DE102018205590A1 - POWER SUPPLY AND COMMUNICATION SYSTEM FOR LIGHTING SYSTEMS WITH THE SAME - Google Patents

Abstract

A power supply apparatus (40) for a lighting system communication system (30) includes an input having a voltage terminal (44) and a ground terminal (46) for connecting to a first power source (42) having an input voltage (U) between those terminals (44, 46), and an output with corresponding terminals (48, 49) for connection to at least one interface (50, 81, 91) of a control and / or operating device. It further includes a current control device (401) having an input (410) and an output node (411), the current control device (401) adapted to provide one of the first power supply source (42) at the input node (410) and from the first Output node (411) to limit output current (le) to a predetermined maximum value (I). For this purpose, a circuit is provided which is designed to detect an output voltage (U) which is present between the voltage connection (48) and the ground connection (49) of the output and, depending on the detected output voltage (U), the input node of the current regulation device (401 ) with a voltage (U), which is reduced compared to the input voltage (U).

Description

Technical area

The present invention relates to a power supply apparatus and a method for supplying power to lighting system lighting systems. The invention further relates to a device having the communication system and a corresponding illumination system.

State of the art

In the context of progressive building automation, digital bus systems are increasingly being used, by means of which, for example, lighting systems comprising a plurality of luminaires can be centrally or decentrally controlled. An appropriate standard is provided, for example, by the DALI protocol (DALI: "Digital Addressable Lighting Interface" or "Digital Addressable Lighting Interface"). This communication standard is defined in IEC IEC 62386 and IEC 60929, Annex E, based on the previous Digital Signal Interface (DSI) standard, and bridges the gap between traditional 1-10 V analogue interfaces and complex digital bus systems such as KNX / EIB (European Installation Bus) or LON (Local Operating Network), etc., which also include the networking and control of other home appliances beyond the lighting.

With the DALI communication standard (currently being discussed), up to a maximum of 64 lighting equipment in buildings can be connected to the bus via interfaces that are controlled or monitored by one or more control units. A larger number of operating devices is made possible by setting up DALI gateways. The lighting control gear can be electronic ballasts, transformers, actuators, sensors or dimmers, etc. The interfaces can have a controller and a memory in which parameters such as up to 16 programmed scene values or up to 16 group addresses (under which numbers of operating devices are grouped together) are stored. Each interface is individually addressable. The bus has a 2-core cable through which all operating and control devices basically receive the same signal in bidirectional data exchange, whereby in the individual case only the operating device addressed in the signal is addressed, except when the system operates in the so-called broadcast mode. All bus topologies (star, line, tree structures) can be used, but ring structures should be avoided.

The DALI communication standard stipulates that the bus is supplied with approx. 16 V DC by default. At the same time, the bus represents a signal line as well as - albeit to a lesser extent - a power supply. Signals are generated by a transmitting interface through pulsed short circuits between the two wires. The respective sequence of voltage drops from 16 volts to 0 volts is detected and evaluated by the other participants or interfaces. The standard allows certain tolerance ranges to be maintained for the transmitter and the receiver. The "HIGH level" may be between +11.5 and +20.5 volts (ie, 16.0 ± 4.5 volts) at the transmitter and between +9.5 volts and +22.5 volts at the receiver (ie , 16.0 ± 6.5 volts). A voltage change of only 2 volts across is tolerated, which in practice limits the maximum length between any two subscribers or interfaces to about 300 meters. The "LOW level" may be correspondingly between -4.5 and +4.5 volts (ie, 0.0 ± 4.5 volts) at the transmitter and between -6.5 volts and +6.5 volts at the receiver ( ie, 0.0 ± 6.5 volts).

By the transmitted signals, e.g. Individual luminaires connected via interfaces and controllers can be set to the desired brightness, color or color temperature values using appropriate ECGs, or these settings can also be made in groups. Furthermore, the (light) scenes stored in said memories can also be called up by the transmitted signals. Status feedbacks such as lamp errors, operating times, temperatures (from connected sensors) or the current or last dimming position used during operation can be used as starting values from the interfaces. In addition, the mains voltage switch of the operating devices can be individually controlled via the bus. Signals can be transmitted according to the standard up to a transmission rate of 1,200 bits per second.

This simple but very efficient design permanently supplies a DC voltage of about 16 volts during operation. To limit the total power consumed, each control gear is given a maximum of 2 milliamperes (mA) of power consumption, so that a total of 128 mA can be used to supply power for 64 connected stations. For control devices such as sensors, however, no express restrictions are provided, but there regularly the currents on the DALI bus can be quite sufficient, so that at least there cost-saving can be dispensed with another power supply. Incidentally, the DALI communication standard specifies a maximum current limit of 250 mA on the bus.

A known power supply device for such a lighting system communication system therefore routinely includes a power control device adapted to supply a power supplied from a power supply source (eg, 16 volts) to its input node and output from it via its output node to an output of the device on the bus limit predetermined maximum value. The maximum values are in practice 30 to 250 mA. Singular current spikes that can exceed 250 mA for a short time (ie, times small relative to the pulse width of the signal) are tolerated. The power supply source includes a switching power supply, which generates a galvanically isolated voltage of eg 16 volts by means of electronic ballast or switching converter.

As described, the usual power consumption by the interfaces involved is generally below this maximum value. As a rule, a controlled current limitation therefore only occurs if one or the other interface periodically short-circuits the signal and ground lines (or cores) of the bus as part of the signal transmission, bit by bit. In this, one of the communication by signal generation or an error corresponding state falls on the power control device from the total power loss, which in the case of DALI communication P = 16 V x 0.25 A = 4 W and in the device (usually at a transistor) is converted into heat. If, according to protocol, the Manchester code is used for signal transmission, then the bus is short-circuited to a maximum of 50% of the time, i. on average a maximum of 2 W power loss during signal transmission. Frequently, with current technology, devices with 4 or more outputs are developed for independently-independent bus systems. The loss line can be here in the event of a fault with a permanent short circuit but therefore already 16 watts. Overheating and failure of the devices is possible. Furthermore, a basically to be avoided effort to drive cooling.

In the Italian publication IT TO 00 2013 0788 A , which is based on the present applicant, a communication system with power supply device and associated interface for a control or operating device is described in which the unwanted power losses are reduced in the power control device. In this case, the output voltage is monitored at the output of the power supply device to which the signal and ground line of the bus is connected. If this breaks down in the case of a transmission of data signals or in the event of an error, then the current control device is regulated to a significantly reduced maximum value for the current limitation as a function of this.

In one in IT TO 00 2013 0788 A described example, the current control device comprises a measuring or shunt resistor through which the current supplied to the bus flows and at which corresponding to the output voltage drops a certain value of the voltage applied to the measuring resistor. If the latter exceeds a threshold, a transistor of the current control device is switched increasingly blocking. The maximum value of the current limit is reduced by making that measuring or shunt resistor variable. In the example, the measuring or shunt resistor is divided into two partial resistors, one of which can be bridged by another transistor. This is controlled by a comparator or Schmitt trigger, which detects the output voltage at the output of the device and compares it with a reference. If the output voltage falls to less than half of the input voltage, which would correspond to a leaving the "HIGH level" in DALI, then a partial resistance is bridged, which is compared to the remaining partial resistance of the shunt resistor so that the output current in this state is controlled to only 25 mA, ie one-tenth of the originally provided current limit.

On the side of acting in this regard as a load interfaces a sufficient supply of electricity in this state is ensured by the fact that in the circuit in question a storage capacitor is set up with upstream diode from which the load (eg a sensor, etc.) temporarily supplied with power , which is charged on average with 16V.

However, the proposed communication system intervenes due to the significantly reduced output current in the structure of the interfaces. Further, it remains unclear how to handle the case where a long-term short circuit occurs on the bus, which is no longer associated with a data signal transmission and possibly corresponds to an error.

Presentation of the invention

It is therefore an object of the invention to provide a device for power supply and a corresponding communication system, which offer a reduction of the power loss in the case of data transmission, at the same time cost-saving design.

The object is achieved by a power supply device for a communication system for lighting systems with the features of claim 1 and by a corresponding communication system with the features of Claim 15 and by a method according to claim 17.

The starting point is a device for supplying power to lighting systems having an input for connection to a first power source, and an output for connecting to interfaces of control and / or operating devices of the communication system. A current control device having an input node and an output node is provided therein and is configured to limit a current provided by the first power source at the input node and from its (i.e., the current control device) to the output via the output node to a predetermined maximum value. This maximum value may be 250 mA or less, as provided for in the IEC 62386 DALI communication standard, but the invention is not limited to specific communication standards and other values as well as standards-compliant or standard-free configurations are also possible. The exact design of the current control device is in the proposed width of secondary importance, because as explained below, in the proposal made here, starting from the detected output voltage is not necessary feedback into the current control device itself, but rather provided on the input node.

The input of the device has a voltage terminal and a ground terminal that can be connected to the first power source. This can thus provide an input voltage between these terminals. In the DALI case, the input voltage may be e.g. 16.0 ± 4.5 volts, however, the first power supply source is not part of the device proposed here. The first power supply source may include a primary switched mode power supply to provide for e.g. in accordance with the DALI communication standard, to ensure galvanic isolation of the control line (bus) from the mains voltage. It may be without limitation of the invention to a blocking or forward converter, etc. Optionally, a secondary switched-mode power supply, such as a buck converter (down converter), may additionally be provided, which supplies a primary-clocked DC voltage, purely illustratively 24 volts, to said input voltage, e.g. 16.0 ± 4.5 volts.

The output of the device is equipped with appropriate connections (voltage connection and ground connection). Due to the galvanic isolation from the mains, the interconnected ground connections at the input and output are "floating" and in the installation practice not linked to PE (physical earth). The two terminals correspond e.g. the 2-core DALI bus.

The invention now provides a circuit which is designed to detect an output voltage which is present between the voltage connection and the ground connection of the output and to supply the input node of the current regulation device with a voltage which is opposite that between the connections, depending on the detected output voltage the input voltage applied to the input is reduced when the device is connected to the first power supply source.

As described, feedback is provided from the output voltage of the device to the input node of the current control device. More specifically, the voltage applied to the input node by the circuit is reduced with respect to the input voltage. This may be that the reduced voltage is recovered from the input voltage by measures of the circuit itself and reduced, i. E. comparatively lower values, or that a corresponding reduced voltage is sourced from an independent source, for which purpose the input voltage at the input of the device is to be separated from the input node and replaced by the reduced voltage from another source.

In any case, the reduced voltage at the input node with otherwise unchanged current regulation means that, for example, in the state of data signal transmission in the communication system, a required amount of current (for example, 250 mA for DALI) can be maintained, while the power loss can be reduced. For example, if the reduced voltage supplied to the input node of the current control device is set to one quarter of the input voltage, the power dissipated primarily in the current control device to heat is reduced to P = 4 V x 0.25 A = 1 W in the state of the shorted bus, ie also to a quarter (in case of signal transmission and using the Manchester code: maximum 0.50 W, see above). Thus, it is possible to save costs for useless consumed power and for the expense of increased cooling capacity and for interventions in the connected interfaces.

According to a further development, the circuit is designed to supply the current control device with the reduced voltage when the output voltage falls below a predetermined threshold, and to supply the current control device with the input voltage when the output voltage of the predetermined Threshold exceeds. It is important, of course, that the reduced voltage at the input node and the threshold of the output voltage are mutually tuned, because the feedback can not otherwise return from the state with reduced power supply to the original state, in which the output voltage substantially corresponds to the input voltage.

According to a development, the circuit comprises a threshold switch, which is connected to the output node of the current control device and outputs a signal depending on a below or exceeding the predetermined threshold value by the output voltage. The threshold switch may be implemented as an operational amplifier as a comparator, Schmitt trigger or the like. But this aspect is not limited to this. A simple realization as an electronic switch and / or as a transistor of any type is also possible. The detection of the output voltage by a threshold switch is a particularly efficient and easy way to implement the desired feedback. "Capture" does not mean that exact values of the output voltage are determined. This includes the (binary) distinction in a value above or below the threshold or the like.

According to a further development, the circuit comprises a first electronic switch whose first terminal is connected to the voltage terminal of the input and whose second terminal is connected to the input node of the current control device, wherein the first electronic switch is designed to open depending on the output from the threshold switch signal or close to prevent or allow the application of the input voltage to the input node. The first electronic switch can be designed as a transistor, in particular as a bipolar or field-effect transistor, etc. Its control electrode or base or gate may be connected to an output of the threshold switch, e.g. be connected to the comparator. The realization of the feedback on the input node of the current control device via the first electronic switch brings a particularly simple and efficient construction with it.

According to a further development, the circuit comprises a second power source providing the reduced voltage and connected to an input node of the power control device and to the second terminal of the first electronic switch and configured to supply the power control device with the reduced voltage. In combination with the first electronic switch, a particular advantage arises in that, with a simple structure, it is possible to switch back and forth between the input voltage due to the first power supply source and the reduced voltage due to the second power supply source, depending on the output voltage at the input node.

The second power supply source may be a power supply independent of the first power supply source or may be connected thereto by another circuit part. For example, it may comprise a voltage regulator which regulates the input voltage provided by the first power supply source to the reduced voltage and then outputs this at its output terminal. The voltage regulator can be a linear regulator or a switching regulator. Also included is the case in which the first power supply source - as described above - a primary clocked switching power supply (for a voltage of eg 24 V) and each connected thereto a secondary clocked switching power supply, namely one, which then the input voltage at the terminals of the Input provides (eg a voltage of 16 or 17 V), and another that provides the reduced voltage at the input node of the power control device (eg, a reduced voltage of 4 V).

If the first electronic switch is closed, the competition between the two voltages can be solved by connecting the output terminal of the voltage regulator to an anode terminal of a rectifier diode whose cathode terminal is connected to the input node of the current control device and to the second terminal of the electronic switch. The rectifier diode ensures that the reduced voltage only becomes active when the first electronic switch opens.

According to a specific embodiment, the threshold switch comprises a comparator whose inverting input is connected to the output voltage at the output of the device and whose non-inverting input is connected to a reference voltage, the signal being output at the output of the comparator depending on a comparison result of the two voltages. Alternatively, the threshold switch may comprise a second electronic switch whose control terminal is connected to the output voltage at the voltage terminal of the output of the device, and whose working electrode is connected via a resistor to a control terminal of the first electronic switch, and whose reference electrode is connected to the ground terminal. Other implementations are also possible. Realize the two variants however, a particularly simple but efficient and reliable structure for the detection of the output voltage level.

According to an advantageous development, the current control device has an input terminal with a first node, which is connected via a shunt resistor to a working electrode of a third electronic switch whose reference electrode is connected to an output terminal of the current control device. For this purpose, a voltage source for providing a predetermined voltage difference is provided, whose positive terminal is connected to the node and whose negative terminal is connected to a control electrode of the third electronic switch. For the implementation of a current control device, in principle, other structures are known. The comparison of the voltage difference across the shunt resistor, which is an immediate consequence of the applied output voltage, i. is dependent thereon, with a voltage source predetermined, i.e., fixed, voltage difference has been found to be particularly advantageous, reliable (among others, temperature), and compatible with the feedback proposed herein with a reduction in the voltage at the input node.

The following aspects relate to the DALI communication standard, but without express limitation, that is, the device may be DALI compliant:

According to one embodiment, the device comprises the first power supply source, wherein the first power supply source is configured to provide the input voltage with a value of 16.0 ± 4.5 volts. The second power source is then configured to provide a reduced voltage at the input of the power control device having a value of 9.5 volts or less, preferably 7 volts or less, more preferably 5 volts or less. A particularly suitable value is around 4 volts. The lower the reduced voltage, the lower the power loss. As described above, the first power supply source may be or include a primary clocked and optionally additionally a secondary clocked switching power supply.

The predetermined maximum value for limiting the current output to the output via the output node may be 250 milliamps or less (e.g., 200 milliamps). Higher values according to extensions or modifications of the standard are also possible.

Further, the value of the reference voltage with which the output voltage is compared may preferably be between 0.1 volts and 9.0 volts, but less than the reduced voltage. The distance between reference voltage and reduced voltage should be clear and include tolerances, e.g. 3.0 up to 4.5 volts to allow safe return (switching) to the original input voltage, e.g. a short circuit to the data signal transmission is completed. Since the upper limit for the reduced voltage is preferably 9.5 volts (lower tolerance limit according to DALI communication standard), and a reference voltage should be greater than 0 volts in each case, there is a limited margin in the range 3.0-6.0 volts for the Reduced voltage may be in a fixed interval with tolerance limits, but may also be variable.

The invention also provides a communication system for lighting systems comprising a power supply device as described above. Furthermore, it comprises at least one, preferably a plurality of interfaces corresponding to one or more control and / or operating devices for connection to the output terminals of the device. The interface is configured to periodically short-circuit the voltage applied between the voltage terminal and the ground terminal at the output of the device to transmit a digital data signal. The connection is via a corresponding bus, e.g. a 2-wire DALI bus. In this, the device and the interface comply with a standard of the IEC 62386 family entitled "Digital Addressable Lighting Interface" (DALI).

The communication system has, for example, the interface of an operating device with LED module, signal bus connections and an associated power supply device. Strictly speaking, such a minimum configuration of a communication system is a communication device. The scope of protection here refers to the interface with integrated power supply. However, the communication system can also refer to individual interfaces of control devices (sensors / actuators or central control units, for example with a connected PC as described in the exemplary embodiments) with integrated power supply, or also to the entire bus, including all connected interfaces.

• - Bereitstellen einer Eingangsspannung zwischen einem Spannungsanschluss und einem Masseanschluss eines Eingangs einer Leistungsversorgungsvorrichtung,
• - Bereitstellen einer Stromregelungsvorrichtung mit einem Eingangs- und einem Ausgangsknoten, wobei die Stromregelungsvorrichtung ausgelegt ist, einen von der ersten Leistungsversorgungsquelle am Eingangsknoten bereitgestellten und von ihr über den Ausgangsknoten an einen Spannungs- und einen Masseanschluss aufweisenden Ausgang der Vorrichtung ausgegebenen Strom auf einen vorbestimmten Maximalwert zu begrenzen,

• - Erfassen einer Ausgangsspannung, die zwischen dem Spannungsanschluss und dem Masseanschluss des Ausgangs anliegt,
• - Vergleichen der Ausgangsspannung mit einer vorgegebenen Referenzspannung,
• - Reduzieren der am Eingangsknoten der Stromregelungsvorrichtung anliegenden Spannung in Abhängigkeit von dem Vergleichsergebnis auf einen vorbestimmten Wert.

A method of providing a lighting system with power communication system includes the following steps:

• Providing an input voltage between a voltage terminal and a ground terminal of an input of a power supply device,
• - Providing a current control device having an input node and an output node, wherein the current control device is configured to limit a current output from the first power supply source at the input node and output from the output node to a voltage and ground terminal of the device to a predetermined maximum value .

• Detecting an output voltage which is present between the voltage connection and the ground connection of the output,
• Comparing the output voltage with a predetermined reference voltage,
• - Reduce the voltage applied to the input node of the current control device voltage in dependence on the comparison result to a predetermined value.

Further advantages, features and details of the invention will become apparent from the claims, the following description of preferred embodiments and from the drawings. In the figures, like reference numerals designate like features and functions.

list of figures

• 1 in schematischer Darstellung ein Blockschaltbild eines mit Ausführungsbeispielen der Erfindung kompatiblen Beleuchtungssystems einschließlich eines Kommunikationssystems;
• 2 ein Vergleichsbeispiel einer Vorrichtung zur Versorgung eines Kommunikationssystems mit Leistung;
• 3 in schematischer Darstellung ein Blockschaltbild eines ersten Ausführungsbeispiels einer Leistungsversorgungsvorrichtung zur Versorgung eines Kommunikationssystems mit Leistung;
• 4 in einem detaillierteres Blockschaltbild ein zweites Ausführungsbeispiel einer Leistungsversorgungsvorrichtung zur Versorgung eines Kommunikationssystems mit Leistung;
• 5 in schematischer Darstellung ein Beispiel eines Kommunikationssystems mit Schnittstellen an einem DALI-Bus, die von der Leistungsversorgungsvorrichtung gemäß 4 oder 8 mit Leistung versorgt werden;
• 6 ein Diagramm mit einem zeitlichen Verlauf verschiedener Spannungen, die in dem Ausführungsbeispiel der 4 im Verlauf eines Datensignalpulses an unterschiedlichen Positionen der gezeigten Schaltung bestimmt wurden: Eingangsspannung Ue, reduzierte Spannung U_red , Signalspannung U_sig , Ausgangsspannung U_a ;
• 7 entsprechend dem Szenario in 7 ein Diagramm mit einem zeitlichen Verlauf hier des Stromes l_e , der durch die Stromregelungsvorrichtung geregelt wird;
• 8 in einem detaillierteren Blockschaltbild ein zu 4 alternatives drittes Ausführungsbeispiel einer Leistungsversorgungsvorrichtung zur Versorgung eines Kommunikationssystems mit Leistung.

Show it:

• 1 a schematic diagram of a block diagram of a compatible with embodiments of the invention lighting system including a communication system;
• 2 a comparative example of a device for supplying a communication system with power;
• 3 a schematic diagram of a block diagram of a first embodiment of a power supply device for supplying a communication system with power;
• 4 in a more detailed block diagram, a second embodiment of a power supply device for supplying a communication system with power;
• 5 a schematic representation of an example of a communication system with interfaces on a DALI bus, the of the power supply device according to 4 or 8th be supplied with power;
• 6 a diagram with a time course of different voltages, which in the embodiment of the 4 were determined in the course of a data signal pulse at different positions of the circuit shown: input voltage Ue, reduced voltage U _red , Signal voltage U _sig , Output voltage U _a ;
• 7 according to the scenario in 7 a diagram with a time course here of the stream l _e controlled by the flow control device;
• 8th in a more detailed block diagram on 4 alternative third embodiment of a power supply device for supplying a communication system with power.

Preferred embodiments of the invention

In the figures, the same or similar components or the same or similar components are provided with the same reference numerals.

1 shows a schematic representation of a block diagram of a compatible with embodiments of the invention illumination system 10 , The lighting system comprises a number of lights 110 For example, one or more LED (light emitting diode) LED modules or fluorescent lamps, etc., each (or together) by an electronic ballast (ECG) 100 with suitably prepared power from a mains power line M (to be supplied with, for example 230 volts AC) to which they are connected. The electronic ballast 100 can EMC filter, rectifier, power factor correction and depending on the type of luminaire further electronic components, which are known in the art in detail.

A control or monitoring of the electronic ballasts 100 and lights 110 takes place in each case by operating devices 80 that have a microcontroller 82 with memory as well as an interface 81 for connection to a signal bus 70 have, which is formed in this embodiment as a DALI communication bus (standard of the family IEC 62386 ) and a 2-wire line. The DALI communication bus 70 connects the interfaces 81 the operating devices 80 with an interface 50 a communication system 30 which acts as a controller. For this purpose, the communication system also has a microcontroller 60 with memory on. Furthermore, the communication system 30 a power supply device 40 to supply the communication system 30 with power up. The power supply device 40 For example, it has its own connection to the mains power line (eg 230 V AC). On the output side it is with the signal bus 70 connected and fed there a DC voltage of 16-17 V, for example.

In addition to the power supply device 40 and the interfaces 50 . 81 the control and operating devices are on the DALI communication bus 70 also interfaces 91 from sensors 90 or actuators (not shown) connected. These also have a microcontroller 92 with memory, but need, for example, no network connection, as the over the DALI communication bus 70 supplied power can be completely sufficient.

A control or monitoring device 20 such as a PC, a server, etc. is connected to the communication system 30 connected and allowed interaction by the user of the lighting system 10 , The control unit 20 can the transmission of transmission signals to the operating devices 80 or the sensors 90 etc. as well as sent by them and over the interface 50 receive received signals and evaluate. The ones from the sensors 90 For example, transmitted signals may include environmental information such as time, temperatures, humidity, pressure, voltage or other mechanical or electrical quantities, etc. The from the control unit 20 triggered signals may include control information, such as the retrieval of status information such as dimming position (current brightness value), operating time, lamp failure, the activation of a mains voltage switch in the operating device 80 , changed dimming values or the activation of stored scenes, new group assignment (configuration) etc. The transmission of the signals takes place on the 2-wire line by targeted pulsed short-circuiting of the two lines with otherwise constant by 16 V voltage. Data coding takes place with the DALI communication standard with Manchester code, ie the edges of the pulses are evaluated instead of the "HIGH" or "LOW" pulses per se. The DALI communication standard offers a fundamentally polarized connection to the 2-core cable. Subsequently, the two wires are subjectively referred to as control line and ground line. The polarity reversal is ensured for example by bridge rectifier.

Hereinafter, the power supply device 40 closer look. The DA-LI communication standard requires a galvanic isolation of the system from the mains connection, which is why primarily clocked switching power supplies (not shown, eg flyback converters or flyback converters) are provided which provide the required voltage of 16.0 V ± 4.5 volts. Alternatively, secondary switched-mode switching power supplies (not shown, eg buck converters) may be provided downstream, which stabilize an intermediate voltage of approximately 24 V provided by the primary clocked switching power supply to the required voltage of 16.0 V ± 4.5 volts.

In the examples shown below, a power supply device 40 an input with a voltage connection 44 and a mass connection 46 on which the voltage of 16.0 V ± 4.5 volts is applied. In the examples, the input voltage is about 17 volts. The voltage and the state-dependent current supplied are from a power supply source 42 supplied, which represents, for example, the one or the above-mentioned switching power supplies. The power source 42 may be part of the device 40 it does not have to be.

2 shows a comparative example of a power supply device 40 , It includes the entrance with the connections 44 . 46 , between which the input voltage Ue is applied, a current control device 401 and an output with connections 48 . 49 for corresponding connection to the control and ground line of the signal bus 70 (DALI communication bus). An ohmic resistance R22 and a capacitor C1 serve to stabilize the between the terminals 48 . 49 Output voltage output Ua.

The flow control device 401 is designed to be at the output terminals 48 . 49 on the signal bus 70 (DALI communication bus) to a maximum value of 250 mA (or less). This is the voltage connection 44 the input via a measuring resistor R23 with the emitter of a PNP bipolar transistor Q4 connected. Its collector is in turn directly connected to the voltage connection 48 connected to the output.

At the same time, the emitter of another PNP bipolar transistor Q9 with the voltage connection 44 connected to the input. Its collector has an ohmic resistance R20 connected to ground GND (or to the ground faults 46 respectively. 49 input and output). Furthermore, the base of the bipolar transistor Q4 likewise with the collector of the further bipolar transistor Q9 connected, and the base of this further bipolar transistor Q9 is about a resistance R21 with the emitter of the bipolar transistor Q4 connected.

In normal operation (16 or 17 V, no short-circuit) during operation, the ohmic resistance is reached R23 only a very low voltage. The bipolar transistor Q4 is activated and a current flows in the direction of the load to the output terminal 48 out. Now become the connections 48 . 49 shorted to a DALI signal pulse on the connected signal bus 70 For example, the short circuit may be from the interface of the controller / communication system 30 be effected when the data transmission from the control device 20 is initiated), so flows stronger current and the voltage between the terminals of the ohmic resistance R23 rises and exceeds the threshold voltage of the further bipolar transistor Q9 which is now becoming increasingly conductive, allowing the bipolar transistor Q4 increasingly locks. A current flows through the ohmic resistance R20 from. The components are dimensioned such that via the partially deactivated or partially blocked bipolar transistor Q4 a regulated current of up to 250 mA can flow.

The initially mentioned document IT TO 00 2013 0788 A provides feedback from an output node directly to the ohmic resistor R23 in the current control device by varying this resistance depending on the output voltage. In an example case, the measuring resistor is varied so that the maximum value for the current limitation in the event of a short circuit (output voltage equal to zero) is only 25 mA. The heat predominantly in the transistor Q4 converted loss line in the state of the shorted bus is therefore only P = 16 V x 0.025 A = 0.4 W. As described, but there is the problem that among other things the current flow provided in this state may not be sufficient for the supply of connected devices.

Embodiments of the present invention now provide for leaving the current control device untouched and instead to provide feedback to the input node of the current control device, less affecting the current regulation itself but reducing the voltage applied to it.

3 shows a schematic block diagram of a first embodiment of the invention, with which the basic principle is clear. The power source 42 , the connections 44 . 26 the entrance, the flow control device 401 and the connections 48 . 49 of the output are provided unchanged. The flow control device 401 For example, the in 2 be shown. However, there is an additional circuit that has a threshold switch 402 , a first electronic switch 403 and a second power supply source 404 includes. The threshold switch 402 detects the between the output terminals 48 . 49 applied output voltage U _a and determines whether it exceeds a threshold or not. Below the output voltage U _a the threshold (eg, because the output terminals are shorted, ie, U _a = 0 V), the threshold switch outputs a signal to the first electronic switch 403 out, so that this is opened. As a result, the at the connections 44 . 46 the input voltage applied to the input U _e from an entrance node 410 the flow control device 401 separated. Instead, the flow control device 401 now with power from the second power source 404 supplied, with one opposite to the input voltage U _e (17 V) reduced voltage U _red , which is for example 4V here. As shown, the second power source is 404 even with the connections 44 . 46 connected to the input, so its power itself from that of the first power source 42 , The second power source 404 can be designed as a simple voltage regulator, but with regard to the reduction of power loss is a realization of its own switching power supply for the second power supply source 404 possibly more advantageous.

4 shows in more detail a second embodiment of the invention. The basic structure with the power supply source 42 , the connections 44 . 26 the entrance, the flow control device 401 that made of threshold switch 402 , first electronic switch 403 and second power source 404 existing feedback circuit and the connections 48 . 49 the output is also present here.

The flow control device 401 includes an entrance node 410 that has a resistive resistance R6 with the emitter of a PNP bipolar transistor Q4 ("Third" electronic switch) is connected. The ohmic resistance R6 is here designed as a measuring or shunt resistor and its resistance value is for example 4-5 Ω. The collector of the PNP bipolar transistor is connected to an output node 411 the flow control device 401 and the voltage connection 48 the device 40 connected. The third electronic switch is designed as a Darlington transistor and comprises a correspondingly interconnected further PNP bipolar transistor Q3 , The entrance node 410 is also connected to a positive terminal of a voltage source 45 connected. At the voltage source 45 For example, without limitation of the scope of protection, it may be, for example, a battery, or an electronic component such as a linear series regulator (eg, LM317) or a precision shunt regulator (eg, TL431), etc. Present provides the voltage source 45 a constant voltage reference U _ref1 of approximately 1.25 V. The negative terminal of the voltage source 45 is with the anode of a diode D1 whose cathode is connected to the anode of another diode D3 connected is. The cathode of the other diode D3 is over an ohmic resistance R7 with the ground potential as well as with the base of the Darlington transistor or the PNP bipolar transistor Q3 , ie connected to the control electrode of the third electronic switch. The resistance of the ohmic resistor R7 is for example 5-10 kΩ. The two diodes D1 and D3 serve as compensation diodes with respect to the base-emitter paths of the bipolar transistors Q3 and Q4 , The from the voltage source 45 Supplied voltage reference is used for the actual current limitation.

As long as on the signal bus 70 there is no short circuit for signal transmission, the voltage drop across the shunt resistor R6 less than the voltage reference of the voltage source 45 , The base current for the PNP bipolar transistors Q3 and Q4 flows in this respect over the ohmic resistance R7 and controls the two transistors Q3 . Q4 the Darlington circuit. If the load is too high or in the event of a short circuit, the shunt resistance increases R6 falling voltage and exceeds the voltage reference. As a result, the base current and the third electronic switch ( Q3 . Q4 ) locks increasingly. The voltage at the output node 411 or between the connections 48 . 49 (Output voltage U _a ) decreases accordingly.

The threshold switch 402 detects this output voltage U _a , where here is a comparator U3 whose inverting input is connected to the output node 411 the flow control device 401 or with the voltage connection 48 connected to the output. The non-inverting input of the comparator U3 is with a reference voltage U _ref2 connected. This is obtained from a voltage divider, the one between the voltage connection 44 and the ground connection 46 of the input (ie, the input voltage U _e is applied) in series ohmic resistance R12 and two diodes D2 and D4 is formed. The resistance of the ohmic resistor R12 is for example 50 kQ. Due to the two arranged from the tapping point of the voltage divider to ground diodes D2 and D4 is the reference voltage U _ref2 approximately 1.4V. In this and other embodiments, the threshold or reference voltage may also be selected higher and implemented by other or other devices.

At the usually high output voltage U _a is from the comparator U3 due to comparison with the lower reference voltage U _ref2 a low level signal is output at the output thereof, which is the first electronic switch 403 More specifically, the base of a PNP bipolar transistor representing this switch is supplied Q2 via a base resistor R1 (eg 5 kΩ) is supplied. An investigator of the PNP bipolar transistor Q2 is with the voltage connection 44 connected to the input. The first electronic switch is closed in this state. If the load or short-circuited output voltage is too high, the reference voltage will become U _ref2 fell below, and the comparator U3 gives according to its voltage supply from the voltage connection 44 A signal from high level off. The PNP bipolar transistor Q2 now locks, the first electronic switch 403 it is open. The entrance node 410 is thus separated from the direct supply of input voltage.

The second power source 404 is from an actual voltage source 43 and a diode D5 constructed, with the anode to the positive terminal of the voltage source 43 connected is. The cathode of the diode D5 is connected to the collector of the PNP bipolar transistor Q2 and with the entrance node 410 the flow control device 401 connected. The voltage source 43 may include a voltage regulator. The supply of the voltage source 43 with power can be from the first power source 42 , from whose switching power supplies, or from a separate source. The voltage source 43 provides a substantially constant voltage U _red , which is reduced compared to the input voltage Ue and in the embodiment 4 Volt is. As soon as the first electronic switch 403 or the PNP bipolar transistor Q2 open, the voltage is reduced U _red over the diode D5 on the entrance node 410 imprinted.

For the flow control device 401 This has only minor consequences, because of the comparison between the shunt resistance R6 decreasing resistance and the voltage reference U _ref1 does not change much. The bipolar current controller realized here is quite stable compared to input voltage fluctuations. The current limit is still active at a maximum value of 250 mA. The power loss with a short-circuited output is only P = 4 V x 0.25 A = 1 W (or 0.5 W in the case of signal transmission with Manchester Code), without any loss of current flow. There is thus no disturbance of the control or operating devices or the sensors or actuators. A particular advantage arises from the fact that the device for power supply of the communication system can thus be reduced in terms of space, because any cooling surfaces can be made smaller or even entire heat sinks can be dispensed with.

5 shows a schematic circuit diagram for the at the output of the device 40 (Voltage connection 48 to control line and ground connection 49 to ground line) connected signal bus 70 (DALI communication bus). the interface 50 the control unit or the communication system 30 is shown here only with respect to the transfer functions, ie functional units for the reception are omitted. A voltage source includes the microcontroller 60 which has a pulsed voltage across an ohmic resistor R4 (Base resistor) to the base of the NPN bipolar transistor Q1 to specifically target this open and close. A closing of the NPN bipolar transistor Q1 causes a short circuit between the terminals 48 . 49 or the control and ground line of the signal bus 70 , The capacitor C4 and the ohmic resistance R5 serve also here the stabilization. Schematically are in 5 also individual consumers such as control gear 80 or control devices (sensors 90 ).

The 6 and 7 show the result of a simulation for a single short circuit pulse (here purely for example from about 0.4 ms to about 0.85 ms) the time courses at various points in the circuit diagram of 4 tapped voltages or the resulting current flow.

In 6 are shown the input voltage U _e between the connections 44 . 46 of the input, which is consistently constant at about 17V (dashed line), the output voltage between the terminals 48 . 49 of the output, the voltage Ucomp of the comparator U3 output signal, as well as the possibly reduced voltage at the input node 410 the flow control device 401 ,

In 7 can be seen as a test before the NPN bipolar transistor is closed Q1 (Short circuit of the signal bus for data transmission) the three in 5 shown loads are activated as a load, which is recognizable by the three stages between 0.2 ms and 0.4 ms. The load in these cases is still below the maximum value Imax of 250 mA for the current limitation. The maximum value is due to the dimensioning of the components in the current control device 401 established. In 6 is seen that the output voltage U _a due to the load breaks slightly, but which still has no effect on the voltage acting in the additional circuit voltages Ucomp and U _red exercises.

At the time of short-circuiting (approximately from 0.4 ms), a short-term overshoot in the course of the current ( 7 ), which however is quickly limited again to the maximum value Imax of 250 mA. At the same time, the output voltage breaks U _a ( 6 ) as expected to 0V. The voltage Ucomp from the comparator to the first electronic switch 403 output signal was previously at ground potential (0 V), since the output voltage U _a the reference voltage U _ref2 exceeded. During the short circuit this is no longer the case (the output voltage U _a below 0 V, the reference voltage U _ref2 of 1.4 V), so that the comparator outputs the signal with its supply voltage (17 V). As a result, the first electronic switch opens 403 (the PNP bipolar transistor Q2 locks), and those at the entrance node 410 voltage applied U _red reduces to that of the voltage source 43 over the diode D5 output voltage of 4 V.

Once the NPN bipolar transistor Q1 from the voltage source or the microcontroller 60 the interface 50 the control unit is turned on again, the output voltage increases U _a back to its previous value (about 15V), so the threshold switch 402 in response to this again the low level signal (U _comp = 0 V) to the first electronic switch 403 outputs. This closes again and the entrance node 410 will return to the input voltage ( U _red = U _e ) provided.

An alternative embodiment (third embodiment) is shown in FIG 8th shown. The third embodiment differs from the second embodiment only in terms of the threshold fails 402 ' , Instead of a comparator U3 Here is a simple NPN bipolar transistor Q5 used its base via a base resistor R2 and a diode D4 with the output (voltage connection 48 ) of the device 40 connected is. The emitter of the NPN bipolar transistor Q5 is at the ground potential and the collector is above the base resistor R1 with the base of the PNP bipolar transistor Q2 connected. A signal level change of the threshold switch 402 ' occurs when the output voltage Ua is the reference voltage Uref2 below the threshold switch, which in this case is the threshold voltage of the NPN bipolar transistor Q5 is. Incidentally, the operation is identical to that of the second embodiment. It should be noted that here also the diode D5 of the second embodiment by a Schottky diode D5 is replaced.

Further modifications or alternatives to the exemplary embodiments described above are considered by the person skilled in the art as belonging to the invention, insofar as they are covered by the scope of protection defined by the appended claims. Thus, instead of the bipolar transistors described, it is also possible to use those of the opposite conductivity type or even other types of transistors, such as, for example, MOSFETs. Corresponding adjustments of the circuits will be made routinely by the person skilled in the art.

Furthermore, the invention has been described essentially in connection with the DALI communication system. However, the invention is also applicable to other bus systems based on other protocols and in particular other voltage systems, in particular as far as on the same lines of the bus both signals and a power supply should be made.

LIST OF REFERENCE NUMBERS

10

lighting system

20

Control device (server, PC)

30

communication system

40

Device for power supply

42

First power source

43

Second power source

44

Voltage connection (input)

45

voltage source

46

Ground connection (input)

48

Voltage connection (output)

49

Ground connection (output)

50

Interface (control unit: central control unit)

60

Microcontroller with memory

70

Signal bus, DALI communication bus, 2-core cable

80

control gear

81

Interface (operating device)

82

Microcontroller with memory

90

Sensor, actuator

91

Interface (control unit: sensor, actuator)

92

Microcontroller with memory

100

EVG

110

lamp

401

Current control device

402

threshold switch

403

First electronic switch

404

Second power source

C1

capacitor

C4

capacitor

D1

diode

D2

diode

D3

diode

D4

diode

D5

diode

D6

Schottky diode

M

AC power line

Q1

NPN transistor

Q2

PNP transistor (first electronic switch)

Q3

PNP transistor (third electronic switch in Darlington)

Q4

PNP transistor (third electronic switch in Darlington)

Q5

PNP transistor (second electronic switch

Q9

PNP transistor

R1

Ohmic resistance

R2

Ohmic resistance

R4

Ohmic resistance

R5

Ohmic resistance

R6

Ohmic resistance

R7

Ohmic resistance

R12

Ohmic resistance

R21

Ohmic resistance

R22

Ohmic resistance

R23

Ohmic resistance

U3

comparator

U _a

output voltage

U _comp

voltage output to the electronic switch at the comparator

U _e

input voltage

U _red

Reduced voltage at the input of the current controller

U _ref1

Voltage reference in the current controller

U _ref2

Threshold value or reference voltage at the threshold value switch

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• TO 0020130788 A [0009, 0010, 0049]

Claims (17)

Power supply apparatus (40) for a lighting system communication system (30), comprising: an input having a voltage terminal (44) and a ground terminal (46) for connection to a first power supply source (42) having an input voltage (U _e ) between these connections (44, 46) and an output with corresponding terminals (48, 49) for connection to at least one interface (50, 81, 91) of a control and / or operating device, a current control device (401) having an input - (410) and an output node (411), wherein the current control device (401) is adapted to provide a current (I. 1) provided by the first power supply source (42) at the input node (410) and output therefrom to the output via the output node (411) _e ) to limit to a predetermined maximum value (I _max ), characterized by , a circuit which is designed, an output voltage (U _a ), the intermediate is applied to the voltage terminal (48) and the ground terminal (49) of the output to detect and depending on the detected output voltage (U _a ) to supply the input node of the current control device (401) with a voltage (U _red ), compared to the input voltage ( U _e ) is reduced. Power supply device (40) according to Claim 1 wherein the circuit is _adapted to supply the current control device (401) with the reduced voltage (U _red ) when the output voltage (U _a ) _{falls below} a predetermined threshold value (U _ref2 ), and the current control _device (401) is connected to the input voltage (U _e ) to supply when the output voltage (U _a ) exceeds the predetermined threshold value (U _ref2 ). Power supply device (40) according to Claim 2 wherein the circuit comprises a threshold switch (402) which is connected to the output _node (411) and outputs a signal (U _comp ) as a _{function of undershooting} or exceeding the predetermined threshold value (U _ref2 ) by the output voltage (U _a ). Power supply device (40) according to Claim 3 wherein the circuit comprises a first electronic switch (403) whose first terminal is connected to the voltage terminal (44) of the input and whose second terminal is connected to the input node (410) of the current control device (401), the first electronic switch (403) is designed to open or close depending on the signal (U _comp ) output by the threshold switch (402) to allow or prevent the application of the input voltage (U _e ) to the input node (410). Power supply device (40) according to Claim 4 wherein the circuit comprises a second power source (404) providing the reduced voltage (U _red ) and connected and configured with the input node (410) of the power control device (401) and the second port of the first electronic switch (403) is to supply the current control device (401) with the reduced voltage (U _red ). Power supply device (40) according to Claim 5 in that the second power supply source (404) comprises a voltage regulator which regulates the input voltage (U _e ) provided by the first power supply source (42) to the reduced voltage (U _red ) and then outputs this at its output terminal. Power supply device (40) according to Claim 6 , wherein the voltage regulator is a linear or a switching regulator. Power supply device (40) according to one of Claims 6 to 7 wherein the output terminal of the voltage regulator is connected to an anode terminal of a rectifying diode (D5) whose cathode terminal is connected to the input node (410) of the current regulating device and to the second terminal of the electronic switch (403). Power supply device (40) according to one of Claims 5 to 8th wherein the threshold switch (402) comprises a comparator (U3) whose inverting input is connected to the output voltage (U _a ) at the output of the device and whose non-inverting input is connected to a reference _voltage (U _ref2 ), the signal (U _comp ) depending on a comparison result of the two voltages at the output of the comparator (U3) is output. Power supply device (40) according to one of Claims 5 to 8th wherein the threshold switch (402) comprises a second electronic switch (Q5) whose control terminal is connected to the output voltage (U _a ) at the voltage terminal (48) of the output of the power supply device, and its working electrode via a resistor (R1) to a control terminal the first electronic switch (403) is connected, and whose reference electrode is connected to the ground terminal (46). Power supply device (40) according to one of Claims 5 to 10 , in which the current control device (401) has an input terminal having a first node (410) connected via a shunt resistor (R6) to a working electrode of a third electronic switch (Q3, Q4) whose reference electrode is connected to an output node (411) of the current control device (401), wherein a voltage source (45) is provided for providing a predetermined voltage difference, its positive connection to the node and its negative terminal to a control electrode of the third electronic switch (Q3, Q4) directly or indirectly via one or more diodes (D1, D3) is connected. Power supply device (40) according to one of Claims 5 to 11 , further comprising: the first power supply source (42), wherein the first power supply source is configured to provide the input voltage (U _e ) with a value of 16 volts, and wherein the second power supply source (43) is configured to provide a reduced voltage (U _red ) with a value of 8 volts or less, preferably 6 volts or less, more preferably 4 volts or less. Power supply device (40) according to one of Claims 5 to 12 wherein the current output to the predetermined maximum value (I _max ) for limiting the current output to the output via the output node (411) is 250 milliamps or less. Power supply device (40) according to one of Claims 9 or 10 to 13 , as far as referring back to Claim 9 , wherein the value of the reference _voltage (U _ref2 ) is between 0.1 volt and 9.5 volts. A communications system (30) for lighting systems, comprising the power supply device (40) of any of the preceding claims, a signal bus (70) for connecting to the ports (48, 49) at the output of the power supply device (40), and at least one interface (50, 81 , 91) of an operating and / or control device for connection to the signal bus (70), wherein the interface (50, 81, 91) is arranged to transmit a digital signal on the signal bus (70) between the voltage connection (48). and periodically short-circuit voltage (U _a ) applied to the ground terminal (49) at the output of the power supply device (40). Communication system (30) according to Claim 15 wherein the power supply device (40), the signal bus (70) and the interface (50, 81, 91) correspond to a standard of the family IEC 62386 entitled "Digital Addressable Lighting Interface" (DALI). A method of powering a lighting system (10) communication system (30) comprising: - providing an input voltage (U _e ) between a voltage terminal (48) and a ground terminal (49) of an input of a power supply device (40) for the communication system (30 ), - providing a current control device (401) having an input (401) and an output node (411), the current control device (401) being arranged to supply one at the input node and from the output node to one, a voltage (48 ) and a ground (49) having output of the power supply device (40) current limited to a predetermined maximum value (I _max ), - detecting an output voltage (U _a ) between the voltage terminal (48) and the ground terminal (49) of Output is present, - Comparing the output voltage (U _a ) with a predetermined reference voltage (Uref2), - Reducing The voltage (U _red ) applied to the input node (410) of the current control device (401) is reduced to a predetermined value as a function of the comparison result.

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