EP2534532B1 - Interface providing electrical isolation in the reception path - Google Patents

Description

The invention generally relates to the field of interfaces for operating devices of building technology, in particular for connected bulbs. The interface has a reception branch for incoming signals, for example from a bus, and optionally also a transmission branch. The interface can be designed to receive digital and / or analog signals. The signals may have amplitudes in the low-voltage range (eg below 15 volts) and / or mains voltage range (220V to 250 volts). The incoming signals can be DC or AC signals.

The reception branch of the interfaces addressed by the invention has a potential separation element.

From the WO 2006/010416 For example, a bidirectional interface is known, via which an operating device for a light source can exchange digital data via a bus with a control center. The interface consists of a receiving branch with subsequent potential separation element and a transmission channel. The reception branch and the transmission channel are combined at the ports intended for connection to the bus. This allows the reception branch to read the data given by the transmission channel onto the bus, which is also desirable. The reception branch is supposed to check the data output by the transmission channel and - if time errors are detected - correct. Further documents are known EP 0 556 544 A1 . GB 2 265 712 A and DE 10 2007 013 758 A1 ,

The invention deals with another problem which is not limited to the combination of the reception branch with a transmission channel, but is related to the presence of an electrical isolation element adjacent to the reception branch, which is necessary for a galvanic isolation between input and output of the reception branch is.

The potential separator is typically an optocoupler. However, other implementations are possible for a potential separator, for example a transformer operated at a fundamental frequency, modulating a frequency on one side of the transformer for signal transmission which can then be read out on the other side. The signal states can be discriminated digitally via the modulated frequency.

The potential separation elements of the type considered here, which are to be inexpensive components, the property in common is that they have relatively large manufacturing tolerances and also are highly temperature-dependent in operation. Until now, the very different power requirements of the individual potential isolators have been taken into account by the fact that they were always supplied with the maximum power, with the result that the power loss was correspondingly high.

Another aspect is that potential isolators of the type considered here, in particular optocouplers only have an acceptable transmission behavior in the form of still tolerable signal distortion when operated at a certain minimum power. In the case of optocouplers, which are operated with an impressed current from a power source, this means that there is a certain minimum operating current value for each specimen, which must not be fallen below. Otherwise, the signal distortions during the transmission can lead to the fact that the received useful signals can not be evaluated.

The invention is therefore based on the object to make the receiving branch of an interface with potential separator more efficient.

The object is solved by the features of the independent claims. The dependent claims further advantageously form the central idea of the invention.

One aspect of the invention relates to a method according to claim 1.

The control unit can evaluate the defined signal parameters and set the basic power of the potential separation element depending thereon.

The potential separator (2) may be a transformer which is operated at a fundamental frequency, which is aufmoduliert for signal transmission a higher frequency, and
in which the fundamental frequency and / or its amplitude and / or the amplitude of the modulated modulation for the purpose Minimization of the power requirement of the reception branch (1) is / are set.

The signals can be transmitted by a transmission branch of the same interface, whose receiving branch has the potential separation element, or by an external source, such as, for example, a central processing unit or another operating device.

The setting of the basic performance can be carried out, for example, during the fabrication of the interface, during commissioning, and / or at defined intervals.

The adjustment of the basic power may be performed when a temperature fluctuation detected by the control unit exceeds a threshold value.

The basic power can be set depending on a detected temperature.

The distortion which a bit pulse fed to the receiving channel experiences when passing through the potential separation element can be determined and evaluated, and
the power supplied to the potential separation element can be set so low that the distorted bit pulse just yet meets certain minimum conditions with regard to its shape, in particular with regard to its amplitude and / or pulse width

The front pulse edge of the bit pulse (B) supplied to the receiving branch can be compared with that of the bit pulse (C) which is distorted by the passage of the potential separation element, and the delay time (tV) can be determined therefrom, and
the power supplied to the potential separator can be adjusted depending on the delay time.

The adjustment of the power isolator supplied power can be repeated periodically.

For the adjustment of the potential separation element (2) supplied power, the temperature of the potential separation element and / or its environment can be additionally measured and taken into account.

The bit pulse (B) may be a test bit pulse or a payload.

Expediently, an optocoupler is used as potential separator, whose operating current is set in order to minimize the power requirement in the sense described above.

In application of the method for the bidirectional data exchange of an operating device for a light source via a bus with a central station, the receiving branch can be connected together with an adjacent potential separating element together with a transmitting channel, wherein the receiving branch generates a test bit pulse from the receiving branch for determining the Read delay time. The reception branch is also provided with time information about the start edge of the test bit pulse so that the system can determine the delay time between the time of occurrence of the start edge of the original test bit pulse and the time of occurrence of the start edge of the pass the potential separator distorted test bit pulse is.

The start edge of the distorted test bit pulse is typically less steep than that of the original test bit pulse. This also means that the pulse width of the distorted test bit pulse is less than that of the original test bit pulse. If the distortion is particularly strong, this can also result in an amplitude reduction. This fact can be used to determine if the amplitude of a distorted test bit pulse still reaches a certain minimum value. By appropriate dimensioning of the minimum amplitude value, it is possible, irrespective of the delay time, to make a decision as to whether an increase in the power supplied to the potential isolating element is necessary or not.

The delay time and / or the amplitude value are therefore also suitable for validating the useful signals supplied to the reception branch.

The invention further relates to a receiving branch with subsequent potential separation member, with which the task defined above can be solved device technology.

One aspect hereby provides measuring means for measuring the distortion experienced by a bit pulse supplied to the receiving branch when passing through the potential separation element, and also adjusting means for the power supplied to the potential separation element as a function of the measurement result, such that the distorted bit pulse just barely meets certain minimum conditions with regard to its shape, in particular with regard to its amplitude and / or pulse width.

Another aspect of the invention provides an interface for operating devices for lighting, which is designed to carry out a method of the type mentioned above.

Furthermore, the invention provides an integrated circuit, in particular ASIC, microcontroller or hybrid thereof, according to claim 11.

In this case, the circuit can be designed to set the electrical parameter as a function of a temperature detection and / or an evaluation of the signals of the reception branch transmitted by the potential isolation element.

The invention also provides an operating device for lighting means, comprising an interface having such an integrated circuit.

According to one aspect, the invention also provides a lighting system comprising a plurality of operating devices for lighting means, including at least one of the above-mentioned type, wherein the operating devices are connected to one another and / or to a central unit via a signal line, in particular an analogue or digital bus.

The central unit or an operating device can be designed to emit test signals via the signal line, so that a (further) operating device for lighting means under evaluation of these in the receiving branch of a unidirectional or bidirectional interface of a (further) operating device for lighting (adaptive) can set the basic electrical supply of a potential separator of its receiving branch.

In this context, it should be noted that - to avoid unnecessary repetition - the content of all claims to the disclosure of the description should include.

Hereinafter, embodiments of the invention will be described with reference to drawings.

• Figur 1 ein schematisiertes Blockschaltbild einer bidirektionalen Schnittstelle mit einem Empfangszweig und einem sich daran anschließenden Potentialtrennglied sowie einem Sendekanal nach dem Stand der Technik,
• Figuren 2 (a) und (b) zeitliche Verläufe von Testbit-Impulsen vor und nach Passieren des Potentialtrenngliedes,
• Figur 3 ein Blockschaltbild wie Figur 1, jedoch mit einem zusätzlichen Block zur Minimierung des Leistungsbedarfs des Empfangszweigs mit sich daran anschließendem Potentialtrennglied.

Show it:

• FIG. 1 a schematic block diagram of a bidirectional interface with a receiving branch and an adjoining potential separation element and a transmission channel according to the prior art,
• FIGS. 2 (a) and (b) temporal courses of test bit pulses before and after passing the potential separation element,
• FIG. 3 a block diagram like FIG. 1 but with an additional block for minimizing the power requirement of the receiving branch with the potential isolator connected to it.

FIG. 1 shows a bi-directional interface according to the prior art, as according to the WO 2006/010416 is known. This interface is used for bidirectional data exchange of an operating device (ECG) 6 for a light source 7 (preferably a fluorescent tube) with a remote, not shown, or a further operating device via a bus 8. At the terminals for the bus 8, the input of a receiving branch 1 and the output of a transmitting channel 11 are brought together so that data output from the transmitting channel 11 to the bus 8 data from the receiving branch 1 can be read. The exchanged data are all compliant with the DALI standard (DALI = Digital Addressable Lighting Interface).

The output of the receiving branch 1 is followed by an opto-coupler 2 serving for potential separation. This is powered by a power source 3 with operating power. The system further includes a controller 4 that includes an input logic 5 and an output logic 9. The output signals of the optocoupler 2 are supplied to the input logic, which in turn evaluates these signals and the control unit 6 corresponding control commands.

The operating device 6 in turn outputs state information to the output logic 9, which converts these into digital DALI signals and supplies them to the transmission channel 11 via a further potential separation element 10. The latter transmits the digital output signals via the bus 8 to the control center. The digital output signals are - as mentioned above - read from the receiving branch 1, checked and evaluated. The evaluation result can be used to correct the digital signals to be transmitted if time errors have been detected in the previously transmitted signals.

On the assumption that in particular the subsequent to the receiving branch 1 optocoupler 2 should be a low-cost device, has to be accepted be that he shows considerable manufacturing tolerances in terms of its power consumption. In addition, the power consumption of optocouplers is quite strongly temperature-dependent. In order to cover the entire spectrum of power consumption, the optocoupler 2, which adjoins the receiving branch 1, has hitherto been operated with the highest possible current, with the result that the power loss was correspondingly high.

As described at the outset, it is an aspect of the invention to provide a possibility to minimize the power consumed by the receiving branch 1 and the optocoupler 2 connected thereto for operation, without negatively affecting the transmission characteristics such that the received signals are not or only incorrectly readable. This problem is now based on the FIGS. 2 (a) and (b) be explained in more detail.

In FIG. 2 (a) the envelope of a bit signal sequence transmitted by the control center via the bus 8 is represented by A according to the DALI standard. This bit signal sequence has a predetermined gap of at least 10 ms at intervals. In this gap, the transmission channel 11 sends a test bit pulse B generated in it, which the reception branch 1 reads.

FIG. 2 (b) now shows how the test bit pulse is distorted when passing through the optocoupler 2, and the stronger the lower the operating current supplied to the optocoupler 2 from the current source 3. The distorted test bit pulse C is therefore the result of a relatively high operating current, while the more distorted Test bit pulse D is the result of a reduced operating current for the optocoupler 2.

Already the reduced amplitude of the distorted test bit pulse can be used as a criterion for the transmission quality of the receiving branch 1 with the optocoupler 2 following it. However, the amplitude level is only suitable for assessing whether a predetermined amplitude threshold value is exceeded or undershot.

A more accurate evaluation allows the delay time t _v , which corresponds to the time interval between the start edge of the original test bit pulse and the start edge of the distorted test bit pulse, for a given reference voltage U _ref .

• Intern, bspw. durch den Sendezweig der Schnittstelle selbst, und/oder
• Extern, bspw. von einer Zentrale und/oder einem weiteren Betriebsgerät.

The analog or digital signals for setting the potential separation element can thus be generated:

• Internally, for example by the transmission branch of the interface itself, and / or
• Externally, for example from a control center and / or another operating device.

According to the circuit arrangement in the embodiment according to FIG. 3 is now provided that an additional circuit block 13 is provided, which communicates with the input logic 5 and the output logic 9 and generates a control signal for the power source 3, which supplies the optocoupler 2 with operating power. The output logic 9 notifies the block 13 of the timing of the start edge of the test bit pulse B generated in the output logic 9, while the block 13 receives from the input logic the information about the timing at which the amplitude of the distorted test bit -Impulse C the Reference voltage U _ref reached. In this way, the block 13 can determine the delay time t _v and set the current source 3 for the optocoupler so that a certain limit for the delay time t _{v is} just not exceeded. In this case, the operating current for the optocoupler is increased when an extension of the delay time t _{v is} detected, and conversely, the operating current is lowered when the delay time t _v shortens.

The adjustment of the current source 3 for the optocoupler 2 can be made once or continuously repeated.

Since the power consumption of optocouplers is highly dependent on temperature, it is also possible to provide an additional or alternative current control for the current source 3, in which the actual temperature value of the optocoupler and / or its environment is additionally or alternatively taken into account.

If the delay time t _{v is} permanently too long, this can be exploited to validate the signals received from the center, to the effect that the truth content of these signals is no longer considered secure. Conversely, it can be assumed that the signals received from the center are reliable.

When a status request comes from the center, a bit pulse of the response output from the transmission channel 11 may be used instead of a separately generated test bit pulse for measuring the delay time t _v .

• Der Betriebsstrom für einen Optokoppler, der erforderlich ist, um das gesamte Spektrum der Herstellungstoleranzen und der möglichen Betriebstemperaturen abzudecken, musste bisher ohne die erfinderische Maßnahme mit 400 µA angesetzt werden

The power reduction by the method according to the invention described can be impressively demonstrated by the following figures:

• The operating current for an optocoupler, which is required to cover the entire spectrum of manufacturing tolerances and the possible operating temperatures, previously had to be set at 400 μA without the inventive measure

The operating current for an optocoupler operated according to the invention is about 50 μA under normal conditions.

This results in a saved power of 230 V * 350 μA = 80 mW. That is 30% of the total losses of 250 mW in standby mode.

Claims (15)

1. Method for controlling an operating device (6) for lighting means (7) and for adjusting a receiving branch (1), designed for receiving digital signals, with an isolating member (2) connected thereto and with active electrical basic output, comprising the steps:

   - receiving, by means of the receiving branch (1), several digital signals from an internal or an external signal source, and

   - lowering or raising the basic output supplied to the isolating member (2) until a defined signal parameter on the secondary side of the isolating member (2) that is connected to a control unit drops below or exceeds a threshold value, wherein the basic output is lowered when the threshold value is exceeded, and raised when dropping below the threshold value, wherein

   - the control unit determines the defined signal parameter on the secondary side of the isolating member (2).
2. Method according to claim 1, wherein the control unit analyzes the defined signal parameter and adjusts the basic output of the isolating member dependent therefrom.
3. Method according to one of the preceding claims, wherein the isolating member (2) is an optocoupler whose operating current is adjusted for the purpose of minimizing the power requirement of the receiving branch (1).
4. Method according to claim 1 or 2, wherein the isolating member (2) is a transformer operated with a basic frequency on which a higher frequency is modulated for signal transmission, and where the basic frequency and/or its amplitude and/or the amplitude of the modulation is/are adjusted for the purpose of minimizing the power requirement of the receiving branch (1).
5. Method according to one of the preceding claims, wherein the receiving branch (1) forms together with a transmission channel (11) a digital bidirectional interface for the exchange of data, preferably of an operating device (6) for a lighting means (7) with a control center.
6. Method according to one of the preceding claims, wherein the signals are transmitted from a transmission branch of the same interface whose receiving branch has the isolating member.
7. Method according to one of the preceding claims, wherein the adjustment of the basic output is carried out during the fabrication of the interface, during the initial operation, and/or at defined intervals.
8. Method according to one of the preceding claims, wherein the adjustment of the basic output is carried out when a temperature fluctuation determined by the control unit exceeds a limiting value.
9. Method according to one of the preceding claims, wherein the adjustment of the basic output takes place dependent on a determined temperature.
10. Integrated circuit, in particular ASIC, microcontroller or hybrid thereof, for an operating device for lighting means having at least one input and at least one output, wherein the integrated circuit is designed to analyze at the input the signals from a receiving branch (1) of an interface via an isolating member (2) with active electrical basic output, and on the output to directly or indirectly adjust an electrical parameter, in particular an electrical basic energy supply of the isolating member (2), wherein the receiving branch (1) is designed for receiving digital signals, and wherein the integrated circuit is equipped to lower or raise the basic output supplied to the isolating member (2) until a defined signal parameter on the input connected with the secondary side of the isolating member (2) drops below or exceeds a threshold value, wherein the basic output is lowered when the threshold value is exceeded, and raised when dropping below the threshold value, wherein the integrated circuit determines the signal parameter on the secondary side of the isolating member.
11. Circuit according to claim 10, designed to adjust the electrical parameter dependent on a temperature measured and/or an analyzation of the signals of the receiving branch transmitted by the isolating member.
12. Interface for operating devices for lighting means, having a receiving branch (1) for receiving, via the receiving branch, several signals from an internal or an external signal source, and having an isolating member (2) and an integrated circuit according to claim 10, equipped to carry out a method according to claims 1 to 9.
13. Operating device for lighting means, having an interface that has an integrated circuit according to claim 10.
14. Lighting system, having several operating devices for lighting means, of which at least one according to claim 13, wherein the operating devices are interconnected and/or connected with a central unit via a signal line, in particular an analog or digital bus.
15. Lighting system according to claim 14, wherein the central unit or an operating device is designed for transmitting test signals via the signal line, wherein a further operating device for lighting means adjusts the electrical basic supply of an isolating member of its receiving branch by analyzing these test signals in the receiving branch of its unidirectional or bidirectional interface.

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