EP1286572B1 - Ballast for operating at least one low-pressure discharge lamp - Google Patents

Ballast for operating at least one low-pressure discharge lamp Download PDF

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Publication number
EP1286572B1
EP1286572B1 EP02011284A EP02011284A EP1286572B1 EP 1286572 B1 EP1286572 B1 EP 1286572B1 EP 02011284 A EP02011284 A EP 02011284A EP 02011284 A EP02011284 A EP 02011284A EP 1286572 B1 EP1286572 B1 EP 1286572B1
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EP
European Patent Office
Prior art keywords
low
ballast
pressure discharge
transformer
lamps
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EP02011284A
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German (de)
French (fr)
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EP1286572A3 (en
EP1286572A2 (en
Inventor
Juergen Klier
Rene Twardzik
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Osram GmbH
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Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
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Priority to EP08150534A priority Critical patent/EP1915036B1/en
Publication of EP1286572A2 publication Critical patent/EP1286572A2/en
Publication of EP1286572A3 publication Critical patent/EP1286572A3/en
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
    • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
    • H05B41/282—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices
    • H05B41/2825—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices by means of a bridge converter in the final stage
    • H05B41/2827—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices by means of a bridge converter in the final stage using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations

Definitions

  • the invention relates to a ballast for operating at least one low-pressure discharge lamp according to the preamble of patent claim 1.
  • ballast for operating two parallel-connected low-pressure discharge lamps is disclosed on a half-bridge inverter.
  • the ballast has a transformer with two similar windings, which are each connected in one of the two lamp current branches. This transformer works as a differential current transformer. If one of the two lamps ignites earlier than the other, the ignition of the other lamp is supported by means of the transformer.
  • the US 4,574,222 discloses a circuit arrangement for operating parallel-connected discharge lamps with a transformer for balancing the currents in the parallel branches.
  • the DE 42 43 955 A1 discloses a ballast with an inverter for at least one parallel operated gas discharge lamp pair, which is associated with a balancing transformer with two oppositely acting windings.
  • the EP 0 422 594 A1 discloses a dimming device for a fluorescent lamp.
  • ballasts for operating a plurality of low-pressure discharge lamps
  • the problem often arises that the lamps shine differently brightly in dimming operation. If the lamps are arranged in different, parallel-connected current branches, this problem can be caused by different currents in the current branches. On the other hand, this problem also occurs in lamps, which - as in a series circuit of two lamps - in the same branch are arranged.
  • the ballast comprises an inverter provided with a downstream load circuit designed as a resonant circuit into which the lamps are connected, those lamps which are directly connected to the resonant circuit components often shine brighter than the downstream lamps.
  • Both transformers act as differential current transformers.
  • the first transformer ensures symmetrization of the currents in the two parallel-connected current branches, while the second transformer enforces a balancing of the total current before and after the parallel connection of the current branches.
  • the first transformer ensures that the lamps in the two branches light up brightly, while the second transformer ensures that the lamps arranged in the same branch - ie the series-connected lamps of each branch - shine the same brightly.
  • the second transformer compensates for the losses caused by parasitic capacitances. It symmetrizes in its effort to let equal currents flow in its windings, the leakage currents caused by parasitic capacitances.
  • ballast is therefore particularly well suited to the operation of four low-pressure discharge lamps, which are arranged in two parallel current branches, each with a series connection of two low-pressure discharge lamps.
  • this variant of the ballast is also suitable for operating a different number of low-pressure discharge lamps in the two parallel current branches. For example, it is possible to arrange two low-pressure discharge lamps connected in series in the first current branch and to operate only one low-pressure discharge lamp in the second current branch.
  • the ballast according to the invention is advantageously designed as an inverter with a downstream load circuit, wherein the electrical connections for the low-pressure discharge lamps or the power branches are arranged with the electrical connections for at least one low-pressure charge lamp in the load circuit to operate the lamps with a high-frequency alternating current can.
  • the operation of the lamps with a high-frequency alternating current improves the light output and allows easy brightness control of the lamps by changing the AC frequency.
  • a half-bridge inverter is used as the inverter, whose downstream load circuit is designed as a series resonant circuit.
  • the design of the load circuit as a series resonant circuit enables easy ignition of the low-pressure discharge lamps by means of the resonance peaking method.
  • the ballast has a half-bridge inverter consisting essentially of the transistors T1, T2 and a (not shown) driving device for the transistors T1, T2 and the half-bridge capacitor C2 consists.
  • the half-bridge inverter T1, T2 is supplied at its voltage inputs with a DC voltage U, which is generated in a known manner by filtering and rectification of the AC line voltage.
  • the filter and rectifier circuit of the ballast are therefore not shown in the figures and will not be further described here.
  • the inductance L1 is connected at the center tap M1 between the transistors T1, T2 of the half-bridge inverter.
  • the first terminal of the capacitor C1 is connected, while the second terminal of the capacitor C1 is connected to the ground potential.
  • the inductance L1 and the capacitor C1 form a series resonant circuit.
  • the first terminal of the resonance capacitor C1 is connected via a parallel connection of a plurality of low-pressure discharge lamps or a series connection of low-pressure discharge lamps or a combination of both with the first terminal of the half-bridge capacitor C2.
  • the second terminal of the half-bridge capacitor C2 is at ground potential.
  • Half of the supply voltage U of the half-bridge inverter is applied to the half-bridge capacitor C2.
  • the transistors T1, T2 are switched by means of the drive device in a known manner alternately with a frequency of more than 20 kHz, so that the center tap M1 is alternately connected to the ground potential and the positive potential U. Between the center tap M1 and the second terminal of the half-bridge capacitor C2 therefore flows a correspondingly high-frequency alternating current, with which the low-pressure discharge lamps are operated.
  • the ballast for operating low-pressure discharge lamps in particular of fluorescent lamps, which are each provided with two heatable electrode coils for generating a gas discharge. Each electrode coil has two electrical connections, via which the electrode coil can be acted upon by means of a (not shown) heater H in a known manner with a heating current to enable a gentle lamp operation.
  • the ballast is used to operate four low-pressure discharge lamps, in particular fluorescent lamps L40, L41, L42, L43.
  • FIG. 1 the circuit arrangement of this ballast is shown schematically.
  • the ballast has a transformer Tr40 with two windings 40a, 40b same number of turns. The first winding 40a is connected in the first branch, in series with the series connection of the low-pressure discharge lamps L40 and L41.
  • the second winding 40b is connected in the second branch, in series with the series connection of the low-pressure discharge lamps L42 and L43.
  • the two windings 40a, 40b are arranged in the current branches such that they are traversed in opposite directions by the discharge currents of the lamps or the partial currents in the current branches.
  • the transformer Tr40 acts as a differential current transformer and ensures symmetrization of the partial currents in the two parallel-connected current branches.
  • the ballast further has a second transformer Tr41 with two windings 41a, 41b of the same number of turns.
  • the first winding 41a is immediately before the parallel connection of the two current branches and the second winding 41b is arranged immediately after the parallel connection of the two current branches, so that the two windings 41a, 41b are traversed in opposite directions by the total current of the two parallel current branches.
  • the second transformer Tr41 also operates as a differential current transformer. It forces a balancing of the total current immediately before and after the parallel connection of the two current branches. The losses due to parasitic capacitances are thereby compensated, so that the lamps L41 and L43 shine as brightly as the lamps L40 and L42 even with strong dimming.
  • the ballast is used to operate three low-pressure discharge lamps, in particular fluorescent lamps L50, L51, L52.
  • FIG. 2 the circuit arrangement of this ballast is shown schematically.
  • the ballast has a transformer Tr50 with two windings 50a, 50b of the same number of turns. The first winding 50a is connected in the first branch, in series with the series connection of the low-pressure discharge lamps L50 and L51.
  • the second winding 50b is connected in the second branch, in series with the low-pressure discharge lamp L52.
  • the two windings 50a, 50b are arranged in the current branches so that they are traversed in opposite directions by the partial currents in the current branches.
  • the transformer Tr50 acts as a differential current transformer and ensures symmetrization of the partial currents in the two parallel-connected current branches.
  • the ballast further has a second transformer Tr51 with two windings 51a, 51b of the same number of turns.
  • the first winding 51 a is immediately before the parallel connection of the two current branches and the second winding 51 b is arranged immediately after the parallel connection of the two current branches, so that the two windings 51a, 51b are traversed in opposite directions by the total current of the two parallel current branches.
  • the second transformer Tr51 also works as a differential current transformer. It forces a balancing of the total current immediately before and after the parallel connection of the two current branches.
  • the invention serves the ballast for the operation of two low-pressure discharge lamps, in particular fluorescent lamps L60, L61.
  • FIG. 3 the circuit arrangement of this ballast is shown schematically.
  • the ballast has a transformer Tr60 with two windings 60a, 60b of the same number of turns. The first winding 60a is connected in the first branch, in series with the discharge path of the low-pressure discharge lamp L60.
  • the second winding 60b is connected in the second branch, in series with the discharge path of the low-pressure discharge lamp L61.
  • the two windings 60a, 60b are arranged in the current branches such that they are traversed in opposite directions by the discharge currents of the lamps or the partial currents in the current branches.
  • the transformer Tr60 acts as a differential current transformer and ensures symmetrization of the partial currents in the two parallel-connected current branches.
  • the ballast further has a second transformer Tr61 with two windings 61a, 61b of the same number of turns.
  • the first winding 61a is immediately before the parallel connection of the two current branches and the second winding 61b is arranged immediately after the parallel connection of the two current branches, so that the two windings 61a, 61b are traversed in opposite directions by the total current of the two parallel current branches.
  • the second transformer Tr61 also works as a differential current transformer. It forces a balancing of the total current immediately before and after the parallel connection of the two current branches. The losses due to parasitic capacitances are compensated by this, so that the two ends of the lamps L60 and L61 shine brightly even with strong dimming.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Circuit Arrangements For Discharge Lamps (AREA)
  • Discharge-Lamp Control Circuits And Pulse- Feed Circuits (AREA)

Abstract

The ballast includes three branch circuits connected in parallel and to lamps (L10 - L12) and a pair of oppositely wound transformers (Tr10,Tr11). The windings (10a,10b) of the transformer (Tr10) are connected in series with the lamp (L10) and the lamps (L11,L12) respectively. The windings (11a,11b) of the transformer (Tr11) are in series with lamp (L12) and the lamps (L10,L11) respectively.

Description

Die Erfindung betrifft ein Vorschaltgerät zum Betrieb von mindestens einer Niederdruckentladungslampe gemäß dem Oberbegriff des Patentanspruchs 1.The invention relates to a ballast for operating at least one low-pressure discharge lamp according to the preamble of patent claim 1.

I. Stand der Technik I. State of the art

In der Patentschrift US 4,392,085 ist ein Vorschaltgerät zum Betrieb von zwei parallel geschalteten Niederdruckentladungslampen an einem Halbbrückenwechselrichter offenbart. Das Vorschaltgerät weist einen Transformator mit zwei gleichartigen Wicklungen auf, die jeweils in einen der beiden Lampenstromzweige geschaltet sind. Dieser Transformator arbeitet als Differenzstromtransformator. Zündet eine der beiden Lampen früher als die andere, so wird mit Hilfe des Transformators die Zündung der anderen Lampe unterstützt.In the patent US 4,392,085 a ballast for operating two parallel-connected low-pressure discharge lamps is disclosed on a half-bridge inverter. The ballast has a transformer with two similar windings, which are each connected in one of the two lamp current branches. This transformer works as a differential current transformer. If one of the two lamps ignites earlier than the other, the ignition of the other lamp is supported by means of the transformer.

Die US 4,574 222 offenbart eine Schaltungsanordnung zum Betreiben von in Parallelzweigen geschalteten Entladungslampen mit einem Transformator zur Symmetrierung der Ströme in den Parallelzweigen.The US 4,574,222 discloses a circuit arrangement for operating parallel-connected discharge lamps with a transformer for balancing the currents in the parallel branches.

Die DE 42 43 955 A1 offenbart ein Vorschaltgerät mit einem Wechselrichter für mindestens ein parallel betriebenes Gasentladungslampen-Paar, dem ein Symmetriertransformator mit zwei gegensinnig wirkenden Wicklungen zugeordnet ist.The DE 42 43 955 A1 discloses a ballast with an inverter for at least one parallel operated gas discharge lamp pair, which is associated with a balancing transformer with two oppositely acting windings.

Die EP 0 422 594 A1 offenbart eine Dimmeinrichtung für eine Leuchtstofflampe.The EP 0 422 594 A1 discloses a dimming device for a fluorescent lamp.

II. Darstellung der Erfindung II. Presentation of the invention

Bei Vorschaltgeräten zum Betrieb von mehreren Niederdruckentladungslampen, tritt häufig das Problem auf, dass beim Dimmbetrieb die Lampen unterschiedlich hell leuchten. Sind die Lampen in unterschiedlichen, parallel geschalteten Stromzweigen angeordnet, so kann dieses Problem durch unterschiedliche Ströme in den Stromzweigen verursacht sein. Andererseits tritt dieses Problem aber auch bei Lampen auf, die - wie bei einer Serienschaltung von zwei Lampen - in demselben Stromzweig angeordnet sind. Insbesondere, wenn das Vorschaltgerät einen Wechselrichter aufweist, der mit einem nachgeschalteten, als Resonanzkreis ausgeführten Lastkreis versehen ist, in den die Lampen geschaltet sind, leuchten diejenigen Lampen, die unmittelbar mit den Resonanzkreisbauteilen verbunden sind, häufig heller als die nachgeschalteten Lampen. Zusätzlich kann beobachtet werden, dass bei dem Betrieb von nur einer Niederdruckentladungslampe in jedem Stromzweig die beiden Enden der Lampe unterschiedlich hell leuchten. Diese Helligkeitsunterschiede werden um so deutlicher, je stärker die Lampen gedimmt werden. Aus den vorgenannten Gründen muss bei herkömmlichen Betriebsgeräten bzw. Vorschaltgeräten, insbesondere für die Serienschaltung von mehreren Niederdruckentladungslampen die untere Dimmstufe bzw. Helligkeitsstufe auf ungefähr 10% der maximalen Helligkeit begrenzt werden. Die vorgenannten Probleme werden durch parasitäre Kapazitäten zwischen der Lampe bzw. den Lampenleitungen und der Leuchte sowie auch durch parasitäre Kapazitäten innerhalb der Heizkreise verursacht.In the case of ballasts for operating a plurality of low-pressure discharge lamps, the problem often arises that the lamps shine differently brightly in dimming operation. If the lamps are arranged in different, parallel-connected current branches, this problem can be caused by different currents in the current branches. On the other hand, this problem also occurs in lamps, which - as in a series circuit of two lamps - in the same branch are arranged. In particular, when the ballast comprises an inverter provided with a downstream load circuit designed as a resonant circuit into which the lamps are connected, those lamps which are directly connected to the resonant circuit components often shine brighter than the downstream lamps. In addition, it can be observed that in the operation of only one low-pressure discharge lamp in each branch of the current, the two ends of the lamp shine differently bright. These brightness differences become more pronounced the more the lamps are dimmed. For the aforementioned reasons, in conventional control gear or ballasts, in particular for the series connection of several low-pressure discharge lamps, the lower dimming level or brightness level must be limited to approximately 10% of the maximum brightness. The above-mentioned problems are caused by parasitic capacitances between the lamp or lamp leads and the luminaire as well as parasitic capacitances within the heating circuits.

Es ist die Aufgabe der Erfindung, ein Vorschaltgerät bereitzustellen, bei dem die obengenannten Probleme nicht mehr auftreten.It is the object of the invention to provide a ballast in which the above problems no longer occur.

Diese Aufgabe wird durch ein Vorschaltgerät mit den Merkmalen des Patentanspruchs 1 gelöst. Besonders vorteilhafte Ausführungen der Erfindung sind in den abhängigen Patentansprüchen offenbart.This object is achieved by a ballast with the features of claim 1. Particularly advantageous embodiments of the invention are disclosed in the dependent claims.

Gemäß einer bevorzugten Variante der Erfindung besitzt das Vorschaltgerät folgende Merkmale:

  • einen Transformator zur Symmetrierung der Lampenströme,
  • zwei parallel geschaltete Stromzweige, in die jeweils elektrische Anschlüsse für mindestens eine Niederdruckentladungslampe geschaltet sind, wobei
  • der Transformator eine erste Wicklung besitzt, die in den ersten Stromzweig geschaltet ist, und eine zweite Wicklung gleicher Windungszahl besitzt, die mit entgegengesetztem Wicklungssinn in den zweiten Stromzweig geschaltet ist,
  • einen zweiten Transformator zur Symmetrierung der Lampenströme besitzt, wobei
  • der zweite Transformator eine erste und eine zweite Wicklung gleicher Windungszahl besitzt, wobei die erste Wicklung vor der Parallelschaltung der Stromzweige und die zweite Wicklung hinter der Parallelschaltung der Stromzweige angeordnet ist, und wobei
  • die erste und die zweite Wicklung des zweiten Transformators derart angeordnet sind, dass sie bei angeschlossenen Niederdruckentladungslampen gegensinnig von dem Gesamtstrom der Parallelschaltung der Stromzweige durchflossen werden.
According to a preferred variant of the invention, the ballast has the following features:
  • a transformer for balancing the lamp currents,
  • two parallel-connected current branches, in each of which electrical connections for at least one low-pressure discharge lamp are connected, wherein
  • the transformer has a first winding, which is connected in the first current branch, and has a second winding of the same number of turns, which is connected in the opposite direction of the winding into the second branch,
  • has a second transformer for balancing the lamp currents, wherein
  • the second transformer has a first and a second winding of the same number of turns, wherein the first winding is arranged before the parallel connection of the current branches and the second winding behind the parallel connection of the current branches, and wherein
  • the first and the second winding of the second transformer are arranged such that they are traversed in opposite directions of the total current of the parallel connection of the current branches in connected low-pressure discharge lamps.

Beide Transformatoren wirken als Differenzstromtransformatoren. Der erste Transformator gewährleistet eine Symmetrierung der Ströme in den beiden parallel geschalteten Stromzweigen, während der zweite Transformator eine Symmetrierung des Gesamtstroms vor und hinter der Parallelschaltung der Stromzweige erzwingt. Der erste Transformator stellt sicher, dass die Lampen in den beiden Stromzweigen gleich hell leuchten, während der zweite Transformator sicherstellt, dass die in demselben Stromzweig angeordneten Lampen - also die seriell geschalteten Lampen eines jeden Stromzweigs - gleich hell leuchten. Der zweite Transformator kompensiert die Verluste, die durch parasitäre Kapazitäten entstehen. Er symmetriert in seinem Bestreben gleiche Ströme in seinen Wicklungen fließen zu lassen die durch parasitäre Kapazitäten verursachten Ableitströme. Dabei senkt er das Potential des dem Kondensator C1 zugeordneten Lampenanschlusses während er das Potential des dem Kondensator C2 zugeordneten Lampenanschlusses entsprechend erhöht. Dieses Vorschaltgerät eignet sich daher besonders gut zum Betrieb von vier Niederdruckentladungslampen, die in zwei parallelen Stromzweige mit jeweils einer Serienschaltung aus zwei Niederdruckentladungslampen angeordnet sind. Diese Variante des Vorschaltgerätes eignet sich aber auch zum Betrieb einer unterschiedlichen Anzahl von Niederdruckentladungslampen in den beiden parallel geschalteten Stromzweige. Beispielsweise ist es möglich, in den ersten Stromzweig zwei in Serie geschaltete Niederdruckentladungslampen anzuordnen und in dem zweiten Stromzweig nur eine Niederdruckentladungslampe zu betreiben.Both transformers act as differential current transformers. The first transformer ensures symmetrization of the currents in the two parallel-connected current branches, while the second transformer enforces a balancing of the total current before and after the parallel connection of the current branches. The first transformer ensures that the lamps in the two branches light up brightly, while the second transformer ensures that the lamps arranged in the same branch - ie the series-connected lamps of each branch - shine the same brightly. The second transformer compensates for the losses caused by parasitic capacitances. It symmetrizes in its effort to let equal currents flow in its windings, the leakage currents caused by parasitic capacitances. In doing so, it lowers the potential of the lamp terminal associated with the capacitor C1 while correspondingly increasing the potential of the lamp terminal assigned to the capacitor C2. This ballast is therefore particularly well suited to the operation of four low-pressure discharge lamps, which are arranged in two parallel current branches, each with a series connection of two low-pressure discharge lamps. However, this variant of the ballast is also suitable for operating a different number of low-pressure discharge lamps in the two parallel current branches. For example, it is possible to arrange two low-pressure discharge lamps connected in series in the first current branch and to operate only one low-pressure discharge lamp in the second current branch.

Das erfindungsgemäße Vorschaltgerät ist vorteilhafterweise als Wechselrichter mit einem nachgeschalteten Lastkreis ausgebildet ist, wobei die elektrischen Anschlüsse für die Niederdruckentladungslampen bzw. die Stromzweige mit den elektrischen Anschlüssen für mindestens eine Niederdruckladungslampe in dem Lastkreis angeordnet sind, um die Lampen mit einem hochfrequenten Wechselstrom betreiben zu können. Der Betrieb der Lampen mit einem hochfrequenten Wechselstrom verbessert die Lichtausbeute und ermöglicht eine einfache Helligkeitssteuerung der Lampen durch Ändern der Wechselstromfrequenz.The ballast according to the invention is advantageously designed as an inverter with a downstream load circuit, wherein the electrical connections for the low-pressure discharge lamps or the power branches are arranged with the electrical connections for at least one low-pressure charge lamp in the load circuit to operate the lamps with a high-frequency alternating current can. The operation of the lamps with a high-frequency alternating current improves the light output and allows easy brightness control of the lamps by changing the AC frequency.

Gemäß den bevorzugten Ausführungsbeispielen der Erfindung wird als Wechselrichter insbesondere ein Halbbrückenwechselrichter verwendet, dessen nachgeschalteter Lastkreis als Serienresonanzkreis ausgebildet ist. Die Ausbildung des Lastkreises als Serienresonanzkreises ermöglicht eine einfache Zündung der Niederdruckentladungslampen mittels der Methode der Resonanzüberhöhung.According to the preferred embodiments of the invention, in particular a half-bridge inverter is used as the inverter, whose downstream load circuit is designed as a series resonant circuit. The design of the load circuit as a series resonant circuit enables easy ignition of the low-pressure discharge lamps by means of the resonance peaking method.

III. Beschreibung der bevorzugten Ausführungsbeispiele III. Description of the preferred embodiments

Nachstehend wird die Erfindung anhand mehrerer bevorzugter Ausführungsbeispiele näher erläutert. Es zeigen:

Figur 1
Die Schaltungsanordnung eines Vorschaltgerätes gemäß dem vierten Aus- führungsbeispiel der Erfindung in schematischer Darstellung
Figur 2
Die Schaltungsanordnung eines Vorschaltgerätes gemäß dem zweiten Ausführungsbeispiel der Erfindung in schematischer Darstellung
Figur 3
Die Schaltungsanordnung eines Vorschaltgerätes gemäß dem dritten Aus- führungsbeispiel der Erfindung in schematischer Darstellung
The invention will be explained in more detail with reference to several preferred embodiments. Show it:
FIG. 1
The circuit arrangement of a ballast according to the fourth embodiment of the invention in a schematic representation
FIG. 2
The circuit arrangement of a ballast according to the second embodiment of the invention in a schematic representation
FIG. 3
The circuit arrangement of a ballast according to the third embodiment of the invention in a schematic representation

In den Figuren wurden für identische Bauteile des Vorschaltgerätes bzw. der Schaltungsanordnung die gleichen Bezugszeichen gewählt. Bei allen Ausführungsbeispielen der Erfindung besitzt das Vorschaltgerät einen Halbbrückenwechselrichter, der im wesentlichen von den Transistoren T1, T2 und einer (nicht abgebildeten) Ansteuerungsvorrichtung für die Transistoren T1, T2 sowie aus dem Halbbrückenkondensator C2 besteht. Der Halbbrückenwechselrichter T1, T2 wird an seinen Spannungseingängen mit einer Gleichspannung U versorgt, die in bekannter Weise durch Filterung und Gleichrichtung aus der Netzwechselspannung generiert wird. Die Filter-und Gleichrichterschaltung des Vorschaltgerätes sind daher in den Figuren nicht dargestellt und sollen hier auch nicht weiter beschrieben werden. An den Mittenabgriff M1 zwischen den Transistoren T1, T2 des Halbbrückenwechselrichters ist die Induktivität L1 angeschlossen. An die Induktivität L1 ist der erste Anschluß des Kondensators C1 angeschlossen, während der zweite Anschluß des Kondensators C1 mit dem Massepotential verbunden ist. Die Induktivität L1 und der Kondensator C1 bilden einen Serienresonanzkreis. Der erste Anschluß des Resonanzkondensators C1 ist über eine Parallelschaltung von mehreren Niederdruckentladungslampen oder eine Serienschaltung von Niederdruckentladungslampen oder eine Kombination von beiden mit dem ersten Anschluß des Halbbrückenkondensators C2 verbunden. Der zweite Anschluß des Halbbrückenkondensators C2 liegt auf Massepotential. An dem Halbbrückenkondensator C2 liegt die Hälfte der Versorgungsspannung U des Halbbrückenwechselrichters an. Die Transistoren T1, T2 werden mittels der Ansteuerungsvorrichtung in bekannter Weise alternierend mit einer Frequenz von mehr als 20 kHz geschaltet, so dass der Mittenabgriff M1 abwechselnd mit dem Massepotential und dem positiven Potential U verbunden ist. Zwischen dem Mittenabgriff M1 und dem zweiten Anschluß des Halbbrückenkondensators C2 fließt daher ein entsprechend hochfrequenter Wechselstrom, mit dem die Niederdruckentladungslampen betrieben werden. Bei allen Ausführungsbeispielen dient das Vorschaltgerät zum Betrieb von Niederdruckentladungslampen, insbesondere von Leuchtstofflampen, die mit jeweils mit zwei heizbaren Elektrodenwendeln zur Erzeugung einer Gasentladung versehen sind. Jede Elektrodenwendel besitzt zwei elektrische Anschlüsse, über die die Elektrodenwendel mittels einer (nicht abgebildeten) Heizvorrichtung H in bekannter Weise mit einem Heizstrom beaufschlagt werden kann, um einen schonenden Lampenbetrieb zu ermöglichen. In den Figuren sind die elektrischen Anschlüsse der Elektrodenwendeln bzw. der Niederdruckentladungslampen, die mit der Heizvorrichtung H verbunden sind, entsprechend mit dem Bezugszeichen H versehen. Da die Heizvorrichtung H bekannt ist und für die vorliegende Erfindung keine Rolle spielt, wird sie hier nicht weiter erläutert. So weit stimmen alle acht Ausführungsbeispiele überein.In the figures, the same reference numerals have been selected for identical components of the ballast or the circuit arrangement. In all embodiments of the invention, the ballast has a half-bridge inverter consisting essentially of the transistors T1, T2 and a (not shown) driving device for the transistors T1, T2 and the half-bridge capacitor C2 consists. The half-bridge inverter T1, T2 is supplied at its voltage inputs with a DC voltage U, which is generated in a known manner by filtering and rectification of the AC line voltage. The filter and rectifier circuit of the ballast are therefore not shown in the figures and will not be further described here. At the center tap M1 between the transistors T1, T2 of the half-bridge inverter, the inductance L1 is connected. To the inductor L1, the first terminal of the capacitor C1 is connected, while the second terminal of the capacitor C1 is connected to the ground potential. The inductance L1 and the capacitor C1 form a series resonant circuit. The first terminal of the resonance capacitor C1 is connected via a parallel connection of a plurality of low-pressure discharge lamps or a series connection of low-pressure discharge lamps or a combination of both with the first terminal of the half-bridge capacitor C2. The second terminal of the half-bridge capacitor C2 is at ground potential. Half of the supply voltage U of the half-bridge inverter is applied to the half-bridge capacitor C2. The transistors T1, T2 are switched by means of the drive device in a known manner alternately with a frequency of more than 20 kHz, so that the center tap M1 is alternately connected to the ground potential and the positive potential U. Between the center tap M1 and the second terminal of the half-bridge capacitor C2 therefore flows a correspondingly high-frequency alternating current, with which the low-pressure discharge lamps are operated. In all embodiments, the ballast for operating low-pressure discharge lamps, in particular of fluorescent lamps, which are each provided with two heatable electrode coils for generating a gas discharge. Each electrode coil has two electrical connections, via which the electrode coil can be acted upon by means of a (not shown) heater H in a known manner with a heating current to enable a gentle lamp operation. In the figures, the electrical connections of the electrode filaments or the low-pressure discharge lamps, with the H heater are connected, correspondingly provided with the reference H. Since the heater H is known and plays no role in the present invention, it will not be further explained here. So far agree all eight embodiments match.

Gemäß dem ersten Ausführungsbeispiel der Erfindung dient das Vorschaltgerät zum Betrieb von vier Niederdruckentladungslampen, insbesondere Leuchtstofflampen L40, L41, L42, L43. In Figur 1 ist die Schaltungsanordnung dieses Vorschaltgerätes schematisch abgebildet. An den ersten Anschluß des Resonanzkondensators C1 und an den ersten Anschluß des Halbbrückenkondensators C2 sind zwei parallel geschaltete Stromzweige angeschlossen, in die jeweils zwei in Serie geschaltete Niederdruckentladungslampen L40 und L41 bzw. L42 und L43 geschaltet sind. Außerdem besitzt das Vorschaltgerät einen Transformator Tr40 mit zwei Wicklungen 40a, 40b gleicher Windungszahl. Die erste Wicklung 40a ist in den ersten Stromzweig, in Serie zu der Serienschaltung der Niederdruckentladungslampen L40 und L41 geschaltet. Die zweite Wicklung 40b ist in den zweiten Stromzweig, in Serie zu der Serienschaltung der Niederdruckentladungslampen L42 und L43 geschaltet. Die beiden Wicklungen 40a, 40b sind so in den Stromzweigen angeordnet, dass sie gegensinnig von den Entladungströmen der Lampen bzw. den Teilströmen in den Stromzweigen durchflossen werden. Der Transformator Tr40 wirkt als Differenzstromtransformator und gewährleistet eine Symmetrierung der Teilströme in den beiden parallel geschalteten Stromzweigen. Das Vorschaltgerät besitzt ferner einen zweiten Transformator Tr41 mit zwei Wicklungen 41a, 41b gleicher Windungszahl. Die erste Wicklung 41a ist unmittelbar vor der Parallelschaltung der beiden Stromzweige und die zweite Wicklung 41b ist unmittelbar nach der Parallelschaltung der beiden Stromzweige angeordnet, so dass die beiden Wicklungen 41a, 41b gegensinnig von dem Gesamtstrom der beiden parallel geschalteten Stromzweige durchflossen werden. Der zweite Transformator Tr41 arbeitet ebenfalls als Differenzstromtransformator. Er erzwingt eine Symmetrierung des Gesamtstroms unmittelbar vor und hinter der Parallelschaltung der beiden Stromzweige. Die Verluste durch parasitäre Kapazitäten werden dadurch kompensiert, so dass die Lampen L41 und L43 auch bei starker Dimmung genauso hell leuchten wie die Lampen L40 und L42.According to the first embodiment of the invention, the ballast is used to operate four low-pressure discharge lamps, in particular fluorescent lamps L40, L41, L42, L43. In FIG. 1 the circuit arrangement of this ballast is shown schematically. To the first terminal of the resonant capacitor C1 and to the first terminal of the half-bridge capacitor C2, two parallel-connected current branches are connected, in each of which two series-connected low-pressure discharge lamps L40 and L41 or L42 and L43 are connected. In addition, the ballast has a transformer Tr40 with two windings 40a, 40b same number of turns. The first winding 40a is connected in the first branch, in series with the series connection of the low-pressure discharge lamps L40 and L41. The second winding 40b is connected in the second branch, in series with the series connection of the low-pressure discharge lamps L42 and L43. The two windings 40a, 40b are arranged in the current branches such that they are traversed in opposite directions by the discharge currents of the lamps or the partial currents in the current branches. The transformer Tr40 acts as a differential current transformer and ensures symmetrization of the partial currents in the two parallel-connected current branches. The ballast further has a second transformer Tr41 with two windings 41a, 41b of the same number of turns. The first winding 41a is immediately before the parallel connection of the two current branches and the second winding 41b is arranged immediately after the parallel connection of the two current branches, so that the two windings 41a, 41b are traversed in opposite directions by the total current of the two parallel current branches. The second transformer Tr41 also operates as a differential current transformer. It forces a balancing of the total current immediately before and after the parallel connection of the two current branches. The losses due to parasitic capacitances are thereby compensated, so that the lamps L41 and L43 shine as brightly as the lamps L40 and L42 even with strong dimming.

Gemäß dem zweiten Ausführungsbeispiel der Erfindung dient das Vorschaltgerät zum Betrieb von drei Niederdruckentladungslampen, insbesondere Leuchtstofflampen L50, L51, L52. In Figur 2 ist die Schaltungsanordnung dieses Vorschaltgerätes schematisch abgebildet. An den ersten Anschluß des Resonanzkondensators C1 und an den ersten Anschluß des Halbbrückenkondensators C2 sind zwei parallel geschaltete Stromzweige angeschlossen. In den ersten Stromzweig sind zwei in Serie geschaltet Leuchtstofflampen L50, L51 angeordnet. In den zweiten Stromzweig ist nur eine Leuchtstofflampe L52 geschaltet. Außerdem besitzt das Vorschaltgerät einen Transformator Tr50 mit zwei Wicklungen 50a, 50b gleicher Windungszahl. Die erste Wicklung 50a ist in den ersten Stromzweig, in Serie zu der Serienschaltung der Niederdruckentladungslampen L50 und L51 geschaltet. Die zweite Wicklung 50b ist in den zweiten Stromzweig, in Serie zu der Niederdruckentladungslampe L52 geschaltet. Die beiden Wicklungen 50a, 50b sind so in den Stromzweigen angeordnet, dass sie gegensinnig von den Teilströmen in den Stromzweigen durchflossen werden. Der Transformator Tr50 wirkt als Differenzstromtransformator und gewährleistet eine Symmetrierung der Teilströme in den beiden parallel geschalteten Stromzweigen. Das Vorschaltgerät besitzt ferner einen zweiten Transformator Tr51 mit zwei Wicklungen 51a, 51b gleicher Windungszahl. Die erste Wicklung 51 a ist unmittelbar vor der Parallelschaltung der beiden Stromzweige und die zweite Wicklung 51 b ist unmittelbar nach der Parallelschaltung der beiden Stromzweige angeordnet, so dass die beiden Wicklungen 51a, 51b gegensinnig von dem Gesamtstrom der beiden parallel geschalteten Stromzweige durchflossen werden. Der zweite Transformator Tr51 arbeitet ebenfalls als Differenzstromtransformator. Er erzwingt eine Symmetrierung des Gesamtstroms unmittelbar vor und hinter der Parallelschaltung der beiden Stromzweige.According to the second embodiment of the invention, the ballast is used to operate three low-pressure discharge lamps, in particular fluorescent lamps L50, L51, L52. In FIG. 2 the circuit arrangement of this ballast is shown schematically. To the first terminal of the resonant capacitor C1 and to the first terminal of the half-bridge capacitor C2, two parallel-connected current branches are connected. In the first branch, two series-connected fluorescent lamps L50, L51 are arranged. In the second branch, only one fluorescent lamp L52 is connected. In addition, the ballast has a transformer Tr50 with two windings 50a, 50b of the same number of turns. The first winding 50a is connected in the first branch, in series with the series connection of the low-pressure discharge lamps L50 and L51. The second winding 50b is connected in the second branch, in series with the low-pressure discharge lamp L52. The two windings 50a, 50b are arranged in the current branches so that they are traversed in opposite directions by the partial currents in the current branches. The transformer Tr50 acts as a differential current transformer and ensures symmetrization of the partial currents in the two parallel-connected current branches. The ballast further has a second transformer Tr51 with two windings 51a, 51b of the same number of turns. The first winding 51 a is immediately before the parallel connection of the two current branches and the second winding 51 b is arranged immediately after the parallel connection of the two current branches, so that the two windings 51a, 51b are traversed in opposite directions by the total current of the two parallel current branches. The second transformer Tr51 also works as a differential current transformer. It forces a balancing of the total current immediately before and after the parallel connection of the two current branches.

Gemäß dem dritten. Ausührungsbeispiel der Erfindung dient das Vorschaltgerät zum Betrieb von zwei Niederdruckentladungslampen, insbesondere Leuchtstofflampen L60, L61. In Figur 3 ist die Schaltungsanordnung dieses Vorschaltgerätes schematisch abgebildet. An den ersten Anschluß des Resonanzkondensators C1 und an den ersten Anschluß des Halbbrückenkondensators C2 sind zwei parallel geschaltete Stromzweige angeschlossen, in die jeweils eine Niederdruckentladungslampe L60 bzw. L61 geschaltet ist. Außerdem besitzt das Vorschaltgerät einen Transformator Tr60 mit zwei Wicklungen 60a, 60b gleicher Windungszahl. Die erste Wicklung 60a ist in den ersten Stromzweig, in Serie der Entladungsstrecke der Niederdruckentladungslampe L60 geschaltet. Die zweite Wicklung 60b ist in den zweiten Stromzweig, in Serie zu der Entladungsstrecke der Niederdruckentladungslampe L61 geschaltet. Die beiden Wicklungen 60a, 60b sind so in den Stromzweigen angeordnet, dass sie gegensinnig von den Entladungströmen der Lampen bzw. den Teilströmen in den Stromzweigen durchflossen werden. Der Transformator Tr60 wirkt als Differenzstromtransformator und gewährleistet eine Symmetrierung der Teilströme in den beiden parallel geschalteten Stromzweigen. Das Vorschaltgerät besitzt ferner einen zweiten Transformator Tr61 mit zwei Wicklungen 61a, 61b gleicher Windungszahl. Die erste Wicklung 61a ist unmittelbar vor der Parallelschaltung der beiden Stromzweige und die zweite Wicklung 61b ist unmittelbar nach der Parallelschaltung der beiden Stromzweige angeordnet, so dass die beiden Wicklungen 61a, 61 b gegensinnig von dem Gesamtstrom der beiden parallel geschalteten Stromzweige durchflossen werden. Der zweite Transformator Tr61 arbeitet ebenfalls als Differenzstromtransformator. Er erzwingt eine Symmetrierung des Gesamtstroms unmittelbar vor und hinter der Parallelschaltung der beiden Stromzweige. Die Verluste durch parasitäre Kapazitäten werden dadurch kompensiert, so dass die beiden Enden der Lampen L60 und L61 auch bei starker Dimmung gleich hell leuchten.According to the third. Ausührungsbeispiel the invention serves the ballast for the operation of two low-pressure discharge lamps, in particular fluorescent lamps L60, L61. In FIG. 3 the circuit arrangement of this ballast is shown schematically. To the first terminal of the resonant capacitor C1 and to the first terminal of the half-bridge capacitor C2, two parallel-connected current branches are connected, in each of which a low-pressure discharge lamp L60 and L61 is connected. In addition, the ballast has a transformer Tr60 with two windings 60a, 60b of the same number of turns. The first winding 60a is connected in the first branch, in series with the discharge path of the low-pressure discharge lamp L60. The second winding 60b is connected in the second branch, in series with the discharge path of the low-pressure discharge lamp L61. The two windings 60a, 60b are arranged in the current branches such that they are traversed in opposite directions by the discharge currents of the lamps or the partial currents in the current branches. The transformer Tr60 acts as a differential current transformer and ensures symmetrization of the partial currents in the two parallel-connected current branches. The ballast further has a second transformer Tr61 with two windings 61a, 61b of the same number of turns. The first winding 61a is immediately before the parallel connection of the two current branches and the second winding 61b is arranged immediately after the parallel connection of the two current branches, so that the two windings 61a, 61b are traversed in opposite directions by the total current of the two parallel current branches. The second transformer Tr61 also works as a differential current transformer. It forces a balancing of the total current immediately before and after the parallel connection of the two current branches. The losses due to parasitic capacitances are compensated by this, so that the two ends of the lamps L60 and L61 shine brightly even with strong dimming.

Claims (4)

  1. Ballast for operating a plurality of low-pressure discharge lamps,
    - the ballast having a transformer (Tr40; Tr50; Tr60) for balancing the lamp currents,
    - the ballast having two parallel-connected branch circuits to which electric terminals for at least one low-pressure discharge lamp (L40-L43; L50-L52; L60, L61) are connected in each case,
    - the transformer (Tr40; Tr50; Tr60) having a first winding (40a; 50a; 60a) that is connected to the first branch circuit, and having a second winding (40b; 50b; 60b) with the same number of turns that is connected to the second branch circuit with the opposite winding sense,
    characterized in that
    - the ballast has a second transformer (Tr41; Tr51; Tr61) for balancing the total current, directly upstream and downstream of the parallel connection of the branch circuits,
    - the second transformer (Tr41; Tr51; Tr61) having a first (41a; 51a; 61a) and a second winding (41b; 51b; 61b) with the same number of turns per unit length, the first winding (41a; 51a; 61a) being arranged upstream of the parallel connection of the branch circuits, and the second winding (41b; 51b; 61b) being arranged downstream of the parallel connection of the branch circuits, and
    - the first (41a; 51a; 61a) and the second windings (41b; 51b; 61b) of the second transformer (Tr41; Tr51; Tr61) being arranged in such a way that, with the low-pressure discharge lamps (L40-L43; L50-L52; L60, L61) connected, they are flowed through in the opposite sense by the total current of the parallel connection of the branch circuits.
  2. Ballast according to Claim 1, characterized in that the first and the second branch circuits in each case have electric terminals for two low-pressure discharge lamps (L40, L41, L42, L43) to be connected in series.
  3. Ballast according to Claim 1, characterized in that the first branch circuit has electric terminals for the series connection of two low-pressure discharge lamps (L50, L51), and the second branch circuit has electric terminals for one low-pressure discharge lamp (L52).
  4. Ballast according to one or more of the preceding claims, characterized in that the ballast is designed as an inverter (T1, T2) with a downstream load circuit, the electric terminals for the low-pressure discharge lamps or the branch circuits with the electric terminals for at least one low-pressure discharge lamp being arranged in the load circuit.
EP02011284A 2001-07-23 2002-05-22 Ballast for operating at least one low-pressure discharge lamp Expired - Lifetime EP1286572B1 (en)

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DE10134966A DE10134966A1 (en) 2001-07-23 2001-07-23 Ballast for operating at least one low-pressure discharge lamp

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US6717371B2 (en) 2004-04-06
DE50212951D1 (en) 2008-12-11
EP1915036B1 (en) 2010-02-24
CA2394409A1 (en) 2003-01-23
EP1915036A1 (en) 2008-04-23
EP1286572A3 (en) 2005-01-19
ATE459232T1 (en) 2010-03-15
DE50214247D1 (en) 2010-04-08
DE10134966A1 (en) 2003-02-06
EP1286572A2 (en) 2003-02-26
US20030015974A1 (en) 2003-01-23
ATE413086T1 (en) 2008-11-15

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