EP1286572A2 - 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
EP1286572A2
EP1286572A2 EP02011284A EP02011284A EP1286572A2 EP 1286572 A2 EP1286572 A2 EP 1286572A2 EP 02011284 A EP02011284 A EP 02011284A EP 02011284 A EP02011284 A EP 02011284A EP 1286572 A2 EP1286572 A2 EP 1286572A2
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EP
European Patent Office
Prior art keywords
low
pressure discharge
transformer
ballast
winding
Prior art date
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Granted
Application number
EP02011284A
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German (de)
French (fr)
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EP1286572A3 (en
EP1286572B1 (en
Inventor
Juergen Klier
Rene Twardzik
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Osram GmbH
Original Assignee
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
Application granted granted Critical
Publication of EP1286572B1 publication Critical patent/EP1286572B1/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 claims 1, 2 or 4 or according to claim 7.
  • US Pat. No. 4,392,085 describes a ballast for operating two in parallel switched low-pressure discharge lamps on a half-bridge inverter disclosed.
  • the ballast has a transformer with two of the same type Windings, which are each connected in one of the two lamp current branches. This transformer works as a differential current transformer. Ignites one of the two Lamps earlier than the other, so the ignition is turned on with the help of the transformer the other lamp supports.
  • Ballasts for operating several low-pressure discharge lamps occur frequently the problem arises that the lamps have different brightness when dimmed to shine.
  • this problem can be caused by different currents in the current branches be caused.
  • this problem also occurs with lamps, which - as with a series connection of two lamps ⁇ in the same branch are arranged.
  • the ballast has an inverter, the with a downstream load circuit designed as a resonant circuit is provided, in which the lamps are switched, those lamps light up are directly connected to the resonant circuit components, often brighter than that downstream lamps.
  • the two ends of only one low-pressure discharge lamp in each current branch the lamp shine differently bright.
  • This variant of the invention is particularly good for the operation of three connected in parallel Suitable for low pressure discharge lamps. It is characterized by a special simple wiring of the luminaire.
  • the two transformers work due to the opposite arrangement of their first and second windings, respectively like a differential current transformer. Due to the special turns ratio of 2: 1 between the first and second winding on both transformers is guaranteed that all three current branches are symmetrical because the second Windings of the two transformers from the partial currents of two current branches be flowed through.
  • the special arrangement of the windings Both transformers ensure that, on the one hand, the currents in the three current branches Be symmetrized and on the other hand also the losses due to parasitic Capacities in each individual current branch or in each individual lamp are compensated become. Therefore, all three lamps shine equally even with strong dimming bright.
  • the ballast has three in parallel switched current branches, in each of which electrical connections for at least one Low pressure discharge lamp are switched.
  • this ballast has a transformer with three identically constructed and isotropically arranged windings on, which are each arranged in one of the current branches so that they are in the same direction through which the lamp current flows.
  • isotropic means that the transformer with a three-legged core and three identical Windings is equipped, with one winding arranged on each leg is. These windings are arranged in the current branches in such a way that lamp current flows through them in the same direction.
  • the ballast is advantageously with a second Equipped transformer for balancing the lamp current, the both windings of this second transformer have the same number of turns and connected in front of and behind the parallel connection of the three current branches are, so that the windings flow in opposite directions from the total current of the current branches become. This measure ensures that all lamps in are arranged in the same branch of electricity, shine equally brightly.
  • Both transformers act as differential current transformers.
  • the first transformer ensures symmetrization of the currents in the two connected in parallel Current branches, while the second transformer balancing of the total current in front of and behind the parallel connection of the current branches.
  • the first transformer ensures that the lamps are in the two branches shine equally brightly, while the second transformer ensures that those in the same Lamps arranged in a current branch - that is to say the lamps connected in series of each branch of electricity - shine equally brightly.
  • the second transformer compensates the losses caused by parasitic capacities. He symmetrizes in his Seek equal currents to flow in its windings through parasitic ones Capacities caused leakage currents.
  • This ballast is therefore particularly suitable for operating four low-pressure discharge lamps, those in two parallel current branches, each with a series connection are arranged from two low-pressure discharge lamps.
  • This variant of the ballast but is also suitable for operating a different number of Low-pressure discharge lamps in the two branches connected in parallel. For example, it is possible to have two series connected in the first current branch Arrange low-pressure discharge lamps and only one in the second current branch Low pressure discharge lamp to operate.
  • the ballast has electrical Connections for a single low pressure discharge lamp or electrical connections for several low-pressure discharge lamps connected in series. Moreover this ballast has a transformer with two windings of the same number of turns with the first winding when the low-pressure discharge lamp is connected or with connected low-pressure discharge lamps - the low-pressure discharge lamp or the series connection of the low-pressure discharge lamps is immediately upstream, and the second winding of the low-pressure discharge lamp or the series connection of the low-pressure discharge lamps directly is connected downstream, so that the windings of the transformer in opposite directions from Through the lamp current.
  • Windings ensure that the two ends of the on the ballast operated low-pressure discharge lamp appear equally bright even with strong dimming, or that with a series connection of several low-pressure discharge lamps, the low-pressure discharge lamps connected in series shine equally brightly.
  • the windings of the transformer force the current into symmetry the supply lines, directly in front of and behind the low-pressure discharge lamp, or immediately before and after the series connection of the low-pressure discharge lamps.
  • the losses due to parasitic capacitance in the lamps are calculated using the transformer compensated.
  • the ballast according to the invention is advantageously an inverter a downstream load circuit is formed, the electrical connections for the low-pressure discharge lamps or the current branches with the electrical ones Connections for at least one low-pressure charge lamp arranged in the load circuit are to operate the lamps with a high frequency alternating current can. Operation of the lamps with a high frequency alternating current improved the luminous efficacy and enables simple brightness control of the lamps by changing the AC frequency.
  • the downstream Load circuit is designed as a series resonance circuit.
  • the formation of the load circuit as Series resonance circuit enables simple ignition of the low-pressure discharge lamps using the method of increasing the resonance.
  • the ballast has a half-bridge inverter, which essentially consists of transistors T1, T2 and a (not shown) Control device for the transistors T1, T2 and from the half-bridge capacitor C2 exists.
  • the half-bridge inverter T1, T2 is connected to its Voltage inputs are supplied with a DC voltage U in a known manner is generated by filtering and rectification from the AC mains voltage.
  • the filter and rectifier circuit of the ballast are therefore in the figures not shown and shall not be described further here.
  • To the Center tap M1 between the transistors T1, T2 of the half-bridge inverter the inductance L1 is connected.
  • the first connection is to the inductance L1 of capacitor C1 connected while the second connection of the capacitor C1 is connected to ground potential.
  • the inductor L1 and the capacitor C1 form a series resonance circuit.
  • the first port of the resonance capacitor C1 is via a parallel connection of several low pressure discharge lamps or a series connection of low pressure discharge lamps or a combination of both connected to the first terminal of the half-bridge capacitor C2.
  • the second connection of the half-bridge capacitor C2 is at ground potential.
  • To the Half-bridge capacitor C2 is half the supply voltage U of the half-bridge inverter on.
  • the transistors T1, T2 are activated by the control device alternating in a known manner with a frequency of more than 20 kHz switched, so that the center tap M1 alternates with the ground potential and the positive potential U is connected. Between the center tap M1 and the second terminal of the half-bridge capacitor C2 therefore flows accordingly high-frequency alternating current with which the low-pressure discharge lamps operate.
  • the ballast is used for Operation of low-pressure discharge lamps, in particular fluorescent lamps, the each with two heatable electrode coils to generate a gas discharge are provided.
  • Each electrode coil has two electrical connections, via which the electrode coil by means of a heater (not shown) H in can be acted upon in a known manner with a heating current in order to protect it To enable lamp operation.
  • Figures 1 to 8 are the electrical Connections of the electrode filaments or the low-pressure discharge lamps that are connected of the heating device H are correspondingly provided with the reference symbol H. Since the heater H is known and none for the present invention Role, it is not further explained here. So far all eight exemplary embodiments are correct match.
  • the ballast is used for Operation of three low-pressure discharge lamps connected in parallel, in particular Fluorescent lamps L10, L11, L12.
  • the circuit arrangement is this Ballast shown schematically.
  • To the first connection of the resonance capacitor C1 and the first connection of the half-bridge capacitor C2 are three Current branches connected in parallel, each with a low-pressure discharge lamp L10 or L11 or L12 is switched.
  • this ballast has two transformers Tr10, Tr11, each with two windings 10a, 10b, 11a, 11b.
  • the turns ratio of the windings 10a, 10b of the first transformer Tr10 is 2: 1.
  • the turns ratio of the windings is also the same 11a, 11b of the second transformer Tr11 2: 1.
  • the winding 10a of the transformer Tr10 is connected to the first current path, in series with the L10 fluorescent lamp.
  • the second winding 10b of the transformer Tr10 is both in the second Current path, in series with the fluorescent lamp L11, as well as in the third current path, connected in series to the L12 fluorescent lamp.
  • the winding 10a is therefore from the Discharge current flows through the fluorescent lamp L10 while the winding 1Ob is flowed through by the discharge currents of the fluorescent lamps L11 and L12.
  • the two windings 10a, 10b are wound in opposite directions, so that they are in opposite directions through which the discharge current of the lamps flows.
  • the first is analogous to this Winding 11a of the transformer Tr11 in the third current path, in series to Fluorescent lamp L12 switched while the second winding 11b both in the first current path, in series with the fluorescent lamp L10, as well as in the second current path, in series with the fluorescent lamp L11.
  • the winding 11a is therefore flowed through the discharge current of the fluorescent lamp L12, while the Winding 11b from the discharge currents of the fluorescent lamps L10 and L11 is flowed through.
  • the windings 11a, 11b are arranged in opposite directions, so that the discharge currents or lamp currents flow through them in opposite directions.
  • the first transformer Tr10 is the fluorescent lamps L10 to L12 directly connected upstream, while the second transformer Tr11 the fluorescent lamps L10 to L12 is immediately connected. So all three current paths are perfect symmetrical.
  • the two transformers Tr10, Tr11 each work as differential current transformers and ensure that regardless of the Dimming level all three lamps shine equally brightly.
  • the ballast is used for the operation of three low-pressure discharge lamps connected in parallel, in particular Fluorescent lamps L20, L21, L22.
  • the circuit arrangement is this Ballast shown schematically.
  • To the first connection of the resonance capacitor C1 and to the first terminal of the half-bridge capacitor C2 three current branches connected in parallel, each with a low-pressure discharge lamp L20 or L21 or L22 is switched.
  • This also points Ballast a transformer Tr2 with three identically constructed and isotropic arranged windings 2a, 2b, 2c.
  • each of the three connected in parallel Current display is one of the fluorescent lamps L20 or L21 or L22 and in series for Discharge path of the corresponding fluorescent lamp L20 or L21 or L22 one of the windings 2a or 2b or 2c switched.
  • the windings 2a, 2b, 2c of the Transformers Tr2 are arranged in the respective current branch in such a way that they through which the discharge currents of the lamps flow.
  • the ballast is used for Operation of six low-pressure discharge lamps, especially fluorescent lamps L30, L31, L32, L33, L34, L35.
  • Figure 3 is the circuit arrangement of this ballast shown schematically.
  • the ballast also has a transformer Tr30 three identical and isotropically arranged windings 30a, 30b, 30c.
  • the ballast has a second transformer Tr31 with two identical ones Windings 31a, 31b.
  • the first winding 31a is immediately before that of the three Current branches existing parallel connection of the lamps and the second winding 31b is immediately behind the parallel connection consisting of the three current branches of the lamps arranged in such a way that the two windings 31a, 31b the total current of the three current branches flows in opposite directions.
  • the ballast is used for Operation of four low-pressure discharge lamps, in particular fluorescent lamps L40, L41, L42, L43.
  • Figure 4 is the circuit arrangement of this ballast shown schematically.
  • the ballast has a transformer Tr40 with two windings 40a, 40b same number of turns.
  • the first winding 40a is in series in the first current branch connected to the series connection of the low-pressure discharge lamps L40 and L41.
  • the second winding 40b is in the second current 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 in such a way that they are in opposite directions of the discharge currents of the lamps or the partial currents in the current branches be flowed through.
  • the transformer Tr40 acts as a differential current transformer and ensures symmetry of the partial flows in the two connected in parallel Current branches.
  • the ballast also 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 immediately after the parallel connection of the two current branches arranged so that the two windings 41a, 41b in opposite directions from the total current of the two current branches connected in parallel.
  • the second Transformer Tr41 also works as a residual current transformer. He enforces symmetrization of the total current immediately before and after the parallel connection of the two branches. The losses from parasitic capacities are thereby compensated so that the lamps L41 and L43 do the same, even with strong dimming shine brightly like the lamps L40 and L42.
  • the ballast is used for operating three low-pressure discharge lamps, in particular fluorescent lamps L50, L51, L52.
  • Figure 5 is the circuit arrangement of this ballast shown schematically.
  • the ballast has one Transformer Tr50 with two windings 50a, 50b of the same number of turns.
  • the first Winding 50a is in the first branch, in series with the series connection of the low-pressure discharge lamps L50 and L51 switched.
  • the second winding 50b is in the second current branch, connected in series with the low-pressure discharge lamp L52.
  • the two windings 50a, 50b are arranged in the current branches in such a way that they flow in opposite directions from the partial flows in the current branches.
  • the Transformer Tr50 acts as a residual current transformer and ensures one Balancing the partial currents in the two current branches connected in parallel.
  • the ballast also has a second transformer Tr51 with two windings 51a, 51b the same number of turns.
  • the first winding 51a is immediately before the parallel connection of the two current branches and the second winding 51b is immediate arranged after the parallel connection of the two current branches, so that the two windings 51a, 51b in opposite directions from the total current of the two in parallel switched current branches are flowed through.
  • the second transformer Tr51 works also as a differential current transformer. It forces symmetrization of the total current immediately before and after the parallel connection of the two current branches.
  • the ballast is used for operating two low-pressure discharge lamps, in particular fluorescent lamps L60, L61.
  • the circuit arrangement of this ballast is schematic displayed.
  • the ballast also has a transformer Tr60 with two windings 60a, 60b of the same number of turns.
  • the first winding 60a is in the first branch, in series the discharge path of the low-pressure discharge lamp L60 switched.
  • the second winding 60b is in the second current branch, connected in series to the discharge path of the low-pressure discharge lamp L61.
  • the two windings 60a, 60b are arranged in the current branches that they are in opposite directions from the discharge currents of the lamps or the partial currents in flow through the branches.
  • the transformer Tr60 acts as a residual current transformer and ensures a symmetrization of the partial flows in the two current branches connected in parallel.
  • the ballast also has one 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 immediately after the parallel connection two current branches arranged so that the two windings 61a, 61b in opposite directions flowed through by the total current of the two current branches connected in parallel become.
  • the second transformer Tr61 also works as a differential current transformer. It immediately forces a balancing of the total current and behind the parallel connection of the two current branches. The losses from parasitic Capacities are compensated for, so the two ends of the lamps L60 and L61 shine equally bright even with strong dimming.
  • the ballast is used for Operation of two low-pressure discharge lamps connected in series, in particular Fluorescent lamps L70, L71.
  • Figure 7 is the circuit arrangement of this ballast shown schematically.
  • the ballast also has a transformer Tr7 with two windings 7a, 7b same number of turns. Both windings 7a, 7b are in series with the series connection the lamps L70, L71 switched so that they are in opposite directions from the lamp current be flowed through.
  • the first winding 8a is immediately before the series connection the lamps L70, L71 and the second winding 7b immediately behind the Series connection of lamps L70, L71 in the load circuit of the half-bridge inverter T1, T2 switched.
  • the transformer Tr7 works as a differential current transformer. It compensates for the losses caused by parasitic capacities.
  • the ballast is used for Operation of a low-pressure discharge lamp, in particular fluorescent lamp L8.
  • FIG. 8 shows the circuit arrangement of this ballast schematically.
  • the discharge path of the lamp L8 is between the first connection of the resonance capacitor C1 and at the first terminal of the half-bridge capacitor C2 switched into the load circuit of the half-bridge inverter.
  • the ballast has also a transformer Tr8 with two windings 8a, 8b of the same number of turns. Both windings 8a, 8b are in series with the discharge path of the Lamp L8 switched so that the lamp current flows in opposite directions become.
  • the first winding 8a is immediately before the discharge path of the lamp L8 and the second winding 8b immediately behind the discharge path of the lamp L8 connected to the load circuit of the half-bridge inverter T1, T2.
  • the transformer Tr8 works as a differential current transformer. It compensates for the losses through parasitic capacitance and which ensures that both ends of the Fluorescent lamp L8 shine equally bright even with strong dimming.

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 der Patentansprüche 1, 2 oder 4 oder gemäß dem Patentanspruch 7.The invention relates to a ballast for operating at least one low-pressure discharge lamp according to the preamble of claims 1, 2 or 4 or according to claim 7.

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.US Pat. No. 4,392,085 describes a ballast for operating two in parallel switched low-pressure discharge lamps on a half-bridge inverter disclosed. The ballast has a transformer with two of the same type Windings, which are each connected in one of the two lamp current branches. This transformer works as a differential current transformer. Ignites one of the two Lamps earlier than the other, so the ignition is turned on with the help of the transformer the other lamp supports.

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.Ballasts for operating several low-pressure discharge lamps occur frequently the problem arises that the lamps have different brightness when dimmed to shine. Are the lamps in different branches connected in parallel arranged, this problem can be caused by different currents in the current branches be caused. On the other hand, this problem also occurs with lamps, which - as with a series connection of two lamps― in the same branch are arranged. In particular, if the ballast has an inverter, the with a downstream load circuit designed as a resonant circuit is provided, in which the lamps are switched, those lamps light up are directly connected to the resonant circuit components, often brighter than that downstream lamps. In addition, it can be observed that during operation the two ends of only one low-pressure discharge lamp in each current branch the lamp shine differently bright. These differences in brightness are around the clearer the more the lamps are dimmed. For the reasons mentioned above with conventional control gear or ballasts, in particular the lower one for the series connection of several low-pressure discharge lamps Dimming level or brightness level limited to approximately 10% of the maximum brightness become. The aforementioned problems are caused by parasitic capacitances between the lamp or lamp lines and the lamp as well as through causes parasitic capacities 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 der Patentansprüche 1, 2, 4 oder 7 gelöst. Besonders vorteilhafte Ausführungen der Erfindung sind in den abhängigen Patentansprüchen offenbart.This object is achieved by a ballast with the features of the claims 1, 2, 4 or 7 solved. Particularly advantageous embodiments of the invention are shown in the dependent claims.

Für Niederdruckentladungslampen, die in drei parallel geschalteten Stromzweigen angeordnet sind, wird die Aufgabe durch ein Vorschaltgerät mit den Merkmalen des Patentanspruchs 1 oder alternativ mit den Merkmalen des Patentanspruchs 2 gelöst. Für Niederdruckentladungslampen, die in zwei parallel geschalteten Stromzweigen angeordnet sind, wird die Aufgabe der Erfindung durch ein Vorschaltgerät mit den Merkmalen des Patentanspruchs 4 gelöst. Für Niederdruckentladungslampen, die in demselben Stromzweig angeordnet sind, das heißt, für eine Serienschaltung von mehreren Niederdruckentladungslampen oder für den Betrieb einer einzigen Niederdruckentladungslampe, wird die Aufgabe der Erfindung durch ein Vorschaltgerät mit den Merkmalen des Patentanspruchs 7 gelöst.For low-pressure discharge lamps in three current branches connected in parallel are arranged, the task by a ballast with the features of Claim 1 or alternatively solved with the features of claim 2. For low pressure discharge lamps in two current branches connected in parallel are arranged, the object of the invention by a ballast with the Features of claim 4 solved. For low pressure discharge lamps, which in the same current branch are arranged, that is, for a series connection of several low-pressure discharge lamps or for the operation of a single low-pressure discharge lamp, is the object of the invention with a ballast solved the features of claim 7.

Gemäß einer ersten Variante der Erfindung besitzt das Vorschaltgerät drei parallel geschaltete Stromzweige, in die jeweils elektrische Anschlüsse für mindestens eine Niederdruckentladungslampe geschaltet sind. Außerdem weist dieses Vorschaltgerät folgende weiteren Merkmale auf:

  • einen Transformator zur Symmetrierung der Lampenströme, wobei der Transformator eine erste und eine zweite Wicklung besitzt, und wobei die erste Wicklung doppelt so viele Windungen wie die zweite Wicklung besitzt,
  • einen zweiten Transformator zur Symmetrierung der Lampenströme, wobei der zweite Transformator eine erste und eine zweite Wicklung besitzt und die erste Wicklung doppelt so viele Windungen wie die zweite Wicklung besitzt, wobei
  • die Wicklungen der Transformatoren derart angeordnet sind, dass bei angeschlossenen Niederdruckentladungslampen, die Lampenströme zuerst durch die Wicklungen eines der beiden Transformatoren, dann durch die Niederdruckentladungslampen und anschließend erst durch die Wicklungen des anderen Transformators fließen, wobei
  • die erste Wicklung des ersten Transformators derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen von dem Lampenstrom der in den ersten Stromzweig geschalteten Niederdruckentladungslampe bzw. Niederdruckentladungslampen durchflossen wird, wobei
  • die zweite Wicklung des ersten Transformators derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen von den Lampenströmen der in den zweiten und dritten Stromzweig geschalteten Niederdruckentladungslampen durchllossen wird, und wobei die beiden Wicklungen des ersten Transformators gegensinnig gewickelt sind, wobei
  • die erste Wicklung des zweiten Transformators derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen von dem Lampenstrom der in den dritten Stromzweig geschalteten Niederdruckentladungslampe bzw. Niederdruckentladungslampen durchflossen wird, und wobei
  • die zweite Wicklung des zweiten Transformators derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen von den Lampenströmen der in den ersten und zweiten Stromzweig geschalteten Niederdruckentladungslampen durchflossen wird, wobei die beiden Wicklungen des zweiten Transformators gegensinnig gewickelt sind.
According to a first variant of the invention, the ballast has three current branches connected in parallel, in each of which electrical connections for at least one low-pressure discharge lamp are connected. This ballast also has the following additional features:
  • a transformer for balancing the lamp currents, the transformer having a first and a second winding, and the first winding having twice as many turns as the second winding,
  • a second transformer for balancing the lamp currents, the second transformer having a first and a second winding and the first winding having twice as many turns as the second winding, wherein
  • the windings of the transformers are arranged such that when low-pressure discharge lamps are connected, the lamp currents first flow through the windings of one of the two transformers, then through the low-pressure discharge lamps and then only through the windings of the other transformer, where
  • the first winding of the first transformer is arranged in such a way that, when low-pressure discharge lamps are connected, the lamp current of the low-pressure discharge lamp or low-pressure discharge lamps connected in the first current branch flows through them, wherein
  • the second winding of the first transformer is arranged such that it is passed through by the lamp currents of the low-pressure discharge lamps connected in the second and third current branch when low-pressure discharge lamps are connected, and the two windings of the first transformer are wound in opposite directions, whereby
  • the first winding of the second transformer is arranged such that when the low-pressure discharge lamps are connected, the lamp current of the low-pressure discharge lamp or low-pressure discharge lamps connected in the third current branch flows through them, and
  • the second winding of the second transformer is arranged such that the lamp currents of the low-pressure discharge lamps connected in the first and second current branches flow through them when the low-pressure discharge lamps are connected, the two windings of the second transformer being wound in opposite directions.

Diese Variante der Erfindung ist besonders gut zum Betrieb von drei parallel geschalteten Niederdruckentladungslampen geeignet. Sie zeichnet sich durch eine besonders einfache Verdrahtung der Leuchte aus. Die beiden Transformatoren wirken aufgrund der gegensinnigen Anordnung ihrer ersten und zweiten Wicklungen jeweils wie ein Differenzstromtransformator. Durch das spezielle Windungsverhältnis von 2:1 zwischen der ersten und zweiten Wicklung bei beiden Transformatoren ist gewährleistet, dass alle drei Stromzweige symmetrisch ausgebildet sind, da die zweiten Wicklungen der beiden Transformatoren von den Teilströmen zweier Stromzweige durchflossen werden. Außerdem ist durch die spezielle Anordnung der Wicklungen beider Transformatoren sichergestellt, dass einerseits die Ströme in den drei Stromzweigen Symmetriert werden und andererseits auch die Verluste durch parasitäre Kapazitäten in jedem einzelnen Stromzweig bzw. in jeder einzelnen Lampe kompensiert werden. Daher leuchten alle drei Lampen selbst bei starker Dimmung gleichermaßen hell.This variant of the invention is particularly good for the operation of three connected in parallel Suitable for low pressure discharge lamps. It is characterized by a special simple wiring of the luminaire. The two transformers work due to the opposite arrangement of their first and second windings, respectively like a differential current transformer. Due to the special turns ratio of 2: 1 between the first and second winding on both transformers is guaranteed that all three current branches are symmetrical because the second Windings of the two transformers from the partial currents of two current branches be flowed through. In addition, the special arrangement of the windings Both transformers ensure that, on the one hand, the currents in the three current branches Be symmetrized and on the other hand also the losses due to parasitic Capacities in each individual current branch or in each individual lamp are compensated become. Therefore, all three lamps shine equally even with strong dimming bright.

Gemäß einer zweiten Variante der Erfindung besitzt das Vorschaltgerät drei parallel geschaltete Stromzweige, in die jeweils elektrische Anschlüsse für mindestens eine Niederdruckentladungslampe geschaltet sind. Außerdem weist dieses Vorschaltgerät einen Transformator mit drei identisch aufgebauten und isotrop angeordneten Wicklungen auf, die jeweils so in einem der Stromzweige angeordnet sind, dass sie gleichsinnig vom Lampenstrom durchflossen werden. Isotrop bedeutet in diesem Zusammenhang, dass der Transformator mit einem dreischenkligen Kern und drei identischen Wicklungen ausgestattet ist, wobei eine Wicklung auf jedem Schenkel angeordnet ist. Diese Wicklungen sind dabei derart in den Stromzweigen angeordnet, dass sie gleichsinnig vom Lampenstrom durchflossen werden. Durch diese Anordnung der Wicklungen und aufgrund des identischen Aufbaus der Schenkel teilt sich der durch jede Wicklung induzierte magnetische Fluß gleichmäßig auf die anderen Schenkel auf. Eine Änderung des Stroms in einem der drei Stromzweige bewirkt daher automatisch eine entsprechende Änderung des Stroms in den beiden anderen Stromzweigen. Falls in einem der drei Stromzweige mehr als eine Niederdruckentladungslampe angeordnet ist, beispielsweise eine Serienschaltung aus zwei Niederdruckentladungslampen, so ist das Vorschaltgerät vorteilhafterweise mit einem zweiten Transformator zur Symmetrierung des Lampenstroms ausgestattet, wobei die beiden Wicklungen dieses zweiten Transformators die gleiche Windungszahl aufweisen und vor sowie hinter die Parallelschaltung der drei Stromzweige geschaltet sind, so dass die Wicklungen gegensinnig vom Gesamtstrom der Stromzweige durchflossen werden. Durch diese Maßnahme ist gewährleistet, dass alle Lampen, die in demselben Stromzweig angeordnet sind, gleich hell leuchten.According to a second variant of the invention, the ballast has three in parallel switched current branches, in each of which electrical connections for at least one Low pressure discharge lamp are switched. In addition, this ballast has a transformer with three identically constructed and isotropically arranged windings on, which are each arranged in one of the current branches so that they are in the same direction through which the lamp current flows. In this context, isotropic means that the transformer with a three-legged core and three identical Windings is equipped, with one winding arranged on each leg is. These windings are arranged in the current branches in such a way that lamp current flows through them in the same direction. By this arrangement of the windings and due to the identical structure of the legs, the magnetic flux induced by each winding evenly on the others Thighs on. A change in the current in one of the three current branches causes therefore automatically a corresponding change in the current in the other two Current branches. If more than one low-pressure discharge lamp in one of the three current branches is arranged, for example a series connection of two low-pressure discharge lamps, so the ballast is advantageously with a second Equipped transformer for balancing the lamp current, the both windings of this second transformer have the same number of turns and connected in front of and behind the parallel connection of the three current branches are, so that the windings flow in opposite directions from the total current of the current branches become. This measure ensures that all lamps in are arranged in the same branch of electricity, shine equally brightly.

Gemäß einer dritten 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 third variant of the invention, the ballast has the following features:
  • a transformer for balancing the lamp currents,
  • two current branches connected in parallel, 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 winding direction in the second current branch,
  • has a second transformer for balancing the lamp currents, wherein
  • the second transformer has a first and a second winding of the same type. Has number of turns, the first winding being 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 in such a way that when the low-pressure discharge lamps are connected, the total current of the parallel connection of the current branches flows through them in opposite directions.

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 Stromzweigen 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 Stromzweigen. 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 connected in parallel Current branches, while the second transformer balancing of the total current in front of and behind the parallel connection of the current branches. The first transformer ensures that the lamps are in the two branches shine equally brightly, while the second transformer ensures that those in the same Lamps arranged in a current branch - that is to say the lamps connected in series of each branch of electricity - shine equally brightly. The second transformer compensates the losses caused by parasitic capacities. He symmetrizes in his Seek equal currents to flow in its windings through parasitic ones Capacities caused leakage currents. He lowers the potential of the Capacitor C1 associated lamp terminal while the potential of the Capacitor C2 associated lamp connection increased accordingly. This ballast is therefore particularly suitable for operating four low-pressure discharge lamps, those in two parallel current branches, each with a series connection are arranged from two low-pressure discharge lamps. This variant of the ballast but is also suitable for operating a different number of Low-pressure discharge lamps in the two branches connected in parallel. For example, it is possible to have two series connected in the first current branch Arrange low-pressure discharge lamps and only one in the second current branch Low pressure discharge lamp to operate.

Gemäß einer vierten Variante der Erfindung besitzt das Vorschaltgerät elektrische Anschlüsse für eine einzige Niederdruckenetladungslampe oder elektrische Anschlüsse für mehrere in Serie geschaltete Niederdruckentladungslampen. Außerdem weist dieses Vorschaltgerät einen Transformator mit zwei Wicklungen gleicher Windungszahl auf, wobei die erste Wicklung -bei angeschlossener Niederdruckentladungslampe bzw. bei angeschlossenen Niederdruckentladungslampen - der Niederdruckentladungslampe bzw. der Serienschaltung der Niederdruckentladungslampen unmittelbar vorgeschaltet ist, und die zweite Wicklung der Niederdruckentladungslampe bzw. der Serienschaltung der Niederdruckentladungslampen unmittelbar nachgeschaltet ist, so dass die Wicklungen des Transformators gegensinnig vom Lampenstrom durchflossen werden.According to a fourth variant of the invention, the ballast has electrical Connections for a single low pressure discharge lamp or electrical connections for several low-pressure discharge lamps connected in series. Moreover this ballast has a transformer with two windings of the same number of turns with the first winding when the low-pressure discharge lamp is connected or with connected low-pressure discharge lamps - the low-pressure discharge lamp or the series connection of the low-pressure discharge lamps is immediately upstream, and the second winding of the low-pressure discharge lamp or the series connection of the low-pressure discharge lamps directly is connected downstream, so that the windings of the transformer in opposite directions from Through the lamp current.

Mit Hilfe dieses Transformators und der erfmdungsgemäßen Anordnung seiner Wicklungen wird gewährleistet, dass die beiden Enden der an dem Vorschaltgerät betriebenen Niederdruckentladungslampe auch bei starker Dimmung gleich hell erscheinen, bzw. dass bei einer Serienschaltung von mehreren Niederdruckentladungslampen, die in Serie geschalteten Niederdruckentladungslampen gleich hell leuchten. Die Wicklungen des Transformators erzwingen eine Symmetrierung des Stroms in den Zuleitungen, unmittelbar vor und hinter der Niederdruckentladungslampe, bzw. unmittelbar vor und hinter der Serienschaltung der Niederdruckentladungslampen. With the help of this transformer and its arrangement according to the invention Windings ensure that the two ends of the on the ballast operated low-pressure discharge lamp appear equally bright even with strong dimming, or that with a series connection of several low-pressure discharge lamps, the low-pressure discharge lamps connected in series shine equally brightly. The windings of the transformer force the current into symmetry the supply lines, directly in front of and behind the low-pressure discharge lamp, or immediately before and after the series connection of the low-pressure discharge lamps.

Die Verluste durch parasitäre Kapazitäten in den Lampen werden mittels des Transformators kompensiert.The losses due to parasitic capacitance in the lamps are calculated using the transformer compensated.

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 an inverter a downstream load circuit is formed, the electrical connections for the low-pressure discharge lamps or the current branches with the electrical ones Connections for at least one low-pressure charge lamp arranged in the load circuit are to operate the lamps with a high frequency alternating current can. Operation of the lamps with a high frequency alternating current improved the luminous efficacy and enables simple brightness control of the lamps by changing the AC frequency.

Gemäß der bevorzugten Ausführungsbeispiele 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 is used as an inverter used in particular a half-bridge inverter, the downstream Load circuit is designed as a series resonance circuit. The formation of the load circuit as Series resonance circuit enables simple ignition of the low-pressure discharge lamps using the method of increasing the resonance.

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 des ersten Ausführungsbeispiels der Erfindung in schematischer Darstellung
Figur 2
Die Schaltungsanordnung eines Vorschaltgerätes gemäß des zweiten Ausführungsbeispiels der Erfindung in schematischer Darstellung
Figur 3
Die Schaltungsanordnung eines Vorschaltgerätes gemäß des dritten Ausführungsbeispiels der Erfindung in schematischer Darstellung
Figur 4
Die Schaltungsanordnung eines Vorschaltgerätes gemäß des vierten Ausführungsbeispiels der Erfindung in schematischer Darstellung
Figur 5
Die Schaltungsanordnung eines Vorschaltgerätes gemäß des fünften Ausführungsbeispiels der Erfindung in schematischer Darstellung
Figur 6
Die Schaltungsanordnung eines Vorschaltgerätes gemäß des sechsten Ausführungsbeispiels der Erfindung in schematischer Darstellung
Figur 7
Die Schaltungsanordnung eines Vorschaltgerätes gemäß des siebten Ausführungsbeispiels der Erfindung in schematischer Darstellung
Figur 8
Die Schaltungsanordnung eines Vorschaltgerätes gemäß des achten Ausführungsbeispiels der Erfindung in schematischer Darstellung
The invention is explained in more detail below on the basis of several preferred exemplary embodiments. Show it:
Figure 1
The circuit arrangement of a ballast according to the first embodiment of the invention in a schematic representation
Figure 2
The circuit arrangement of a ballast according to the second embodiment of the invention in a schematic representation
Figure 3
The circuit arrangement of a ballast according to the third embodiment of the invention in a schematic representation
Figure 4
The circuit arrangement of a ballast according to the fourth embodiment of the invention in a schematic representation
Figure 5
The circuit arrangement of a ballast according to the fifth embodiment of the invention in a schematic representation
Figure 6
The circuit arrangement of a ballast according to the sixth embodiment of the invention in a schematic representation
Figure 7
The circuit arrangement of a ballast according to the seventh embodiment of the invention in a schematic representation
Figure 8
The circuit arrangement of a ballast according to the eighth embodiment of the invention in a schematic representation

In den Figuren 1 bis 8 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 1 bis 8 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 Figures 1 to 8 were for identical components of the ballast or Circuit arrangement chosen the same reference numerals. In all embodiments According to the invention, the ballast has a half-bridge inverter, which essentially consists of transistors T1, T2 and a (not shown) Control device for the transistors T1, T2 and from the half-bridge capacitor C2 exists. The half-bridge inverter T1, T2 is connected to its Voltage inputs are supplied with a DC voltage U in a known manner is generated by filtering and rectification from the AC mains voltage. The filter and rectifier circuit of the ballast are therefore in the figures not shown and shall not be described further here. To the Center tap M1 between the transistors T1, T2 of the half-bridge inverter the inductance L1 is connected. The first connection is to the inductance L1 of capacitor C1 connected while the second connection of the capacitor C1 is connected to ground potential. The inductor L1 and the capacitor C1 form a series resonance circuit. The first port of the resonance capacitor C1 is via a parallel connection of several low pressure discharge lamps or a series connection of low pressure discharge lamps or a combination of both connected to the first terminal of the half-bridge capacitor C2. The second connection of the half-bridge capacitor C2 is at ground potential. To the Half-bridge capacitor C2 is half the supply voltage U of the half-bridge inverter on. The transistors T1, T2 are activated by the control device alternating in a known manner with a frequency of more than 20 kHz switched, so that the center tap M1 alternates with the ground potential and the positive potential U is connected. Between the center tap M1 and the second terminal of the half-bridge capacitor C2 therefore flows accordingly high-frequency alternating current with which the low-pressure discharge lamps operate. In all embodiments, the ballast is used for Operation of low-pressure discharge lamps, in particular fluorescent lamps, the each with two heatable electrode coils to generate a gas discharge are provided. Each electrode coil has two electrical connections, via which the electrode coil by means of a heater (not shown) H in can be acted upon in a known manner with a heating current in order to protect it To enable lamp operation. In Figures 1 to 8 are the electrical Connections of the electrode filaments or the low-pressure discharge lamps that are connected of the heating device H are correspondingly provided with the reference symbol H. Since the heater H is known and none for the present invention Role, it is not further explained here. So far all eight exemplary embodiments are correct match.

Gemäß des ersten Ausführungsbeispiels der Erfindung dient das Vorschaltgerät zum Betrieb von drei parallel geschalteten Niederdruckentladungslampen, insbesondere Leuchtstofflampen L10, L11, L12. 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 drei parallel geschaltete Stromzweige angeschlossen, in die jeweils eine Niederdruckentladungslampe L10 bzw. L11 bzw. L12 geschaltet ist. Außerdem weist dieses Vorschaltgerät zwei Transformatoren Tr10, Tr11 mit jeweils zwei Wicklungen 10a, 10b, 11a, 11b auf. Das Windungsverhältnis der Wicklungen 10a, 10b des ersten Transformators Tr10 beträgt 2:1. Ebenso beträgt auch das Windungsverhältnis der Wicklungen 11a, 11b des zweiten Transformators Tr11 2:1. Die Wicklung 10a des Transformators Tr10 ist in den ersten Strompfad, in Serie zur Leuchtstofflampe L10 geschaltet. Die zweite Wicklung 10b des Transformators Tr10 ist sowohl in den zweiten Strompfad, in Serie zur Leuchtstofflampe L11, als auch in den dritten Strompfad, in Serie zur Leuchtstofflampe L12 geschaltet. Die Wicklung 10a wird daher von dem Entladungsstrom der Leuchtstofflampe L10 durchflossen, während die Wicklung 1Ob von den Entladungsströmen der Leuchtstofflampen L11 und L12 durchflossen wird. Die beiden Wicklungen 10a, 1Ob sind gegensinnig gewickelt, so dass sie gegensinnig vom Entladungsstrom der Lampen durchflossen werden. Analog dazu ist die erste Wicklung 11a des Transformators Tr11 in den dritten Strompfad, in Serie zur Leuchtstofflampe L12 geschaltet, während die zweite Wicklung 11b sowohl in den ersten Strompfad, in Serie zur Leuchtstofflampe L10, als auch in den zweiten Strompfad, in Serie zur Leuchtstofflampe L11, geschaltet ist. Die Wicklung 11a wird daher von dem Entladungsstrom der Leuchtstofflampe L12 durchflossen, während die Wicklung 11b von den Entladungsströmen der Leuchtstofflampen L10 und L11 durchflossen wird. Die Wicklungen 11a, 11b sind gegensinnig angeordnet, so dass sie gegensinnig von den Entladungsströmen bzw. Lampenströmen durchflossen werden. Der erste Transformator Tr10 ist den Leuchtstofflampen L10 bis L12 unmittelbar vorgeschaltet, während der zweite Transformator Tr11 den Leuchtstofflampen L10 bis L12 unmittelbar nachgeschaltet ist. Alle drei Strompfade sind also vollkommen symmetrisch ausgebildet. Die beiden Transformatoren Tr10, Tr11 wirken jeweils als Differenzstromtransformatoren und gewährleisten, dass unabhängig von der Dimmstufe alle drei Lampen gleich hell leuchten.According to the first embodiment of the invention, the ballast is used for Operation of three low-pressure discharge lamps connected in parallel, in particular Fluorescent lamps L10, L11, L12. In Figure 1, the circuit arrangement is this Ballast shown schematically. To the first connection of the resonance capacitor C1 and the first connection of the half-bridge capacitor C2 are three Current branches connected in parallel, each with a low-pressure discharge lamp L10 or L11 or L12 is switched. In addition, this ballast has two transformers Tr10, Tr11, each with two windings 10a, 10b, 11a, 11b. The turns ratio of the windings 10a, 10b of the first transformer Tr10 is 2: 1. The turns ratio of the windings is also the same 11a, 11b of the second transformer Tr11 2: 1. The winding 10a of the transformer Tr10 is connected to the first current path, in series with the L10 fluorescent lamp. The second winding 10b of the transformer Tr10 is both in the second Current path, in series with the fluorescent lamp L11, as well as in the third current path, connected in series to the L12 fluorescent lamp. The winding 10a is therefore from the Discharge current flows through the fluorescent lamp L10 while the winding 1Ob is flowed through by the discharge currents of the fluorescent lamps L11 and L12. The two windings 10a, 10b are wound in opposite directions, so that they are in opposite directions through which the discharge current of the lamps flows. The first is analogous to this Winding 11a of the transformer Tr11 in the third current path, in series to Fluorescent lamp L12 switched while the second winding 11b both in the first current path, in series with the fluorescent lamp L10, as well as in the second current path, in series with the fluorescent lamp L11. The winding 11a is therefore flowed through the discharge current of the fluorescent lamp L12, while the Winding 11b from the discharge currents of the fluorescent lamps L10 and L11 is flowed through. The windings 11a, 11b are arranged in opposite directions, so that the discharge currents or lamp currents flow through them in opposite directions. The first transformer Tr10 is the fluorescent lamps L10 to L12 directly connected upstream, while the second transformer Tr11 the fluorescent lamps L10 to L12 is immediately connected. So all three current paths are perfect symmetrical. The two transformers Tr10, Tr11 each work as differential current transformers and ensure that regardless of the Dimming level all three lamps shine equally brightly.

Gemäß des zweiten Ausführungsbeispiels der Erfindung dient das Vorschaltgerät zum Betrieb von drei parallel geschalteten Niederdruckentladungslampen, insbesondere Leuchtstofflampen L20, L21, L22. 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 drei parallel geschaltete Stromzweige angeschlossen, in die jeweils eine Niederdruckentladungslampe L20 bzw. L21 bzw. L22 geschaltet ist. Außerdem weist dieses Vorschaltgerät einen Transformator Tr2 mit drei identisch aufgebauten und isotrop angeordneten Wicklungen 2a, 2b, 2c auf. In jeden der drei parallel geschalteten Stromzeige ist eine der Leuchtstofflampen L20 bzw. L21 bzw. L22 und in Serie zur Entladungsstrecke der entsprechenden Leuchtstofflampe L20 bzw. L21 bzw. L22 eine der Wicklungen 2a bzw. 2b bzw. 2c geschaltet. Die Wicklungen 2a, 2b, 2c des Transformators Tr2 sind so in dem jeweiligen Stromzweig angeordnet, dass sie gleichsinnig von den Entladungsströmen der Lampen durchflossen werden.According to the second embodiment of the invention, the ballast is used for the operation of three low-pressure discharge lamps connected in parallel, in particular Fluorescent lamps L20, L21, L22. In Figure 2, the circuit arrangement is this Ballast shown schematically. To the first connection of the resonance capacitor C1 and to the first terminal of the half-bridge capacitor C2 three current branches connected in parallel, each with a low-pressure discharge lamp L20 or L21 or L22 is switched. This also points Ballast a transformer Tr2 with three identically constructed and isotropic arranged windings 2a, 2b, 2c. In each of the three connected in parallel Current display is one of the fluorescent lamps L20 or L21 or L22 and in series for Discharge path of the corresponding fluorescent lamp L20 or L21 or L22 one of the windings 2a or 2b or 2c switched. The windings 2a, 2b, 2c of the Transformers Tr2 are arranged in the respective current branch in such a way that they through which the discharge currents of the lamps flow.

Gemäß des dritten Ausführungsbeispiels der Erfindung dient das Vorschaltgerät zum Betrieb von sechs Niederdruckentladungslampen, insbesondere Leuchtstofflampen L30, L31, L32, L33, L34, L35. 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 drei parallel geschaltete Stromzweige angeschlossen, in die jeweils zwei in Serie geschaltete Niederdruckentladungslampen L30 und L31 bzw. L32 und L33 bzw. L34 und L35 geschaltet sind. Das Vorschaltgerät weist ferner einen Transformator Tr30 mit drei identischen und isotrop angeordneten Wicklungen 30a, 30b, 30c auf. In jeden der drei Stromzweige ist eine dieser Wicklungen 30a bzw. 30b bzw. 30c in Serie zu der Serienschaltung der entsprechenden beiden Leuchtstottlampen L30 und L31 bzw. L32 und L33 bzw. L34 und L35 geschaltet, so dass die Wicklungen 30a, 30b, 30c gleichsinnig von den Teilströmen der Stromzweige durchflossen werden. Ferner besitzt das Vorschaltgerät einen zweiten Transformator Tr31 mit zwei gleichartigen Wicklungen 31a, 31b. Die erste Wicklung 31a ist unmittelbar vor der aus den drei Stromzweigen bestehenden Parallelschaltung der Lampen und die zweite Wicklung 31b ist unmittelbar hinter der aus den drei Stromzweigen bestehenden Parallelschaltung der Lampen angeordnet, und zwar so, dass die beiden Wicklungen 31a, 31b gegensinnig von dem Gesamtstom der drei Stromzweige durchflossen werden.According to the third embodiment of the invention, the ballast is used for Operation of six low-pressure discharge lamps, especially fluorescent lamps L30, L31, L32, L33, L34, L35. In Figure 3 is the circuit arrangement of this ballast shown schematically. To the first connection of the resonance capacitor C1 and the first connection of the half-bridge capacitor C2 are three current branches connected in parallel, in each of which two series connected Low pressure discharge lamps L30 and L31 or L32 and L33 or L34 and L35 are switched. The ballast also has a transformer Tr30 three identical and isotropically arranged windings 30a, 30b, 30c. In everyone one of these windings 30a or 30b or 30c is connected in series to the three current branches the series connection of the corresponding two fluorescent lamps L30 and L31 or L32 and L33 or L34 and L35, so that the windings 30a, 30b, 30c are flowed through in the same direction by the partial currents of the current branches. Further the ballast has a second transformer Tr31 with two identical ones Windings 31a, 31b. The first winding 31a is immediately before that of the three Current branches existing parallel connection of the lamps and the second winding 31b is immediately behind the parallel connection consisting of the three current branches of the lamps arranged in such a way that the two windings 31a, 31b the total current of the three current branches flows in opposite directions.

Gemäß des vierten Ausführungsbeispiels der Erfindung dient das Vorschaltgerät zum Betrieb von vier Niederdruckentladungslampen, insbesondere Leuchtstofflampen L40, L41, L42, L43. In Figur 4 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 fourth embodiment of the invention, the ballast is used for Operation of four low-pressure discharge lamps, in particular fluorescent lamps L40, L41, L42, L43. In Figure 4 is the circuit arrangement of this ballast shown schematically. At the first connection of the resonance capacitor C1 and to the first connection of the half-bridge capacitor C2 are two connected in parallel Current branches connected into the two low-pressure discharge lamps connected in series L40 and L41 or L42 and L43 are connected. Moreover the ballast has a transformer Tr40 with two windings 40a, 40b same number of turns. The first winding 40a is in series in the first current branch connected to the series connection of the low-pressure discharge lamps L40 and L41. The second winding 40b is in the second current 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 in such a way that they are in opposite directions of the discharge currents of the lamps or the partial currents in the current branches be flowed through. The transformer Tr40 acts as a differential current transformer and ensures symmetry of the partial flows in the two connected in parallel Current branches. The ballast also 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 immediately after the parallel connection of the two current branches arranged so that the two windings 41a, 41b in opposite directions from the total current of the two current branches connected in parallel. The second Transformer Tr41 also works as a residual current transformer. He enforces symmetrization of the total current immediately before and after the parallel connection of the two branches. The losses from parasitic capacities are thereby compensated so that the lamps L41 and L43 do the same, even with strong dimming shine brightly like the lamps L40 and L42.

Gemäß des fünften Ausführungsbeispiels der Erfindung dient das Vorschaltgerät zum Betrieb von drei Niederdruckentladungslampen, insbesondere Leuchtstofflampen L50, L51, L52. In Figur 5 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 51a ist unmittelbar vor der Parallelschaltung der beiden Stromzweige und die zweite Wicklung 51b 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 fifth embodiment of the invention, the ballast is used for operating three low-pressure discharge lamps, in particular fluorescent lamps L50, L51, L52. In Figure 5 is the circuit arrangement of this ballast shown schematically. At the first connection of the resonance capacitor C1 and to the first connection of the half-bridge capacitor C2 are two connected in parallel Current branches connected. Two are connected in series in the first current branch Fluorescent lamps L50, L51 arranged. In the second branch is only a fluorescent lamp L52 switched. In addition, the ballast has one Transformer Tr50 with two windings 50a, 50b of the same number of turns. The first Winding 50a is in the first branch, in series with the series connection of the low-pressure discharge lamps L50 and L51 switched. The second winding 50b is in the second current branch, connected in series with the low-pressure discharge lamp L52. The two windings 50a, 50b are arranged in the current branches in such a way that they flow in opposite directions from the partial flows in the current branches. The Transformer Tr50 acts as a residual current transformer and ensures one Balancing the partial currents in the two current branches connected in parallel. The ballast also has a second transformer Tr51 with two windings 51a, 51b the same number of turns. The first winding 51a is immediately before the parallel connection of the two current branches and the second winding 51b is immediate arranged after the parallel connection of the two current branches, so that the two windings 51a, 51b in opposite directions from the total current of the two in parallel switched current branches are flowed through. The second transformer Tr51 works also as a differential current transformer. It forces symmetrization of the total current immediately before and after the parallel connection of the two current branches.

Gemäß des sechsten Ausführungsbeispiels der Erfindung dient das Vorschaltgerät zum Betrieb von zwei Niederdruckentladungslampen, insbesondere Leuchtstofflampen L60, L61. In Figur 6 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, 61b 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 sixth embodiment of the invention, the ballast is used for operating two low-pressure discharge lamps, in particular fluorescent lamps L60, L61. In Figure 6, the circuit arrangement of this ballast is schematic displayed. To the first connection of the resonance capacitor C1 and the first connection of the half-bridge capacitor C2 are two connected in parallel Current branches connected, each in a low-pressure discharge lamp L60 or L61 is switched. The ballast also has a transformer Tr60 with two windings 60a, 60b of the same number of turns. The first winding 60a is in the first branch, in series the discharge path of the low-pressure discharge lamp L60 switched. The second winding 60b is in the second current branch, connected in series to the discharge path of the low-pressure discharge lamp L61. The two windings 60a, 60b are arranged in the current branches that they are in opposite directions from the discharge currents of the lamps or the partial currents in flow through the branches. The transformer Tr60 acts as a residual current transformer and ensures a symmetrization of the partial flows in the two current branches connected in parallel. The ballast also has one 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 immediately after the parallel connection two current branches arranged so that the two windings 61a, 61b in opposite directions flowed through by the total current of the two current branches connected in parallel become. The second transformer Tr61 also works as a differential current transformer. It immediately forces a balancing of the total current and behind the parallel connection of the two current branches. The losses from parasitic Capacities are compensated for, so the two ends of the lamps L60 and L61 shine equally bright even with strong dimming.

Gemäß des siebten Ausführungsbeispiels der Erfindung dient das Vorschaltgerät zum Betrieb von zwei in Serie geschalteten Niederdruckentladungslampen, insbesondere Leuchtstofflampen L70, L71. In Figur 7 ist die Schaltungsanordnung dieses Vorschaltgerätes schematisch abgebildet. An den ersten Anschluß des Resonanzkondensators C1 und an den ersten Anschluß des Halbbrückenkondensators C2 ist die Serienschaltung der beiden Leuchtstofflampen L70, L71 angeschlossen. Das Vorschaltgerät besitzt außerdem einen Transformator Tr7 mit zwei Wicklungen 7a, 7b gleicher Windungszahl. Beide Wicklungen 7a, 7b sind in Serie zu der Serienschaltung der Lampen L70, L71 geschaltet, so dass sie gegensinnig von dem Lampenstrom durchflossen werden. Die erste Wicklung 8a ist unmittelbar vor der Serienschaltung der Lampen L70, L71 und die zweite Wicklung 7b unmittelbar hinter der Serienschaltung der Lampen L70, L71 in den Lastkreis des Halbbrückenwechselrichters T1, T2 geschaltet. Der Transformator Tr7 arbeitet als Differenzstromtransformator. Er kompensiert die Verluste durch parasitäre Kapazitäten.According to the seventh embodiment of the invention, the ballast is used for Operation of two low-pressure discharge lamps connected in series, in particular Fluorescent lamps L70, L71. In Figure 7 is the circuit arrangement of this ballast shown schematically. To the first connection of the resonance capacitor C1 and to the first connection of the half-bridge capacitor C2 is the series connection of the two fluorescent lamps L70, L71 connected. The ballast also has a transformer Tr7 with two windings 7a, 7b same number of turns. Both windings 7a, 7b are in series with the series connection the lamps L70, L71 switched so that they are in opposite directions from the lamp current be flowed through. The first winding 8a is immediately before the series connection the lamps L70, L71 and the second winding 7b immediately behind the Series connection of lamps L70, L71 in the load circuit of the half-bridge inverter T1, T2 switched. The transformer Tr7 works as a differential current transformer. It compensates for the losses caused by parasitic capacities.

Gemäß des achten Ausführungsbeispiels der Erfindung dient das Vorschaltgerät zum Betrieb einer Niederdruckentladungslampe, insbesondere Leuchtstofflampe L8. In Figur 8 ist die Schaltungsanordnung dieses Vorschaltgerätes schematisch abgebildet. Die Entladungsstrecke der Lampe L8 ist zwischen dem ersten Anschluß des Resonanzkondensators C1 und an dem ersten Anschluß des Halbbrückenkondensators C2 in den Lastkreis des Halbbrückenwechselrichters geschaltet. Das Vorschaltgerät besitzt außerdem einen Transformator Tr8 mit zwei Wicklungen 8a, 8b gleicher Windungszahl. Beide Wicklungen 8a, 8b sind in Serie zu der Entladungsstrecke der Lampe L8 geschaltet, so dass sie gegensinnig von dem Lampenstrom durchflossen werden. Die erste Wicklung 8a ist unmittelbar vor der Entladungsstrecke der Lampe L8 und die zweite Wicklung 8b unmittelbar hinter der Entladungsstrecke der Lampe L8 in den Lastkreis des Halbbrückenwechselrichters T1, T2 geschaltet. Der Transformator Tr8 arbeitet als Differenzstromtransformator. Er kompensiert die Verluste durch parasitäre Kapazitäten und die gewährleistet dadurch, dass beide Enden der Leuchtstofflampe L8 auch bei starker Dimmung gleich hell leuchten.According to the eighth embodiment of the invention, the ballast is used for Operation of a low-pressure discharge lamp, in particular fluorescent lamp L8. In FIG. 8 shows the circuit arrangement of this ballast schematically. The discharge path of the lamp L8 is between the first connection of the resonance capacitor C1 and at the first terminal of the half-bridge capacitor C2 switched into the load circuit of the half-bridge inverter. The ballast has also a transformer Tr8 with two windings 8a, 8b of the same number of turns. Both windings 8a, 8b are in series with the discharge path of the Lamp L8 switched so that the lamp current flows in opposite directions become. The first winding 8a is immediately before the discharge path of the lamp L8 and the second winding 8b immediately behind the discharge path of the lamp L8 connected to the load circuit of the half-bridge inverter T1, T2. The transformer Tr8 works as a differential current transformer. It compensates for the losses through parasitic capacitance and which ensures that both ends of the Fluorescent lamp L8 shine equally bright even with strong dimming.

Claims (9)

Vorschaltgerät zum Betrieb von mehreren Niederdruckentladungslampen, wobei das Vorschaltgerät drei parallel geschaltete Stromzweige besitzt, in die jeweils elektrische Anschlüsse für mindestens eine Niederdruckentladungslampe (L10, L11, L12) geschaltet sind,
dadurch gekennzeichnet, dass das Vorschaltgerät einen Transformator (Tr10) zur Symmetrierung der Lampenströme aufweist, der Transformator (Tr10) eine erste (10a) und eine zweite Wicklung (lOb) besitzt, wobei die erste Wicklung (10a) doppelt so viele Windungen wie die zweite Wicklung (10b) besitzt, das Vorschaltgerät einen zweiten Transformator (Tr11) zur Symmetrierung der Lampenströme aufweist, wobei der zweite Transformator (Tr11) eine erste (11a) und eine zweite Wicklung (11b) besitzt und die erste Wicklung (11a) doppelt so viele Windungen wie die zweite Wicklung (11b) besitzt, die Wicklungen (10a, 10b, 11a, 11b) der Transformatoren (Tr10, Tr11) derart angeordnet sind, dass bei angeschlossenen Niederdruckentladungslampen (L10, L11, L12), die Lampenströme zuerst durch die Wicklungen (10a, 10b bzw. 11a, 11b) eines der beiden Transformatoren (Tr10 bzw. Tr11), dann durch die Niederdruckentladungslampen (L10, L11, L12) und anschließend erst durch die Wicklungen (11a, 11b bzw. 10a, 10b) des anderen Transformators (Tr11 bzw. Tr10) fließen, die erste Wicklung (10a) des ersten Transformators (Tr10) derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen (L10, L11, L12) von dem Lampenstrom der in den ersten Stromzweig geschalteten Niederdruckentladungslampe (L10) bzw. Niederdruckentladungslampen durchflossen wird, die zweite Wicklung (10b) des ersten Transformators (Tr10) derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen (L10, L11, L12) von den Lampenströmen der in den zweiten und dritten Stromzweig geschalteten Niederdruckentladungslampen (L11, L12) durchflossen wird, wobei die beiden Wicklungen (10a, 10b) des ersten Transformators (Tr10) gegensinnig gewickelt sind, die erste Wicklung (11a) des zweiten Transformators (Tr11) derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen (L10, L11, L12) von dem Lampenstrom der in den dritten Stromzweig geschalteten Niederdruckentladungslampe (L12) bzw. Niederdruckentladungslampen durchflossen wird, die zweite Wicklung (llb) des zweiten Transformators (Tr11) derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen (L10, L11, L12) von den Lampenströmen der in den ersten und zweiten Stromzweig geschalteten Niederdruckentladungslampen (L10, L11) durchflossen wird, wobei die beiden Wicklungen (11a, 11b) des zweiten Transformators (Tr11) gegensinnig gewickelt sind. Ballast for operating a plurality of low-pressure discharge lamps, the ballast having three current branches connected in parallel, in each of which electrical connections for at least one low-pressure discharge lamp (L10, L11, L12) are connected,
characterized in that the ballast has a transformer (Tr10) for balancing the lamp currents, the transformer (Tr10) has a first (10a) and a second winding (10b), the first winding (10a) having twice as many turns as the second winding (10b), the ballast has a second transformer (Tr11) for symmetrizing the lamp currents, the second transformer (Tr11) having a first (11a) and a second winding (11b) and the first winding (11a) twice as many turns as the second winding ( 11b), the windings (10a, 10b, 11a, 11b) of the transformers (Tr10, Tr11) are arranged such that when low-pressure discharge lamps (L10, L11, L12) are connected, the lamp currents first through the windings (10a, 10b or 11a, 11b) one of the two transformers (Tr10 or Tr11), then flow through the low-pressure discharge lamps (L10, L11, L12) and then only through the windings (11a, 11b or 10a, 10b) of the other transformer (Tr11 or Tr10), the first winding (10a) of the first transformer (Tr10) is arranged such that when the low-pressure discharge lamps (L10, L11, L12) are connected, the lamp current of the low-pressure discharge lamp (L10) or low-pressure discharge lamps connected in the first current branch flows through them, the second winding (10b) of the first transformer (Tr10) is arranged such that when the low-pressure discharge lamps (L10, L11, L12) are connected, the lamp currents of the low-pressure discharge lamps (L11, L12) connected in the second and third current branches flow through them, the the two windings (10a, 10b) of the first transformer (Tr10) are wound in opposite directions, the first winding (11a) of the second transformer (Tr11) is arranged such that when the low-pressure discharge lamps (L10, L11, L12) are connected, the lamp current of the low-pressure discharge lamp (L12) or low-pressure discharge lamps connected in the third current branch flows through them, the second winding (11b) of the second transformer (Tr11) is arranged such that when the low-pressure discharge lamps (L10, L11, L12) are connected, the lamp currents of the low-pressure discharge lamps (L10, L11) connected in the first and second current branches flow through, the two windings (11a, 11b) of the second transformer (Tr11) are wound in opposite directions. Vorschaltgerät zum Betrieb von mehreren Niederdruckentladungslampen, wobei das Vorschaltgerät drei parallel geschaltete Stromzweige besitzt, in die jeweils elektrische Anschlüsse für mindestens eine Niederdruckentladungslampe (L20, L21, L22; L30, L31, L32; L33, L34, L35) geschaltet sind,
dadurch gekennzeichnet, dass das Vorschaltgerät einen Transformator (Tr2; Tr30) zur Symmetrierung der Lampenströme aufweist, der Transformator (Tr2; Tr30) drei identisch aufgebaute und isotrop angeordnete Wicklungen (2a, 2b, 2c; 30a, 30b, 30c) besitzt, die jeweils so in einem der Stromzweige angeordnet sind, dass sie gleichsinnig vom Lampenstrom durchflossen werden. Ballast for operating a plurality of low-pressure discharge lamps, the ballast having three current branches connected in parallel, in each of which electrical connections for at least one low-pressure discharge lamp (L20, L21, L22; L30, L31, L32; L33, L34, L35) are connected,
characterized in that the ballast has a transformer (Tr2; Tr30) for balancing the lamp currents, the transformer (Tr2; Tr30) has three identically constructed and isotropically arranged windings (2a, 2b, 2c; 30a, 30b, 30c), which are each arranged in one of the current branches so that the lamp current flows through them in the same direction. Vorschaltgerät nach Anspruch 2, dadurch gekennzeichnet, dass mindestens einer der drei parallel geschalteten Stromzweige elektrische Anschlüsse für eine Serienschaltung von mehreren Niederdruckentladungslampen (L30, L31, L32; L33, L34, L35) aufweist, und das Vorschaltgerät einen zweiten Transformator (Tr31) mit zwei Wicklungen (31a, 31b) gleicher Windungszahl zur Symmetrierung der Lampenströme besitzt, wobei die erste Wicklung (31a) des zweiten Transformators (Tr31) vor der Parallelschaltung der drei Stromzweige und die zweite Wicklung (31b) hinter der Parallelschaltung der drei Stromzweige angeordnet ist, so dass die beiden Wicklungen (31a, 31b) des zweiten Transformators (Tr31) bei angeschlossenen Niederdruckentladungslampen (L30, L31, L32; L33, L34, L35) gegensinnig von dem Gesamstrom der Stromzweige durchflossen werden.Ballast according to Claim 2, characterized in that at least one of the three current branches connected in parallel has electrical connections for a series connection of several low-pressure discharge lamps (L30, L31, L32; L33, L34, L35), and the ballast has a second transformer (Tr31) with two Has windings (31a, 31b) of the same number of turns for symmetrizing the lamp currents, the first winding (31a) of the second transformer (Tr31) before the parallel connection of the three current branches and the second winding (31b) behind the parallel connection of the three current branches, so that the two windings (31a, 31b) of the second transformer (Tr31) with connected low-pressure discharge lamps (L30, L31, L32; L33, L34, L35) flow through in opposite directions from the total current of the current branches. Vorschaltgerät zum Betrieb von mehreren Niederdruckentladungslampen, wobei das Vorschaltgerät einen Transformator (Tr40; Tr50; Tr60) zur Symmetrierung der Lampenströme aufweist, das Vorschaltgerät zwei parallel geschaltete Stromzweige besitzt, in die jeweils elektrische Anschlüsse für mindestens eine Niederdruckentladungslampe (L40-L43; L50-L52; L60, L61) geschaltet sind, der Transformator (Tr40; Tr50; Tr60) eine erste Wicklung (40a; 50a; 60a) besitzt, die in den ersten Stromzweig geschaltet ist, und eine zweite Wicklung (40b; 50b; 60b) gleicher Windungszahl besitzt, die mit entgegengesetztem Wicklungssinn in den zweiten Stromzweig geschaltet ist, dadurch gekennzeichnet, dass das Vorschaltgerät einen zweiten Transformator (Tr41; Tr51; Tr61) zur Symmetrierung der Lampenströme besitzt, der zweite Transformator (Tr41; Tr51; Tr61) eine erste (41a; 51a; 61a) und eine zweite Wicklung (41b; 51b; 61b) gleicher Windungszahl besitzt, wobei die erste Wicklung (41a; 51a; 61a) vor der Parallelschaltung der Stromzweige und die zweite Wicklung (41b; 51b; 61b) hinter der Parallelschaltung der Stromzweige angeordnet ist, und die erste (41a; 51a; 61a) und die zweite Wicklung (41b; 51b; 61b) des zweiten Transformators (Tr41; Tr51; Tr61) derart angeordnet sind, dass sie bei angeschlossenen Niederdruckentladungslampen (L40-L43; L50-L52; L60, L61) gegensinnig von dem Gesamtstrom der Parallelschaltung der Stromzweige durchflossen werden. Ballast for the operation of several low-pressure discharge lamps, wherein the ballast has a transformer (Tr40; Tr50; Tr60) for balancing the lamp currents, the ballast has two current branches connected in parallel, in each of which electrical connections for at least one low-pressure discharge lamp (L40-L43; L50-L52; L60, L61) are connected, the transformer (Tr40; Tr50; Tr60) has a first winding (40a; 50a; 60a) which is connected in the first current branch, and a second winding (40b; 50b; 60b) with the same number of turns, which has an opposite winding direction in the second current branch is switched, characterized in that the ballast has a second transformer (Tr41; Tr51; Tr61) for balancing the lamp currents, the second transformer (Tr41; Tr51; Tr61) has a first (41a; 51a; 61a) and a second winding (41b; 51b; 61b) with the same number of turns, the first winding (41a; 51a; 61a) before the current branches are connected in parallel and the second winding (41b; 51b; 61b) is arranged behind the parallel connection of the current branches, and the first (41a; 51a; 61a) and the second winding (41b; 51b; 61b) of the second transformer (Tr41; Tr51; Tr61) are arranged such that they are connected when the low-pressure discharge lamps (L40-L43; L50-L52; L60, L61) the total current of the parallel connection of the current branches flows through in opposite directions. Vorschaltgerät nach Anspruch 4, dadurch gekennzeichnet, dass der erste und der zweite Stromzweig jeweils elektrische Abschlüsse für zwei in Serie zu schaltende Niederdruckentladungslampen (L40, L41, L42, L43) aufweisen.Ballast according to claim 4, characterized in that the first and the second current branch each have electrical terminations for two series-connected low-pressure discharge lamps (L40, L41, L42, L43). Vorschaltgerät nach Anspruch 4, dadurch gekennzeichnet, dass der erste Stromzweig elektrische Anschlüsse für die Serienschaltung von zwei Niederdruckentladungslampen (L50, L51) und der zweite Stromzweig elektrische Anschlüsse für eine Niederdruckentladungslampe (L52) aufweist.Ballast according to claim 4, characterized in that the first current branch has electrical connections for the series connection of two low-pressure discharge lamps (L50, L51) and the second current branch has electrical connections for a low-pressure discharge lamp (L52). Vorschaltgerät zum Betrieb von einer oder mehreren in Serie geschalteten Niederdruckentladungslampen, wobei das Vorschaltgerät einen Transformator (Tr8; Tr7) mit zwei Wicklungen (8a, 8b; 7a, 7b) gleicher Windungszahl aufweist, und wobei die erste Wicklung (8a; 7a) der Niederdruckentladungslampe (L8) bzw. der Serienschaltung der Niederdruckentladungslampen (L70, L71) unmittelbar vorgeschaltet ist, und die zweite Wicklung (8b; 7b) der Niederdruckentladungslampe (L8) bzw. der Serienschaltung der Niederdruckentladungslampen (L70, L71) unmittelbar nachgeschaltet ist, so dass die Wicklungen des Transformators (Tr8; Tr7) bei angeschlossener Niederdruckentladungslampe (L8) bzw. bei angeschlossenen Niederdruckentladungslampen (L70, L71) gegensinnig vom Lampenstrom durchflossen werden.Ballast for the operation of one or more series connected Low pressure discharge lamps, the ballast being a transformer (Tr8; Tr7) with two windings (8a, 8b; 7a, 7b) with the same number of turns and wherein the first winding (8a; 7a) of the low pressure discharge lamp (L8) or the series connection of the low-pressure discharge lamps (L70, L71) is connected directly upstream, and the second winding (8b; 7b) the low-pressure discharge lamp (L8) or the series connection of the low-pressure discharge lamps (L70, L71) is connected immediately downstream, so that the windings of the transformer (Tr8; Tr7) when the low-pressure discharge lamp is connected (L8) or with connected low pressure discharge lamps (L70, L71) the lamp current flows in opposite directions. Vorschaltgerät nach einem oder mehreren der vorstehenden Ansprüche, dadurch gekennzeichnet, dass das Vorschaltgerät als Wechselrichter (T1, T2) mit einem nachgeschalteten Lastkreis ausgebildet ist, wobei die elektrischen Anschlüsse für die Niederdruckentladungslampen bzw. die Stromzweige mit den elektrischen Anschlüssen für mindestens eine Niederdruckentladungslampe in dem Lastkreis angeordnet sind. 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 electrical connections for the low-pressure discharge lamps or the current branches with the electrical connections for at least one low-pressure discharge lamp in the Load circuit are arranged. Vorschaltgerät nach Anspruch 10, dadurch gekennzeichnet, dass der Wechselrichter als Halbbrückenwechselrichter mit zwei Schalttransistoren (T1, T2) und einem Halbbrückenkondensator (C2) ausgebildet ist, der Lastkreis als Serienresonanzkreis mit einer Resonanzinduktivität (L1) und einem Resonanzkondensator (C1) ausgebildet ist, jeweils ein Anschluß des Resonanzkondensators (C1) und des Halbbrückenkondensators (C2) auf Massepotential liegen, der zweite Anschluß des Resonanzkondensators (C1) über die Resonanzinduktivität (L1) mit dem Mittenabgriff (M1) des Halbbrückenwechselrichters verbunden ist, und die Stromzweige bzw. die Serienschaltung bzw. die elektrischen Anschlüsse für die mindestens eine Niederdruckentladungslampe zwischen den zweiten Anschluß des Resonanzkondensators (C1) und den zweiten Anschluß des Halbbrückenkondensators (C2) geschaltet sind. Ballast according to claim 10, characterized in that the inverter is designed as a half-bridge inverter with two switching transistors (T1, T2) and a half-bridge capacitor (C2), the load circuit is designed as a series resonance circuit with a resonance inductance (L1) and a resonance capacitor (C1), one connection each of the resonance capacitor (C1) and the half-bridge capacitor (C2) are at ground potential, the second connection of the resonance capacitor (C1) is connected to the center tap (M1) of the half-bridge inverter via the resonance inductance (L1), and the current branches or the series circuit or the electrical connections for the at least one low-pressure discharge lamp are connected between the second connection of the resonance capacitor (C1) and the second connection of the half-bridge capacitor (C2).
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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US6717371B2 (en) 2004-04-06
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EP1915036A1 (en) 2008-04-23
US20030015974A1 (en) 2003-01-23
ATE413086T1 (en) 2008-11-15
EP1286572A3 (en) 2005-01-19
EP1286572B1 (en) 2008-10-29
ATE459232T1 (en) 2010-03-15
EP1915036B1 (en) 2010-02-24
DE50212951D1 (en) 2008-12-11

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