WO2011141363A1

WO2011141363A1 - Method and device for operating a discharge lamp

Info

Publication number: WO2011141363A1
Application number: PCT/EP2011/057275
Authority: WO
Inventors: Michael Bönigk
Original assignee: Osram Gesellschaft mit beschränkter Haftung
Priority date: 2010-05-11
Filing date: 2011-05-06
Publication date: 2011-11-17
Also published as: DE102010028838A1

Abstract

The invention relates to a method for operating a discharge lamp, in which the discharge lamp is operated using a commutation pulse current, wherein the amplitude of the commutation pulse current is controlled. Moreover, the invention relates to a device, an operating unit comprising such a device, and a luminaire comprising the device or the operating unit.

Description

description

Method and device for operating a

discharge lamp

The invention relates to a method and a device for operating a discharge lamp. Furthermore, accordingly, a control gear and a lamp

proposed.

High pressure discharge lamps need for their

proper operation of a defined energetic household. If this is disturbed, changes in the operating behavior of the high-pressure discharge lamp occur,

for example, to a shortening of the lamp life due to electrode erosion or flicker caused by an undefined discharge arc approach.

DE 10 2004 020 397 A1 shows a method for operating a high-pressure discharge lamp with a temporally periodically running, bipolar supply current and a

predetermined electric power, wherein the

High-intensity discharge lamp in periodically recurring time intervals immediately after the zero crossing of the supply current, an additional electric power is supplied to stabilize the lamp operation, and wherein the time-averaged overall performance of the

corresponds to predetermined electrical power. To avoid flicker phenomena

Discharge lamp, in particular a mercury-free

Gas discharge or xenon lamp will be on

Commutation (in) pulsed mode used. Of the

Commutation pulse can before and after the zero crossing or just immediately after the zero crossing of the

Use commutating size. Task of this

Commutation pulse current is both the increase of DC link voltage, ie a voltage across the lamp, immediately during or after the zero crossing (reaching a renewed firing tip by a rapid change in voltage) as well as the provision of an excessive current or an overload immediately after one

Re-ignition of the arc with previous transition to a low-current phase after commutation.

In order to achieve a stable arc approach as quickly as possible, the electrode is heated up quickly by an excessively high current or overload

(thermal emissivity of the electrode).

The increased electrical power converted during the commutation pulse is provided by a supply circuit or a converter via an intermediate circuit with a screening capacitor and a bridge circuit of the lamp. Does the converter accept the

Energy supply, so will the sudden

Energy increase by means of another capacitor, which is located in front of the converter, buffered. For both

Capacitors means the commutation pulse an increased AC load and thus requires the use of expensive and large capacitors.

Furthermore, the increased current flow during the

Commutation pulses to increased heat throughout the system (the power loss corresponds to the square of the flowing current multiplied by the resistance), but especially in the active devices (e.g.

Transistors of the bridge circuit). Therefore, be

Components of higher performance classes, higher

Temperature range or extended cooling measures used.

Due to the increased current flow during the

Commutation is also increasing electromagnetic radiation, which must be limited accordingly (eg by means of filters, shielding, etc.).

All these effects lead to the fact that the electronic control gear (also referred to as ballast)

more expensive and the required space increases.

Known electronic control gear for discharge lamps provide a constant commutation pulse. This leads to unnecessarily high Kommutierungsimpulsstrom at new lamps, which have a low burning voltage and thus a low internal resistance. It is disadvantageous that the circuit or the components of

Circuit of the operating device must be permanently designed for this high current.

With increasing aging of the discharge lamp increases their internal resistance and thus the burning voltage, the

Commutation pulse current decreases. In this case, it is particularly disadvantageous that the screen or support capacitors for the maximum commutation pulse current and the effective AC load (if the lamp is new and has only a low impedance) must be designed.

The same applies to the interpretation of the active

Components (e.g., transistors of the bridge circuit,

Transistors of the converter) and for the required EMC measures. This increases the cost of the electronic control gear and increases the volume required by this. The object of the invention is to avoid the above-mentioned disadvantages and in particular to provide a possibility of an efficient

To provide commutating pulse current, which effectively prevents flicker of a discharge lamp. This object is achieved according to the features of the independent claims. Further developments of the invention will become apparent from the dependent claims.

To achieve the object, a method for operating a discharge lamp is specified,

- In which the discharge lamp with a

Commutation pulse current is operated, wherein the amplitude of the commutation pulse current is controlled.

The commutation pulse current is a pulse signal which can be superimposed on the commutation signal for operation of the discharge lamp. In particular, by means of the commutation pulse, an increase of the intermediate circuit voltage as well as a power increase on the discharge lamp.

The adaptation of the commutation pulse current has the

Advantage that specifically caused by aging of the discharge lamp effects can be met. For example, the impedance of the discharge lamp increases with increasing age or with increasing duration of use. By means of the amplitude-controlled or increased commutation pulse current, it is possible to apply a signal to e.g. flicker of the discharge lamp perceivable by the human eye

counteract. The effectively usable life of the discharge lamp can thus be significantly extended, since the discharge lamp lights up evenly longer and thus must be replaced later.

Another advantage is that the

Commutation pulse current is then used when it is needed. This allows the components of the

Lamp or the electronic control gear for the

Discharge lamp must not be designed for continuous operation of a maximum commutation pulse current. Of the maximum commutation pulse current occurs only at the end of the life of the discharge lamp for a (based on the total usable duration of the discharge lamp)

relatively short time on, a greater stress on the components takes place only during this time.

A further development is that the amplitude of the

Commutation pulse current is regulated depending on an impedance and / or a burning voltage of the discharge lamp.

Another development is that the amplitude of the discharge lamp is increased with increasing burning voltage and / or increasing impedance of the discharge lamp.

In particular, it is a development that the amplitude of the commutation pulse current is adjusted so that a flicker of the discharge lamp is not perceptible by the human eye.

Also it is a continuing education that at a

Firing voltage of the discharge lamp below a

predetermined firing voltage of the commutation pulse current is turned off.

Conversely, the commutation pulse current only decreases

Reaching the preset burning voltage switched on or increased. This allows e.g. a complete omission of the commutation pulse current in the event that it is not yet needed (for example, a new lamp).

Furthermore, it is a development that a current through the discharge lamp and / or a voltage at the

Discharge lamp for adjusting the

Commutation pulse current is / will be evaluated. The current through the discharge lamp may be a partial current or a substantially proportional proportion of the current through the discharge lamp.

In particular, the current is suitable for detecting a change in the current through the discharge lamp.

The voltage on the discharge lamp may be a (proportional) voltage or a partial voltage or a substantially proportional portion of the voltage on the discharge lamp. In particular, the voltage is suitable for changing the burning voltage of the

Detect discharge lamp. Within the scope of an additional development, the current through the discharge lamp and / or the voltage at the discharge lamp is / are determined by means of an integrating regulator (I regulator), in particular one with a voltage regulator

Proportional component (PI controller), evaluated for setting the commutation pulse current.

For example, the (P) I controller can be a unit for

Control pulse width modulation, which affects the brightness of the gas discharge lamp.

A next development is that the current through the discharge lamp and / or the voltage at the discharge lamp by means of a processing unit

is evaluated / be such that an overcurrent or a power increase is set.

The processing unit may be e.g. to act a microcontroller or a microprocessor.

It should be noted that the microprocessor a

any calculator or processor with appropriate

Hardware and / or software (or firmware) may be. Also, the microprocessor may be implemented as FPGA or ASIC. An embodiment is that the current increase or the power increase on the basis of the processing unit by means of a bridge circuit of the discharge lamp

provided.

The bridge circuit may be e.g. one

Half bridge or a full bridge act. An alternative embodiment is that the

Current increase or the power increase is adjusted by means of a pulse width modulation for controlling the discharge lamp. A next embodiment is that the discharge lamp is a gas discharge lamp, a high-pressure discharge lamp, in particular a mercury-free discharge lamp or a xenon lamp. The above object is also achieved by a device for controlling a discharge lamp comprising a processing unit, which is set up such that the method described here is feasible. It should be noted that it is in the

Processing unit e.g. can be a microcontroller or a microprocessor. The processing unit may in particular comprise an I-controller or a PI controller. On the basis of the processing unit, a

Bridge circuit for operating the discharge lamp

be controlled. Also, by means of

Processing unit to be driven a unit for pulse width modulation of the discharge lamp. In particular, the processing unit detects as inputs a current (proportion) which flows through the discharge lamp or a voltage which (at least proportionally) at the

Discharge lamp drops. The processing unit may be a Adjusting current increase or an increase in power based on the input variables, and thus, depending on the detected voltage and / or the detected current change the amplitude of the Kommutierungsimpulsstroms.

Also, the above object is achieved by means of an operating device (also referred to as electronic

Ballast) comprising the one described herein

Contraption .

Furthermore, the above object is achieved by means of a lamp comprising the device described or the operating device described. Embodiments of the invention are illustrated and explained below with reference to the drawing.

FIG. 1 shows a schematic circuit diagram for operating a

Discharge lamp, in particular one

High pressure discharge lamp, with one

amplitude-controlled commutation pulse signal. The discharge lamp is e.g. one

High pressure discharge lamp, a mercury-free

Gas discharge lamp or a xenon lamp

Flicker appearances of a discharge lamp occur

especially with extended lamp life. In this state, the discharge lamp has a higher impedance and thus has a higher operating voltage than a new discharge lamp. With the risen

Firing voltage follows a lower current at the same power, which causes a reduced electrode temperature, which in turn impedes thermal emission of the electrodes. An operation with commutation (im) pulse (the

Control signal (commutation signal or

Commutation current) of the discharge lamp can be superimposed) allows a stabilizing behavior of the discharge lamp against flicker phenomena.

However, discharge lamps require lower

Firing voltage (ie, for example, discharge lamps that are still new) only a very small amplitude of

Kommutierungsspulstrom or can be completely dispensed with a sufficiently rapid change (du / dt) of the commutating voltage to a separate Kommutierungsimpuls (Ström).

Only with increasing age of the discharge lamp is a correspondingly high commutation pulse current required in order to increase the impedance of the discharge lamp

counteract.

Thus, it is in particular proposed to adapt the amplitude of the commutation pulse current such that at low operating voltage (low internal resistance or low impedance) of the discharge lamp a lower

Commutation pulse current is set. This low commutation pulse current is for one

flicker-stabilized operation of the discharge lamp

sufficient . Alternatively, at low burning voltage and e.g.

sufficiently rapid change of the commutating voltage on the Kommutierungsimpulsstrom be completely dispensed with. If the burning voltage increases, the amplitude of the

Commutation pulse current can be increased. This has the advantage that no high

Commutation pulse current is provided when the discharge lamp does not need this. Furthermore, it is advantageous that the temporal

Changing the commutating voltage (du / dt) or the commutating current (di / dt) is not unnecessarily increased and thus reduces or prevents EMC interference. The commutation pulse current only loads at the end of the

Lifespan of the discharge lamp the electronic

Operating device or components of the electronic

Operating device.

Thus, as a further advantage that the

Components with regard to e.g. more effective

AC resistance, maximum pulse current resistance, temperature resistance, etc. and the EMC measures can only be designed for a Kommutierungsimpulsstrom which flows at the end of the life of the discharge lamp. This allows the use clearly

less expensive components with low demands on the volume required by the electronic control gear.

For example, the amplitude of the

Commutation pulse current or a power of the

Commutation pulse and thus the change of

be commutated voltage by means of a control or by means of a control circuit with a

corresponding characteristic.

A property or a state of the discharge lamp can be determined via a lamp voltage or a lamp current or by a combination of these parameters. For example, an elevation (i.e.

Influencing the amplitude of the commutation pulse current or the commutation pulse power) for a Mercury-free discharge lamp can be determined as follows:

The elevation may be e.g. one

Current overshoot "I_Überhöhung" or one

Power overshoot "P_überhhung" act. In the case of a closed-loop control by means of a current setpoint specification, the said factor can be chosen such that, for the highest possible superelevation at maximum lamp voltage Umax or at minimum lamp current Imin, the following applies at least:

The factor in regulation by means of power setpoint input can be chosen so that for the largest possible

Exaggeration at maximum lamp voltage Umax or at minimum lamp current at least the following applies:

It should be noted that the power overshoot is not proportional to the current overshoot, as the

Lamp impedance (during commutation) can vary and thus the voltage U and the current I do not run parallel.

For example, the operating device may have an integrating controller (I controller) or a PI controller (ie an I controller with a proportional component). The controlled system of the I-controller (or the PI-controller) evaluates a voltage of the discharge lamp, the power is set via a current setpoint.

By way of example, a D4 system with power of 35W is assumed below. The following applies: largest permitted elevation:

This is followed by a current at U _max

The maximum permitted current increase at Umax results

This results in the factor due to equation (1)

Thus follows a current increase in dependence on the actual voltage according to

Fig. 1 shows a schematic circuit diagram for operating a discharge lamp 118, in particular one

High-pressure discharge lamp, with an amplitude-controlled commutation pulse signal.

A supply voltage 120 is connected on the input side to a filter 101. An output of the filter 101 is over a primary side of a transformer 102 is connected to the drain terminal of an n-channel MOSFET 103 and the other output of the filter 101 is connected to the source terminal of the MOSFET 103.

The secondary side of the transformer 102 is connected on the one hand to the anode of a diode 104 and on the other hand to a node 122. The cathode of the diode 104 is connected to a node 121. Between the node 121 and the

Node 122, a capacitor 109 is arranged.

The node 121 is connected to a node 123 via a resistor 111, and the node 122 is connected to a node 124 via a resistor 110. The node 123 is connected to the node 124 via a resistor 112.

The node 121 is connected to the drain of an n-channel MOSFET 113 and to the drain of an n-channel

Mosfets 115 connected. The node 124 is connected to the source of an n-channel MOSFET 114 and to the source of an n-channel MOSFET 116. The source terminal of the mosfet 113 and the drain terminal of the

Mosfets 114 are connected to a node 125. Of the

Source of MOSFET 115 and the drain of MOSFET 116 are connected to a node 126.

Between the nodes 125 and 126, a series circuit comprising an ignition element 117 and the discharge lamp 118 is arranged.

The circuit further comprises a microcontroller 108 with a PI controller 106 and an implementation of the

Equation (1) or (3) indicated as unit 107. The node 123 provides as input to the PI controller 106, a current through the discharge lamp and the node 124 provides as input to the PI controller 106 and for the unit 107, a voltage across the discharge lamp. Based on this voltage ("actual" value in equation (3)), the unit 107 determines the current increase according to

Equation (3) and provides this to the PI controller 106. The PI controller 106 controls a unit for

Pulse width modulation 105 accordingly, which is connected on the one hand to the gate terminal of the Mosfets 103 and on the other hand to its source terminal. Furthermore, the microcontroller 108 is provided with a

Drive unit 119 connected by means of which the full bridge shown in Fig.l, ie the gate terminals of the MOSFET 113 to 116, are controlled.

Claims

claims

1. Method for operating a discharge lamp,

- In which the discharge lamp with a

Commutation pulse current is operated, the

Amplitude of the commutation pulse current is regulated.

2. The method of claim 1, wherein the amplitude of the commutation pulse current is regulated as a function of an impedance and / or a burning voltage of the discharge lamp.

3. The method of claim 2, wherein the amplitude of the discharge lamp is increased with increasing the burning voltage and / or increasing impedance of the discharge lamp.

4. The method according to any one of the preceding claims, wherein the amplitude of the Kommutierungsimpulsstroms is set so that a flicker of the

Discharge lamp from the human eye not

is perceptible.

5. The method according to any one of the preceding claims, wherein at a burning voltage of the discharge lamp below a predetermined operating voltage of

Commutation pulse is switched off.

6. The method according to any one of the preceding claims, wherein a current through the discharge lamp and / or a

Voltage is evaluated at the discharge lamp for setting the commutation pulse current / are.

7. The method of claim 6, wherein the current through the discharge lamp and / or the voltage at the

Discharge lamp by means of an integrating regulator, in particular one with a proportional Proportion, is evaluated for setting the commutation pulse current.

8. The method according to any one of claims 6 or 7, wherein the current through the discharge lamp and / or the

Voltage at the discharge lamp by means of a

Processing unit is evaluated / be such that a current overshoot or a

Performance increase is set.

9. The method according to claim 8, wherein the current increase or the power increase on the basis of

Processing unit is provided by means of a bridge circuit of the discharge lamp.

10. The method according to any one of claims 8 or 9, wherein the current increase or the power increase is adjusted by means of a pulse width modulation for controlling the discharge lamp.

11. The method according to any one of the preceding claims, wherein the discharge lamp is a gas discharge lamp, a high-pressure discharge lamp, in particular a

mercury-free discharge lamp or a xenon lamp.

12. Device for controlling a discharge lamp

comprising a processing unit arranged such that the method according to one of the preceding claims is feasible.

13. operating device comprising a device according to

Claim 12.

14. luminaire comprising a device according to claim 12 or an operating device according to claim 13.