DE4330114B4 - Circuit arrangement for controlling a plurality of consumers, in particular ballast for lamps - Google Patents

Abstract

Circuit arrangement comprising a central unit, for example a central control unit (5}, and a plurality of peripheral units (3, 4) connected to the latter via a bus (1), for example control units (4) for lamps, each of which has a Coupling unit (3) are connected to the bus (1), each coupling unit (3) having a receiving branch (RV, V2) for transmitting information from the central unit (5) to the peripheral unit and a transmitting branch (VA, T4 , R5) for the transmission of information from the peripheral unit to the central unit (5), the central unit (5) delivering information in the form of a modulated AC or pulse voltage to the bus (1) and the transmitting branch thereby Outputs information to the bus (1) that the output resistance of the transmission branch is varied, and wherein the circuit arrangement also has overvoltage protection for the reception and / or transmission branch, characterized in that in S A switch (T1) controlled by an overvoltage detector (ZD3, T2) is arranged with the transmitting branch, which opens in the event of overvoltage and switches the transmitting branch ...

Description

The invention relates to a Circuit arrangement for controlling a plurality of consumers, such as lamps. Especially when using gas discharge lamps needed each of these lamps has its own ballast to the gas discharge lamp the necessary ignition or supply operating voltage. If a large number of such lamps are used, it is convenient to the respective ballasts from a central control unit from a central data line head for.

From the GB 2,072,467 A or the DE 30 49 821 T1 , from which the preamble of claim 1 is based, a circuit arrangement is known in which a central control unit is connected via a data bus to a plurality of peripheral units, the functions of which are controlled via the data bus. Each peripheral unit has a coupling unit which is divided into a receiving branch and a transmitting branch. The receiving branch is used to transmit information from the central control unit to the peripheral unit, the central control unit providing information in the form of a modulated AC or pulse voltage to the data bus. The transmission branch is used to transmit information from the peripheral unit to the central control unit. The information is transferred from the peripheral unit to the data bus by varying the output resistance of the transmission branch.

Furthermore, from the EP 0 490 329 A1 a circuit arrangement for controlling the brightness and the operating behavior of gas discharge lamps is known. A central control unit controls a large number of ballasts for gas discharge lamps via a data bus. Each ballast is connected to the data line via a coupling unit. In this case, data is transmitted from the data line to the respective ballast via a capacitor circuit or by means of a transformer. If feedback signals are to be transmitted from the ballast to the central control unit, then when there is no data on the data line, it is possible to couple these signals from the ballast into the data line via the same coupling unit.

Both known circuit arrangements have the possibility the peripheral unit by means of appropriate control signals to put it into a state of rest in which there was only one diminished Has current, but the receiving branch of the coupling unit remains complete even when idle activated, whereby the data bus is loaded even if none Signals are present. This leads especially when a large number used by peripheral units to a significant extent Power consumption in the central unit.

Another disadvantage of both circuit arrangements is that the coupling unit can easily be damaged by an overvoltage on the data bus. This can happen, for example, if the circuit arrangement is installed in the context of conventional house installations, for example lamp systems. An accidental connection of the data bus with a mains voltage line - 220 volts or 380 volts - would damage the coupling unit of the circuit arrangement immediately, which would put the entire arrangement out of operation. In the circuit arrangement of the GB 2,072,467 A or the DE 30 49 821 T1 Although a controllable switch is provided which is opened as soon as a short circuit caused by a component that has failed due to overvoltages is detected, damage to the circuit arrangement by overvoltages in the receiving and / or transmitting branch is not avoided in this way.

The object of the invention is therefore based on a circuit arrangement for controlling a plurality of To further educate consumers of the type described in the introduction, that secure operation is always guaranteed.

This object is achieved with the solved in claim 1 means.

Accordingly, the coupling unit has a receiving branch for transmitting control information from the central control unit to the consumer assigned to the coupling unit, and a transmitting branch for transmitting feedback information from the consumer to the central control unit. It is further provided that both the receiving branch and the transmitting branch in the coupling unit have protection against overvoltages. This protection is achieved by an overvoltage detector and a switch controlled by the detector, which opens as soon as an overvoltage occurs and decouples the transmission branch from the bus. In contrast to the circuit arrangement of the GB 2,072,467 A or the DE 30 49 821 T1 This means that the failure of a component is not initially waited for and safe operation is always guaranteed.

According to claims 2 to 5, easy to set up advantageous embodiments of the overvoltage protection in the transmission branch are described, wherein according to claims 2 and 3 an additional protection device against overvoltages at the output of the transmission branch is described, which is provided for the case that the invention according to the invention seen switch does not separate the transmission branch sufficiently quickly from the bus.

According to claims 6 and 7 is a further development of surge protection described on the receiving branch.

According to claims 8 to 10, there is an advantageous Further training in that the Consumers and the central control unit at a common Data line are connected, which means the circuitry for Connect the consumer to the central control unit is minimized. Since the Consumers from the data line in the respective coupling units are galvanically isolated, an undesirable occurrence of equalizing currents is avoided, the use of an optocoupler to transmit rectangular signals allows without this transformer to have to use which are considerably more expensive to buy.

According to claims 11 to 14 is another advantageous embodiment of the invention given that the central Control unit when it does not output data signals on the data line outputs a signal whose voltage level is from the voltage level the data signals are different. As a result, the coupling device signals that the central control device is not in the transmitting state but in the receiving state, making it possible in a simple way is by means of a switching device, for example with a Zener diode, to switch the receiving branch inactive in the coupling unit.

According to claims 15 to 17 is an advantageous Continuing education given that the electricity consumption in the Coupling device, for example, by means of a MOS field-effect transistor constant current source formed is monitored, so that at a faulty connection or another in the case of a defective component employment the circuit arrangement is avoided.

After all, there is an advantageous one Development of the invention according to claims 18 and 1. in that the Coupling unit has reverse polarity protection, for example with a rectifier bridge circuit is formed. In this way, the coupling unit is connected simplifies the data line while damaging the Coupling unit or the consumer protected by incorrect wiring. The Rectifier bridge circuit brings the advantage especially in connection with the optocouplers with that the Coupling unit to transmit square wave signals largely without distortion can.

The invention is described below Reference to the drawings in more detail explained.

It shows:

1 2 shows a block diagram of the circuit arrangement,

2 a circuit diagram of an embodiment of the circuit arrangement

3 (a) and (B) Variations on the embodiment according to 2 ,

In 1 a block diagram is shown in which a central unit or central control unit 5 with a data bus or a data line 1 connected is. Also on the data line 1 several coupling units 3 connected the data line to consumers 4 Docking. The central control unit ( 5 ) Signals output on the data line are therefore also at the inputs of all consumers 4 on. It is therefore necessary, if individual consumers are to be controlled, to code the data signals in a consumer-specific manner. To forward data from the data line to the consumer, the coupling unit has an input branch for a connection directed to the consumer. Analogously to the data transmission from the consumer to the data line, there is a connection directed from the consumer to the coupling unit, which forms a transmission branch.

In 2 A circuit diagram for an exemplary embodiment of the circuit arrangement is shown, connection points between two components being referred to as nodes with the reference symbols of the components. The central control unit 5 is on the data line formed from a two-wire line 1 connected, the central control unit 5 has a signal generator which generates rectangular data signals which in this case have a peak level of 12 V. Furthermore, a DC voltage generator DC with an internal resistance Ri is provided, which emits a DC voltage of 4 V. Both generators generate their signals against a common ground potential, to which one of the two connections of the data line is also connected. A setting switch S is connected with its movable working contact to your second connection of the data line and is connected with its fixed selector contacts to one output of each of the two generators.

At the other end of the data line 1 is an electronic ballast EVG for example for a gas discharge lamp with its coupling unit 3 coupled. At the interface between the data line 1 and the electronic ballast is on the device side, ie in the coupling unit 3 , first a BR rectifier bridge circuit. The AC voltage connections of the bridge circuit are connected to the interface, while the connections +/- to the subsequent components of the coupling unit 3 are connected. A self-conducting MOS field-effect transistor T3 is connected to its drain connection to the plus connection of the bridge circuit BR. A resistor R3 is connected in parallel between the gate connection and your source connection. At the same time, a series connection is best Starting from a PTC thermistor RK, a Zener diode ZD1, a resistor RV and an optocoupler V2 between the resistor R3 and your minus connection of the rectifier BR, the anode connection of the Zener diode ZD1 via the resistor RV with your anodes -Connection of the transmitter diode of the optocoupler V2 is connected. For the sake of simplicity, the minus connection of the bridge rectifier BR is referred to as the minus line. Furthermore, a series circuit is connected between your node R3 / RK and the negative line, which consequently consists of a transistor T1, resistors R1 and R5 and your output of an optocoupler V 1. Here, the transistor T1 is connected with its collector to the positive terminal of the bridge rectifier BR and with its emitter terminal to the resistor R1. At the base connection of the transistor T1 is the collector of a transistor T2, whose emitter is connected to the minus line. is. At the same time, one terminal of a resistor R4 is connected to the collector of transistor T2, while the other terminal is connected to node RK / ZD1. A Zener diode ZD3 is connected to its cathode at the same node, while a resistor R6 is connected in series with its anode to the minus connection of the bridge rectifier. Between your base terminal of transistor T2 and your node ZD3 / R6 is a resistor R? connected. Furthermore, a parallel circuit consisting of a Zener diode ZD4 and a transistor T4 is connected between the node R1 / RS and the negative line, the Zener diode with its cathode contact and the transistor T4 with its collector being connected to this node: the emitter of the transistor T4 is connected to the negative line and your base connection to your RS / V1 node. Finally, a Zener diode ZD2 is connected with its anode to the negative lead and with its cathode to the node RK / ZD1. On the receiving side of the optocoupler V2 are the connections of the receiving transistor with the data input lines DS and Gnd of a control unit 4 of the electronic ballast, while from the transmission side of the optocoupler V1 the connections of the transmission diode with connections of error feedback lines RS and Gnd of the control unit 4 of the electronic ballast are connected. According to the in 2 In the illustrated embodiment, the respective ground lines Gnd of the data line and the error feedback lines can be combined and implemented as a common ground line Gnd.

Below is the operation of the previously referring to FIG 2 described circuitry explained. If the central control unit 5 is in the transmission mode, data signals are generated by the square-wave signal generator in accordance with the desired transmission data. These have a signal level of 12 V and are switched to the data line via the setting switch S. 1 guided. The fact that at the input of the coupling unit 3 the bridge circuit BR is located, has the polarity of the signal generator or the connection arrangement of the data line 1 with the central control unit or with your electronic ballast no meaning. Thus, the coupling unit 3 The signals recorded are always routed with the correct polarity to the transmitter diode of the optocoupler V2. Here, by converting the electrical signals into light signals and by converting the light signals into electrical signals on the receiving side, there is a galvanic separation between the control unit 4 of the electronic ballast and the data line 1 , The data signals forwarded in this way become the processing devices of the control unit 4 performed and processed there in the usual way.

Are from the central control unit 5 no data signals on the data line 1 transmitted, the control switch S switches to the DC voltage generator DC. Now lies on the data line 1 a DC voltage of, for example, 4 V, which makes the electronic ballast ready to receive the central control unit 5 is signaled, whereby the polarity of the DC voltage generator DC is of no importance due to the bridge rectifier BR in the input of the control unit. Characterized in that the Zener diode ZD1 has a Zener voltage, the value of which is lower than the signal level of the data signal generator and greater than the level of the DC voltage generator DC, for example 4.7 V, the receiving unit of the central control unit S of the optocoupler V2 by means of the Zener diode ZD1 switched off. The transmission diode of the optocoupler V2 thus does not consume any electrical energy via the data line when the central control unit is in the receiving mode 1 must be supplied.

Is the 4 V DC voltage delivered by your DC voltage generator on the data line? 1 is determined by the Zener diode ZD as an allowable voltage if the Zener voltage of this Zener diode is between 15 V and 20 V. The transistor T1 is now controlled via the resistor R4, as a result of which the voltage forwarded by the rectifier BR is present on the data line between the collector and emitter of the transistor T4, which is initially blocking, via the resistor R1. Because the collector / base section of the receiving transistor of the optocoupler V1 is in reverse polarity, only the reverse current of the receiving transistor is conducted on this circuit branch, so that as long as no data is to be output from the electronic ballast into the data line, also from your optocoupler V1 does not consume any significant current to be supplied via the data line. As soon as a signal from the control unit of the electronic ballast via the feedback signal line RS, such as an error feedback, to the central control unit, these signals are sent out via the transmission diode of the optocoupler V 1. These signals are analogous to the data transmission in the optocoupler V 1 also first converted into optical signals and then recovered as electrical signals, which also creates the connection between the control unit 4 of the electronic ballast and the data line 1 is galvanically isolated. By receiving the optical signal emitted by the transmitting diode of the optocoupler V 1, the conductivity of the input transistor is modulated, which switches the transistor T4 on via the voltage drop across the resistor RS, thereby placing a load on the DC voltage generator DC in the central control unit 5 he follows. This load is in the central control unit 5 determined and evaluated at the resistor Ri.

The maximum power consumption of the coupling unit 3 is limited by the self-conducting MOS field effect transistor V3. This is inherently conductive without a signal between the gate connection and the source connection. Through a current that flows through the drain-source path and thus also through the resistor R3, a voltage drop occurs at a resistor R3, which simultaneously causes a voltage signal between the gate connection and the source connection. In accordance with these signals, the conductivity of the transistor T3 is reduced, which limits the current consumption of the coupling unit 3 he follows. This current limitation essentially serves as a safety device which is intended to prevent damage to the components in the coupling unit when it is at the interface of the coupling unit 3 an incorrectly dimensioned signal source is connected. The current flow through the optocoupler V2 is limited by the resistor RV. Since a current limiting device is already provided with the MOS field effector T3, this resistance RV itself can be omitted. However, since the MOS field-effect transistor T3 serves to limit the current of the input transistor of the optocoupler V1 and the transmission diode of the optocoupler V2, the use of the resistor RV is recommended on the one hand because of the differences in components and because of the strong temperature dependency of the MOS field-effect transistor T3. The same applies analogously to the resistor R1.

The constant current source with the MOS field effect transistor T3, as in 3 shown, are also replaced by other circuit arrangements which represent constant current sources or current limiting devices. For this purpose, temperature-stable circuit arrangements should preferably be selected. If the protective effect of this current limiting device can be completely dispensed with, the constant current source can be as in 2 and 3 is indicated by dashed lines, can be omitted, the simple replacement of the constant current source by a resistor would also be conceivable.

As soon as at the entrance of the coupling unit 3 If an impermissibly high voltage is present, this is short-circuited by the Zener diode ZD2, which has a Zener voltage of, for example, 20 volts. In this way, the impermissibly high voltage in the receiving branch of the coupling unit 3 derived in front of your optocoupler V2. In the exemplary embodiment specified, voltages which are above 20 volts are therefore defined as an impermissibly high voltage. However, this definition depends entirely on the permissible limit values of the optocoupler V2, so that the Zener diode ZD2 must also be dimensioned accordingly in a differently selected optocoupler.

In the transmission branch of the coupling unit 3 The Zener diode ZD first recognizes that an impermissibly high voltage is present, which makes it conductive, so that a voltage drops across the resistor R6, which voltage is supplied via the resistor R2 to the base of the transistor T2. This becomes conductive and short-circuits the base-emitter voltage of the transistor T1, so that it switches off and changes into a non-conductive state. In this way, impermissibly high voltages from the transistor T4 and the optocoupler V1 in the transmission branch of the coupling unit 3 kept away. Since the previously described switching off of the transmission branch does not proceed sufficiently quickly in some cases, the Zener diode ZD4 is additionally provided for the brief occurrence of an overvoltage.

When using Zener diodes as overvoltage protection, care must be taken that the Zener diode must carry a high current when discharging an overvoltage, as a result of which a large amount of electrical energy is converted into thermal energy in the Zener diode. This can easily damage the Zener diode, which would then open the connection if it melts, which would lead to the elimination of the provided overvoltage protection. For this reason, the coupling unit was in the receiving branch 3 the PTC thermistor RK is provided, which initially has a very low resistance, but increases its resistance value with a continuously high current flow, along with its heating. In this way, if there is a permanent overvoltage, this is taken over by the PTC thermistor and the current flow through the Zener diode ZD2 is limited. Analog protection of the Zener diode ZD4 is not necessary, since at the latest when the circuit arrangement with the transistors T1 and T2 is switched off, the Zener diode ZD4 no longer dissipates excess voltage. It should also be pointed out that for the transmission branch of the coupling unit 3 Overvoltage protection from a Zener diode with a PTC thermistor alone does not work satisfactorily. The PTC thermistor was too badly affecting the data transmission during the transmission of signals to the data bus, since a flow of high currents is provided for the function of the transmission branch, which is determined by the resistance modulation by means of the transistor T4. A PTC thermistor in the transmission branch of the coupling unit would, in the event that the resistance of the transistor T4 is varied with, for example, a rectangular curve, lead to this curve being blended. When monitoring the load on the DC voltage source DC at the resistor RI in the central control unit 5 Such loops could then lead to the reception in the central control unit 5 is disturbed.

As in the dashed line in 2 Any number of similar electronic ballasts can be connected to the data line 1 via respective coupling units 3 be connected. This results in an arrangement such as that of a 1 is shown. The advantage of the circuit arrangement described is particularly evident when using a large number of such electronic ballasts. Without switching off the transmission diode of the optocoupler V2, the DC voltage generator DC would be constantly loaded with a DC signal, which would result in an unnecessarily high dimensioning with regard to the load capacity of the DC voltage generator DT in the central control unit when using many devices 5 was necessary. In the circuit arrangement described above, the central control unit takes place in reception mode 5 on the other hand, a load on the DC voltage generator only in the case of a feedback coming from one of the electronic ballasts. Thus, the effort for the DC voltage wave DC in the central control unit 5 are minimized, which significantly reduces the manufacturing costs for such an arrangement.

Claims (19)

Circuit arrangement consisting of a central unit, for example a central control unit ( 5 }, and a plurality of them via a bus ( 1 ) connected peripheral units ( 3 . 4 ), for example control units ( 4 ) for lamps, each with a coupling unit ( 3 ) by bus ( 1 ) are connected, each coupling unit ( 3 ) a receiving branch (RV, V2) for the transmission of information from the central unit ( 5 ) to the peripheral unit and a transmission branch (VA, T4, R5) for transmitting information from the peripheral unit to the central unit ( 5 ), the central unit ( 5 ) Information in the form of a modulated AC or pulse voltage on the bus ( 1 ) and the transmission branch thereby sends information to the bus ( 1 ) outputs that the output resistance of the transmission branch is varied, and the circuit arrangement furthermore has overvoltage protection for the reception and / or transmission branch, characterized in that a switch (T1.) controlled by an overvoltage detector (ZD3, T2) is connected in series with the transmission branch ) is arranged, which opens in the event of overvoltage and the transmission branch from the bus ( 1 ) decouples .. Circuit arrangement according to claim 1, characterized in that between the switch (T1) and the transmission branch a quick Circuit breaker (ZD4) is provided which has a short-term overvoltage derives. Circuit arrangement according to claim 2, characterized in that the fast circuit breaker is a Zener diode (ZD4) connected in parallel to the transmission branch, whose Zener voltage is below a permissible voltage for the transmission branch. Circuit arrangement according to one of claims 1 to 3, characterized in that the overvoltage detector is a zener diode (ZD3) has a first transistor when an overvoltage is detected (T2) activated, which switches the switch (T1) non-conductive. Circuit arrangement according to one of claims 1 to 4, characterized in that in series with the transmission branch arranged switch is a second transistor (T1). Circuit arrangement according to one of the preceding Expectations, characterized in that a Zener diode is connected in parallel with the receiving branch which derives overvoltages occurring at the receiving branch. Circuit arrangement according to claim 6, characterized in that as overload protection a PTC thermistor (RK) is provided, which is used for parallel connection Receiving branch and Zener diode (ZD2) is connected in series. Circuit arrangement according to one of the preceding claims, characterized in that the central control unit ( 5 ) is either switched to a transmission mode or a reception mode and has an output device which has at least one of the control unit's transmission mode ( 5 ) signal or a control unit receiving operation ( 5 } signal. Circuit arrangement according to one of the preceding claims, characterized in that that when the control unit is not in operation ( 5 ) the transmission branch of the coupling units ( 3 ) is constantly active and the receiving branch of the coupling units ( 3 ) is inactive and consumes no or very little quiescent current. Circuit arrangement according to one of the preceding claims, characterized in that each coupling unit ( 3 ) both in the receiving branch and in the transmitting branch each have a transmission device which galvanically isolate the bus line from the consumer. Circuit arrangement according to claim 10, characterized in that the respective transmission facility is formed with an optocoupler (V1, V2). Circuit arrangement according to claim 11, characterized in that each coupling unit ( 3 ) has a switching device (ZD1) which connects the receiving branch of the coupling unit ( 3 ) is put into the inactive state when the central control unit ( 5 ) does not output a signal indicating the transmission mode. Circuit arrangement according to claim 12, characterized in that the switching device has a switch, the switching state depends on the circuit level of the signals coming from the data line. Circuit arrangement according to claim 13, characterized in that the switch is formed with a Zener diode (ZD1). Circuit arrangement according to one of the preceding claims, characterized characterized in that a current limiting circuit in the coupling unit is provided, the maximum current consumption of the coupling unit certainly. Circuit arrangement according to claim 15, characterized in that the current limiting circuit by means of a constant current source is formed. Circuit arrangement according to claim 16, characterized in that the constant current source is a MOS field effect transistor (T3) contains. Circuit arrangement according to one of the preceding claims, characterized in that the coupling unit ( 3 ) for connection to the bus line ( 1 ) has reverse polarity protection. Circuit arrangement according to claim 18, characterized in that reverse polarity protection with a rectifier bridge circuit (BR) is formed.