Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
  • H05B41/14—Circuit arrangements
  • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from DC by means of a converter, e.g. by high-voltage DC
  • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from DC by means of a converter, e.g. by high-voltage DC using static converters
  • H05B41/288—Circuit arrangements in which the lamp is fed by power derived from DC by means of a converter, e.g. by high-voltage DC using static converters with semiconductor devices and specially adapted for lamps without preheating electrodes, e.g. for high-intensity discharge lamps, high-pressure mercury or sodium lamps or low-pressure sodium lamps
  • H05B41/2881—Load circuits; Control thereof
  • H05B41/2882—Load circuits; Control thereof the control resulting from an action on the static converter
  • H05B41/2883—Load circuits; Control thereof the control resulting from an action on the static converter the controlled element being a DC/AC converter in the final stage, e.g. by harmonic mode starting
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
  • H05B41/14—Circuit arrangements
  • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from DC by means of a converter, e.g. by high-voltage DC
  • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from DC by means of a converter, e.g. by high-voltage DC using static converters
  • H05B41/288—Circuit arrangements in which the lamp is fed by power derived from DC by means of a converter, e.g. by high-voltage DC using static converters with semiconductor devices and specially adapted for lamps without preheating electrodes, e.g. for high-intensity discharge lamps, high-pressure mercury or sodium lamps or low-pressure sodium lamps
  • H05B41/292—Arrangements for protecting lamps or circuits against abnormal operating conditions
  • H05B41/2928—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the lamp against abnormal operating conditions
• • 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 present invention relates to a circuit arrangement for operating a high-pressure discharge lamp comprising a bridge circuit having at least two switches and a control device which is designed to control the at least two switches. It also relates to an operating method for a high-pressure discharge lamp in a circuit arrangement comprising a half-bridge circuit with exactly two switches, a control device which switches the first and the second switch of the half-bridge circuit on and off alternately at a first frequency, and during the off-phase of a switch drives the other switch with a square wave signal of a second frequency, which is greater than the first frequency, and a predetermined duty cycle.
• the present invention generally relates to the problem of extinguishing high-pressure discharge lamps.
• high pressure discharge lamps are connected to a full bridge circuit, i. H. on a bridge circuit with four switches.
• a full bridge circuit i. H. on a bridge circuit with four switches.
• the object of the present invention is therefore to provide the circuit arrangement mentioned at the outset or the operating method mentioned at the outset. ren educate such that the operation of as many types of high pressure discharge lamps is also possible using a half-bridge circuit.
• the present invention is based on the finding that a half-bridge circuit is less "stiff" in comparison to a full-bridge circuit, ie has less voltage reserves (insufficient open circuit voltage) DC link voltage Uzw, which is applied to the half-bridge circuit, as well as the time course of the current I L through the lamp and the voltage U L on the lamp
• the zero line for the voltage U L is marked “4", while the zero line for the current I L is denoted by "3".
• a control device which alternately the first and the second switches of the half bridge circuit switched at a first frequency and off and during the off phase of the one switch to another switch with a square-wave signal of a second frequency , which is greater than the first frequency, and a predetermined Einschaltdau
• the first frequency is in the embodiment of Fig. 1 at 160 Hz, while the second frequency is 90 kHz.
• the duty cycle of the square wave signal of the second frequency is constant and is about 6 ⁇ s.
• FIG. 1 provides the following result: Because of the real transducer output characteristic, which is flatter in a half-bridge circuit than in a full-bridge circuit, the burning voltage of the high-pressure discharge lamp after commutation increases due to the extremely non-linear load which constitutes a high-pressure discharge lamp.
• the lamp current I L rises after the commutation only to about half of nominal value and then decreases due to plasma cooling and consequent further increase in the burning voltage to zero.
• a power controller would be considered, which regulates the power converted in the high-pressure discharge lamp to its desired value.
• power regulators are inherently slow ( ⁇ approximately 100 ms) and can not counteract the sudden high resistance of the high-pressure discharge lamp, see FIG. 1, ( ⁇ approximately 4 ms) almost fast enough.
• a measurement of the lamp current I L is possible with reasonable effort in a half-bridge circuit only in one direction with respect to the first frequency. Monitoring in the other direction would therefore be "blind” and could not counteract the increase in the burning voltage taking place during such a cycle.
• a measurement of the lamp current in both current directions continuously or at a high sampling rate results in an undesirably high outlay, especially if, as in the exemplary embodiment , the first frequency is relatively low.
• the invention takes a different approach. First, it is based on the knowledge that an increase in the burning voltage must be counteracted by an increase in the lamp current. An increase of the burning voltage can be detected easily with a voltage measuring device. This can be done without much effort for both directions - A -
• the first frequency is also based on keeping the first frequency essentially constant, but instead increasing the switch-on duration of the signal with which one switch of the half-bridge circuit is activated during the off phase of the other switch, at least for a predefinable period of time. This can cause an increase in the lamp current, which together with the increase in the operating voltage of the lamp leads to a power converted in the lamp, which is sufficient to prevent cooling of the plasma, which would cause the lamp to extinguish.
• the second frequency is reduced. This offers the advantage that the half-bridge switches then turn on when the current in the lamp inductor is equal to zero. This reduces the switching losses in the half-bridge switches.
• the second frequency is at least 15 kHz, while the first frequency is at most 500 Hz.
• the predefinable time duration of the increase of the duty cycle is at least 30 ⁇ s, in particular at least 100 ⁇ s, and at most 3 ms, in particular at most 500 ⁇ s.
• the voltage measuring device, the reference value device, the comparison device and the Control device dimensioned such that the period between the actual exceeding of the at least one limit value and the control of the two switches of the half-bridge circuit with the increased duty cycle is a maximum of 1 ms, in particular a maximum of 0.3 ms.
• the at least one threshold may be a constant threshold, but may also be a threshold that depends on the average voltage across the high pressure discharge lamp.
• the latter realization takes into account an age-related shift in the standard burning voltage and makes it possible to detect a deviation independently of the life of the high-pressure discharge lamp.
• the average voltage of the high-pressure discharge lamp is preferably updated at equidistant times, for example every 50 to 100 ms.
• control device is designed to measure the increase of the duty cycle as a function of the measured voltage across the high-pressure discharge lamp and / or the time average of the voltage across the high-pressure discharge lamp and / or from the relevant limit value.
• the control device can furthermore be designed to ignore an exceeding of the limit value by the voltage measured at the high-pressure discharge lamp after the commutation of the current by the high-pressure discharge lamp for a predefinable period of time, in particular for at least 10 ⁇ s. This will ensure that the lamp voltage is not removed until after the period of ignoring, i. H. is evaluated after the originating from the commutation overshoot the lamp voltage. This overshoot is to be distinguished from the unwanted increase in the burning voltage, which is possible due to its limited time.
• Preferred embodiments of the circuit arrangement according to the invention are characterized in that after an enlargement of the input switching period for the predetermined period of time, the duty cycle is reduced stepwise or continuously back to the initial value. In this case, several intermediate stages may be provided. By this measure, a undershoot in the lamp current can be reliably avoided.
• control device may also be designed to increase the duty cycle stepwise or continuously.
• Figure 2 is a schematic representation of the structure of a circuit arrangement according to the invention.
• FIG. 3 shows the time profile of, in particular, the lamp voltage U L and the lamp current IL in a circuit arrangement according to the invention according to FIG. 2.
• FIG. 2 shows a schematic representation of the construction of an exemplary embodiment of a circuit arrangement according to the invention.
• the so-called intermediate circuit voltage Uzw is applied to the two switches S1, S2 in a half-bridge arrangement.
• this is approximately 200 to 500 V and is usually generated from the mains voltage via a rectifier and a smoothing capacitor.
• the half-bridge center HB is connected via a lamp inductor L 0 to a first terminal of the lamp LA.
• a capacitor Ci is connected, which is designed together with the lamp inductor L 0 for igniting the lamp LA.
• the current flowing through the lamp is denoted by I L , the voltage drop across the lamp to U L.
• the other terminal of the lamp LA is connected on the one hand via a coupling capacitor C ⁇ i with the pregnant Vietnamesespan- voltage Uzw, on the other hand via a coupling capacitor C ⁇ 2 with a reference potential, in this case ground.
• the first lamp terminal is connected via a first voltage divider comprising the resistors R1 and R2, the second terminal of the lamp LA via a second voltage divider comprising the resistors R3 and R4 to the reference potential.
• the respective taps of the two voltage dividers are connected to a voltage measuring device 10 for measuring the actual value of the voltage U L across the high-pressure discharge lamp LA for determining a voltage which is correlated with the lamp voltage U L.
• a reference value device 12 provides at least one upper limit value for the voltage U L across the high-pressure discharge lamp LA to a comparison device 14.
• the comparison device 14 is designed to provide the actual value of the voltage U L over the high-pressure discharge lamp LA, which is supplied by the voltage measuring device 10, with the at least one upper limit value for the Voltage U L across the high pressure discharge lamp LA, which provides the reference value device 12 to compare.
• the circuit arrangement of Fig. 2 further comprises a control device 16 which is adapted to alternately turn on and off the first switch S1 and the second switch S2 of the bridge circuit at a first frequency, and the other during the off phase of the one switch S1, S2 Switch S2, S1 with a square wave signal of a second frequency, which is greater than the first frequency, and to control a predetermined duty cycle.
• a control device 16 which is adapted to alternately turn on and off the first switch S1 and the second switch S2 of the bridge circuit at a first frequency, and the other during the off phase of the one switch S1, S2 Switch S2, S1 with a square wave signal of a second frequency, which is greater than the first frequency, and to control a predetermined duty cycle.
• the comparison device determines that the actual value of the voltage U L across the high-pressure discharge lamp LA, in particular the amount thereof, is above the at least one limit value, it controls the control device 16 in such a way that it supplies the presettable duty cycle of the signal with which the one switch S1, S2 of the half-bridge circuit is driven during the off phase of the other switch S2, S1, at least for a predeterminable period of time increased. This increase in the switch-on time leads to an increase in the current I L through the high-pressure discharge lamp LA.
• FIG. 3 shows the time course of various variables, although it should be pointed out that the representation of FIG. 3 is increased by a factor of 10 in comparison to the representation of FIG.
• the zero lines for the lamp voltage U L and the lamp current I L coincide and correspond to the center line of the representation, as shown to the left by the overlap of a 3 and a 4.
• the lamp voltage U L is increased due to the non-linear characteristic of the high-pressure discharge lamp LA.
• the lamp current I L remains well below its nominal value, in this case 0.4 A.
• the lamp is operated with too little power and the plasma begins to cool.
• the second frequency is reduced by about 50%.
• the signal provided by the comparison device 14 to the control device 16 is denoted by Us, see also FIG. 2.
• the signal applied to the respectively active switch S1, S2 by the control device 16 is designated by Usi / Us2.
• the predefinable time duration of the increase of the switch-on duration .DELTA.t amounts in the present case to 300 .mu.s.
• the lamp current I L increases significantly to a value that is above the nominal value.
• the burning voltage U L of the high-pressure discharge lamp decreases as a result of the current increase to normal values.
• the duty cycle ⁇ t is lowered back to the normal value, so that the lamp is then operated at its nominal current.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Circuit Arrangements For Discharge Lamps (AREA)

Applications Claiming Priority (2)

Publications (2)

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• 2006
  • 2006-02-20 DE DE102006007754A patent/DE102006007754A1/de not_active Withdrawn
• 2007
  • 2007-02-08 WO PCT/EP2007/051230 patent/WO2007096253A1/fr not_active Ceased
  • 2007-02-08 US US12/223,918 patent/US8089220B2/en not_active Expired - Fee Related
  • 2007-02-08 CN CN2007800059465A patent/CN101385399B/zh not_active Expired - Fee Related
  • 2007-02-08 EP EP07712190A patent/EP1994805B1/fr not_active Not-in-force
  • 2007-02-08 CA CA002642576A patent/CA2642576A1/fr not_active Abandoned
  • 2007-02-08 DE DE502007002487T patent/DE502007002487D1/de active Active
  • 2007-02-08 AT AT07712190T patent/ATE454027T1/de active

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