EP0585727B1 - DC-AC converter with two charging capacitors connected in series - Google Patents

DC-AC converter with two charging capacitors connected in series Download PDF

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Publication number
EP0585727B1
EP0585727B1 EP93113170A EP93113170A EP0585727B1 EP 0585727 B1 EP0585727 B1 EP 0585727B1 EP 93113170 A EP93113170 A EP 93113170A EP 93113170 A EP93113170 A EP 93113170A EP 0585727 B1 EP0585727 B1 EP 0585727B1
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EP
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Prior art keywords
capacitors
series
smoothing
inverter
centre tap
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EP93113170A
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German (de)
French (fr)
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EP0585727A1 (en
Inventor
Bernard Ing. Apsner
Norbert Ing. Primisser
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Tridonic Bauelemente GmbH
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Tridonic Bauelemente GmbH
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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

Definitions

  • the present invention relates to an inverter of known type with two in series switched controllable switches between the inputs of the inverter, which a series circuit formed from two bridge capacitors is connected in parallel. At a Such a circuit arrangement connects the load circuit to the two center taps mentioned series circuits of switches and capacitors such as this from DE 40 21 640 A1 is known. Inverters of the type mentioned are particularly in Ballasts that control gas discharge lamps are used.
  • Inverters of the type described above tend to be instable as a result of partially negative characteristic of the lamp. These instabilities can Fluctuations in the supply voltage or changes in temperature occur.
  • the invention is therefore based on the object of an inverter circuit to specify, which avoids the above-mentioned instabilities in a simple manner.
  • instabilities in inverters of the type described above can be avoided in that the inverter has a relatively large Capacity is connected in parallel.
  • Such can for example in the form of a Smoothing capacitor of the rectifier circuit may be present.
  • This can occurring instabilities apparently not to be avoided, since the usually as Smoothing capacitors used electrolytic capacitors in the Inverter frequency in the kilohertz range have a different behavior than in Grid frequency, i.e. in this frequency range they no longer act as pure Capacitors.
  • a ballast for gas discharge lamps, the inverter of the above Art includes, is known for example from EP 0 392 834.
  • the one revealed in it Circuit arrangement contains an inverter with two series connected controllable switches, a load circuit of the lamp and a charging capacitor, one capacitive charge pump circuit and a smoothing capacitor of the rectifier.
  • the capacitive charge pump circuit is a trick circuit consisting of four capacitors and two diodes to reduce the harmonic content.
  • a Ballast for a gas discharge lamp with one powered by the mains Rectifier that has a smoothing circuit between its two outputs and in turn supplies an inverter that has two series and includes controllable switches located between the two inputs; one parallel to the two controllable switches arranged in series from two directly connected bridge capacities; and a load that the center tap of the Series connection of the two switches with the center tap of the bridge capacities connects.
  • the smoothing circuit consists of two series and directly connected smoothing capacities, the center tap of the Bridge capacities is directly with the center tap of the two smoothing capacities connected is.
  • the measure according to the invention leads to the goal without considerable additional effort, since the two smoothing capacitors now used and connected in series are only exposed to half the rectified AC voltage and accordingly even have to endure half the maximum voltage.
  • Figure 1 shows an example of the structure of a self-oscillating inverter.
  • Series connection of two controllable switches 101, 102 preferably transistors or field effect transistors.
  • An output terminal c of the inverter is via a Primary winding 109 of a transformer to one designated as the center tap p Potential point connected to the collector of lower transistor 102 connected.
  • the emitter and the base of the upper transistor 101 are opposite the potential point p biased by resistors 105 and 104, respectively.
  • Base bias resistor 104 is a series connection of another resistor 103 and a secondary winding 110 of the transformer.
  • the start The oscillation process is carried out by a start pulse which is sent to the base via a diac 112 of the lower transistor 102 is transmitted.
  • a start pulse which is sent to the base via a diac 112 of the lower transistor 102 is transmitted.
  • the inverter hears everyone Zero crossing of the input voltage to swing on. In this case it is not only at the start of the inverter but also at every zero crossing Input voltage triggering of the switches necessary.
  • both switches are open at the beginning. If a trigger signal is now transmitted to the lower switch 102, this closes and a load current can flow. Via the transmitter, i.e. over its primary winding 109, after a certain time the lower switch becomes by means of the secondary winding 111 opened again and the upper switch 101 by means of the secondary winding 110 closed. The while the lower switch 102 is closed over the reactor 115 and switch 102 current flowing to ground will open maintain the switch through the choke 115. This forced flow of electricity leads without the freewheeling diodes 113, 114 to excessive voltage on components of the Inverter that can destroy them.
  • bipolar transistors are used, which can of course be replaced by, for example, field effect transistors.
  • Field effect transistors are generally dashed in the prior art drawn external freewheeling diodes waived, since the field effect transistors already have such diodes internally.
  • FIG. 3 shows an inverter circuit with one connected to it Gas discharge lamp.
  • the one indicated in FIG. 1 attacking terminal c Load circuit has inductance 215 and a parallel connection from the Gas discharge lamp 216 and a capacitor 217, which are arranged in series and end at a terminal d.
  • Form inductor 215 and capacitor 217 the series resonant circuit necessary for the operation of the gas discharge lamp 216.
  • Point d is the center tap of a series connection of two bridge capacitors 218, 219, the between the positive input a and the reference potential input b of the Inverter is arranged.
  • the one electrolytic capacitor according to the invention by two in Series-connected and directly connected smoothing capacitors 220, 221 lower capacity and half maximum voltage replaced, for the commercial Electrolytic capacitors can be used.
  • 221 directly interconnecting conductor 222 can bridge capacitors 218, 219 through the smoothing capacitances 220, 221 are capacitively stabilized.
  • the gas discharge lamp 216 is largely stable and independent of voltage and temperature fluctuations.

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  • Circuit Arrangements For Discharge Lamps (AREA)
  • Inverter Devices (AREA)

Abstract

A ballast for a gas-discharge lamp having a rectifier which is supplied from the mains, has two smoothing capacitors (220, 221) in a series circuit between its two outputs and, for its part, supplies an invertor which comprises two controllable switches (201, 202) which are arranged in series and are connected between the two inputs (A, B); a series circuit which is arranged in parallel with the two controllable switches (201,202) and consists of two further capacitors (218,219); and a series circuit consisting of a primary winding (209) of a saturable transformer, an inductor (215) and a parallel circuit comprising a capacitor (217) and the gas-discharge lamp (216), the series circuit connecting the centre tap of the two switches (201, 202) to the centre tap of the two further capacitors (218, 219), and the centre tap of the two further capacitors (218, 219) being connected via a conductor (222) to the centre tap of the two smoothing capacitors (220, 221). <IMAGE>

Description

Die vorliegende Erfindung betrifft einen Wechselrichter bekannter Art mit zwei in Serie geschalteten steuerbaren Schaltern zwischen den Eingängen des Wechselrichters, denen eine aus zwei Brücken-Kondensatoren gebildete Serienschaltung parallel liegt. Bei einer solchen Schaltungsanordnung verbindet der Lastkreis die beiden Mittelabgriffe der genannten Serienschaltungen aus Schaltern und Kondensatoren wie dies aus der DE 40 21 640 A1 bekannt ist. Wechselrichter der genannten Art werden insbesondere in Vorschaltgeräten, die Gasentladungslampen ansteuern, eingesetzt.The present invention relates to an inverter of known type with two in series switched controllable switches between the inputs of the inverter, which a series circuit formed from two bridge capacitors is connected in parallel. At a Such a circuit arrangement connects the load circuit to the two center taps mentioned series circuits of switches and capacitors such as this from DE 40 21 640 A1 is known. Inverters of the type mentioned are particularly in Ballasts that control gas discharge lamps are used.

Wechselrichter der vorstehend bezeichneten Art neigen zu Instabilitäten in Folge der teilweise negativen Kennlinie der Lampe. Diese Instabilitäten können bei Schwankungen der Versorgungsspannung oder bei Temperaturänderungen auftreten.Inverters of the type described above tend to be instable as a result of partially negative characteristic of the lamp. These instabilities can Fluctuations in the supply voltage or changes in temperature occur.

Der Erfindung liegt daher die Aufgabe zugrunde, eine Wechselrichlerschaltung anzugeben, die oben genannte Instabilitäten auf einfache Art und Weise vermeidet.The invention is therefore based on the object of an inverter circuit to specify, which avoids the above-mentioned instabilities in a simple manner.

Es ist bekannt, daß Instabilitäten bei Wechselrichtern der oben beschriebenen Art dadurch vermieden werden können, daß dem Wechselrichter eine relativ große Kapazität parallel geschaltet wird. Eine solche kann beispielsweise in Form eines Glättungskondensators der Gleichrichterschaltung vorhanden sein. Diese vermag die auftretenden Instabilitäten jedoch offenbar nicht zu vermeiden, da die üblicherweise als Glättungskondensatoren verwendeten Elektrolytkondensatoren bei der Wechselrichterfrequenz im Kilohertz-Bereich ein anderes Verhalten aufweisen als bei Netzfrequenz, d.h. sie wirken in diesem Frequenzbereich nicht mehr als reine Kondensatoren.It is known that instabilities in inverters of the type described above can be avoided in that the inverter has a relatively large Capacity is connected in parallel. Such can for example in the form of a Smoothing capacitor of the rectifier circuit may be present. This can occurring instabilities apparently not to be avoided, since the usually as Smoothing capacitors used electrolytic capacitors in the Inverter frequency in the kilohertz range have a different behavior than in Grid frequency, i.e. in this frequency range they no longer act as pure Capacitors.

Ein Vorschaltgerät für Gasentladungslampen, das einen Wechselrichter der genannten Art beinhaltet, ist beispielsweise aus der EP 0 392 834 bekannt. Die darin offenbarte Schaltungsanordnung enthält einen Wechselrichter mit zwei in Serie geschalteten steuerbaren Schaltern, einem Lastkreis der Lampe und einem Ladekondensator, eine kapazitive Ladungspumpschaltung und einen Glättungskondensator des Gleichrichters. Die kapazitive Ladungspumpschaltung ist eine Trickschaltung aus vier Kondensatoren und zwei Dioden zur Verringerung des Oberwellengehaltes. A ballast for gas discharge lamps, the inverter of the above Art includes, is known for example from EP 0 392 834. The one revealed in it Circuit arrangement contains an inverter with two series connected controllable switches, a load circuit of the lamp and a charging capacitor, one capacitive charge pump circuit and a smoothing capacitor of the rectifier. The capacitive charge pump circuit is a trick circuit consisting of four capacitors and two diodes to reduce the harmonic content.

Weiter ist aus der US 4,914,558 ein Vorschaltgerät für Gasentladungslampen mit Wechselrichter bekannt, der zwei in Serie geschaltete steuerbare Schalter, einen Lastkreis mit Gasentladungslampen und einen Ladekondensator aufweist. Außerdem enthält die Schaltung einen Glättungskondensator des Gleichrichters und eine sogenannte Hochleistungsfaktorschaltung aus vier Dioden und vier Kondensatoren zur Verbesserung des Leistungsfaktors.From US 4,914,558 is a ballast for gas discharge lamps Known inverter, the two series-connected controllable switches, one Load circuit with gas discharge lamps and a charging capacitor. Furthermore the circuit includes a rectifier smoothing capacitor and one So-called high-power factor circuit consisting of four diodes and four capacitors Improvement of the power factor.

Beide genannten Vorschaltgeräte enthalten zwar einen Glättungskondensator, dieser kann aber auftretende Instabilitäten des Wechselrichters aus zuvor beschriebenen Gründen nicht vermeiden.Both ballasts mentioned contain a smoothing capacitor can occur instabilities of the inverter from previously described Don't avoid reasons.

Die zuvor genannte Aufgabe der vorliegenden Erfindung wird gelöst durch ein Vorschaltgerät für eine Gasentladungslampe mit einem vom Netz gespeisten Gleichrichter, der eine Glättungsschaltung zwischen seinen beiden Ausgängen aufweist und seinerseits einen Wechselrichter versorgt, der zwei in Serie angeordnete und zwischen den beiden Eingängen liegende steuerbare Schalter umfaßt; einer parallel zu den beiden steuerbaren Schaltern angeordneten Serienschaltung aus zwei direkt verbundenen Brücken-Kapazitäten; und einer Last, die den Mittelabgriff der Serienschaltung der beiden Schalter mit dem Mittelabgriff der Brücken-Kapazitäten verbindet. Dabei besteht die Glättungsschaltung aus zwei in Serie geschalteten und unmittelbar miteinander verbundenen Glättungskapazitäten, wobei der Mittelabgriff der Brücken-Kapazitäten ist direkt mit dem Mittelabgriff der beiden Glättungskapazitäten verbunden ist.The aforementioned object of the present invention is achieved by a Ballast for a gas discharge lamp with one powered by the mains Rectifier that has a smoothing circuit between its two outputs and in turn supplies an inverter that has two series and includes controllable switches located between the two inputs; one parallel to the two controllable switches arranged in series from two directly connected bridge capacities; and a load that the center tap of the Series connection of the two switches with the center tap of the bridge capacities connects. The smoothing circuit consists of two series and directly connected smoothing capacities, the center tap of the Bridge capacities is directly with the center tap of the two smoothing capacities connected is.

Die erfindungsgemäße Maßnahme führt ohne erheblichen Mehraufwand zum Ziel, da die beiden nunmehr verwendeten und in Serie geschalteten Glättungskondensatoren jeweils nur der halben gleichgerichteten Wechselspannung ausgesetzt sind und demnach auch nur die halbe Maximalspannung aushalten müssen. Bei Verwendung von handelsüblichen Glättungskondensatoren bedeutet dies, daß anstelle eines großen Bauelementes zwei kleinere Bauelemente verwendet werden können.The measure according to the invention leads to the goal without considerable additional effort, since the two smoothing capacitors now used and connected in series are only exposed to half the rectified AC voltage and accordingly even have to endure half the maximum voltage. When using commercially available smoothing capacitors, this means that instead of a large one Component two smaller components can be used.

Ein Ausführungsbeispiel der Erfindung wird nun anhand der Zeichnungen beschrieben. Darin zeigen:

  • Fig. 1 einen in einem Vorschaltgerät eingesetzten Wechselrichter;
  • Fig. 2 den Stromverlauf des durch den Schalter 102 fließenden Stroms
  • Fig. 3 ein weiteres Ausführungsbeispiel eines Wechselrichters mit angeschlossener Last.
    • An embodiment of the invention will now be described with reference to the drawings. In it show:
  • 1 shows an inverter used in a ballast;
  • 2 shows the current profile of the current flowing through the switch 102
  • Fig. 3 shows another embodiment of an inverter with a connected load.

    • Figur 1 zeigt beispielhaft den Aufbau eines selbstschwingenden Wechselrichters. Zwischen den Eingangsklemmen a und b, die üblicherweise mit den entsprechenden Ausgängen eines Gleichrichters bzw. eines Sperrwandlers verbunden sind, liegt eine Serienschaltung aus zwei steuerbaren Schaltern 101, 102, vorzugsweise Transistoren oder Feldeffekttransistoren. Eine Ausgangsklemme c des Wechselrichters ist über eine Primärwicklung 109 eines Übertragers an einen als Mittelpunktabgriff p bezeichneten Potentialpunkt, der mit dem Kollektor des unteren Transistors 102 verbunden ist, angeschlossen. Der Emitter, sowie die Basis des oberen Transistors 101 sind gegenüber dem Potentialpunkt p über Widerstände 105 bzw. 104 vorgespannt. Parallel zu dem Basisvorspannwiderstand 104 liegt eine Reihenschaltung aus einem weiteren Widerstand 103 und einer Sekundärwicklung 110 des Übertragers. Die gleiche Anordnung zur Vorspannung über die Widerstände 107, 108 und zur Steuerung über eine Sekundärwicklung 111 und den Widerstand 106 weist der zwischen dem Potentialpunkt p und dem Bezugspotential liegende Transistor 103 auf. Allerdings sind die im Steuerkreis befindlichen Sekundärwicklungen 110, 111 gegensinnig angeordnet. Mit dem Ausgang c des Wechselrichters ist ein Lastkreis verbunden, der eine ohmschinduktive Last aufweist. Aus Übersichtlichkeitsgründen wurde jedoch auf die Darstellung des kompletten Lastkreises verzichtet und lediglich eine Induktivität 115 eingezeichnet. Ein solcher Lastkreis besteht normalerweise aus zumindest einer Serienschaltung aus einer Spule und einem Kondensator, wobei die Gasentladungslampe oder allgemein die Last parallel zum Kondensator geschaltet ist. Eine mit ihrer Anode an Punkt c angeschlossene Freilaufdiode 113 ist mit dem Eingang a und die mit ihrer Kathode an den Punkt c angeschlossene Freilaufdiode 114 mit dem Bezugspotential verbunden.Figure 1 shows an example of the structure of a self-oscillating inverter. Between the input terminals a and b, usually with the corresponding Outputs of a rectifier or a flyback converter are connected Series connection of two controllable switches 101, 102, preferably transistors or field effect transistors. An output terminal c of the inverter is via a Primary winding 109 of a transformer to one designated as the center tap p Potential point connected to the collector of lower transistor 102 connected. The emitter and the base of the upper transistor 101 are opposite the potential point p biased by resistors 105 and 104, respectively. In parallel to that Base bias resistor 104 is a series connection of another resistor 103 and a secondary winding 110 of the transformer. The same arrangement for Bias across resistors 107, 108 and for control via a Secondary winding 111 and the resistor 106 has between the potential point p and the reference potential lying transistor 103. However, in the Control circuit located secondary windings 110, 111 arranged in opposite directions. With the output c of the inverter is connected to a load circuit, which is an ohmic inductive Has load. For reasons of clarity, however, the Representation of the complete load circuit is dispensed with and only one inductance 115 drawn. Such a load circuit usually consists of at least one Series connection of a coil and a capacitor, the gas discharge lamp or generally the load is connected in parallel to the capacitor. One with its anode at point c connected freewheeling diode 113 is connected to the input a and with Free-wheeling diode 114 connected to point c with the reference potential connected.

    Die spezielle Funktionsweise eines Wechselrichters ist aus dem Stand der Technik bekannt und wird aus diesem Grund nachfolgend nicht näher erläutert.The special mode of operation of an inverter is state of the art is known and is therefore not explained in more detail below.

    Allgemein werden die beiden Transistoren über die Sekundärwicklungen 110, 111 vom Übertrager so gesteuert, daß sie abwechselnd öffnen und schließen, wodurch am Ausgang c eine im wesentlichen rechteckförmige Wechselspannung entsteht. Der Start des Schwingvorgangs erfolgt durch einen Startimpuls, der über ein Diac 112 zur Basis des unteren Transistors 102 übertragen wird. Ein solches Triggern ist immer dann notwendig, wenn der Wechselrichter nicht mit einer konstanten Gleichspannung gespeist wird. Liegt am Eingang des Wechselrichters bspw. die vom Gleichrichter gelieferte gleichgerichtete Wechselspannung, hört der Wechselrichter bei jedem Nulldurchgang der Eingangsspannung auf zu schwingen. In diesem Fall ist demnach nicht nur beim Start des Wechselrichters sondern auch bei jedem Nulldurchgang der Eingangsspannung ein Triggern der Schalter notwendig.In general, the two transistors via the secondary windings 110, 111 from Transmitter controlled so that they open and close alternately, which on Output c produces an essentially rectangular AC voltage. The start The oscillation process is carried out by a start pulse which is sent to the base via a diac 112 of the lower transistor 102 is transmitted. There is always such a trigger necessary if the inverter does not have a constant DC voltage is fed. Is at the input of the inverter, for example that of the rectifier supplied rectified AC voltage, the inverter hears everyone Zero crossing of the input voltage to swing on. In this case it is not only at the start of the inverter but also at every zero crossing Input voltage triggering of the switches necessary.

    Es soll davon ausgegangen werden, daß zu Beginn beide Schalter geöffnet sind. Wird nun ein Triggersignal an den unteren Schalter 102 übertragen, schließt dieser und ein Laststrom kann fließen. Über den Übertrager, d.h. über dessen Primärwicklung 109, wird nach einer bestimmten Zeit der untere Schalter mittels der Sekundärwicklung 111 wieder geöffnet und der obere Schalter 101 mittels der Sekundärwicklung 110 geschlossen. Der während des geschlossenen Zustands des unteren Schalters 102 über die Drossel 115 und den Schalter 102 nach Masse fließende Strom wird beim Öffnen des Schalters durch die Drossel 115 aufrechterhalten. Dieser erzwungene Stromfluß führt ohne die Freilaufdioden 113, 114 zu Spannungsüberhöhungen an Bauteilen des Wechselrichters, die zur Zerstörung derselben führen können.It should be assumed that both switches are open at the beginning. If a trigger signal is now transmitted to the lower switch 102, this closes and a load current can flow. Via the transmitter, i.e. over its primary winding 109, after a certain time the lower switch becomes by means of the secondary winding 111 opened again and the upper switch 101 by means of the secondary winding 110 closed. The while the lower switch 102 is closed over the reactor 115 and switch 102 current flowing to ground will open maintain the switch through the choke 115. This forced flow of electricity leads without the freewheeling diodes 113, 114 to excessive voltage on components of the Inverter that can destroy them.

    In dem eben beschriebenen Fall kann der erzwungene Stromfluß über die obere Freilaufdiode 113 abfließen, ohne die Primärwicklung 109 des Übertragers zu passieren. Wären die Freilaufdioden so angeordnet, wie dies die gestrichelte Darstellung in Figur 1 zeigt, würde der erzwungene Stromfluß über die obere Freilaufdiode 113 auch durch die Primärwicklung 109 fließen. Dies hätte zur Folge, daß in der Sekundärwicklung 110 bzw. 111 eine Spannung induziert wird, die dem Abschaltvorgang des Transistors 101 entgegenwirkt. Figur 2 zeigt, daß dem Strom durch den Transistor 102 nach dem Absinken auf Null nochmals ein kleiner Stromhöcker folgt. Ein solcher zusätzlich fließender Strom verbraucht Energie und verschlechtert damit den Wirkungsgrad des Wechselrichters und die gewünschte Schaltgenauigkeit.In the case just described, the forced current flow through the upper Freewheeling diode 113 drain off without the primary winding 109 of the transformer happen. If the freewheeling diodes were arranged as shown in dashed lines Representation in Figure 1 shows the forced current flow across the top Free-wheeling diode 113 also flow through the primary winding 109. As a result, that a voltage is induced in the secondary winding 110 or 111, the Switching off of transistor 101 counteracts. Figure 2 shows that the current through the transistor 102 after sinking to zero again a small one Stromhöcker follows. Such an additional flowing current consumes energy and deteriorates the efficiency of the inverter and the desired Switching accuracy.

    In der angegebenen Schaltungsanordnung werden bipolare Transistoren verwendet, die sich selbstverständlich durch bspw. Feldeffekttransistoren ersetzten lassen. Bei Feldeffekttransistoren wird grundsätzlich im Stand der Technik auf die gestrichelt eingezeichneten externen Freilaufdioden verzichtet, da die Feldeffekttransistoren bereits intern über solche Dioden verfügen. In the specified circuit arrangement, bipolar transistors are used, which can of course be replaced by, for example, field effect transistors. At Field effect transistors are generally dashed in the prior art drawn external freewheeling diodes waived, since the field effect transistors already have such diodes internally.

    Figur 3 zeigt eine Wechselrichterschaltung mit einer daran angeschlossenen Gasentladunglsampe. Aus Übersichtlichkeitsgründen wurde der Aufbau des Wechselrichters stark vereinfacht dargestellt, da er im wesentlichen dem in Figur 1 gezeigten entspricht. Der in Figur 1 nur angedeutete an Klemme c angreifende Lastkreis weist die Induktivität 215 und eine Parallelschaltung aus der Gasentladungslampe 216 und einer Kondensator 217 auf, die in Reihe angeordnet sind und an einer Klemme d enden. Die Induktivität 215 und der Kondensator 217 bilden den für den Betrieb der Gasentladungslampe 216 notwendigen Serienschwingkreis. Der Punkt d ist der Mittelabgriff einer Serienschaltung aus zwei Brückenkapazitäten 218, 219, die zwischen dem positiven Eingang a und dem Bezugspotentialeingang b des Wechselrichters angeordnet ist. Zu dieser Serienschaltung parallel liegt eine weitere Serienschaltung aus zwei Glättungskapazitäten 220, 221, vorzugsweise Elektrolytkondensatoren, wobei die Mittelabgriffe der beiden Serienschaltungen mittels eines Leiters 222 direkt verbunden sind. FIG. 3 shows an inverter circuit with one connected to it Gas discharge lamp. For reasons of clarity, the structure of the Inverter is shown in a highly simplified manner, since it essentially corresponds to that in FIG shown shown. The one indicated in FIG. 1 attacking terminal c Load circuit has inductance 215 and a parallel connection from the Gas discharge lamp 216 and a capacitor 217, which are arranged in series and end at a terminal d. Form inductor 215 and capacitor 217 the series resonant circuit necessary for the operation of the gas discharge lamp 216. Of the Point d is the center tap of a series connection of two bridge capacitors 218, 219, the between the positive input a and the reference potential input b of the Inverter is arranged. There is another parallel to this series connection Series connection of two smoothing capacitors 220, 221, preferably Electrolytic capacitors, with the center taps of the two series circuits using a conductor 222 are directly connected.

    Allgemein neigen selbstschwingende Wechselrichter der vorstehend bezeichneten Art zu Instabilitäten infolge der teilweise negativen Kennlinie der Gasentladungslampe. Diese Instabilitäten können bei Schwankungen der Versorgungsspannung oder bei Temperaturänderungen auftreten. Zur Stabilisierung der von einem Gleichrichter zur Verfügung gestellten Versorgungsspannung, die an den Eingängen a, b des gezeigten Wechselrichters anliegt, wird üblicherweise eine Glättungsschaltung aus nur einem Elektrolytkondensator mit großer Kapazität gewählt. Dieser zur Glättung der Eingangsspannung des Wechselrichters eingesetzte Elektrolytkondensator weist jedoch bei den hier auftretenden Betriebsfrequenzen im Kilohertz-Bereich ein anderes Verhalten auf als bei niedrigen Frequenzen, d.h. er arbeitet nicht mehr als reine Kapazität.In general, self-oscillating inverters of the type described above tend to Instabilities due to the partially negative characteristic of the gas discharge lamp. This Instabilities can occur in the event of fluctuations in the supply voltage or Temperature changes occur. To stabilize the from a rectifier Provided supply voltage, which at the inputs a, b of the shown Inverter is present, is usually a smoothing circuit from only one Large capacity electrolytic capacitor selected. This to smooth the However, the input voltage of the inverter used electrolytic capacitor has the operating frequencies in the kilohertz range are different Behavior on than at low frequencies, i.e. he no longer works as pure Capacity.

    Aus diesem Grund wird der eine Elektrolytkondensator erfindungsgemäß durch zwei in Serie geschaltete und direkt miteinander verbundene Glättungskapazitäten 220, 221 niedrigerer Kapazität und halber Maximalspannung ersetzt, für die handelsübliche Elektrolytkondensatoren eingesetzt werden können. Mit Hilfe des die beiden Mittelabgriffe der Kapazitäten-Serienschaltungen 218, 219 und 220, 221 direkt miteinander verbindenden Leiters 222 können die Brückenkapazitäten 218, 219 durch die Glättungskapazitäten 220, 221 kapazitiv stabilisiert werden.For this reason, the one electrolytic capacitor according to the invention by two in Series-connected and directly connected smoothing capacitors 220, 221 lower capacity and half maximum voltage replaced, for the commercial Electrolytic capacitors can be used. With the help of the two Center taps of the capacitance series circuits 218, 219 and 220, 221 directly interconnecting conductor 222 can bridge capacitors 218, 219 through the smoothing capacitances 220, 221 are capacitively stabilized.

    Das Ergebnis ist, daß die Gasentladungslampe 216 weitgehend stabil und unabhängig von Spannungs- und Temperaturschwankungen arbeitet.The result is that the gas discharge lamp 216 is largely stable and independent of voltage and temperature fluctuations.

    Claims (6)

    1. Ballast for a gas-discharge lamp having a mains-supplied rectifier, which comprises a smoothing circuit (220, 221) between its two outputs and in turn supplies an inverter, which comprises two controllable switches (201, 202) arranged in series and located between the two inputs (A, B):
      a series connection arranged parallel to the two controllable switches (201, 202) and comprising two directly connected bridge capacitors (218, 219); and
      a load, which connects the centre tap of the series connection of the two switches (201, 202) with the centre tap of the bridge capacitors (218, 219),
      characterised in that the smoothing circuit consists of two smoothing capacitors (220, 221) connected in series and directly to each other; and
      the centre tap of the bridge capacitors (218, 219) is directly connected to the centre tap of the two smoothing capacitors (220, 221).
    2. Ballast according to claim 1,
      characterised in that
      the controllable switches (201, 202) are transistors and/or field-effect transistors.
    3. Ballast according to claim 1 or claim 2,
      characterised in that
      the load comprises a series connection consisting of a primary winding (209) of a transformer, an inductor (215) and a parallel connection consisting of a capacitor (217) and the gas-discharge lamp (216).
    4. Ballast according to claim 3,
      characterised in that
      the transformer comprises secondary windings (211, 216), wherein one secondary winding (211 or 216 respectively) is arranged in the control circuit of each switch (201 or 202 respectively).
    5. Ballast according to claim 4,
      characterised in that
      at least one control circuit of one switch (211) is connected with a trigger element (212).
    6. Ballast according to any one of the preceding claims,
      characterised in that
      the smoothing capacitors (220, 221) are electrolytic capacitors.
    EP93113170A 1992-08-28 1993-08-17 DC-AC converter with two charging capacitors connected in series Expired - Lifetime EP0585727B1 (en)

    Applications Claiming Priority (2)

    Application Number Priority Date Filing Date Title
    DE4228682A DE4228682A1 (en) 1992-08-28 1992-08-28 Ballast for a gas discharge lamp with an inverter circuit
    DE4228682 1992-08-28

    Publications (2)

    Publication Number Publication Date
    EP0585727A1 EP0585727A1 (en) 1994-03-09
    EP0585727B1 true EP0585727B1 (en) 1998-11-18

    Family

    ID=6466668

    Family Applications (1)

    Application Number Title Priority Date Filing Date
    EP93113170A Expired - Lifetime EP0585727B1 (en) 1992-08-28 1993-08-17 DC-AC converter with two charging capacitors connected in series

    Country Status (3)

    Country Link
    EP (1) EP0585727B1 (en)
    AT (1) ATE173576T1 (en)
    DE (2) DE4228682A1 (en)

    Families Citing this family (1)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    US6731075B2 (en) 2001-11-02 2004-05-04 Ampr Llc Method and apparatus for lighting a discharge lamp

    Citations (1)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    DE4021640A1 (en) * 1990-07-06 1992-01-09 Zumtobel Ag BRIGHTNESS CONTROL CIRCUIT ARRANGEMENT

    Family Cites Families (7)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    DE2909605A1 (en) * 1979-03-12 1980-09-25 Patra Patent Treuhand CONTROL UNIT FOR OPERATING A DISCHARGE LAMP
    GB2124042B (en) * 1982-06-01 1986-10-01 Control Logic Reduction of harmonics in gas discharge lamp ballasts
    AU2388284A (en) * 1983-01-28 1984-08-02 Control Logic Pty. Ltd. Inverter circuit
    US4996462A (en) * 1988-07-27 1991-02-26 Siemens Aktiengesellschaft Electronic ballast for fluoroscent lamps
    US4914558A (en) * 1989-03-06 1990-04-03 Jon Flickinger Series resonant inverter and method of lamp starting
    EP0392834B1 (en) * 1989-04-14 1995-02-15 TLG plc Ballast circuits for gas discharge lamps
    IL93265A0 (en) * 1990-02-04 1990-11-29 Gaash Lighting Ind Electronic ballast for gas discharge lamp

    Patent Citations (1)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    DE4021640A1 (en) * 1990-07-06 1992-01-09 Zumtobel Ag BRIGHTNESS CONTROL CIRCUIT ARRANGEMENT

    Also Published As

    Publication number Publication date
    EP0585727A1 (en) 1994-03-09
    DE59309134D1 (en) 1998-12-24
    DE4228682A1 (en) 1994-03-03
    ATE173576T1 (en) 1998-12-15

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