EP0082421A1 - Shielded transformer embedded in an isolating mass for a high-frequency commutating element, in particular isolating transformer in a colour television receiver - Google Patents

Shielded transformer embedded in an isolating mass for a high-frequency commutating element, in particular isolating transformer in a colour television receiver Download PDF

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Publication number
EP0082421A1
EP0082421A1 EP82111403A EP82111403A EP0082421A1 EP 0082421 A1 EP0082421 A1 EP 0082421A1 EP 82111403 A EP82111403 A EP 82111403A EP 82111403 A EP82111403 A EP 82111403A EP 0082421 A1 EP0082421 A1 EP 0082421A1
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EP
European Patent Office
Prior art keywords
transformer
isolating
plastic cup
air gap
embedded
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.)
Ceased
Application number
EP82111403A
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German (de)
French (fr)
Inventor
Gerhard Dipl.-Ing. Meindl
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Siemens AG
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Siemens AG
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Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Publication of EP0082421A1 publication Critical patent/EP0082421A1/en
Ceased 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
    • H01F27/36—Electric or magnetic shields or screens
    • 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
    • H01F27/36—Electric or magnetic shields or screens
    • H01F27/363—Electric or magnetic shields or screens made of electrically conductive material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F19/00—Fixed transformers or mutual inductances of the signal type
    • H01F19/04—Transformers or mutual inductances suitable for handling frequencies considerably beyond the audio range
    • H01F19/08—Transformers having magnetic bias, e.g. for handling pulses
    • H01F2019/085—Transformer for galvanic isolation

Definitions

  • the invention relates to a shielded transformer embedded in insulating potting compound for a switching power supply operated in particular at higher frequencies, in particular flyback converter power supply in a color television receiver, with a multi-legged core made of ferromagnetic material which carries at least one coil winding and which is only inside a coil winding in a leg enveloped by the latter has at least one air gap and is otherwise magnetically closed.
  • switching power supplies are required which contain a flyback converter with a transformer for supplying certain working voltages.
  • the flyback converter usually works with either the line frequency or an unsynchronized frequency of 18 to 25 kHz.
  • the associated transformers have a ferromagnetic core, which is usually composed of ferrites in E or U shape.
  • a major problem is the high DC magnetization of the transformer.
  • it is necessary to design the ferromagnetic core with an air gap.
  • a core with a significant air gap on the other hand, has a magnetically closed one Core is an increased stray magnetic field, which in television receivers, for example, with its influence. the picture tube, is harmful. If one wanted to arrange an air gap within the coil body to reduce stray field, there would be considerable eddy current losses in the winding lying above the air gap with the risk of the coil overheating.
  • transformers For electrical and magnetic shielding of transformers, it is also known to use the transformer in a metal cup instead of the aforementioned shielding and to fill the spaces with potting compound, in particular epoxy resin. Apart from the relatively high costs for the metal cups, they are also undesirable in all cases in which the risk of contact with electrically conductive, non-insulated parts of adjacent components can occur.
  • a transformer of the type mentioned at the beginning, which meets the contradictory demands for sufficient AC inductance, stray field poverty and low loss performance fully fulfilled without the need for a ferromagnetic shield is known from DT-AS 23 05 957.
  • the winding located directly above the air gap consists of a high-frequency wire.
  • the invention has for its object to provide a shielded, embedded in insulating potting transformer of the type mentioned, the potting and shielding can be created with the least possible effort.
  • the transformer is cast in a plastic cup, the inner and / or outer surface of which carries at least in the region adjacent to the air gap an at least annularly closed metallization.
  • This metallized plastic cup replaces the metal cup previously used in part. Since this plastic cup is part of the finished, i.e. encapsulated transformer, there is also no need to clear the casting mold of any resin residues.
  • the metal layer applied, in particular vapor-deposited, to the inner and / or outer surface takes over the electrical or magnetic shielding of the transformer; the ring-shaped, soldered or welded metal foil is therefore unnecessary.
  • a transformer shielded in this way and encapsulated in potting compound has, apart from its reduced production method, also an increased quality.
  • the transformer be used in a compact design, i.e. are arranged closely adjacent to other components, it is advisable to metallize the plastic cup only on its inner surface in order to maintain the insulating effect of the plastic housing.
  • the entire inner and / or outer surface of the plastic cup can of course also be covered with a metal layer.
  • the transformer has a bobbin 6 equipped with a flange part 7, which carries the primary and secondary windings 4 of the transformer.
  • E-cores 1, 2, in particular ferrite cores, are pushed onto the coil former.
  • the mutually facing end faces of the central slugs of the E-cores 1, 2 thereby delimit an air gap 5.
  • electrical connecting pins 8 are embedded with their one ends.
  • the arrangement consisting of the E-cores, the coil former 6, 7 and the windings 4, is inserted into a plastic cup 3 and embedded in this cup by means of potting compound 9, in particular cast resin.
  • potting compound 9 in particular cast resin.
  • the inner surface of the plastic cup 3 is covered with a metal layer 10.
  • the metal layer 10 can also be replaced by a metal layer which only surrounds the area adjacent to the air gap in a ring.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Coils Or Transformers For Communication (AREA)
  • Insulating Of Coils (AREA)

Abstract

Screened transformer for a commutating element, in particular an isolator transformer, in a colour television receiver having a multi-limbed core (1, 2), carrying at least one coil winding (4), of ferromagnetic material which has at least one air gap (5), only within a coil winding in a limb enveloped by this coil winding, and otherwise is magnetically closed, the transformer being embedded in a plastic cup (3) cast by means of an insulating mass (9), the inner and/or outer surface of the plastic cup (3) having an at least annular closed metallisation (10), at least in the region adjacent to the air gap (5). <IMAGE>

Description

Die Erfindung betrifft einen geschirmten, in isolierende Vergußmasse eingebetteten Transformator für ein insbesondere bei höheren Frequenzen betriebenes Schaltnetzteil, insbesondere Sperrwandlernetzteil in einem Farbfernsehempfänger, mit einem mehrschenkligen, mindestens einen Spulenwickel tragenden Kern aus ferromagnetischem Material, der nur innerhalb eines Spulenwickels in einem von diesem umhüllten Schenkel wenigstens einen Luftspalt aufweist und im übrigen magnetisch geschlossen ist.The invention relates to a shielded transformer embedded in insulating potting compound for a switching power supply operated in particular at higher frequencies, in particular flyback converter power supply in a color television receiver, with a multi-legged core made of ferromagnetic material which carries at least one coil winding and which is only inside a coil winding in a leg enveloped by the latter has at least one air gap and is otherwise magnetically closed.

In der Fernsehempfangstechnik, insbesondere in Farbfernsehempfängern benötigt man Schaltnetzteile, die einen Sperrwandler mit einem Transformator zur Lieferung bestimmter Arbeitsspannungen enthalten. Der Sperrwandler arbeitet üblicherweise entweder mit der Zeilenfrequenz oder einer nicht synchronisierten Frequenz von 18 bis 25 kHz. Die zugehörigen Transformatoren haben einen ferromagnetischen Kern, der gewöhnlich aus Ferriten in E- oder U-Form zusammengesetzt ist. Ein wesentliches Problem ist dabei die hohe Gleichstrommagnetisierung des Transformators. Um deren nachteilige Auswirkung auf die Wechselstrominduktivität herabzusetzen, ist es erforderlich, den ferromagnetischen Kern mit Luftspalt auszuführen. Ein Kern mit einem nennenswerten Luftspalt hat andererseits gegenüber einem magnetisch geschlossenen Kern ein erhöhtes magnetisches Streufeld, das in Fernsehempfängern, beispielsweise mit seinem Einfluß auf. die Bildröhre, schädlich ist. Wollte man zur Streufeldverminderung einen Luftspalt innerhalb des Spulenkörpers anordnen, ergäben sich in der über dem Luftspalt liegenden Wicklung erhebliche Wirbelstromverluste mit der Gefahr einer Überhitzung der Spule.In television reception technology, especially in color television receivers, switching power supplies are required which contain a flyback converter with a transformer for supplying certain working voltages. The flyback converter usually works with either the line frequency or an unsynchronized frequency of 18 to 25 kHz. The associated transformers have a ferromagnetic core, which is usually composed of ferrites in E or U shape. A major problem is the high DC magnetization of the transformer. In order to reduce their adverse effect on the AC inductance, it is necessary to design the ferromagnetic core with an air gap. A core with a significant air gap, on the other hand, has a magnetically closed one Core is an increased stray magnetic field, which in television receivers, for example, with its influence. the picture tube, is harmful. If one wanted to arrange an air gap within the coil body to reduce stray field, there would be considerable eddy current losses in the winding lying above the air gap with the risk of the coil overheating.

Zur Abschirmung solcher störender Streufelder ist es aus dem Siemens-Datenbuch 1981/82 "Ferrit-Wickelbauteile", z. B. Seite 92, bekannt, um die Außenschenkel der E-Kerne eine Kupferfolie anzuordnen, die als Abschirmung wirkt, wobei der so geschirmte Transformator mittels geeigneter Hilfsmittel in elektrisch isolierende Vergußmasse eingebettet ist. Die Ausführung dieser Schirmung ist jedoch umständlich. So müssen beispielsweise die einander überlappenden Folienenden miteinander verschweißt oder verlötet und die üblich verwendeten Vergußbehälter häufig vor jedem erneuten Gießvorgang zusätzlich von Rückständen aus dem vorhergehenden Gießvorgang befreit bzw. gereinigt werden.To shield such interfering stray fields, it is from the Siemens data book 1981/82 "ferrite winding components", for. B. page 92, known to arrange the outer legs of the E-cores a copper foil, which acts as a shield, the shielded transformer is embedded in suitable insulating means in electrically insulating potting compound. The implementation of this shield is cumbersome. For example, the overlapping film ends must be welded or soldered to one another and the commonly used potting containers must also be freed or cleaned of residues from the previous casting process before each new casting process.

Zur elektrischen und magnetischen Abschirmung von Transformatoren ist es auch bekannt, anstatt der vorerwähnten Schirmung den Transformator in einen Metallbecher einzusetzen und die Freiräume mit Vergußmasse, insbesondere Epoxidharz, auszufüllen. Abgesehen von den verhältnismäßig hohen Kosten für die Metallbecher, sind diese auch in all den Fällen unerwünscht, in denen die Gefahr einer Berührung mit elektrisch leitenden, nicht isolierten Teilen benachbarter Bauelemente auftreten kann.For electrical and magnetic shielding of transformers, it is also known to use the transformer in a metal cup instead of the aforementioned shielding and to fill the spaces with potting compound, in particular epoxy resin. Apart from the relatively high costs for the metal cups, they are also undesirable in all cases in which the risk of contact with electrically conductive, non-insulated parts of adjacent components can occur.

Ein Transformator der eingangs genannten Art, der die widersprüchlichen Forderungen nach ausreichender Wechselstrominduktivität, Streufeldarmut und geringer Verlustleistung voll erfüllt, ohne einen ferromagnetischen Schirm zu benötigen,ist durch die DT-AS 23 05 957 bekannt. Die unmittelbar über dem Luftspalt befindliche Wicklung besteht dabei aus einer Hochfrequenzlitze.A transformer of the type mentioned at the beginning, which meets the contradictory demands for sufficient AC inductance, stray field poverty and low loss performance fully fulfilled without the need for a ferromagnetic shield is known from DT-AS 23 05 957. The winding located directly above the air gap consists of a high-frequency wire.

Der Erfindung liegt die Aufgabe zugrunde, einen geschirmten, in isolierende Vergußmasse eingebetteten Transformator der eingangs erwähnten Art zu schaffen, dessen Verguß und Schirmung mit möglichst geringem Aufwand erstellbar sind.The invention has for its object to provide a shielded, embedded in insulating potting transformer of the type mentioned, the potting and shielding can be created with the least possible effort.

Zur Lösung dieser Aufgabe wird bei einem Transformator gemäß Oberbegriff des Patentanspruches 1 erfindungsgemäß vorgeschlagen, daß der Transformator in einen Kunststoffbecher eingegossen ist, dessen Innen- und/oder Außenfläche mindestens in dem zum Luftspalt benachbarten Bereich eine zumindest ringförmig geschlossene Metallisierung trägt.To achieve this object, it is proposed according to the invention in a transformer according to the preamble of claim 1 that the transformer is cast in a plastic cup, the inner and / or outer surface of which carries at least in the region adjacent to the air gap an at least annularly closed metallization.

Dieser metallisierte Kunststoffbecher ersetzt den bisher zum Teil verwendeten Metallbecher. Da dieser Kunststoffbecher als quasi verlorener Becher Bestandteil des fertigen, d.h. vergossenen Transformators ist, entfällt auch die erwähnte Befreiung der Gießform von eventuellen Gießharzrückständen. Die auf die Innen- und/oder Außenfläche aufgebrachte, insbesondere aufgedampfte Metallschicht übernimmt die elektrische beziehungsweise magnetische Abschirmung des Transformators; die ringförmig angeordnete, verlötete oder verschweißte Metallfolie erübrigt sich damit. Ein so geschirmter und in Vergußmasse gebetteter Transformator besitzt, abgesehen von seiner verbilligten Herstellungsweise, auch eine gesteigerte Qualität.This metallized plastic cup replaces the metal cup previously used in part. Since this plastic cup is part of the finished, i.e. encapsulated transformer, there is also no need to clear the casting mold of any resin residues. The metal layer applied, in particular vapor-deposited, to the inner and / or outer surface takes over the electrical or magnetic shielding of the transformer; the ring-shaped, soldered or welded metal foil is therefore unnecessary. A transformer shielded in this way and encapsulated in potting compound has, apart from its reduced production method, also an increased quality.

Soll der Transformator in Schaltnetzteilen in gedrängter Bauweise, d.h. eng benachbart zu anderen Bauelementen angeordnet werden, so empfiehlt es sich, den Kunststoffbecher nur auf seiner Innenfläche zu metallisieren, um die Isolationswirkung des Kunststoffgehäuses aufrecht zu erhalten.Should the transformer be used in a compact design, i.e. are arranged closely adjacent to other components, it is advisable to metallize the plastic cup only on its inner surface in order to maintain the insulating effect of the plastic housing.

Je nach Bedarf kann selbstverständlich auch die gesamte Innen- und/oder Außenfläche des Kunststoffbechers mit einer Metallschicht bedeckt sein.Depending on requirements, the entire inner and / or outer surface of the plastic cup can of course also be covered with a metal layer.

Die Erfindung wird nachstehend anhand der Figur, die einen Transformator nach der Erfindung in geschnittener Darstellung zeigt, näher erläutert.The invention is explained below with reference to the figure, which shows a transformer according to the invention in a sectional view.

Der Transformator besitzt einen mit einem Flanschteil 7 ausgestatteten Spulenkörper 6, der die Primär-und Sekundärwicklungen 4 des Transformators trägt. Auf den Spulenkörper sind E-Kerne 1, 2, insbesondere Ferritkerne, aufgeschoben. Die zueinander gekehrten Stirnflächen der Mittelbutzen der E-Kerne 1, 2 begrenzen dabei einen Luftspalt 5. In den Spulenkörperflansch 7 sind elektrische Anschlußstifte 8 mit ihren einen Enden eingebettet.The transformer has a bobbin 6 equipped with a flange part 7, which carries the primary and secondary windings 4 of the transformer. E-cores 1, 2, in particular ferrite cores, are pushed onto the coil former. The mutually facing end faces of the central slugs of the E-cores 1, 2 thereby delimit an air gap 5. In the coil former flange 7, electrical connecting pins 8 are embedded with their one ends.

Die Anordnung, bestehend aus den E-Kernen, dem Spulenkörper 6, 7 und den Wicklungen 4, ist in einen Kunststoffbecher 3 eingesetzt und mittels Vergußmasse 9, insbesondere Gießharz, in diesen Becher eingebettet. Zur Schirmung ist die Innenfläche des Kunststoffbechers 3 mit einer Metallschicht 10 bedeckt.The arrangement, consisting of the E-cores, the coil former 6, 7 and the windings 4, is inserted into a plastic cup 3 and embedded in this cup by means of potting compound 9, in particular cast resin. For shielding, the inner surface of the plastic cup 3 is covered with a metal layer 10.

Wie bereits erwähnt, kann die Metallschicht 10 auch durch eine Metallschicht ersetzt sein, die lediglich den zum Luftspalt benachbarten Bereich ringförmig umschließt.As already mentioned, the metal layer 10 can also be replaced by a metal layer which only surrounds the area adjacent to the air gap in a ring.

Claims (3)

1. Geschirmter, in isolierende Vergußmasse eingebetteter Transformator für ein insbesondere bei höheren Frequenzen betriebenes Schaltnetzteil, insbesondere Sperrwandlernetzteil, in einem Farbfernsehempfänger mit einem mehrschenkligen, mindestens einen Spulenwickel tragenden Kern aus ferromagnetischem Material, der nur innerhalb eines Spulenwickels in einem von diesen umhüllten Schenkel wenigstens einen Luftspalt aufweist, und im übrigen magnetisch geschlossen ist, dadurch gekennzeichnet, daß der Transformator in einen Kunststoffbecher (3) eingegossen ist, dessen Innen- und/oder Außenfläche-mindestens in dem zum Luftspalt (5) benachbarten Bereich eine zumindest ringförmig geschlossene Metallisierung (10) trägt..1.Shielded transformer embedded in insulating potting compound for a switching power supply, in particular flyback converter power supply, operated in particular at higher frequencies, in a color television receiver with a multi-legged core made of ferromagnetic material which carries at least one coil winding and which only has at least one within a coil winding in a leg enveloped by these Has air gap, and is otherwise magnetically closed, characterized in that the transformer is cast into a plastic cup (3), the inner and / or outer surface of which - at least in the area adjacent to the air gap (5) - has an at least annularly closed metallization (10 ) wearing.. 2. Transformator nach Anspruch 1, dadurch gekennzeichnet, daß die gesamte Innenfläche des Kunststoffbechers (3) mit einer Metallschicht (10) bedeckt ist.2. Transformer according to claim 1, characterized in that the entire inner surface of the plastic cup (3) is covered with a metal layer (10). 3. Transformator nach Anspruch 1, dadurch gekennzeichnet, daß die gesamte Außenfläche des Kunststoffbechers (3) mit einer Metallschicht bedeckt ist.3. Transformer according to claim 1, characterized in that the entire outer surface of the plastic cup (3) is covered with a metal layer.
EP82111403A 1981-12-23 1982-12-09 Shielded transformer embedded in an isolating mass for a high-frequency commutating element, in particular isolating transformer in a colour television receiver Ceased EP0082421A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19813151170 DE3151170A1 (en) 1981-12-23 1981-12-23 SHIELDED TRANSMITTER EMBEDDED IN INSULATING POWDER FOR AN INSBES. SWITCHING POWER SUPPLY OPERATED AT HIGHER FREQUENCIES, IN PARTICULAR. LOCKING CONVERTER POWER SUPPLY IN A COLOR TELEVISION RECEIVER
DE3151170 1981-12-23

Publications (1)

Publication Number Publication Date
EP0082421A1 true EP0082421A1 (en) 1983-06-29

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EP82111403A Ceased EP0082421A1 (en) 1981-12-23 1982-12-09 Shielded transformer embedded in an isolating mass for a high-frequency commutating element, in particular isolating transformer in a colour television receiver

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EP (1) EP0082421A1 (en)
DE (1) DE3151170A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0727794A1 (en) * 1995-02-20 1996-08-21 ACTIA Société Anonyme Transformer, in particular for energy converter, and resonant energy converter with such a transformer
EP4283641A4 (en) * 2021-01-27 2024-04-03 Huawei Technologies Co., Ltd. Isolation transformer and power converter

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1010204B (en) * 1952-03-14 1957-06-13 Siemens Ag Coil arrangement with ferromagnetic core
FR1284438A (en) * 1961-03-22 1962-02-09 Philips Nv Line transformer for television sets
FR1515497A (en) * 1966-04-08 1968-03-01 Gen Electric Method of producing a conductive coating on a molded electrical apparatus
US3517361A (en) * 1968-06-19 1970-06-23 Stevens Arnold Inc Shielded transformer
DE2305957A1 (en) * 1973-02-07 1974-08-15 Siemens Ag TRANSFORMER FOR SWITCHING POWER SUPPLIES

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1010204B (en) * 1952-03-14 1957-06-13 Siemens Ag Coil arrangement with ferromagnetic core
FR1284438A (en) * 1961-03-22 1962-02-09 Philips Nv Line transformer for television sets
FR1515497A (en) * 1966-04-08 1968-03-01 Gen Electric Method of producing a conductive coating on a molded electrical apparatus
US3517361A (en) * 1968-06-19 1970-06-23 Stevens Arnold Inc Shielded transformer
DE2305957A1 (en) * 1973-02-07 1974-08-15 Siemens Ag TRANSFORMER FOR SWITCHING POWER SUPPLIES

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0727794A1 (en) * 1995-02-20 1996-08-21 ACTIA Société Anonyme Transformer, in particular for energy converter, and resonant energy converter with such a transformer
FR2730849A1 (en) * 1995-02-20 1996-08-23 Actia TRANSFORMER, IN PARTICULAR FOR ENERGY CONVERTER, AND RESONANCE ENERGY CONVERTER PROVIDED WITH SUCH A TRANSFORMER
EP4283641A4 (en) * 2021-01-27 2024-04-03 Huawei Technologies Co., Ltd. Isolation transformer and power converter

Also Published As

Publication number Publication date
DE3151170A1 (en) 1983-06-30

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