EP0679046B1 - Circuit for operating low-pressure discharge lamps - Google Patents

Circuit for operating low-pressure discharge lamps Download PDF

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Publication number
EP0679046B1
EP0679046B1 EP95103597A EP95103597A EP0679046B1 EP 0679046 B1 EP0679046 B1 EP 0679046B1 EP 95103597 A EP95103597 A EP 95103597A EP 95103597 A EP95103597 A EP 95103597A EP 0679046 B1 EP0679046 B1 EP 0679046B1
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EP
European Patent Office
Prior art keywords
capacitor
circuit
diodes
circuit arrangement
electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP95103597A
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German (de)
French (fr)
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EP0679046A1 (en
Inventor
Eugen Statnic
Gunther Dr. Löhmann
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Osram GmbH
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Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
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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
    • 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
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/355—Power factor correction [PFC]; Reactive power compensation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S315/00—Electric lamp and discharge devices: systems
    • Y10S315/07—Starting and control circuits for gas discharge lamp using transistors

Definitions

  • the invention relates to a circuit arrangement for operating low-pressure discharge lamps according to the preamble of claim 1.
  • high-frequency operation enables of low-pressure discharge lamps compared to lamp operation at mains frequency a significant reduction in the size of the control gear and improved Operating conditions for the lamps, e.g. B. better ignition behavior, no flickering and higher luminous efficacy, but on the other hand requires more circuitry, for sufficient radio interference suppression and as sinusoidal as possible Ensure grid current draw with a power factor close to one.
  • a circuit arrangement corresponding to the preamble of claim 1 is for example disclosed in European patent EP 0 372 303. It contains a half-bridge inverter with two alternating switching transistors whose center tap is a series resonance circuit consisting of resonance inductance, Coupling capacitor and resonance capacitance is connected. In the series resonance circuit a low-pressure discharge lamp is also integrated. Also points this circuit has an active harmonic filter that complies with the IEC regulations guaranteed sinusoidal mains current draw. This harmonic filter will formed by four diodes, which are interconnected like a bridge rectifier and in the forward DC direction between the DC voltage output of the mains voltage rectifier and the positive pole of the one feeding the inverter Smoothing capacitor are integrated in the circuit.
  • the four diodes of the Harmonic filters interrupt the charge transport to the smoothing capacitor in the Switching cycle of the inverter.
  • the diodes are controlled in each case via the center tap between the diodes connected in series.
  • the Center tap of a first pair of diodes is here on the one hand via a pump capacitor directly to the center tap of the half-bridge inverter and on the other hand another pump capacitor between the resonance inductor and the coupling capacitor led to a tap in the series resonance circuit, during the Center tap of the second pair of diodes via a DC isolating capacitor and an inductor is connected to a tap in the series resonance circuit.
  • this circuit arrangement allows an almost sinusoidal mains current draw and achieve a network power factor greater than 0.9.
  • the circuit arrangement according to the invention contains an inverter with a downstream LC output circuit, in which a low-pressure discharge lamp is integrated is.
  • the inverter is connected to a high-frequency filter, a mains voltage rectifier and one, parallel to the DC voltage output of the mains voltage rectifier horizontal smoothing capacitor supplied with DC voltage.
  • a high-frequency bridge rectifier in the forward DC direction, consisting of two arranged parallel to each other Series connections of two diodes integrated into the circuit.
  • the circuit arrangement according to the invention has a storage inductor which between the positive pole of the DC voltage output of the mains voltage rectifier and the input of the high frequency bridge rectifier inserted into the circuit is.
  • the center tap between the first two diodes connected in series is connected to a first lamp electrode via a negative feedback capacitance, during the center tap between the two second diodes connected in series to the second lamp electrode and to the negative pole via a backup capacitor of the smoothing capacitor connected.
  • the Storage choke at the input of the high-frequency bridge rectifier also exercises a step-up effect, so that the circuit arrangement according to the invention especially for the operation of low pressure discharge lamps with comparatively high operating voltage, e.g. B., for the operation of miniature fluorescent lamps and Fluorescent lamps with a sharp rise in operating voltage during the aging process, is suitable.
  • the circuit arrangement according to the invention has also one parallel to the DC voltage output of the mains voltage rectifier switched capacitor, which together with the storage inductor Low pass forms.
  • This low-pass filter allows the high-frequency to be further weakened Voltage components on the mains connection side of the circuit arrangement.
  • the circuit arrangement according to the invention is also for Operation of miniature fluorescent lamps suitable, their electrodes during operation are exposed to a particularly high thermal load because these lamps compared to T8 or T10 fluorescent lamps, a much higher power density exhibit.
  • the highly schematic Figure 1 illustrates the principle of the invention Circuit arrangement.
  • the circuit arrangement according to the invention contains a Mains connection connected radio interference suppression filter FI with a downstream mains voltage rectifier GL, to whose DC voltage output a capacitor C1 is connected in parallel.
  • the circuit arrangement has an inverter WR with an LC output circuit, consisting of a resonance inductor LR, a resonance capacitance CR, a coupling capacitor CK and a low pressure discharge lamp L by a smoothing capacitor C2, which is parallel to Input of the inverter WR and parallel to the DC voltage output of the Mains voltage rectifier GL is switched.
  • the positive output of the mains voltage rectifier GL is also via a storage choke L1 and a high-frequency rectifier bridge, that formed by the four diodes D1, D2, D3 and D4 is, with the positive pole of the smoothing capacitor C2 and with an input of the Inverter WR and via the resonance capacitance CR with a tap in the LC output circuit of the inverter WR connected.
  • the high-frequency rectifier bridge interrupts the charging of the smoothing capacitor C2 in the switching rhythm of the inverter WR.
  • the high-frequency rectifier bridge is controlled via the center taps between the diodes D1, D2 and between the diodes D3, D4.
  • the potential at the center tap of the diodes D1, D2 is due to the voltage drop determined on the negative feedback capacitor CG, which with the center tap between the diodes D1, D2 and with a tap in the electrode heating circuit, consisting of the Electrode filaments E1, E2 and a heating capacitor CL, is connected.
  • the center tap of the diode pair D3, D4 is on the one hand directly with the lamp electrode E2 and on the other hand via a support capacitor CS with the negative pole of the smoothing capacitor C2 connected.
  • the voltage drop across the support capacitor CS is proportional to the lamp current and determines the potential at the center tap between the diodes D3, D4 and thus the blocking behavior of this diode pair.
  • the parallel diode D5 connected to the support capacitor CS clamps the negative components of the Support capacitor voltage to the zero line, d. that is, to the negative pole of the smoothing capacitor C2.
  • the diodes D1 and D3 remain in the blocked and the diodes D2 and D4 in the conductive State, so that the charging of the smoothing capacitor C2 from the line rectifier GL is interrupted.
  • the instantaneous value of the mains voltage lies above the voltages at the negative feedback CG or support capacitor CS, see above the diode branches D1, D2 or D3, D4 are transparent and the smoothing capacitor C2 is supplied via the mains voltage rectifier GL.
  • the coupling capacitor CK is recharged and accordingly the state of charge of the capacitors CG and CS also changes, so that with suitable dimensioning of the components of the LC output circuit and the Capacitors CG, CS and the storage choke L1, the high-frequency rectifier bridge the charging of the smoothing capacitor C2 in the switching rhythm of the inverter WR interrupts.
  • the storage choke L1 has a step-up effect, by during the pass phase of the high frequency rectifier bridge releases the energy stored in its magnetic field to the smoothing capacitor C2.
  • the storage choke L1 forms together with the parallel to the output of the Mains voltage rectifier GL switched capacitor C1 a low pass, the high-frequency voltage components further weakened.
  • FIG. 2 shows a detailed circuit diagram of a particularly preferred embodiment the circuit arrangement according to the invention.
  • Main component of this circuit is a self-oscillating, current-feedback half-bridge inverter with two alternating switching transistors T1, T2, its supply voltage from the smoothing capacitor C2 connected in parallel with its input.
  • the smoothing capacitor C2 is connected via a radio interference filter FI and a rectifier GL with an output capacitor connected in parallel to its DC voltage output Cl and the high-frequency rectifier bridge D1, D2, D3, D4 from Mains fed.
  • a radio interference filter FI and a rectifier GL with an output capacitor connected in parallel to its DC voltage output Cl and the high-frequency rectifier bridge D1, D2, D3, D4 from Mains fed.
  • LC output circuit in particular a series resonance circuit consisting of a resonance inductor LR, a coupling capacitor CK and a resonance capacitance CR connected.
  • the primary winding RKA is one in the series resonance circuit Toroidal transformer integrated.
  • a T2 miniature fluorescent lamp is parallel to the resonance capacity CR L switched with a power consumption of 13 watts.
  • the Synonym "T2" means that the fluorescent lamp L has a diameter (vertical to the discharge path) of approx. 2/8 inch (approx. 7 mm).
  • the trained as spirals Lamp electrodes E1, E2 are each with their second connection via a Sidac SI and a PTC thermistor R connected together. They form together with these components a heating circuit lying parallel to the resonance capacitance CR, the one Preheating of the electrode filaments E1, E2 before lamp ignition enables.
  • the Sidac SI interrupts the heating circuit, so that the PTC thermistor R is switched out of the LC output circuit of the inverter.
  • the Discharge path of the fluorescent lamp L is parallel to the resonance capacitance CR and connected in parallel to the series connection of Sidac SI and PTC thermistor R. Closed becomes the series resonance circuit consisting of the components RKA, LR, CK and CR of the half-bridge inverter T1, T2 via a backup capacitor CS, the a connection with the resonance capacitance CR and the first connection of the Lamp electrode E2 is connected, and its other connection to the negative pole of the Smoothing capacitor C2 and to the negative output of the mains voltage rectifier GL is led.
  • the electrode filaments El, E2 of the lamp L are therefore not in the Series resonance circuit integrated and are therefore only after lamp ignition flowed through by the discharge current.
  • the primary winding RKA of the toroidal transformer controls the switching behavior of the Transistors T1, T2 via the integrated in the respective base circuit of the transistors T1, T2 Secondary winding RKB or RKC and the basic series resistors R1, R4.
  • the transistor half bridge also includes the emitter resistors R3, R6 Resistors R2, R5 and the only connected in parallel to the base-emitter path schematically illustrated starting circuit ST, which starts the inverter triggers.
  • a detailed description of how the half-bridge inverter works, including the start circuit ST, can be found for example in the Book "Schaltnetzmaschine" by W. Hirschmann / A. Hauenstein, ed. Siemens AG, edition 1990 on page 63.
  • Resistors R2 and R5 only improve that Switching behavior of the transistors T1, T2, by removing the charge carriers faster from the space charge zone of the base-emitter interface.
  • High-frequency rectifier bridge consisting of diodes D1, D2, D3, D4, which in DC forward direction between the positive output of the line rectifier GL and the positive pole of the smoothing capacitor C2 integrated into the circuit is.
  • the diodes D1 and D2, like the diodes D3 and D4, are in series switched to each other.
  • the diode pair D1, D2 is parallel to the diode pair D3, D4 arranged.
  • the anode connections of the diodes D1, D3 are via a storage inductor L1 connected to the positive output of the mains voltage rectifier GL.
  • the Cathode connections of the diodes D2, D4 are with the positive pole of the smoothing capacitor C2 and connected to the collector of transistor T1.
  • the center tap between the diodes D1, D2 is in each case connected via a negative feedback capacitor CG a connection of the coupling capacitor CK and the resonance capacitance CR and connected to the first connection of the electrode coil El.
  • the center tap between the diodes D3, D4 is on the one hand directly to the connection point of resonance capacitance CR and electrode coil E2 connected and the other via the support capacitor CS with the negative pole of the smoothing capacitor C2 and with connected to the negative output of the mains voltage rectifier GL.
  • Parallel to Support capacitor CS is connected to a diode D5, the negative components of the Support capacitor voltage clamps to the negative pole of the smoothing capacitor C2.
  • the high-frequency rectifier bridge interrupts the Charging of the smoothing capacitor C2 in the switching rhythm of the half-bridge inverter.
  • the circuit arrangement according to the invention has a safety shutdown, the inverter if the lamp is defective or in the event of an abnormal one Operating state switches off.
  • An essential part of this safety shutdown is a thyristor TH, whose control electrode is controlled by a diac DI.
  • Thyristor TH is on the one hand via an ohmic holding resistor R10 with the collector of the transistor T1 and on the other hand with the negative pole of the smoothing capacitor C2 connected.
  • the control electrode of the thyristor TH is via the diac DI and an electrolytic capacitor C3 with the negative pole of the smoothing capacitor C2 connected.
  • the base connection of transistor T1 is via a diode D6 and a ohmic resistor R7 connected to the anode of thyristor TH.
  • Parallel voltage dividing resistors R15, R16, R17 are connected to the smoothing capacitor C2.
  • the center tap between the resistors R15 and R16 is via a diode D8 connected to the positive pole of the electrolytic capacitor C3.
  • the center tap between the negative feedback capacitor CG, the electrode coil El, the Coupling capacitor CK and the resonance capacitance CR is across the resistors R8, R9 and R11 connected to the negative pole of the smoothing capacitor C2.
  • Of the Center tap between the resistors R9 and R11 is connected via a diode D7 connected to the positive pole of the electrolytic capacitor C3.
  • an ohmic resistor R13 is also connected.
  • the center tap between the control electrode of the thyristor TH and the diac DI is via an ohmic Resistor R14 connected to the negative pole of smoothing capacitor C2.
  • the voltage divider R15, R16, R17 detects the voltage drop across the smoothing capacitor C2. If this exceeds a predetermined critical value, the Electrolytic capacitor C3 is charged via diode D8 to the breakover voltage of Diacs DI and the thyristor TH turns on, so that the base of the transistor T1 with is connected to the negative pole of the smoothing capacitor C2. This will Transistor T1 withdraws the control signal and the half-bridge inverter is switched off.
  • the voltage divider R8, R9, R11 detects the ignition or Operating voltage of the miniature fluorescent lamp L.
  • the electrolytic capacitor C3 via the diode D7 also to the breakover voltage of Diacs DI charged so that the thyristor TH turns on and the transistor T1 the control signal is withdrawn.
  • the resistor R13 and the electrolytic capacitor C3 define a time constant so that the thyristor TH during the ignition phase the lamp L is not activated.

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Description

Die Erfindung betrifft eine Schaltungsanordnung zum Betrieb von Niederdruckentladungslampen gemäß dem Obergriff des Patentanspruchs 1.The invention relates to a circuit arrangement for operating low-pressure discharge lamps according to the preamble of claim 1.

Insbesondere handelt es sich um eine Schaltungsanordnung zum hochfrequenten Betrieb von Niederdruckentladungslampen. Einerseits ermöglicht der Hochfrequenzbetrieb von Niederdruckentladungslampen gegenüber einem Lampenbetrieb mit Netzfrequenz eine deutliche Verringerung der Betriebsgeräteabmessungen sowie verbesserte Betriebsbedingungen für die Lampen, z. B. besseres Zündverhalten, kein Flimmem und höhere Lichtausbeute, erfordert aber andererseits einen höheren Schaltungsaufwand, um eine ausreichende Funkentstörung und eine möglichst sinusförmige Netzstromentnahme mit einem Leistungsfaktor nahe bei eins zu gewährleisten.In particular, it is a circuit arrangement for high-frequency operation of low pressure discharge lamps. On the one hand, high-frequency operation enables of low-pressure discharge lamps compared to lamp operation at mains frequency a significant reduction in the size of the control gear and improved Operating conditions for the lamps, e.g. B. better ignition behavior, no flickering and higher luminous efficacy, but on the other hand requires more circuitry, for sufficient radio interference suppression and as sinusoidal as possible Ensure grid current draw with a power factor close to one.

Eine dem Oberbegriff des Patentanspruchs 1 entsprechende Schaltungsanordnung ist beispielsweise in der europäischen Patentschrift EP 0 372 303 offenbart. Sie enthält einen Halbbrückenwechselrichter mit zwei alternierend schaltenden Transistoren, an deren Mittenabgriff ein Serienresonanzkreis, bestehend aus Resonanzinduktivität, Kopplungskondensator und Resonanzkapazität, angeschlossen ist. In den Serienresonanzkreis ist ferner eine Niederdruckentladungslampe integriert. Außerdem weist diese Schaltung ein aktives Oberwellenfilter auf, das eine den IEC-Vorschriften genügende sinusförmige Netzstromentnahme gewährleistet. Dieses Oberwellenfilter wird von vier Dioden gebildet, die ähnlich einem Brückengleichrichter miteinander verschaltet sind und in Gleichstromvorwärtsrichtung zwischen dem Gleichspannungsausgang des Netzspannungsgleichrichters und dem Pluspol des den Wechselrichter speisenden Glättungskondensators in die Schaltung integriert sind. Die vier Dioden des Oberwellenfilters unterbrechen den Ladungstransport zum Glättungskondensator im Schalttakt des Wechselrichters. Die Ansteuerung der Dioden erfolgt dabei jeweils über den Mittenabgriff zwischen den in Reihe zueinander geschalteten Dioden. Der Mittenabgriff eines ersten Diodenpaares ist hier einerseits über einen Pumpkondensator direkt zum Mittenabgriff des Halbbrückenwechselrichters und andererseits über einen weiteren Pumpkondensator zwischen die Resonanzinduktivität und den Kopplungskondensator zu einem Abgriff im Serienresonanzkreis geführt, während der Mittenabgriff des zweiten Diodenpaares über einen Gleichstromtrennkondensator und eine Induktivität mit einem Abgriff im Serienresonanzkreis verbunden ist. Mit Hilfe dieser Schaltungsanordnung lassen sich eine nahezu sinusförmige Netzstromentnahme und ein Netzleistungsfaktor größer als 0,9 erreichen.A circuit arrangement corresponding to the preamble of claim 1 is for example disclosed in European patent EP 0 372 303. It contains a half-bridge inverter with two alternating switching transistors whose center tap is a series resonance circuit consisting of resonance inductance, Coupling capacitor and resonance capacitance is connected. In the series resonance circuit a low-pressure discharge lamp is also integrated. Also points this circuit has an active harmonic filter that complies with the IEC regulations guaranteed sinusoidal mains current draw. This harmonic filter will formed by four diodes, which are interconnected like a bridge rectifier and in the forward DC direction between the DC voltage output of the mains voltage rectifier and the positive pole of the one feeding the inverter Smoothing capacitor are integrated in the circuit. The four diodes of the Harmonic filters interrupt the charge transport to the smoothing capacitor in the Switching cycle of the inverter. The diodes are controlled in each case via the center tap between the diodes connected in series. Of the Center tap of a first pair of diodes is here on the one hand via a pump capacitor directly to the center tap of the half-bridge inverter and on the other hand another pump capacitor between the resonance inductor and the coupling capacitor led to a tap in the series resonance circuit, during the Center tap of the second pair of diodes via a DC isolating capacitor and an inductor is connected to a tap in the series resonance circuit. With help this circuit arrangement allows an almost sinusoidal mains current draw and achieve a network power factor greater than 0.9.

Es ist die Aufgabe der Erfindung, eine Schaltungsanordnung zum Betrieb von Niederdruckentladungslampen bereitzustellen, die eine möglichst sinusförmige Netzstromentnahme gewährleistet, einen gegenüber dem Stand der Technik verbesserten Netzleistungsfaktor aufweist und die außerdem auch zum Betrieb von Niederdruckentladungslampen mit vergleichsweise hoher Betriebsspannung geeignet ist.It is the object of the invention to provide a circuit arrangement for operating low-pressure discharge lamps to provide the most sinusoidal mains current guaranteed an improved over the prior art Has network power factor and also for the operation of low-pressure discharge lamps is suitable with a comparatively high operating voltage.

Diese Aufgabe wird erfindungsgemäß durch die kennzeichnenden Merkmale des Patentanspruchs 1 gelöst. Besonders bevorzugte Ausführungen der Erfindung sind in den Unteransprüchen beschrieben.This object is achieved by the characterizing features of the claim 1 solved. Particularly preferred embodiments of the invention are in described the subclaims.

Die erfindungsgemäße Schaltungsanordnung enthält einen Wechselrichter mit einem nachgeschalteten LC-Ausgangskreis, in den eine Niederdruckentladungslampe integiert ist. Der Wechselrichter wird über ein Hochfrequenzfilter, einen Netzspannungsgleichrichter und einen, parallel zum Gleichspannungsausgang des Netzspannungsgleichrichters liegenden Glättungskondensator mit Gleichspannung versorgt. Zwischen dem Gleichspannungsausgang des Netzspannungsgleichrichters und dem Pluspol des Glättungskondensators ist, in Gleichstromvorwärtsrichtung, ein Hochfrequenz-Brückengleichrichter, bestehend aus zwei parallel zueinander angeordneten Reihenschaltungen von jeweils zwei Dioden in die Schaltung integriert. Außerdem besitzt die erfindungsgemäße Schaltungsanordnung eine Speicherdrossel, die zwischen dem Pluspol des Gleichspannungsausganges des Netzspannungsgleichrichters und dem Eingang des Hochfrequenz-Brückengleichrichters in die Schaltung eingefügt ist. Der Mittenabgriff zwischen den beiden ersten in Reihe geschalteten Dioden ist über eine Gegenkopplungskapazität mit einer ersten Lampenelektrode verbunden, während der Mittenabgriff zwischen den beiden zweiten in Reihe geschalteten Dioden an die zweite Lampenelektrode sowie über einen Stützkondensator an den Minuspol des Glättungskondensators angeschlossen.The circuit arrangement according to the invention contains an inverter with a downstream LC output circuit, in which a low-pressure discharge lamp is integrated is. The inverter is connected to a high-frequency filter, a mains voltage rectifier and one, parallel to the DC voltage output of the mains voltage rectifier horizontal smoothing capacitor supplied with DC voltage. Between the DC voltage output of the mains voltage rectifier and the positive pole of the smoothing capacitor is a high-frequency bridge rectifier in the forward DC direction, consisting of two arranged parallel to each other Series connections of two diodes integrated into the circuit. Furthermore the circuit arrangement according to the invention has a storage inductor which between the positive pole of the DC voltage output of the mains voltage rectifier and the input of the high frequency bridge rectifier inserted into the circuit is. The center tap between the first two diodes connected in series is connected to a first lamp electrode via a negative feedback capacitance, during the center tap between the two second diodes connected in series to the second lamp electrode and to the negative pole via a backup capacitor of the smoothing capacitor connected.

Durch diese erfindungsgemäße Verschaltung der Speicherdrossel und des Hochfrequenz-Brückengleichrichters werden eine den IEC-Vorschriften genügende sinusförmige Netzstromentnahme und ein Netzleistungsfaktor größer als 0,98 erreicht. Die Speicherdrossel am Eingang des Hochfrequenz-Brückengleichrichters übt außerdem eine hochsetzstellende Wirkung aus, so daß sich die erfindungsgemäße Schaltungsanordnung besonders zum Betrieb von Niederdruckentladungslampen mit vergleichsweise hoher Betriebsspannung, z. B., zum Betrieb von Miniaturleuchtstofflampen und Leuchtstofflampen mit starkem Anstieg der Betriebsspannung während des Alterungsprozesses, eignet.Through this inventive circuit of the storage choke and the high-frequency bridge rectifier become a sinusoidal shape that complies with the IEC regulations Grid current draw and a grid power factor greater than 0.98 reached. The Storage choke at the input of the high-frequency bridge rectifier also exercises a step-up effect, so that the circuit arrangement according to the invention especially for the operation of low pressure discharge lamps with comparatively high operating voltage, e.g. B., for the operation of miniature fluorescent lamps and Fluorescent lamps with a sharp rise in operating voltage during the aging process, is suitable.

Bei einem bevorzugten Ausführungsbeispiel besitzt die erfindungsgemäße Schaltungsanordnung ferner einen parallel zum Gleichspannungsausgang des Netzspannungsgleichrichters geschalteten Kondensator, der zusammen mit der Speicherdrossel einen Tiefpaß bildet. Dieser Tiefpaß ermöglicht eine weitere Abschwächung der hochfrequenten Spannungsanteile auf der Netzanschlußseite der Schaltungsanordnung.In a preferred exemplary embodiment, the circuit arrangement according to the invention has also one parallel to the DC voltage output of the mains voltage rectifier switched capacitor, which together with the storage inductor Low pass forms. This low-pass filter allows the high-frequency to be further weakened Voltage components on the mains connection side of the circuit arrangement.

Außerdem sind bei dem bevorzugten Ausführungsbeispiel die als vorheizbare Wendeln ausgebildeten Lampenelektroden vorteilhafterweise derart in den LC-Ausgangskreis des Wechselrichters integriert, daß die Elektrodenwendeln nach erfolgter Zündung der Niederdruckentladungslampe nicht noch von einem Heizstrom durchflossen werden, der die Elektrodenwendeln zusätzlich zum Strom über die Entladungsstrecke belasten würde. Dadurch ist die erfindungsgemäße Schaltungsanordnung auch zum Betrieb von Miniaturleuchtstofflampen geeignet, deren Elektroden während des Betriebes einer besonders hohen thermischen Belastung ausgesetzt sind, da diese Lampen im Vergleich zu T8- oder T10-Leuchtstofflampen eine wesentlich höhere Leistungsdichte aufweisen.In addition, in the preferred embodiment, are as preheatable coils trained lamp electrodes advantageously in such a way in the LC output circuit of the inverter integrated that the electrode coils after ignition the low-pressure discharge lamp is not yet flowed through by a heating current the electrode coils in addition to the current over the discharge path would burden. As a result, the circuit arrangement according to the invention is also for Operation of miniature fluorescent lamps suitable, their electrodes during operation are exposed to a particularly high thermal load because these lamps compared to T8 or T10 fluorescent lamps, a much higher power density exhibit.

Nachstehend wird die Erfindung anhand eines bevorzugten Ausführungsbeispiels näher erläutert. Es zeigen:

Figur 1
das Prinzip der erfindungsgemäßen Schaltungsanordnung in stark schematisierter Darstellung
Figur 2
die Schaltungsanordnung gemäß eines bevorzugten Ausführungsbeispiels
The invention is explained in more detail below on the basis of a preferred exemplary embodiment. Show it:
Figure 1
the principle of the circuit arrangement according to the invention in a highly schematic representation
Figure 2
the circuit arrangement according to a preferred embodiment

Die stark schematisierte Figur 1 veranschaulicht das Prinzip der erfindungsgemäßen Schaltungsanordnung. Die erfindungsgemäße Schaltungsanordnung enthält ein am Netzanschluß angeschlossenes Funkentstörfilter FI mit einem nachgeschalteten Netzspannungsgleichrichter GL, zu dessen Gleichspannungsausgang ein Kondensator C1 parallel geschaltet ist. Außerdem besitzt die Schaltungsanordnung einen Wechselrichter WR mit einem LC-Ausgangskreis, bestehend aus einer Resonanzinduktivität LR, einer Resonanzkapazität CR, einem Kopplungskondensator CK und einer Niederdruckentladungslampe L, der von einem Glättungskondensator C2, der parallel zum Eingang des Wechselrichters WR und parallel zum Gleichspannungsausgang des Netzspannunngsgleichrichters GL geschaltet ist. Der positive Ausgang des Netzspannungsgleichrichters GL ist ferner über eine Speicherdrossel L1 und über eine Hochfrequenz-Gleichrichterbrücke, die von den vier Dioden D1, D2, D3 und D4 gebildet wird, mit dem Pluspol des Glättungskondensators C2 und mit einem Eingang des Wechselrichters WR sowie über die Resonanzkapazität CR mit einem Abgriff im LC-Ausgangskreis des Wechselrichters WR verbunden. Die Hochfrequenz-Gleichrichterbrücke unterbricht die Aufladung des Glättungskondensators C2 im Schaltrhythmus des Wechselrichters WR. Gesteuert wird die Hochfrequenz-Gleichrichterbrücke über die Mittenabgriffe zwischen den Dioden D1, D2 und zwischen den Dioden D3, D4. Das Potential am Mittenabgriff der Dioden D1, D2 wird durch den Spannungsabfall am Gegenkopplungskondensator CG bestimmt, der mit dem Mittenabgriff zwischen den Dioden D1, D2 und mit einem Abgriff im Elektrodenheizkreis, bestehend aus den Elektrodenwendeln E1, E2 und einem Heizkondensator CL, verbunden ist. Der Mittenabgriff des Diodenpaares D3, D4 ist zum einen direkt mit der Lampenelektrode E2 und zum anderen über einen Stützkondensator CS mit dem Minuspol des Glättungskondensators C2 verbunden. Der Spannungsabfall am Stützkondensator CS ist proportional zum Lampenstrom und bestimmt das Potential am Mittenabgriff zwischen den Dioden D3, D4 und damit das Sperrverhalten dieses Diodenpaares. Die parallel zum Stützkondensator CS geschaltete Diode D5 klemmt die negativen Anteile der Stützkondensatorspannung an die Null-Linie, d. h., an den Minuspol des Glättungskondensators C2. Solange der Momentanwert der Netzspannung niedriger als die Spannung am Gegenkopplungskondensator CG bzw. am Stützkondensator CS ist, verbleiben die Dioden D1 und D3 im gesperrten und die Dioden D2 und D4 im leitenden Zustand, so daß die Aufladung des Glättungskondensators C2 vom Netzgleichrichter GL unterbrochen ist. Liegt hingegen der Momentanwert der Netzspannung oberhalb der Spannungen am Gegenkopplungs- CG bzw. Stützkondensator CS, so sind die Diodenzweige D1, D2 bzw. D3, D4 durchlässig und der Glättungskondensator C2 wird über den Netzspannungsgleichrichter GL versorgt. Im Schalttakt des Wechselrichters WR wird der Kopplungskondensator CK umgeladen und entsprechend ändert sich auch der Ladezustand der Kondensatoren CG und CS, so daß, bei geeigneter Dimensionierung der Bauelemente des LC-Ausgangskreises und der Kondensatoren CG, CS sowie der Speicherdrossel L1, die Hochfrequenz-Gleichrichterbrücke die Aufladung des Glättungskondensators C2 im Schaltrhythmus des Wechselrichters WR unterbricht. Die Speicherdrossel L1 hat eine hochsetzstellende Wirkung, indem sie während der Durchlaßphase der Hochfrequenz-Gleichrichterbrücke die in ihrem Magnetfeld gespeicherte Energie an den Glättungskondensator C2 abgibt. Außerdem bildet die Speicherdrossel L1 zusammen mit dem parallel zum Ausgang des Netzspannungsgleichrichters GL geschalteten Kondensator C1 einen Tiefpaß, der hochfrequente Spannungsanteile weiter abschwächt.The highly schematic Figure 1 illustrates the principle of the invention Circuit arrangement. The circuit arrangement according to the invention contains a Mains connection connected radio interference suppression filter FI with a downstream mains voltage rectifier GL, to whose DC voltage output a capacitor C1 is connected in parallel. In addition, the circuit arrangement has an inverter WR with an LC output circuit, consisting of a resonance inductor LR, a resonance capacitance CR, a coupling capacitor CK and a low pressure discharge lamp L by a smoothing capacitor C2, which is parallel to Input of the inverter WR and parallel to the DC voltage output of the Mains voltage rectifier GL is switched. The positive output of the mains voltage rectifier GL is also via a storage choke L1 and a high-frequency rectifier bridge, that formed by the four diodes D1, D2, D3 and D4 is, with the positive pole of the smoothing capacitor C2 and with an input of the Inverter WR and via the resonance capacitance CR with a tap in the LC output circuit of the inverter WR connected. The high-frequency rectifier bridge interrupts the charging of the smoothing capacitor C2 in the switching rhythm of the inverter WR. The high-frequency rectifier bridge is controlled via the center taps between the diodes D1, D2 and between the diodes D3, D4. The potential at the center tap of the diodes D1, D2 is due to the voltage drop determined on the negative feedback capacitor CG, which with the center tap between the diodes D1, D2 and with a tap in the electrode heating circuit, consisting of the Electrode filaments E1, E2 and a heating capacitor CL, is connected. The center tap of the diode pair D3, D4 is on the one hand directly with the lamp electrode E2 and on the other hand via a support capacitor CS with the negative pole of the smoothing capacitor C2 connected. The voltage drop across the support capacitor CS is proportional to the lamp current and determines the potential at the center tap between the diodes D3, D4 and thus the blocking behavior of this diode pair. The parallel diode D5 connected to the support capacitor CS clamps the negative components of the Support capacitor voltage to the zero line, d. that is, to the negative pole of the smoothing capacitor C2. As long as the instantaneous value of the mains voltage is lower than that Voltage at the negative feedback capacitor CG or at the backup capacitor CS, The diodes D1 and D3 remain in the blocked and the diodes D2 and D4 in the conductive State, so that the charging of the smoothing capacitor C2 from the line rectifier GL is interrupted. However, the instantaneous value of the mains voltage lies above the voltages at the negative feedback CG or support capacitor CS, see above the diode branches D1, D2 or D3, D4 are transparent and the smoothing capacitor C2 is supplied via the mains voltage rectifier GL. In the switching cycle of the Inverter WR, the coupling capacitor CK is recharged and accordingly the state of charge of the capacitors CG and CS also changes, so that with suitable dimensioning of the components of the LC output circuit and the Capacitors CG, CS and the storage choke L1, the high-frequency rectifier bridge the charging of the smoothing capacitor C2 in the switching rhythm of the inverter WR interrupts. The storage choke L1 has a step-up effect, by during the pass phase of the high frequency rectifier bridge releases the energy stored in its magnetic field to the smoothing capacitor C2. In addition, the storage choke L1 forms together with the parallel to the output of the Mains voltage rectifier GL switched capacitor C1 a low pass, the high-frequency voltage components further weakened.

Figur 2 zeigt ein detailliertes Schaltbild eines besonders bevorzugten Ausführungsbeispiels der erfindungsgemäßen Schaltungsanordnung. Hauptbestandteil dieser Schaltung ist ein selbstschwingender, stromrückgekoppelter Halbbrückenwechselrichter mit zwei alternierend schaltenden Transistoren T1, T2, der seine Versorgungsspannung von dem parallel zu seinem Eingang geschalteten Glättungskondensator C2 erhält. Der Glättungskondensator C2 wird über ein Funkentstörfilter FI und einen Gleichrichter GL mit einem parallel zu seinem Gleichspannungsausgang geschalteten Ausgangskondensator Cl und die Hochfrequenz-Gleichrichterbrücke D1, D2, D3, D4 vom Netz gespeist. Am Mittenabgriff der Schalttransistoren T1, T2 ist ein LC-Ausgangskreis, insbesondere ein Serienresonanzkreis, bestehend aus einer Resonanzinduktivität LR, einem Kopplungskondensator CK und einer Resonanzkapazität CR, angeschlossen. Außerdem ist in den Serienresonanzkreis noch die Primärwicklung RKA eines Ringkerntransformators integriert. Parallel zur Resonanzkapazität CR ist eine T2-Miniaturleuchtstofflampe L mit einer Leistungsaufnahme von 13 Watt geschaltet. Das Synonym "T2" bedeutet, daß die Leuchtstofflampe L einen Durchmesser (senkrecht zur Entladungsstrecke) von ca. 2/8 Zoll (ca. 7 mm) besitzt. Die als Wendeln ausgebildeten Lampenelektroden E1, E2 sind jeweils mit ihrem zweiten Anschluß über einen Sidac SI und einen Kaltleiter R miteinander verbunden. Sie bilden zusammen mit diesen Bauteilen einen parallel zur Resonanzkapazität CR liegenden Heizkreis, der ein Vorheizen der Elektrodenwendeln E1, E2 vor der Lampenzündung ermöglicht. Nach erfolgter Lampenzündung unterbricht der Sidac SI den Heizkreis, so daß der Kaltleiter R aus dem LC-Ausgangskreis des Wechselrichters herausgeschaltet wird. Die Entladungsstrecke der Leuchtstofflampe L ist parallel zur Resonanzkapazität CR und parallel zur Reihenschaltung aus Sidac SI und Kaltleiter R geschaltet. Geschlossen wird der aus den Bauelementen RKA, LR, CK und CR bestehende Serienresonanzkreis des Halbbrückenwechselrichters T1, T2 über einen Stützkondensator CS, dessen einer Anschluß mit der Resonanzkapazität CR und dem ersten Anschluß der Lampenelektrode E2 verbunden ist, und dessen anderer Anschluß zum Minuspol des Glättungskondensators C2 und zum negativen Ausgang des Netzspannungsgleichrichters GL geführt ist. Die Elektrodenwendeln El, E2 der Lampe L sind also nicht in den Serienresonanzkreis integriert und werden daher nach erfolgter Lampenzündung nur vom Entladungsstrom durchflossen.Figure 2 shows a detailed circuit diagram of a particularly preferred embodiment the circuit arrangement according to the invention. Main component of this circuit is a self-oscillating, current-feedback half-bridge inverter with two alternating switching transistors T1, T2, its supply voltage from the smoothing capacitor C2 connected in parallel with its input. The smoothing capacitor C2 is connected via a radio interference filter FI and a rectifier GL with an output capacitor connected in parallel to its DC voltage output Cl and the high-frequency rectifier bridge D1, D2, D3, D4 from Mains fed. At the center tap of the switching transistors T1, T2 there is an LC output circuit, in particular a series resonance circuit consisting of a resonance inductor LR, a coupling capacitor CK and a resonance capacitance CR connected. In addition, the primary winding RKA is one in the series resonance circuit Toroidal transformer integrated. A T2 miniature fluorescent lamp is parallel to the resonance capacity CR L switched with a power consumption of 13 watts. The Synonym "T2" means that the fluorescent lamp L has a diameter (vertical to the discharge path) of approx. 2/8 inch (approx. 7 mm). The trained as spirals Lamp electrodes E1, E2 are each with their second connection via a Sidac SI and a PTC thermistor R connected together. They form together with these components a heating circuit lying parallel to the resonance capacitance CR, the one Preheating of the electrode filaments E1, E2 before lamp ignition enables. After When the lamp is ignited, the Sidac SI interrupts the heating circuit, so that the PTC thermistor R is switched out of the LC output circuit of the inverter. The Discharge path of the fluorescent lamp L is parallel to the resonance capacitance CR and connected in parallel to the series connection of Sidac SI and PTC thermistor R. Closed becomes the series resonance circuit consisting of the components RKA, LR, CK and CR of the half-bridge inverter T1, T2 via a backup capacitor CS, the a connection with the resonance capacitance CR and the first connection of the Lamp electrode E2 is connected, and its other connection to the negative pole of the Smoothing capacitor C2 and to the negative output of the mains voltage rectifier GL is led. The electrode filaments El, E2 of the lamp L are therefore not in the Series resonance circuit integrated and are therefore only after lamp ignition flowed through by the discharge current.

Die Primärwicklung RKA des Ringkerntransformators steuert das Schaltverhalten der Transistoren T1, T2 über die in den jeweiligen Basiskreis der Transistoren T1, T2 integrierte Sekundärwicklung RKB bzw. RKC und die Basisvorwiderstände R1, R4. Zur Transistorhalbbrücke gehören ferner noch die Emitterwiderstände R3, R6, die parallel zur Basis-Emitter-Strecke geschalteten Widerstände R2, R5 und die nur schematisch dargestellte Startschaltung ST, die das Anschwingen des Wechselrichters auslöst. Eine ausführliche Beschreibung der Funktionsweise des Halbbrückenwechselrichters, einschließlich der Startschaltung ST, findet man beispielsweise in dem Buch "Schaltnetzteile" von W. Hirschmann/ A. Hauenstein, Hrsg. Siemens AG, Ausgabe 1990 auf der Seite 63. Die Widerstände R2 und R5 verbessern lediglich das Schaltverhalten der Transistoren T1, T2, indem sie ein schnelleres Ausräumen der Ladungsträger aus der Raumladungszone der Basis-Emitter-Grenzschicht ermöglichen.The primary winding RKA of the toroidal transformer controls the switching behavior of the Transistors T1, T2 via the integrated in the respective base circuit of the transistors T1, T2 Secondary winding RKB or RKC and the basic series resistors R1, R4. The transistor half bridge also includes the emitter resistors R3, R6 Resistors R2, R5 and the only connected in parallel to the base-emitter path schematically illustrated starting circuit ST, which starts the inverter triggers. A detailed description of how the half-bridge inverter works, including the start circuit ST, can be found for example in the Book "Schaltnetzteile" by W. Hirschmann / A. Hauenstein, ed. Siemens AG, edition 1990 on page 63. Resistors R2 and R5 only improve that Switching behavior of the transistors T1, T2, by removing the charge carriers faster from the space charge zone of the base-emitter interface.

Ein weiterer Hauptbestandteil der erfindungsgemäßen Schaltungsanordnung ist die Hochfrequenz-Gleichrichterbrücke, bestehend aus den Dioden D1, D2, D3, D4, die in Gleichstromvorwärtsrichtung zwischen den postiven Ausgang des Netzspannungsgleichrichters GL und den Pluspol des Glättungskondensators C2 in die Schaltung integriert ist. Die Dioden D1 und D2 sind, ebenso wie die Dioden D3 und D4, in Reihe zueinander geschaltet. Das Diodenpaar D1, D2 ist parallel zum Diodenpaar D3, D4 angeordnet. Die Anodenanschlüsse der Dioden Dl, D3 sind über eine Speicherdrossel L1 an den postiven Ausgang des Netzspannungsgleichrichters GL angeschlossen. Die Kathodenanschlüsse der Dioden D2, D4 sind mit dem Pluspol des Glättungskondensators C2 und mit dem Kollektor des Transistors T1 verbunden. Der Mittenabgriff zwischen den Dioden D1, D2 ist über einen Gegenkopplungskondensator CG jeweils mit einem Anschluß des Kopplungskondensators CK und der Resonanzkapazität CR sowie mit dem ersten Anschluß der Elektrodenwendel El verbunden. Der Mittenabgriff zwischen den Dioden D3, D4 ist zum einen direkt an den Verbindungspunkt von Resonanzkapazität CR und Elektrodenwendel E2 angeschlossen und zum anderen über den Stützkondensator CS mit dem Minuspol des Glättungskondensators C2 sowie mit dem negativen Ausgang des Netzspannungsgleichrichters GL verbunden. Parallel zum Stützkondensator CS ist eine Diode D5 geschaltet, die die negativen Anteile der Stützkondensatorspannung an den Minuspol des Glättungskondensators C2 klemmt. Wie bereits oben beschrieben, unterbricht die Hochfrequenz-Gleichrichterbrücke die Aufladung des Glättungskondensators C2 im Schaltrhythmus des Halbbrückenwechselrichters. Die Bauelemente mit denselben Bezugszeichen in den Figuren 1 und 2 sind identisch und haben auch dieselbe Funktion.Another main component of the circuit arrangement according to the invention is that High-frequency rectifier bridge, consisting of diodes D1, D2, D3, D4, which in DC forward direction between the positive output of the line rectifier GL and the positive pole of the smoothing capacitor C2 integrated into the circuit is. The diodes D1 and D2, like the diodes D3 and D4, are in series switched to each other. The diode pair D1, D2 is parallel to the diode pair D3, D4 arranged. The anode connections of the diodes D1, D3 are via a storage inductor L1 connected to the positive output of the mains voltage rectifier GL. The Cathode connections of the diodes D2, D4 are with the positive pole of the smoothing capacitor C2 and connected to the collector of transistor T1. The center tap between the diodes D1, D2 is in each case connected via a negative feedback capacitor CG a connection of the coupling capacitor CK and the resonance capacitance CR and connected to the first connection of the electrode coil El. The center tap between the diodes D3, D4 is on the one hand directly to the connection point of resonance capacitance CR and electrode coil E2 connected and the other via the support capacitor CS with the negative pole of the smoothing capacitor C2 and with connected to the negative output of the mains voltage rectifier GL. Parallel to Support capacitor CS is connected to a diode D5, the negative components of the Support capacitor voltage clamps to the negative pole of the smoothing capacitor C2. As already described above, the high-frequency rectifier bridge interrupts the Charging of the smoothing capacitor C2 in the switching rhythm of the half-bridge inverter. The components with the same reference numerals in FIGS. 1 and 2 are identical and also have the same function.

Um eine Zerstörung des Betriebsgerätes im Falle eines anomalen Betriebszustandes zu vermeiden, besitzt die erfindungsgemäße Schaltungsanordnung eine Sicherheitsabschaltung, die den Wechselrichter bei defekter Lampe oder im Falle eines anomalen Betriebszustandes abschaltet. Wesentliches Bestandteil dieser Sicherheitsabschaltung ist ein Thyristor TH, dessen Steuerelektrode über einen Diac DI angesteuert wird. Der Thyristor TH ist einerseits über einen ohmschen Haltewiderstand R10 mit dem Kollektor des Transistors T1 und andererseits mit dem Minuspol des Glättungskondensators C2 verbunden. Die Steuerelektrode des Thyristors TH ist über den Diac DI und einen Elektrolytkondensator C3 mit dem Minuspol des Glättungskondensators C2 verbunden. Der Basisanschluß des Transistors T1 ist über eine Diode D6 und einen ohmschen Widerstand R7 an die Anode des Thyristors TH angeschlossen. Parallel zum Glättungskondensator C2 sind Spannungsteilerwiderstände R15, R16, R17 geschaltet. Der Mittenabgriff zwischen den Widerständen R15 und R16 ist über eine Diode D8 mit dem Pluspol des Elektrolytkondensators C3 verbunden. Der Mittenabgriff zwischen dem Gegenkopplungskondensator CG, der Elektrodenwendel El, dem Kopplungskondensator CK und der Resonanzkapazität CR ist über die Widerstände R8, R9 und R11 an den Minuspol des Glättungskondensators C2 angeschlossen. Der Mittenabgriff zwischen den Widerständen R9 und R11 ist über eine Diode D7 mit dem Pluspol des Elektrolytkondensators C3 verbunden. Parallel zum Elektrolytkondensator C3 ist ferner ein ohmscher Widerstand R13 geschaltet. Der mittenabgriff zwischen der Steuerelektrode des Thyristors TH und dem Diac DI ist über einen ohmschen Widerstand R14 mit dem Minuspol des Glättungskondensators C2 verbunden.To destroy the control gear in the event of an abnormal operating condition avoid, the circuit arrangement according to the invention has a safety shutdown, the inverter if the lamp is defective or in the event of an abnormal one Operating state switches off. An essential part of this safety shutdown is a thyristor TH, whose control electrode is controlled by a diac DI. Of the Thyristor TH is on the one hand via an ohmic holding resistor R10 with the collector of the transistor T1 and on the other hand with the negative pole of the smoothing capacitor C2 connected. The control electrode of the thyristor TH is via the diac DI and an electrolytic capacitor C3 with the negative pole of the smoothing capacitor C2 connected. The base connection of transistor T1 is via a diode D6 and a ohmic resistor R7 connected to the anode of thyristor TH. Parallel voltage dividing resistors R15, R16, R17 are connected to the smoothing capacitor C2. The center tap between the resistors R15 and R16 is via a diode D8 connected to the positive pole of the electrolytic capacitor C3. The center tap between the negative feedback capacitor CG, the electrode coil El, the Coupling capacitor CK and the resonance capacitance CR is across the resistors R8, R9 and R11 connected to the negative pole of the smoothing capacitor C2. Of the Center tap between the resistors R9 and R11 is connected via a diode D7 connected to the positive pole of the electrolytic capacitor C3. Parallel to the electrolytic capacitor C3, an ohmic resistor R13 is also connected. The center tap between the control electrode of the thyristor TH and the diac DI is via an ohmic Resistor R14 connected to the negative pole of smoothing capacitor C2.

Der Spannungsteiler R15, R16, R17 detektiert den Spannungsabfall am Glättungskondensator C2. Übersteigt dieser einen vorgegebenen kritischen Wert, so wird der Elektrolytkondensator C3 über die Diode D8 auf die Kippspannung des Diacs DI aufgeladen und der Thyristor TH schaltet durch, so daß die Basis des Transistors T1 mit dem Minuspol des Glättungskondensators C2 verbunden ist. Dadurch wird dem Transistor T1 das Steuersignal entzogen und der Halbbrückenwechselrichter abgeschaltet. Der Spannungsteiler R8, R9, R11 detektiert die Zünd- bzw. Betriebsspannung der Miniatur-Leuchtstofflampe L. Bei nicht zündwilliger Lampe L bzw. bei zu hoher Lampenbetriebsspannung (beispielsweise alterungsbedingt), wird der Elektrolytkondensator C3 über die Diode D7 ebenfalls auf die Kippspannung des Diacs DI aufgeladen, sodaß der Thyristor TH durchschaltet und dem Transistor T1 das Steuersignal entzogen wird. Der Widerstand R13 und der Elektrolytkondensator C3 definieren eine Zeitkonstante, so daß der Thyristor TH während der Zündphase der Lampe L nicht angesteuert wird.The voltage divider R15, R16, R17 detects the voltage drop across the smoothing capacitor C2. If this exceeds a predetermined critical value, the Electrolytic capacitor C3 is charged via diode D8 to the breakover voltage of Diacs DI and the thyristor TH turns on, so that the base of the transistor T1 with is connected to the negative pole of the smoothing capacitor C2. This will Transistor T1 withdraws the control signal and the half-bridge inverter is switched off. The voltage divider R8, R9, R11 detects the ignition or Operating voltage of the miniature fluorescent lamp L. If the lamp L does not ignite or if the lamp operating voltage is too high (for example due to aging) the electrolytic capacitor C3 via the diode D7 also to the breakover voltage of Diacs DI charged so that the thyristor TH turns on and the transistor T1 the control signal is withdrawn. The resistor R13 and the electrolytic capacitor C3 define a time constant so that the thyristor TH during the ignition phase the lamp L is not activated.

Eine geeignete Dimensionierung der elektrischen Bauelemente des oben näher beschriebenen Ausführungsbeispiels ist in der Tabelle 1 angegeben. R1, R4 10 Ω R2, R5 82 Ω R3, R6 0,56 Ω R7 100 Ω R8, R9, R16, R17 500 kΩ R10 68 kΩ R11 82 kΩ R13 1 MΩ R14 1 kΩ R15 47 kΩ C1 47 nF C2 4,7 µF C3 2,2 µF CS 4,7 nF CK 68 nF CR 2,2 nF CG 1 nF L1 1,5 mH LR 4,5 mH RKA:RKB:RKC 7:2:2 Windungen D1 - D8 RGL34J T1, T2 BUD 620 TH C106M A suitable dimensioning of the electrical components of the exemplary embodiment described in more detail above is given in Table 1. R1, R4 10 Ω R2, R5 82 Ω R3, R6 0.56 Ω R7 100 Ω R8, R9, R16, R17 500 kΩ R10 68 kΩ R11 82 kΩ R13 1 MΩ R14 1 kΩ R15 47 kΩ C1 47 nF C2 4.7 µF C3 2.2 µF CS 4.7 nF CK 68 nF CR 2.2 nF CG 1 nF L1 1.5 mH LR 4.5 mH RKA: RKB: RKC 7: 2: 2 turns D1 - D8 RGL34J T1, T2 BUD 620 TH C106M

Claims (5)

  1. Circuit arrangement for operating low-pressure discharge lamps, having
    a mains connection,
    an interference suppression filter (FI),
    a mains voltage rectifier (GL),
    an invertor (WR) which is connected to the DC voltage output of the mains voltage rectifier (GL) and has an LC output circuit,
    a smoothing capacitor (C2) in parallel with the input of the invertor (WR),
    at least one low-pressure discharge lamp (L) integrated into the LC output circuit of the invertor (WR),
    a radiofrequency bridge rectifier comprising two series circuits, arranged in parallel with one another, of in each case two diodes (D1, D2; D3, D4) which are integrated into the circuit in the DC forward direction between the DC voltage output of the mains voltage rectifier (GL) and the smoothing capacitor (C2),
    characterized in that
    the circuit arrangement has a storage inductor (L1) which is connected to the positive pole of the DC voltage output of the mains voltage rectifier (GL) and to the anode terminals of the diodes (D1, D3) of the radiofrequency bridge rectifier (D1, D2; D3, D4),
    the centre tap between the two first series-connected diodes (D1, D2) is connected via a negative feedback capacitor (CG) to a first lamp electrode (E1), and
    the centre tap between the two second series-connected diodes (D3, D4) is connected to the second lamp electrode (E2) as well as, via a support capacitor (CS), to the negative pole of the smoothing capacitor (C2).
  2. Circuit arrangement for operating low-pressure discharge lamps according to Claim 1, characterized in that the circuit arrangement has a capacitor (C1) which is connected in parallel with the DC voltage output of the mains voltage rectifier (GL).
  3. Circuit arrangement for operating low-pressure discharge lamps according to Claim 1, characterized in that the circuit arrangement has a fluorescent lamp (L) with preheatable electrode filaments (E1, E2).
  4. Circuit arrangement for operating low-pressure discharge lamps according to Claims 1 and 3, characterized in that
    the invertor (WR) is a half-bridge invertor with two alternatingly switching switching transistors (T1, T2), and the LC output circuit includes at least a resonance inductor (LR), a resonance capacitor (CR) and a coupling capacitor (CK),
    a first terminal of the first electrode filament (E1) is connected via the negative-feedback capacitor (CG) to the centre tap between the diodes (D1, D2),
    the first terminal of the first electrode filament (E1) is connected via the resonance capacitor (CR) to the centre tap between the diodes (D3, D4),
    the first terminal of the first electrode filament (E1) is connected via the coupling capacitor (CK) and the resonance inductor (LR) to the centre tap between the switching transistors (T1, T2) of the invertor (WR),
    a first terminal of the second electrode filament (E2) is connected to the resonance capacitor (CR) and to the centre tap between the diodes (D3, D4), and
    the second terminal of the first electrode filament (E1) is connected via components (SI, R) of an electrode heating circuit to the second terminal of the second electrode filament (E2).
  5. Circuit arrangement for operating low-pressure discharge lamps according to one or more of the preceding claims, characterized in that the circuit arrangement has a safety shutdown which switches off the circuit in the case of an anomalous operating state.
EP95103597A 1994-03-25 1995-03-13 Circuit for operating low-pressure discharge lamps Expired - Lifetime EP0679046B1 (en)

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DE4410492 1994-03-25
DE4410492A DE4410492A1 (en) 1994-03-25 1994-03-25 Circuit arrangement for operating low-pressure discharge lamps

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EP0679046B1 true EP0679046B1 (en) 1999-06-02

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JPH07272885A (en) 1995-10-20
DE59506071D1 (en) 1999-07-08
US5521467A (en) 1996-05-28
EP0679046A1 (en) 1995-10-25
DE4410492A1 (en) 1995-09-28
JP3599823B2 (en) 2004-12-08

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