gap, the air gap is split into a plurality of partial air gaps, so that the spatial extent of the magnetic stray field is reduced. The invention is employed particularly for switching power supplies for television sets. <IMAGE>

Description

Die Erfindung betrifft die besondere Ausgestaltung eines Luftspaltes bei einem Transformator mit Ferritkern, wobei das magnetische Streufeld räumlich eingeschränkt wird. Der Transformator nach der Erfindung ist besonders geeignet für Schaltnetzteile bei Fernsehempfängern.The invention relates to the special configuration of an air gap in a transformer with a ferrite core, the stray magnetic field being spatially restricted. The transformer according to the invention is particularly suitable for switching power supplies in television receivers.

Aus der DE-OS 35 05 976 ist bekannt, wie durch speziell bemessene Luftspalte bei einem Transformator für einen Fernsehempfänger eine gute Entkopplung zwischen bestimmten Wicklungen erreicht werden kann.From DE-OS 35 05 976 it is known how a good decoupling between certain windings can be achieved by specially dimensioned air gaps in a transformer for a television receiver.

Aufgabe der Erfindung ist es, den Luftspalt bei einem Transformator für ein Schaltnetzteil so auszubilden, daß ein besonders geringer magnetischer Streufluß erreicht wird.The object of the invention is to design the air gap in a transformer for a switching power supply in such a way that a particularly low magnetic leakage flux is achieved.

Bei Transformatoren für Schaltnetzteile nach Figur 1 ist es notwendig, im zugehörigen Ferritkern 1 einen oder mehrere Luftspalte vorzusehen, einmal, um bestimmte Kopplungsverhältnisse zwischen den Wicklungen herzustellen, zum anderen, um die Sättigungsmagnetisierung des Ferritkerns zu vermeiden.In the case of transformers for switched-mode power supplies according to FIG. 1, it is necessary to provide one or more air gaps in the associated ferrite core 1, firstly in order to establish certain coupling ratios between the windings and secondly to avoid the magnetization of the ferrite core by saturation.

Ein solcher Luftspalt erzeugt, insbesondere wenn er einige Millimeter lang sein muß, ein erhebliches magnetisches Streufeld. Dieses Streufeld wiederum erzeugt in benachbarten Kupferwicklungen Wirbelströme, die zu einer unzulässigen Erwärmung des Transformators führen können.Such an air gap generates a considerable stray magnetic field, especially if it has to be a few millimeters long. This stray field in turn generates eddy currents in neighboring copper windings, which can lead to inadmissible heating of the transformer.

Erfindungsgemäß wird deshalb zur räumlichen Begrenzung des magnetischen Streufeldes durch Einlegen von Ferritscheiben 4, die in Materialbeschaffenheit und Querschnitt dem Ferritkern entsprechen, zwischen den Kernschenkeln 2, 3 des Ferritkerns der Luftspalt in mehrere Teilluftspalte 5 aufgeteilt, derart, daß die Addition der Längen der Teilluftspalte der Länge des insgesamt erforderlichen Luftspaltes entspricht. Durch diese erfindungsgemäße Maßnahme wird das magnetische Streufeld räumlich erheblich eingeengt, und die Wirbelstromverluste in den benachbarten Wicklungen werden vermieden. Zur Halterung und Fixierung der Ferritscheiben innerhalb des Luftspaltes des Ferritkernes ist ein kammartig ausgebildetes Kunststoffteil 6 nach Figur 2 vorgesehen, das mittels Kleber oder Vergußmasse mit den Ferritscheiben und dem Ferritkern fest verbunden wird. Obwohl der Luftspalt mit Kunststoff ausgefüllt ist, bleibt die magnetische Wirkung unverändert, weil das Material sich magnetisch wie Luft verhält. Luftspalt, Ferritscheiben und Kunststoffteil sind zur klareren Darstellung in Fig. 1 nicht maßstabsgerecht gezeichnet.According to the invention, the air gap is therefore divided into a plurality of partial air gaps 5 between the core legs 2, 3 of the ferrite core in order to limit the magnetic stray field by inserting ferrite disks 4 which correspond to the material and cross section of the ferrite core, such that the addition of the lengths of the partial air gaps Length of the total required air gap corresponds. By this measure according to the invention, the stray magnetic field is considerably restricted in space, and the eddy current losses in the adjacent windings are avoided. To hold and fix the ferrite disks within the air gap of the ferrite core, a comb-shaped plastic part 6 according to FIG. 2 is provided, which is firmly connected to the ferrite disks and the ferrite core by means of adhesive or potting compound. Although the air gap is filled with plastic, the magnetic effect remains unchanged because the material behaves magnetically like air. Air gap, ferrite disks and plastic part are not drawn to scale in FIG. 1 for clarity.

Claims (2)

1. Luftspalt bei einem Transformator mit Ferritkern für ein Schaltnetzteil, insbesondere für die Stromversorgung eines Fernsehgerätes, dadurch gekennzeichnet, daß der Luftspalt zwischen den Schenkeln (2, 3) des Ferritkernes durch eingelegte Plättchen (4), die in Materialbeschaffenheit und Querschnitt den Schenkeln des Ferritkerns entsprechen, in mehrere Luftspalte (5) aufgeteilt ist, so daß die Addition der Längen der einzelnen Luftspalte die wirksame Gesamtlänge des Luftspaltes ergibt.1. Air gap in a transformer with a ferrite core for a switching power supply, in particular for the power supply of a television, characterized in that the air gap between the legs (2, 3) of the ferrite core by inserted plates (4), the material properties and cross section of the legs of the Correspond to the ferrite core, is divided into several air gaps (5), so that the addition of the lengths of the individual air gaps results in the effective total length of the air gap. 2. Luftspalt bei einem Transformator nach A 1, dadurch gekennzeichnet, daß die eingelegten Plättchen (4) durch ein mit Schlitzen versehenes Kunststoffteil (6) in ihrer Position gehaltert werden, derart, daß die mit Kunststoff gefüllten Spalte in der Länge gleich sind.2. Air gap in a transformer according to A 1, characterized in that the inserted plates (4) are held in their position by a slotted plastic part (6) in such a way that the gaps filled with plastic are the same in length.
EP89110974A 1988-08-26 1989-06-16 Air gap in a transformer for a switching power supply Withdrawn EP0355298A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3828985 1988-08-26
DE19883828985 DE3828985C1 (en) 1988-08-26 1988-08-26

Publications (2)

Publication Number Publication Date
EP0355298A2 true EP0355298A2 (en) 1990-02-28
EP0355298A3 EP0355298A3 (en) 1990-08-22

Family

ID=6361651

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89110974A Withdrawn EP0355298A3 (en) 1988-08-26 1989-06-16 Air gap in a transformer for a switching power supply

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EP (1) EP0355298A3 (en)
DE (1) DE3828985C1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104021919A (en) * 2014-05-09 2014-09-03 无锡晶磊电子有限公司 Blocky combined magnetic core for filter inductor
DE102017223322A1 (en) 2017-12-20 2019-06-27 Robert Bosch Gmbh Transformer core and transformer
WO2020051077A1 (en) * 2018-09-07 2020-03-12 Abb Schweiz Ag Leakage reactance plate for power transformer
EP4379757A1 (en) * 2022-11-30 2024-06-05 Delta Electronics (Thailand) Public Co., Ltd. Magnetic component

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103680842B (en) * 2013-12-03 2017-02-08 佛山市顺德区万信电子电器有限公司 Soft magnetic alloy iron core transformer capable of removing eddy current

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2037089A (en) * 1978-11-22 1980-07-02 Philips Nv Ferromagnetic core having a gap
EP0193057A2 (en) * 1985-02-21 1986-09-03 Deutsche Thomson-Brandt GmbH Transformer for a television receiver

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1080475A (en) * 1966-06-13 1967-08-23 British Lighting Ind Ltd A choke having a winding of foil

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2037089A (en) * 1978-11-22 1980-07-02 Philips Nv Ferromagnetic core having a gap
EP0193057A2 (en) * 1985-02-21 1986-09-03 Deutsche Thomson-Brandt GmbH Transformer for a television receiver

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104021919A (en) * 2014-05-09 2014-09-03 无锡晶磊电子有限公司 Blocky combined magnetic core for filter inductor
DE102017223322A1 (en) 2017-12-20 2019-06-27 Robert Bosch Gmbh Transformer core and transformer
WO2019120882A1 (en) 2017-12-20 2019-06-27 Robert Bosch Gmbh Transformer core and transformer
CN111466002A (en) * 2017-12-20 2020-07-28 罗伯特·博世有限公司 Transformer core and transformer
WO2020051077A1 (en) * 2018-09-07 2020-03-12 Abb Schweiz Ag Leakage reactance plate for power transformer
CN112655059A (en) * 2018-09-07 2021-04-13 Abb电网瑞士股份公司 Leakage reactance plate for power transformer
US11139109B2 (en) 2018-09-07 2021-10-05 Abb Power Grids Switzerland Ag Leakage reactance plate for power transformer
EP4379757A1 (en) * 2022-11-30 2024-06-05 Delta Electronics (Thailand) Public Co., Ltd. Magnetic component

Also Published As

Publication number Publication date
DE3828985C1 (en) 1989-09-14
EP0355298A3 (en) 1990-08-22

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