EP2258149B1 - Detection of the type of an hid lamp by a multi-lamp operating device and lighting system - Google Patents

Abstract

In the field of electronic ballast devices, ballast devices are known that can be used with different types of lamps. With those so-called multi-lamp ballast devices, there is a need to precisely detect the lamp and thus the wattage thereof. The invention relates to a method for detecting the nominal output of a high-pressure discharge lamp (EL) connected to a multi-lamp operating device among different nominal outputs (Pmin, Pmax), wherein the multi-lamp operating device can create different operating outputs (Pmin, Pmax), corresponding to the different nominal outputs. The high-pressure discharge lamp (EL) is operated (S1) with the lowest operating output (Pmin). It is determined whether the operating point (N1) resulting from said operating output is within the range (12) of the voltage/current characteristic line of the high-pressure discharge lamp (EL) having a positive gradient (Δ). If this is the case, it is detected that the nominal output of the connected high-pressure discharge lamp (EL) corresponds to the operating output set in the first step (S1).

Description

The present invention relates to control gear for high pressure gas discharge (HID) lamps. In particular, the invention relates to operating devices which are able to discriminate the type, in particular the wattage (rated power class), of a connected HID lamp in order, for example, to set operating parameters for the HID lamp as a function of the discrimination.

By "type recognition" or "discrimination" is thus to be understood that an operating device evaluates predetermined feedback variables (measured values) in order to set operating parameters for connected lighting means, for example, based on a table or function.

The invention also relates to a lighting system comprising a luminaire with such an operating device.

In the field of electronic ballasts ballasts are known that have been designed for a particular lamp type, and those that can be used with different lamp types. In these so-called multi-lamp (multi-lamp) ballasts, which can operate different types of lamps ie in particular lamps with different power ratings (wattages), so there is a need that actually connected lamp and thus to recognize their wattage in order to operate optimally, ie with adjusted operating parameters (voltage, current, frequency, etc.).

"Multi-lamps" or "multi-lamps" thus includes operating devices that can operate one or more lamps.

Low-pressure gas discharge lamps can be relatively easily identified by an operating device by detecting the coil resistance. To detect a low-pressure gas discharge lamp, the current actual values of the filament resistance, the lamp voltage of the connected gas discharge lamp or the outside temperature are measured, for example via a resistance measuring element, a voltage measuring element or a temperature measuring element and fed to the operating device for evaluation, the latter depending on the value of the detected parameters can close to a specific lamp type.

On the other hand, such a spiral detection is not possible with high-pressure discharge lamps (also called HID lamps, from the English term "high-intensity discharge").

It is therefore in the US2004 / 0113567A1 It has been proposed to first ignite the high-pressure discharge lamp and then to conclude the lamp type on the basis of at least one value of the U / I characteristic curve. For this purpose, after starting the electrical discharge, an output parameter of the lamp is monitored.

From the publication DE 195 30 485 A1 For example, a method and a circuit arrangement for operating an electric lamp of a given type of lamp at a defined energy source are known. The method comprises the step of detecting a lamp type information of the lamp and the step of driving the lamp depending on the lamp type designating information. The lamp-type-designating information may, for example, be predetermined by a sensor which detects an individual operating state or an input device.

From the document `Dimming Control And Characteristics Of High-frequency Operated Metal Halide Lamps' by the authors X. Cao and others are described a dimming control and characteristics of high frequency metal halide (MH) lamps. Lamp power is compared based on two equipment topologies. The dimming range and the stability control of the MH lamps will be described, with the dimming range ranging between 100% and 30%. It is known that the combination of the equipment topology and the dimming process can affect the dimming performance.

In the publication WO 2008/001245 A1 a method for detecting a faulty operation of a gas discharge lamp is described. The method includes the steps of determining the lamp impedance and placing the lamp in an annealing mode when it is detected that the lamp has a positive impedance. The lamp current is varied and the lamp voltage changes resulting from the lamp current change are analyzed to determine the lamp impedance. In one embodiment, the lamp current is set to a first value at a first measurement time, and a first lamp voltage occurring at the first measurement time is measured, while at a second measurement time the lamp current is set to a second value and the second lamp voltage is increased the second measuring time occurs, is measured. The ratio of the two lamp voltages is then analyzed.

The problem with this is that with this detection of the so-called equivalent impedance, different wattages (for example, 70 or 150 watts) show the same value and therefore can not be clearly distinguished on the basis of this parameter. Furthermore, the lamp detection is made even more difficult because these parameters can change significantly depending on the type of lamp during the life of the lamp. A disadvantage of this known method is thus that the lamp detection is not reliable.

The invention has accordingly set itself the task of providing an improved technology for detecting the type, in particular the power class ("Wattage") of a high-pressure discharge lamp, which in particular the use of multi-lamp operating devices is facilitated.

The object is solved by the characterizing features of the claims, wherein the combination of the claims is characterized as a particularly advantageous solution to the problem.

The invention proposes a method for discriminating different high-pressure discharge lamps (EL) connected to a multi-lamp operating device, in particular high-pressure discharge lamps (EL) of different rated power (Pmin, Pmax). The discrimination is based on the gradient, in particular the sign of the gradient of the detected current / voltage characteristic of the HID lamp at a predetermined, preferably constant in all measurements operating point of the characteristic of the HID lamp. The operating device is thus equipped to detect the lamp voltage and the lamp current or a parameter that determines this alone or in combination and to keep the operating point constant via a control.

• Die Hochdruck-Entladungslampe wird mit der kleinsten Betriebsleistung betrieben.
• Es wird ermittelt, ob der mit dieser Betriebsleistung sich ergebende Betriebspunkt sich im Bereich der Spannung/Strom-Kennlinie der Hochdruck-Entladungslampe mit positiver Steigung befindet. Falls ja, wird erkannt, dass die Nennleistung der angeschlossenen Hochdruck-Entladungslampe der im ersten Schritt eingestellten Betriebsleistung entspricht.
• Falls der Betriebspunkt sich nicht im Bereich der Spannung/Strom-Kennlinie mit positiver Steigung befindet, wird erkannt, dass die Nennleistung der angeschlossenen Hochdruck-Entladungslampe nicht der im ersten Schritt eingestellten Betriebsleistung entspricht.

According to a further aspect of the present invention, a method is provided for distinguishing a high-pressure discharge lamp, which is connected to a multi-lamp operating device, at different rated powers. The multi-lamp operating device can produce different operating powers that correspond to the different rated powers. The following steps are planned:

• The high-pressure discharge lamp is operated with the lowest operating power.
• It is determined whether the operating point resulting from this operating power is within the range of the voltage / current characteristic of the positive slope high pressure discharge lamp. If so, it is detected that the rated output of the connected high-pressure discharge lamp corresponds to the operating power set in the first step.
• If the operating point is not in the range of the positive-slope voltage / current characteristic, it is detected that the rated output of the connected high-pressure discharge lamp does not correspond to the operating power set in the first step.

In a method of detecting a rated power with a smaller and a larger rated power, if the operating point is not in the range of the positive-voltage voltage / current characteristic, it is decided that the rated power of the connected high-pressure discharge lamp corresponds to the larger rated power.

In a multi-rated power detection method, if the operating point is not in the positive slope voltage / current characteristic range, the first three steps of the next smallest operating power are recursively performed until the operating point is in the voltage range / Current characteristic with positive slope is located.

To determine the slope, the supplied operating power is preferably reduced, starting from the operating point, in such a way that a second operating point is established.

The difference between the lamp voltage of the operating point and the lamp voltage of the second operating point is then determined.

Preferably, the lamp voltages of the operating point and the second operating point are temporarily stored.

The slope can preferably be determined at the operating point.

According to a further aspect of the present invention, an integrated circuit is provided, which is designed for carrying out such a method.

According to another aspect of the present invention, a multi-lamp operating apparatus is provided for operating high-pressure gas discharge lamps having a control unit that performs such a method.

The invention also relates to a luminaire with a light source and such a control gear. Furthermore, the invention also relates to a lighting system having a lamp with such a control gear.

Further features, advantages and properties will now be described in more detail, with reference to the figures of the accompanying drawings and with reference to preferred embodiments.

• Fig. 1 schematisch eine Ausführungsform der vorliegenden Erfindung,
• Fig. 2 die U/I-Kennlinie einer Hochdruck-Gasentladungslampe,
• Fig. 3 im Vergleich zwei U/I-Kennlinien von Hochdruck-Gasentladungslampen mit unterschiedlichen Wattagen,
• Fig. 4 ein Diagramm der erfindungsgemäßen Verfahren zur Erkennung von Lampentypen, und
• Fig. 5 ein Diagramm einer erfindungsgemäßen Lampentypen-Erkennung unter drei verschiedenen Nennleistungen.

Showing:

• Fig. 1 schematically an embodiment of the present invention,
• Fig. 2 the U / I characteristic of a high-pressure gas discharge lamp,
• Fig. 3 compared two U / I characteristics of high-pressure gas discharge lamps with different wattages,
• Fig. 4 a diagram of the method according to the invention for the detection of lamp types, and
• Fig. 5 a diagram of a lamp type detection according to the invention under three different power ratings.

In Fig. 1 schematically an embodiment of the present invention is shown. In the Fig. 1 shown Circuitry is part of an electronic ballast and includes controllable switches S1-S4 of a DC / AC inverter, which are connected in a full bridge. As switches S1-S4, field effect transistors are preferably used.

To the full bridge, a DC voltage Ubus is applied, which comes from a suitable DC voltage source of the corresponding electronic ballast, in which the circuit arrangement is used. The DC voltage Ubus can be generated for example by implementing an applied mains voltage by a combination of a radio interference suppression and rectifier. Alternatively, however, any other DC voltage source can be used.

In the bridge branch of in Fig. 1 shown full bridge circuit ("full bridge") is a to be controlled gas discharge lamp EL, in particular a high pressure gas discharge lamp arranged. In the Fig. 1 shown circuitry is particularly suitable for the operation of metal halide high-pressure gas discharge lamps that require very high ignition voltages. High-pressure gas discharge lamps differ from low-pressure gas discharge lamps in particular in that they require higher ignition voltages and higher pressure occurs in their smaller lamp body. Furthermore, high-pressure gas discharge lamps have a higher luminance.

With the bridge branch of in Fig. 1 The full bridge shown is coupled to a series resonant circuit comprising an inductor L1 and a capacitor C1, the capacitor C1 being connected to a tap point of the inductor L1 attacks and is connected via a further controllable switch S5 in parallel with the switch S4. In addition, a smoothing or filtering circuit is provided, which has a further inductance L2 and a further capacitance C2, wherein these components as in Fig. 1 are shown interconnected. To the full bridge, a resistor R1 is also connected, which serves as a current measuring resistor (shunt).

A voltage divider R2, R3 is used to measure the input voltage and, as already mentioned, the resistor R1 is used to measure the lamp current.

Furthermore, in Fig. 1 a central control circuit 1 is shown, which is fed by a supply voltage VDD. The control circuit 1 can be designed as an integrated circuit, in particular as an application-specific integrated circuit (ASIC) or a microprocessor (or a hybrid version thereof).

The actuation of the switches S1-S4 of the full bridge and of the switch S5 takes place via connections A1 to A5 of the control circuit 1 connected to the gates of the transistors. Via further measuring connections M1, M2, the lamp voltage and the lamp current can be detected.

The aforementioned series resonant circuit with the inductance L1 and the capacitance C1 serves in combination with the further capacitance C2 in particular for igniting the high-pressure gas discharge lamp EL. For this purpose, the series resonant circuit is excited to resonance, ie, a frequency corresponding to the resonant frequency (or a multiple thereof) of the lamp is supplied. The suggestion of the Resonant circuit is preferably carried out by alternately switching the switches S1 and S2.

After ignition, normal operation of the lamp is initiated. The full bridge with the controllable switches S1-S4 is operated in a known manner during normal operation, d. H. the two bridge diagonals with the switches S1 and S4 or S2 and S3 are alternately activated and deactivated, and thus the respective switches of the two bridge diagonals alternately or complementary to each other and switched off.

The activated bridge diagonal consists of a high-frequency clocked switch and a low-frequency clocked switch. Preferably, S1, S2 are the high-frequency clocked switches and S3, S4 are the low-frequency clocked switches.

The switching on and off of the switches S1-S4 is preferably carried out with the aid of a high-frequency pulse-width-modulated control signal of the control circuit 1, which is screened with the aid of the existing of the components L2 and C2 filter or smoothing circuit, so that at the gas discharge lamp EL only the linear average current is applied.

With the aid of the pulse-width-modulated control signal, the power supplied to the lamp EL can thus be controlled or regulated taking into account the lamp voltage and lamp current detected by the measuring terminals M1, M2.

The detection of the lamp EL is not tied to the full bridge circuit nor to the described operating method. For example, a half-bridge circuit (with two switches connected in series and complementarily clocked) can also be selected for operating the lamp EL. Also, the detection is not tied to the type of operation of the lamp EL. For example, as an alternative to the above-described method with a low-frequency square-wave voltage, a high-frequency operation can also be selected. In this high-frequency operation, for example, a half-bridge circuit may be selected as the circuit arrangement. The two switches of the half-bridge circuit are alternately clocked. The lamp EL is also arranged in this arrangement in a series resonant circuit of at least one inductor and at least one capacitor. After the lamp EL has been ignited, it can continue to be operated with a high-frequency alternating voltage, which results in resonance in the series resonant circuit due to the alternating timing of the two switches of the half-bridge circuit, ie. H. the two switches are driven at a frequency corresponding to the resonant frequency (or a multiple thereof, "harmonic")) of the lamp. In order to achieve resonant excitation, it is sufficient if this frequency is only close to the resonance frequency.

In Fig. 2 shows the voltage / current characteristic K1 of a 70 watt high pressure gas discharge lamp.

As is known, at low current values, this illustrated U / I characteristic first shows a first region 11 with a negative resistance gradient, ie up to a minimum reversal point 13 the voltage decreases with increasing current. Thereafter, in a second region 12, the voltage of the high-pressure gas discharge lamp increases again with increasing current.

In the second region 12, the resistance gradients are again positive. Especially in this second area 12, i. in the ascending branch, is the normal operating point N1 of the high pressure gas discharge lamp EL to ensure stable lamp operation.

In the vicinity of the normal operating point N1, the slope of the voltage / current characteristic of the high-pressure gas discharge lamp is therefore positive. If the lamp current is initially reduced, the lamp voltage is reduced. This behavior persists until the reverse minimum point 13.

If now 70 watts of power are supplied to this 70 watt high-pressure gas discharge lamp, then the corresponding operating point N1 of this lamp is in a region 12 of the U / I characteristic curve with a positive resistance gradient.

In Fig. 3 In addition, the U / I characteristic K2 of a 150 watt high-pressure gas discharge lamp is shown.

If this 150 watt lamp is operated with the abovementioned 70 watt lamp power of 70 watts, the operating point N2 results for the circuit arrangement. Due to the overall shifted characteristic K2, however, this new operating point N2 has a negative resistance gradient.

The invention now makes use of the fact that the normal operating point of a high-pressure gas discharge lamp in the ascending branch 12 of the U / I characteristic curve is selected. From the sign and / or the amount of the gradient of the U / I characteristic at the operating point N1, N2 can be closed according to the invention, whether the high-pressure gas discharge lamp EL is operated with a suitable power.

The invention thus proposes a differential measurement of the U / I characteristic. This can be exploited to detect the sign and / or the magnitude of the gradient of the V / I characteristic at an operating point, in turn depending on it (for example, by a table adjustment) set operating parameters for the operation of the lamp.

A multi-lamp ballast that can operate different types of lamps, according to the invention can detect the connected high-pressure gas discharge lamp by the gradient of the U / I characteristic is determined directly or indirectly at the operating point and its sign is checked. The absolute value of the gradient is preferably not relevant, as long as conclusions about the sign of the gradient can only be made on the basis of the direct or indirect U / I measurement.

If this determined gradient is negative, then the operating point of the lamp is in a region 11, where the voltage decreases with increasing current. It can be concluded that the lamp EL is operated at too low a power. On the other hand, if this determined gradient is positive, the operating point of the lamp is in a region 12 with a simultaneous increase in the lamp current and the lamp voltage, indicating a suitable power supply.

Fig. 4 shows how a multi-lamp ballast can detect the connected high-pressure gas discharge lamp or its Wattage.

It is assumed that the multi-lamp ballast lamps with a first power Pmin of e.g. 70 watts or with a larger second power Pmax of e.g. Can operate 150 watts.

In a first method step S1 after ignition, the connected high-pressure gas discharge lamp EL is supplied with the lower power Pmin by appropriate control of the switches S1-S4.

The operating point N1 of the lamp is then determined S2, i. the lamp current and the lamp voltage are detected. This detection of the lamp parameters takes place, for example, via the above-described measuring terminals M1, M2 of the control circuit 1.

The value of the lamp current and lamp voltage, which is measured directly or indirectly and results from the supply of the first power Pmin, is stored in a next step S3 in a memory unit 5 of the control circuit 1 in order to be able to access it later.

The power generated by the full bridge is then reduced S4 so that the average current applied to the high pressure gas discharge lamp EL also decreases. For example, this generated power is reduced by a maximum of 10%.

In order to determine the new operating point N1 ', both lamp current and lamp voltage S5 are again measured and stored in the memory unit 5 S6.

The slope Δ of the voltage / current characteristic of the connected high-pressure gas discharge lamp between the operating points N1 and N1 'is then calculated using the following equation S7: $$\mathrm{\Delta }\mathrm{=}\left(\mathrm{V}\mathrm{1}\mathrm{-}\mathrm{V}\mathrm{1}\mathrm{\text{'}}\right)\mathrm{/}\left(\mathrm{I}\mathrm{1}\mathrm{-}\mathrm{I}\mathrm{1}\mathrm{\text{'}}\right)$$

If this slope Δ positive S8, it can be concluded S9 that the high-pressure gas discharge lamp connected to the electronic ballast has the rated power Pmin, in which case the ballast will operate the lamp with this power Pmin.

Additionally or alternatively, the amount of the gradient can also be evaluated.

Otherwise, it can be seen from the ballast or from the control circuit 1 S9 'that the connected lamp has the rated power Pmax and is to operate with this power Pmax.

Instead of calculating the slope Δ or the resistance gradient S7 and then determining the sign of the slope Δ S8, alternatively, only the sign of the difference (V1-V1 ') can be determined, since the difference (I1-I1') actually remains positive ,

This method can also be used with a ballast that can provide more than two output powers. A multi-lamp ballast can be provided, for example, for operating lamps with 3 different nominal powers P1, P2 and P3, where P1 <P2 <P3.

Even in such a case, the ballast can recognize the wattage of the connected lamp itself, in which the in relation to Fig. 4 described recursively. For this purpose, first the recognition method of Fig. 4 is performed such that the gas discharge lamp with the lowest power P1 is operated, see step S11 Fig. 5 ,

Similar to the first embodiment, it is then determined at the operating point of this lower wattage P1 whether the lamp is already in the range of the U / I characteristic curve with positive gradient or positive resistance gradient S12. If this gradient is positive, the gas discharge lamp can be closed to a nominal power P1 S13.

Otherwise, this power P1 can be excluded so that only the possible nominal powers P2 and P3 are available for selection. The recursive application of the recognition method means that the lamp is now operated with the power P2 S13 'and that it is checked whether the resistance gradient is now positive or not S14, which should suggest a nominal power P2 or P3 S15, S15' ,

It is not necessary that the lamp must be detected each time the lamp is started. The operating device can store in a memory related information from a once performed lamp detection. The memory may be integrated in the control circuit 1 or may also be external (inside the operating device or at least within the lighting system), the control circuit 1 being able to access it. After a successful detection of the lamp, the control circuit 1 store in the memory information about the detected lamp type or according to the detection to be selected operating parameters for the lamp. This information can be retrieved from the memory during a restart. This storage of the information about the recognized lamp type offers the advantage that recognition does not have to be performed every time the lamp is started. For example, detection of the lamp can only be carried out when the operating device is first put into operation. There is also the possibility that the detection of the lamp type can be initiated by signaling or detection of a lamp replacement. This can be done for example by removing the lamp during operation or by external signaling. This signaling from the outside can be done, for example, by a repeated switching on and off of the network or by an external control command, which is sent via an existing interface. The memory is advantageously a non-volatile memory, which is still available even after switching off the operating device. As a memory, a fuse can be used, which can be blown to signal a specific type of lamp.

The advantages of the present invention, for example, taking into account the in Fig. 3 shown curves K1, K2 visible. These characteristics K1, K2 describe the course of the lamp voltage as a function of the lamp current for two lamps with a respective rated power of 70 and 150 watts. At the respective operating points N1 and N2, equivalent resistances of 118 or 110 ohms result, so that detection according to the prior art can actually easily confuse the two lamps. With the help of the lamp type detection according to the invention based on the slope of the U / I curve, however, can be clearly distinguished between the two types of lamps.

Another advantage of this invention is due to the fact that a high independence of temperature influences or aging phenomena of the lamp can be achieved by this method. Since it is not necessary to compare absolute values with a defined value table for given lamp types for the detection of the lamp, but only the gradient of the current / voltage characteristic at a given operating point is evaluated, it is irrelevant whether the current / voltage characteristic of the lamp due to a Temperature variation or aging of the lamp has moved. The gradient of the current / voltage characteristic of the lamp changes in such a temperature fluctuation or aging of the lamp, however, only in a negligible amount.

Claims (8)

1. Method for discriminating a high-pressure discharge lamp (EL) connected to an operating device, the operating device being designed to provide operational parameters for different high-pressure discharge lamps (EL), in particular high-pressure discharge lamps (EL) with different rated powers (Pmin, Pmax), characterized in that the method comprises the following steps:

   - (S1) the high-pressure discharge lamp (EL) is operated at a first operating power (Pmin)(S1),

   - (S8) it is determined whether the operating point (N1) resulting with this operating power is in the region (12) of the voltage/current characteristic of the high-pressure discharge lamp (EL) with a positive gradient (Δ),

   - (S9) if so, it is identified that the rated power of the connected high-pressure discharge lamp (EL) corresponds to the operating power set in the first step (S1).
2. Method according to Claim 1, wherein if the operating point (N1) is not in the region (12) of the voltage/current characteristic with a positive gradient (Δ), it is identified (S9') that the rated power of the connected high-pressure discharge lamp (EL) does not correspond to the operating power set in the fist step (S3).
3. Method according to Claim 1 or 2 for identifying a rated power from among the first rated power (Pmin) and a higher rated power (Pmax), wherein if the operating point (N1) is not in the region (12) of the voltage/current characteristic with a positive gradient (Δ), it is identified (S9') that the rated power of the connected high-pressure discharge lamp (EL) corresponds to the higher rated power (Pmax).
4. Method according to one of the preceding claims for identifying a rated power from among more than two rated powers (P1, P2, P3), wherein if the operating point (N1) is not located in the region (12) of the voltage/current characteristic with a positive gradient (Δ), steps (S1), (S8) and (S9) are implemented recursively with the next-lowest operating power until the operating point (N1) is in the region (12) of the voltage/current characteristic with a positive gradient.
5. Method according to one of the preceding claims, wherein in order to determine (S8) the gradient (Δ) on the basis of the operating point (N1), the supplied operating power is reduced such that a second operating point (N1') is set.
6. Method according to Claim 5, wherein the difference between the lamp voltage (V1) of the operating point (N1) and the lamp voltage (V1') of the second operating point (N1') is determined.
7. Method according to Claim 6, wherein the lamp voltages (V1, V1') of the operating point (N1) and of the second operating point (N1') are buffer-stored (5).
8. Method according to one of the preceding claims, wherein the gradient (Δ) is determined at the operating point (N1).

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