EP1765043A2 - Method and apparatus to balance the potential at lamp terminals - Google Patents

Method and apparatus to balance the potential at lamp terminals Download PDF

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Publication number
EP1765043A2
EP1765043A2 EP06012556A EP06012556A EP1765043A2 EP 1765043 A2 EP1765043 A2 EP 1765043A2 EP 06012556 A EP06012556 A EP 06012556A EP 06012556 A EP06012556 A EP 06012556A EP 1765043 A2 EP1765043 A2 EP 1765043A2
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EP
European Patent Office
Prior art keywords
lamp
potential
converter
pressure discharge
low
Prior art date
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Granted
Application number
EP06012556A
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German (de)
French (fr)
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EP1765043B1 (en
EP1765043A3 (en
Inventor
Olaf Busse
Markus Heckmann
Reinhard Lecheler
Alfons Lechner
Siegfried Mayer
Thomas Pollischansky
Bernd Rudolph
Bernhard Schemmel
Kay Dr. Schmidtmann
Harald Schmitt
Thomas Dr. Siegmund
Arwed Storm
Horst Werni
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Osram GmbH
Original Assignee
Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
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Publication of EP1765043A3 publication Critical patent/EP1765043A3/en
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Publication of EP1765043B1 publication Critical patent/EP1765043B1/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
    • H05B41/295—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 and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps
    • H05B41/298—Arrangements for protecting lamps or circuits against abnormal operating conditions
    • H05B41/2981—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the circuit against abnormal operating conditions
    • 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 present invention relates to an electronic ballast with a converter and lamp terminals for operating a low-pressure discharge lamp.
  • Electronic ballasts for operating low-pressure discharge lamps are known in many designs. They usually contain a converter that operates the low-pressure discharge lamp. Basically, a converter from a rectified AC power supply or a DC power supply generates a power supply for the high-frequency power lamp to be operated.
  • a converter can be realized as a half-bridge circuit.
  • two counter-switching high-frequency switching series-connected switching elements are connected to a DC voltage supply.
  • a high-frequency usable to supply the low-pressure discharge lamp AC voltage as an output voltage.
  • lamp terminals via which the low-pressure discharge lamp connected to the converter or the electronic ballast is, between the AC output of the converter and one of the supply potentials of the converter.
  • the invention is based on the technical problem of providing an improved electronic ballast for low-pressure discharge lamps with regard to safety.
  • the invention relates to an electronic ballast for operating a low-pressure discharge lamp with a converter having a switching element and an AC output to the AC power supply of the low-pressure discharge lamp, and lamp terminals, via which the low-pressure discharge lamp between the AC output and one of the supply potentials of the converter can be switched, characterized in that the AC output side lamp terminal is electrically isolated from the AC output of the converter by means of a separation capacitor, and the lamp terminal connected to the one of the supply potentials of the converter is galvanically isolated from said supply potential by means of a separation capacitor so that the converter and the low pressure discharge lamp are AC coupled.
  • the invention is based on the recognition that low-pressure discharge lamps can be operated via high-frequency alternating current and thus no direct current component must be present. It follows that with regard to the operation of the low-pressure discharge lamp, the lamp terminals can be galvanically - Gleichstromhold - separated from the converter.
  • the AC output side lamp terminal is electrically isolated from the AC output of the converter by means of a separation capacitor.
  • the supply potential-side lamp terminal is also electrically isolated from the corresponding supply potential by means of a further separation capacitor.
  • At least one of the lamp terminals possibly via a resistor, connected to a definition potential.
  • the definition potential determines the time-averaged potential at the lamp terminals.
  • the time-averaged potentials at the two lamp terminals cancel each other out and can thus assume the same value. Therefore, during operation of a low-pressure discharge lamp, it does not matter to which lamp terminal the definition potential is connected.
  • the definition potential By means of the definition potential, the temporally averaged potential at the lamp terminals can thus be set.
  • the definition potential is between the two Supply potential lines of the converter connected a series circuit of two high-impedance resistors.
  • the potential at the connection node between these two resistors forms the definition potential.
  • the voltage divider has high-impedance resistors so that it does not represent a low-ohmic current path between the supply potentials of the converter. With this voltage divider circuit, the definition potential, depending on the dimensioning of the two resistors, can assume values between the values of the two supply potentials of the converter.
  • the reference potential of an electronic ballast is not identical in many designs with the ground potential; it can have a temporally variable as well as a constant potential difference with respect to this.
  • the time-varying proportion of the potential difference is characterized by the rectification and filtering of the mains supply and ballast internal switching operations.
  • the temporally constant proportion of the potential difference between the reference potential of the electronic ballast and the ground potential can also be considerable.
  • the ground potential itself is chosen as the definition potential.
  • One of the two lamp connections is connected to the earth potential with high resistance.
  • both lamp terminals are connected to the definition potential, that the two lamp terminals are connected to each other with high impedance. Since both lamp terminals are connected to the definition potential, the same potential is present at both lamp terminals, even if no low-pressure discharge lamp is connected, or such is not in operation.
  • the definition potential is set so that the time average potential of the lamp terminals corresponds approximately to the ground potential. This improves the contact safety at the lamp terminals.
  • Figure 1 shows a part of the circuit structure of a first electronic ballast according to the invention.
  • Parallel to the switching elements S1 and S2 of the converter is connected to the supply potentials N and P voltage divider circuit of two resistors R1 and R2.
  • the connection node between these two resistors R1 and R2 sets a definition potential DP.
  • the definition potential DP is connected to the lamp terminal KL1, possibly via a resistor, not shown here.
  • the reference potential N of an electronic ballast can have a temporally mean potential difference with respect to the ground potential GND, in particular with electronic ballasts of the protection class II, which do not have their own ground terminal GND.
  • the lamp terminals KL1 and KL2 are galvanically isolated from the converter S1, S2.
  • the time averaged potential of the lamp terminals is set via the definition potential DP.
  • the two resistors R1 and R2 of the voltage divider are designed very high impedance, so that no current flows from the voltage divider to the lamp terminals KL1, KL2.
  • the definition potential DP can assume values which lie between the supply potential N and the supply potential P of the converter S1, S2.
  • the definition potential DP is set via the dimensioning of the resistors R1, R2 so that the potential difference between the lamp terminals and the ground potential GND is as small as possible, or this corresponds to the time average.
  • Figure 2 shows a part of the circuit structure of a second electronic ballast according to the invention.
  • FIG. 1 shows a series connection of the lamp inductor L1, the separation capacitor C1, the lamp terminals KL1 and KL2 of the low-pressure discharge lamp LA and the separation capacitor C2.
  • the resonant capacitor CR is connected in parallel with the lamp LA.
  • the lamp terminals KL1, KL2 are both connected to the definition potential DP, but in such a way that only one high-impedance current path is formed in parallel to the lamp LA.
  • FIG. 2 shows a corresponding resistor R3.
  • FIG. 3 shows a third exemplary embodiment according to the invention, specifically the series connection of the lamp inductor L1, the separation capacitor C1, the two lamp terminals KL1, KL2 with the low-pressure discharge lamp LA and the separation capacitor C2. Parallel to the lamp LA, the resonance capacitor CR is switched again.
  • the definition potential DP is now not determined via the voltage divider R1, R2, but instead one of the lamp terminals KL1, KL2 is connected to the ground potential GND in a high-impedance manner via a resistor R4.
  • the ground potential GND here corresponds to the definition potential DP.

Abstract

Electronic ballast has alternating current output side (M) lamp connection (KL1) which is galvanically separated from alternating current output of converter (S1,S2) by means of isolation capacitor (C1). Lamp connection (KL2) is attached to one of the supply unit potentials (N,P) of the converter is galvanically separated from the supply unit potential by means of an isolation capacitor (C2). The converter and the low pressure discharge lamp (LA) are coupled in alternating current manner. Independent claims are also included for the following: (A) Kit of an electronic ballast; and (B) Method for operation electronic ballast.

Description

Technisches GebietTechnical area

Die vorliegende Erfindung bezieht sich auf ein elektronisches Vorschaltgerät mit einem Wandler und Lampenanschlüssen zum Betrieb einer Niederdruckentladungslampe.The present invention relates to an electronic ballast with a converter and lamp terminals for operating a low-pressure discharge lamp.

Stand der TechnikState of the art

Elektronische Vorschaltgeräte zum Betrieb von Niederdruckentladungslampen sind in vielfältigen Ausführungen bekannt. In der Regel enthalten sie einen Wandler, der die Niederdruckentladungslampe betreibt. Grundsätzlich erzeugt ein Wandler aus einer gleichgerichteten Wechselspannungsversorgung oder einer Gleichspannungsversorgung eine Versorgungsleistung für die mit hochfrequentem Strom zu betreibende Lampe.Electronic ballasts for operating low-pressure discharge lamps are known in many designs. They usually contain a converter that operates the low-pressure discharge lamp. Basically, a converter from a rectified AC power supply or a DC power supply generates a power supply for the high-frequency power lamp to be operated.

Ein Wandler kann als Halbbrückenschaltung realisiert sein. Dabei sind zwei gegensinnig hochfrequent schaltende in Serie geschaltete Schaltelemente an eine Gleichspannungsversorgung angeschlossen. Zwischen einem der Versorgungspotentiale des Wandlers und dem Verbindungsknoten zwischen den Schaltelementen des Wandlers liegt eine hochfrequente, zur Versorgung der Niederdruckentladungslampe nutzbare Wechselspannung als Ausgangsspannung.A converter can be realized as a half-bridge circuit. In this case, two counter-switching high-frequency switching series-connected switching elements are connected to a DC voltage supply. Between one of the supply potentials of the converter and the connection node between the switching elements of the converter is a high-frequency, usable to supply the low-pressure discharge lamp AC voltage as an output voltage.

Üblicherweise liegen Lampenanschlüsse, über welche die Niederdruckentladungslampe an den Wandler bzw. das elektronische Vorschaltgerät angeschlossen ist, zwischen dem Wechselstromausgang des Wandlers und einem der Versorgungspotentiale des Wandlers.Usually there are lamp terminals, via which the low-pressure discharge lamp connected to the converter or the electronic ballast is, between the AC output of the converter and one of the supply potentials of the converter.

Darstellung der ErfindungPresentation of the invention

Der Erfindung liegt das technische Problem zugrunde, ein im Hinblick auf die Sicherheit verbessertes elektronisches Vorschaltgerät für Niederdruckentladungslampen anzugeben.The invention is based on the technical problem of providing an improved electronic ballast for low-pressure discharge lamps with regard to safety.

Die Erfindung betrifft ein elektronisches Vorschaltgerät zum Betrieb einer Niederdruckentladungslampe mit einem Wandler, der ein Schaltelement und einen Wechselstromausgang zur Wechselstromversorgung der Niederdruckentladungslampe aufweist, und Lampenanschlüssen, über die die Niederdruckentladungslampe zwischen den Wechselstromausgang und eines der Versorgungspotentiale des Wandlers geschaltet werden kann, dadurch gekennzeichnet, dass der wechselstromausgangsseitige Lampenanschluss mittels eines Trennungskondensators von dem Wechselstromausgang des Wandlers galvanisch getrennt ist und der an das eine der Versorgungspotentiale des Wandlers angeschlossene Lampenanschluss mittels eines Trennungskondensators von diesem Versorgungspotential galvanisch getrennt ist, so dass der Wandler und die Niederdruckentladungslampe wechselstrommäßig gekoppelt sind.The invention relates to an electronic ballast for operating a low-pressure discharge lamp with a converter having a switching element and an AC output to the AC power supply of the low-pressure discharge lamp, and lamp terminals, via which the low-pressure discharge lamp between the AC output and one of the supply potentials of the converter can be switched, characterized in that the AC output side lamp terminal is electrically isolated from the AC output of the converter by means of a separation capacitor, and the lamp terminal connected to the one of the supply potentials of the converter is galvanically isolated from said supply potential by means of a separation capacitor so that the converter and the low pressure discharge lamp are AC coupled.

Bevorzugte Ausgestaltungen der Erfindung sind in den abhängigen Ansprüchen angegeben und werden im Folgenden näher erläutert. Die Offenbarung bezieht sich dabei stets sowohl auf die Verfahrenskategorie, als auch die Vorrichtungskategorie der Erfindung.Preferred embodiments of the invention are specified in the dependent claims and are explained in more detail below. The disclosure always refers to both the process category and the device category of the invention.

Die Erfindung beruht auf der Erkenntnis, dass Niederdruckentladungslampen über hochfrequenten Wechselstrom betrieben werden können und damit kein Gleichstromanteil vorhanden sein muss. Daraus folgt, dass bezüglich des Betriebs der Niederdruckentladungslampe die Lampenanschlüsse galvanisch - gleichstrommäßig - vom Wandler getrennt sein können.The invention is based on the recognition that low-pressure discharge lamps can be operated via high-frequency alternating current and thus no direct current component must be present. It follows that with regard to the operation of the low-pressure discharge lamp, the lamp terminals can be galvanically - Gleichstrommäßig - separated from the converter.

Bei der Erfindung wird der wechselstromausgangseitige Lampenanschluss mittels eines Trennungskondensators von dem Wechselstromausgang des Wandlers galvanisch getrennt. Auch der versorgungspotentialseitige Lampenanschluss wird mittels eines weiteren Trennungskondensators von dem entsprechenden Versorgungspotential galvanisch getrennt. Damit ist eine an die Lampenanschlüsse angeschlossene Niederdruckentladungslampe nur noch wechselstrommäßig mit dem Wandler gekoppelt. Dank der galvanischen Entkopplung der Lampenanschlüsse von dem Wandler sind die zeitlich gemittelten Lampenanschlusspotentiale nicht mehr durch die zeitlich gemittelten Potentiale im Wandler bestimmt.In the invention, the AC output side lamp terminal is electrically isolated from the AC output of the converter by means of a separation capacitor. The supply potential-side lamp terminal is also electrically isolated from the corresponding supply potential by means of a further separation capacitor. Thus, a low-pressure discharge lamp connected to the lamp terminals is only coupled to the converter with alternating current. Thanks to the galvanic decoupling of the lamp terminals of the converter, the time averaged lamp terminal potentials are no longer determined by the time averaged potentials in the converter.

So ist es möglich, dass eventuell vorhandene große Potentialdifferenzen zwischen Teilen des elektronischen Vorschaltgerätes und dem Erdpotential nicht an den Lampenanschlüssen anliegen. Obwohl die Lampenanschlüsse von dem Wandler galvanisch getrennt sind, treten während des Betriebes einer Niederdruckentladungslampe ferner keine großen statischen Ladungen an den Lampenanschlüssen auf, weil diese statischen Ladungen durch den Stromfluss durch die Lampe ausgeglichen werden. Somit ist die Berührsicherheit verbessert.So it is possible that any existing large potential differences between parts of the electronic ballast and the ground potential are not applied to the lamp terminals. Further, while the lamp terminals are galvanically isolated from the transducer, during operation of a low pressure discharge lamp, there are no large static charges on the lamp terminals because these static charges are balanced by current flow through the lamp. Thus, the touch safety is improved.

Vorzugsweise ist zumindest einer der Lampenanschlüsse, evtl. über einen Widerstand, an ein Definitionspotential angeschlossen. Über das Definitionspotential wird das zeitlich gemittelte Potential an den Lampenanschlüssen festgelegt. Durch den Wechselstrombetrieb der Niederdruckentladungslampe gleichen sich die zeitlich gemittelten Potentiale an den beiden Lampenanschlüssen aus und können so den gleichen Wert annehmen. Daher spielt es während des Betriebes einer Niederdruckentladungslampe keine Rolle, an welchen Lampenanschluss das Definitionspotential geschaltet ist. Mittels des Definitionspotentials kann also das zeitlich gemittelte Potential an den Lampenanschlüssen eingestellt werden.Preferably, at least one of the lamp terminals, possibly via a resistor, connected to a definition potential. The definition potential determines the time-averaged potential at the lamp terminals. As a result of the alternating current operation of the low-pressure discharge lamp, the time-averaged potentials at the two lamp terminals cancel each other out and can thus assume the same value. Therefore, during operation of a low-pressure discharge lamp, it does not matter to which lamp terminal the definition potential is connected. By means of the definition potential, the temporally averaged potential at the lamp terminals can thus be set.

Es gibt verschiedene Möglichkeiten, das Definitionspotential festzulegen. Bei einer bevorzugten Ausführungsform der Erfindung wird zwischen die beiden Versorgungspotentialleitungen des Wandlers eine Serienschaltung aus zwei hochohmigen Widerständen geschaltet. Das Potential am Verbindungsknoten zwischen diesen beiden Widerständen bildet das Definitionspotential. Der Spannungsteiler weist hochohmige Widerstände auf, damit er keinen nieder-ohmigen Strompfad zwischen den Versorgungspotentialen des Wandlers darstellt. Mit dieser Spannungsteilerschaltung kann das Definitionspotential, je nach Dimensionierung der beiden Widerstände, Werte zwischen den Werten der beiden Versorgungspotentiale des Wandlers annehmen.There are several ways to set the definition potential. In a preferred embodiment of the invention is between the two Supply potential lines of the converter connected a series circuit of two high-impedance resistors. The potential at the connection node between these two resistors forms the definition potential. The voltage divider has high-impedance resistors so that it does not represent a low-ohmic current path between the supply potentials of the converter. With this voltage divider circuit, the definition potential, depending on the dimensioning of the two resistors, can assume values between the values of the two supply potentials of the converter.

Das Bezugspotential eines elektronischen Vorschaltgerätes ist in vielen Bauformen nicht identisch mit dem Erdpotential; es kann gegenüber diesem sowohl einen zeitlich veränderlichen, als auch einen konstanten Potentialunterschied aufweisen. Der zeitlich veränderliche Anteil des Potentialunterschiedes ist geprägt durch die Gleichrichtung und Filterung der Netzversorgung und vorschaltgerätinterne Schaltvorgänge. Der zeitlich konstante Anteil des Potentialunterschiedes zwischen dem Bezugspotential des elektronischen Vorschaltgerätes und dem Erdpotential kann ebenfalls beträchtlich sein. Mittels des oben beschriebenen Spannungsteilers kann das Definitionspotential im zeitlichen Mittel so eingestellt werden, dass das Lampenanschlusspotential in etwa im zeitlichen Mittel dem Erdpotential entspricht. Mit verringerter mittlerer Spannung zwischen den Lampenanschlüssen und dem Erdpotential ist die Berührsicherheit verbessert.The reference potential of an electronic ballast is not identical in many designs with the ground potential; it can have a temporally variable as well as a constant potential difference with respect to this. The time-varying proportion of the potential difference is characterized by the rectification and filtering of the mains supply and ballast internal switching operations. The temporally constant proportion of the potential difference between the reference potential of the electronic ballast and the ground potential can also be considerable. By means of the voltage divider described above, the definition potential can be adjusted in the time average so that the lamp terminal potential corresponds approximately to the earth potential in the time average. With reduced mean voltage between the lamp terminals and ground potential, the touch safety is improved.

Bei einer alternativen bevorzugten Ausführungsform der Erfindung wird als Definitionspotential das Erdpotential selbst gewählt. Dabei ist einer der beiden Lampenanschlüsse hochohmig mit dem Erdpotential verbunden.In an alternative preferred embodiment of the invention, the ground potential itself is chosen as the definition potential. One of the two lamp connections is connected to the earth potential with high resistance.

Bei einer weiteren bevorzugten Ausführungsform der Erfindung werden beide Lampenanschlüsse so an das Definitionspotential angeschlossen, dass die beiden Lampenanschlüsse hochohmig miteinander verbunden sind. Dadurch, dass beide Lampenanschlüsse an das Definitionspotential angeschlossen sind, liegt an beiden Lampenanschlüssen das gleiche Potential an, auch wenn keine Niederdruckentladungslampe angeschlossen ist, bzw. eine solche nicht im Betrieb ist.In a further preferred embodiment of the invention, both lamp terminals are connected to the definition potential, that the two lamp terminals are connected to each other with high impedance. Since both lamp terminals are connected to the definition potential, the same potential is present at both lamp terminals, even if no low-pressure discharge lamp is connected, or such is not in operation.

Vorzugsweise ist das Definitionspotential so eingestellt, dass das zeitlich mittlere Potential der Lampenanschlüsse in etwa dem Erdpotential entspricht. Damit ist die Berührsicherheit an den Lampenanschlüssen verbessert.Preferably, the definition potential is set so that the time average potential of the lamp terminals corresponds approximately to the ground potential. This improves the contact safety at the lamp terminals.

Kurze Beschreibung der ZeichnungenBrief description of the drawings

Im Folgenden soll die Erfindung anhand von Ausführungsbeispielen näher erläutert werden. Die dabei offenbarten Einzelmerkmale können auch in anderen Kombinationen erfindungswesentlich sein. Die vorstehende und die folgende Beschreibung beziehen sich auf die Vorrichtungskategorie und die Verfahrenskategorie der Erfindung, ohne dass dies im Einzelnen noch explizit erwähnt wird.

Figur 1
zeigt einen Teil des Schaltungsaufbaus eines ersten erfindungsgemäßen elektronischen Vorschaltgerätes.
Figur 2
zeigt einen Teil des Schaltungsaufbaus eines zweiten erfindungsgemäßen elektronischen Vorschaltgerätes.
Figur 3
zeigt einen Teil des Schaltungsaufbaus eines dritten erfindungsgemäßen elektronischen Vorschaltgerätes.
In the following, the invention will be explained in more detail with reference to exemplary embodiments. The individual features disclosed may also be essential to the invention in other combinations. The above and following description refers to the device category and the method category of the invention, although not explicitly mentioned in detail.
FIG. 1
shows a part of the circuit structure of a first electronic ballast according to the invention.
FIG. 2
shows a part of the circuit structure of a second electronic ballast according to the invention.
FIG. 3
shows a part of the circuit structure of a third electronic ballast according to the invention.

Bevorzugte Ausführung der ErfindungPreferred embodiment of the invention

Figur 1 zeigt einen Teil des Schaltungsaufbaus eines ersten erfindungsgemäßen elektronischen Vorschaltgerätes.Figure 1 shows a part of the circuit structure of a first electronic ballast according to the invention.

Zwischen zwei Versorgungspotentiale N, P sind zwei eine Halbbrücke bildende Schaltelemente S1 und S2, beispielsweise MOSFETs, in Serie geschaltet. Der Verbindungsknoten zwischen den beiden Schaltelementen S1 und S2 entspricht einem Wechselstromausgang M. Zwischen den Wechselstromausgang M und das Versorgungspotential N des Wandlers sind Lampenanschlüsse KL1 und KL2 geschaltet. An den Lampenanschlüssen KL1 und KL2 ist eine Niederdruckentladungslampe LA angeschlossen. Parallel zu dieser Lampe LA ist ein Resonanzkondensator CR geschaltet. Dem wechselstromausgangsseitigen Lampenanschluss KL1 ist ein Trennungskondensator C1 vorgeschaltet, und dem versorgungspotentialseitigen Anschluss KL2 ist ein Trennungskondensator C2 nachgeschaltet. Zwischen den Wechselstromausgang M und den Trennungskondensator C1 ist eine Lampendrossel L1 geschaltet. Parallel zu den Schaltelementen S1 und S2 des Wandlers liegt eine an den Versorgungspotentialen N und P angeschlossene Spannungsteilerschaltung aus zwei Widerständen R1 und R2. Der Verbindungsknoten zwischen diesen beiden Widerständen R1 und R2 legt ein Definitionspotential DP fest. Das Definitionspotential DP ist mit dem Lampenanschluss KL1, evtl. über einen hier nicht gezeigten Widerstand, verbunden.Between two supply potentials N, P are two half-bridge forming switching elements S1 and S2, for example MOSFETs, connected in series. The connection node between the two switching elements S1 and S2 corresponds to an AC output M. Between the AC output M and the supply potential N of the converter are switched lamp terminals KL1 and KL2. At the lamp terminals KL1 and KL2 a low-pressure discharge lamp LA is connected. Parallel to this lamp LA, a resonance capacitor CR is connected. The AC output-side lamp terminal KL1 is preceded by a separation capacitor C1, and the supply potential-side terminal KL2 is followed by a separation capacitor C2. Between the AC output M and the separation capacitor C1, a lamp inductor L1 is connected. Parallel to the switching elements S1 and S2 of the converter is connected to the supply potentials N and P voltage divider circuit of two resistors R1 and R2. The connection node between these two resistors R1 and R2 sets a definition potential DP. The definition potential DP is connected to the lamp terminal KL1, possibly via a resistor, not shown here.

Das Bezugspotential N eines elektronischen Vorschaltgerätes kann gegenüber dem Erdpotential GND einen zeitlich mittleren Potentialunterschied aufweisen, insbesondere bei elektronischen Vorschaltgeräten der Schutzklasse II, welche nicht über einen eigenen Erdanschluss GND verfügen.The reference potential N of an electronic ballast can have a temporally mean potential difference with respect to the ground potential GND, in particular with electronic ballasts of the protection class II, which do not have their own ground terminal GND.

Mittels der beiden Trennungskondensatoren C1 und C2 sind die Lampenanschlüsse KL1 und KL2 galvanisch von dem Wandler S1, S2 getrennt. Das zeitlich gemittelte Potential der Lampenanschlüsse wird über das Definitionspotential DP festgelegt. Die beiden Widerstände R1 und R2 des Spannungsteilers sind sehr hochohmig ausgelegt, so dass kein Strom vom Spannungsteiler zu den Lampenanschlüssen KL1, KL2 fließt. Je nach Dimensionierung der beiden Widerstände R1 und R2 kann das Definitionspotential DP Werte annehmen, welche zwischen dem Versorgungspotential N und dem Versorgungspotential P des Wandlers S1, S2 liegen. Das Definitionspotential DP wird über die Dimensionierung der Widerstände R1, R2 so eingestellt, dass die Potentialdifferenz zwischen den Lampenanschlüssen und dem Erdpotential GND möglichst klein ist, bzw. diesem im zeitlichen Mittel entspricht.By means of the two separation capacitors C1 and C2, the lamp terminals KL1 and KL2 are galvanically isolated from the converter S1, S2. The time averaged potential of the lamp terminals is set via the definition potential DP. The two resistors R1 and R2 of the voltage divider are designed very high impedance, so that no current flows from the voltage divider to the lamp terminals KL1, KL2. Depending on the dimensioning of the two resistors R1 and R2, the definition potential DP can assume values which lie between the supply potential N and the supply potential P of the converter S1, S2. The definition potential DP is set via the dimensioning of the resistors R1, R2 so that the potential difference between the lamp terminals and the ground potential GND is as small as possible, or this corresponds to the time average.

Figur 2 zeigt einen Teil des Schaltungsaufbaus eines zweiten erfindungsgemäßen elektronischen Vorschaltgerätes.Figure 2 shows a part of the circuit structure of a second electronic ballast according to the invention.

Wie in Figur 1 liegt hier eine Serienschaltung aus der Lampendrossel L1, dem Trennungskondensator C1, den Lampenanschlüssen KL1 und KL2 der Niederdruckentladungslampe LA und dem Trennungskondensator C2 vor. Wie in Figur 1 ist der Lampe LA der Resonanzkondensator CR parallel geschaltet. Anders als in Figur 1 sind jedoch die Lampenanschlüsse KL1, KL2 beide an das Definitionspotential DP angeschlossen, allerdings so, dass parallel zu der Lampe LA nur ein hochohmiger Strompfad entsteht. In Figur 2 ist ein entsprechender Widerstand R3 eingezeichnet. Durch diese in Figur 2 gezeigte Schaltungsanordnung werden die Potentiale der Lampenanschlüsse auch dann durch das Definitionspotential DP festgelegt, wenn keine Lampe angeschlossen ist, bzw. die Lampe LA nicht in Betrieb ist. Somit ist die Berührsicherheit auch dann verbessert.As in FIG. 1, a series connection of the lamp inductor L1, the separation capacitor C1, the lamp terminals KL1 and KL2 of the low-pressure discharge lamp LA and the separation capacitor C2 is present here. As in FIG. 1, the resonant capacitor CR is connected in parallel with the lamp LA. Unlike in FIG. 1, however, the lamp terminals KL1, KL2 are both connected to the definition potential DP, but in such a way that only one high-impedance current path is formed in parallel to the lamp LA. FIG. 2 shows a corresponding resistor R3. By means of this circuit arrangement shown in FIG. 2, the potentials of the lamp terminals are also defined by the definition potential DP when no lamp is connected, or the lamp LA is not in operation. Thus, the touch safety is improved.

Figur 3 zeigt ein drittes erfindungsgemäßes Ausführungsbeispiel, und zwar wieder die Serienschaltung aus der Lampendrossel L1, dem Trennungskondensator C1, den beiden Lampenanschlüssen KL1, KL2 mit der Niederdruckentladungslampe LA und dem Trennungskondensator C2. Parallel zu der Lampe LA ist wieder der Resonanzkondensator CR geschaltet. Anders als in den Figuren 1 und 2 wird nun allerdings das Definitionspotential DP nicht über den Spannungsteiler R1, R2 festgelegt, vielmehr ist einer der Lampenanschlüsse KL1, KL2 hochohmig über einen Widerstand R4 an das Erdpotential GND angeschlossen. Damit entspricht das Erdpotential GND hier dem Definitionspotential DP.FIG. 3 shows a third exemplary embodiment according to the invention, specifically the series connection of the lamp inductor L1, the separation capacitor C1, the two lamp terminals KL1, KL2 with the low-pressure discharge lamp LA and the separation capacitor C2. Parallel to the lamp LA, the resonance capacitor CR is switched again. Unlike in FIGS. 1 and 2, however, the definition potential DP is now not determined via the voltage divider R1, R2, but instead one of the lamp terminals KL1, KL2 is connected to the ground potential GND in a high-impedance manner via a resistor R4. Thus, the ground potential GND here corresponds to the definition potential DP.

Claims (9)

Elektronisches Vorschaltgerät zum Betrieb einer Niederdruckentladungslampe (LA) mit: • einem Wandler (S1, S2), der ein Schaltelement (S1, S2) und einen Wechselstromausgang (M) zur Wechselstromversorgung der Niederdruckentladungslampe (LA) aufweist, und • Lampenanschlüssen (KL1, KL2), über die die Niederdruckentladungslampe (LA) zwischen den Wechselstromausgang (M) und eines der Versorgungspotentiale (N, P) des Wandlers geschaltet werden kann, dadurch gekennzeichnet, dass
der wechselstromausgangsseitige (M) Lampenanschluss (KL1) mittels eines Trennungskondensators (C1) von dem Wechselstromausgang (M) des Wandlers (S1, S2) galvanisch getrennt ist und der an das eine der Versorgungspotentiale (N, P) des Wandlers angeschlossene Lampenanschluss (KL2) mittels eines Trennungskondensators (C2) von diesem Versorgungspotential (N, P) galvanisch getrennt ist, so dass der Wandler (S1, S2) und die Niederdruckentladungslampe (LA) wechselstrommäßig gekoppelt sind.Electronic ballast for operating a low-pressure discharge lamp (LA) with: A converter (S1, S2) having a switching element (S1, S2) and an AC output (M) for AC power supply of the low-pressure discharge lamp (LA), and • lamp connections (KL1, KL2), via which the low-pressure discharge lamp (LA) can be switched between the AC output (M) and one of the supply potentials (N, P) of the converter, characterized in that
the AC output side (M) lamp terminal (KL1) is electrically isolated from the AC output (M) of the converter (S1, S2) by means of a separation capacitor (C1) and the lamp terminal (KL2) connected to one of the supply potentials (N, P) of the converter is electrically isolated from this supply potential (N, P) by means of a separation capacitor (C2), so that the converter (S1, S2) and the low-pressure discharge lamp (LA) are AC-coupled. Elektronisches Vorschaltgerät nach Anspruch 1, bei dem zumindest einer der Lampenanschlüsse (KL1, KL2) an ein Definitionspotential (DP, GND) zur Definition der Lampenanschlusspotentiale (KL1, KL2) angeschlossen ist.Electronic ballast according to claim 1, wherein at least one of the lamp terminals (KL1, KL2) is connected to a definition potential (DP, GND) for defining the lamp terminal potentials (KL1, KL2). Elektronisches Vorschaltgerät nach Anspruch 2, bei dem das Definitionspotential (DP, GND) über einen Spannungsteiler (R1, R2) festgelegt ist, welcher zwischen die Versorgungspotentialleitungen (N, P) des Wandlers (S1, S2) geschaltet ist.Electronic ballast according to claim 2, wherein the definition potential (DP, GND) is determined via a voltage divider (R1, R2) is, which is connected between the supply potential lines (N, P) of the converter (S1, S2). Elektronisches Vorschaltgerät nach Anspruch 2, bei dem zumindest einer der Lampenanschlüsse (KL1, KL2) hochohmig (R4) mit dem Erdpotential (GND) als Definitionspotential (DP) verbunden ist.Electronic ballast according to claim 2, wherein at least one of the lamp terminals (KL1, KL2) is connected to high impedance (R4) to the ground potential (GND) as a definition potential (DP). Elektronisches Vorschaltgerät nach Anspruch 2, 3 oder 4, bei dem beide Lampenanschlüsse (KL1, KL2) so an das Definitionspotential (DP, GND) angeschlossen sind, dass die beiden Lampenanschlüsse (KL1, KL2) hochohmig (R3) miteinander verbunden sind.Electronic ballast according to claim 2, 3 or 4, in which both lamp terminals (KL1, KL2) are connected to the definition potential (DP, GND) such that the two lamp terminals (KL1, KL2) are connected to each other with high resistance (R3). Elektronisches Vorschaltgerät nach einem der vorangehenden Ansprüche, bei dem das Definitionspotential (DP) so eingestellt ist, dass das zeitlich mittlere Potential der Lampenanschlüsse (KL1, KL2) etwa dem Erdpotential (GND) entspricht, so dass die Berührsicherheit des elektronischen Vorschaltgerätes erhöht ist.Electronic ballast according to one of the preceding claims, wherein the definition potential (DP) is adjusted so that the time average potential of the lamp terminals (KL1, KL2) corresponds approximately to the ground potential (GND), so that the contact reliability of the electronic ballast is increased. Satz aus einem elektronischen Vorschaltgerät nach einem der vorangehenden Ansprüche und einer zum Betrieb mit diesem Vorschaltgerät geeigneten Niederdruckentladungslampe (LA).Set of an electronic ballast according to one of the preceding claims and a suitable for operation with this ballast low-pressure discharge lamp (LA). Verfahren zum Betrieb eines elektronischen Vorschaltgerätes mit einer Niederdruckentladungslampe (LA), bei dem • ein Wandler (S1, S2), der ein Schaltelement (S1, S2) und einen Wechselstromausgang (M) aufweist, die Niederdruckentladungslampe (LA) mit Wechselstrom versorgt und • die Niederdruckentladungslampe (LA) an Lampenanschlüssen (KL1, KL2) zwischen den Wechselstromausgang (M) und eines der Versorgungspotentiale (N, P) des Wandlers geschaltet ist, dadurch gekennzeichnet, dass
der wechselstromausgangsseitige (M) Lampenanschluss (KL1) mittels eines Trennungskondensators (C1) von dem Wechselstromausgang (M) des Wandlers (S1, S2) galvanisch getrennt ist und der an das eine der Versorgungspotentiale (N, P) des Wandlers angeschlossene Lampenanschluss (KL2) mittels eines in Serie geschalteten Trennungskondensators (C2) von diesem Versorgungspotential (N, P) galvanisch getrennt ist, so dass der Wandler (S1, S2) und die Niederdruckentladungslampe (LA) wechselstrommäßig koppeln.Method for operating an electronic ballast with a low-pressure discharge lamp (LA), in which A converter (S1, S2) having a switching element (S1, S2) and an AC output (M), the low pressure discharge lamp (LA) supplied with AC power and The low-pressure discharge lamp (LA) is connected to lamp terminals (KL1, KL2) between the AC output (M) and one of the supply potentials (N, P) of the converter, characterized in that
the AC output side (M) lamp terminal (KL1) is electrically isolated from the AC output (M) of the converter (S1, S2) by means of a separation capacitor (C1) and the lamp terminal (KL2) connected to one of the supply potentials (N, P) of the converter is electrically isolated from this supply potential (N, P) by means of a series-connected separation capacitor (C2), so that the converter (S1, S2) and the low-pressure discharge lamp (LA) couple AC-connected. Verfahren nach Anspruch 8 unter Verwendung eines Vorschaltgerätes nach einem der Ansprüche 1 bis 6 oder eines Satzes aus einem elektronischen Vorschaltgerät und einer Niederdruckentladungslampe nach Anspruch 7.Method according to claim 8 using a ballast according to one of claims 1 to 6 or a set of an electronic ballast and a low-pressure discharge lamp according to claim 7.
EP20060012556 2005-06-20 2006-06-19 Method and apparatus to balance the potential at lamp terminals Expired - Fee Related EP1765043B1 (en)

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DE200510028418 DE102005028418A1 (en) 2005-06-20 2005-06-20 Electronic ballast for operating low pressure discharge lamp has lamp connection attached to alternating current output side which is galvanically separated from alternating current output of converter by means of isolation capacitor

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5424614A (en) 1994-03-03 1995-06-13 Usi Lighting, Inc. Modified half-bridge parallel-loaded series resonant converter topology for electronic ballast
US6552500B1 (en) 1999-07-26 2003-04-22 Microlights Limited Electric lights

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Publication number Priority date Publication date Assignee Title
US5877595A (en) * 1996-09-06 1999-03-02 General Electric Company High power factor ballast circuit with complementary converter switches
US6078143A (en) * 1998-11-16 2000-06-20 General Electric Company Gas discharge lamp ballast with output voltage clamping circuit
US7154232B2 (en) * 2003-06-24 2006-12-26 International Rectifier Corporation Ballast control IC with multi-function feedback sense

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5424614A (en) 1994-03-03 1995-06-13 Usi Lighting, Inc. Modified half-bridge parallel-loaded series resonant converter topology for electronic ballast
US6552500B1 (en) 1999-07-26 2003-04-22 Microlights Limited Electric lights

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EP1765043B1 (en) 2013-07-31
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CN1886023B (en) 2011-10-05
DE102005028418A1 (en) 2006-12-28

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