EP2887774B1 - Circuit for operating a lamp unit which can be operated with alternating current and method for operating such a lamp unit - Google Patents

Description

The invention relates to a circuit for operating a lamp unit operable with alternating current. Furthermore, the invention relates to a method for operating such a lamp unit.

Modern lighting systems are increasingly using LED lamps and CFLi lamps (compact self-ballasted flourescent lamps). These bulbs have a much higher efficiency than incandescent bulbs. However, the mentioned more efficient bulbs also bring problems. Thus, in most cases it is intended to be able to adjust the brightness of the illuminant, i. to dim this. In general, in this case the light source is driven by a phase angle signal, which is known to be characterized by a steeply rising edge. This can lead to high inrush currents, which in turn leads to switching losses in the control unit (dimmer).

Since a dimmer is often designed only for limited loads, it is used in particular in more powerful lighting systems in combination with at least one power supplement. Such power supplement includes an output stage which provides an additional power supply to the light source and in turn receives the signal of the dimmer. In the extreme case, the majority of the current is provided by the power addition, so that the current provided by the dimmer can be addressed more as a "control current", which serves essentially to control the power addition. In principle, however, this power also contributes to the supply of the light source. In normal building installation systems, both the dimmer and the power supplement are connected to the same supply network.

DE 10 2010 000 533 B4 describes a circuit with a controller and a power addition, wherein a current transformer is used in the power addition for detecting the dimmer current. The current transformer is read out by means of a microcontroller, which in turn controls the output stage, to which one or more incandescent lamps are connected. While this prior art circuit works reliably, it can not guarantee a delay-free control of the output stage in all cases. This is primarily due to the limited computing capacity of the microcontroller used and the associated long processing times. Also by the use of the current transformer, the performance of the circuit is limited.

WO 2009/120555 discloses a dimmer control circuitry that includes a sensor module, a logic processing module, and a load control signal generator module. The sensor module is configured to detect a line angle of a phase-angle signal, wherein the phase-angle signal is generated by periodically intersecting a periodic voltage signal at the line angle. The logic processing module is in communication with the sensor module and is configured to generate a modulated output signal as a function of the line angle. The load control signal generator module is in communication with the logic processing module and is configured to generate a load control signal as a function of the modulated output signal.

Starting from the prior art according to DE 10 2010 000 533 B4 Therefore, the object of the invention is to propose a circuit and a method with which a delay-free control of an additional power by a dimmer in the phase control is possible, especially without having to require a more powerful microcontroller.

The circuit-related problem is solved by a circuit having the features of claim 1. The method-related object is achieved by a method having the features of claim 8.

According to the invention, a circuit for operating a lamp unit operable with alternating current is provided. Here, the term lamp unit is to be interpreted broadly and refers in the broadest sense an arrangement of one or more lamps, in particular LEDs or CFLis can be used.

The circuit comprises a control circuit for receiving the phase gating signal of a dimmer and for driving one to the Lamp unit connected power amplifier according to the received phase gating signal. The task of the control circuit is thus the best possible synchronization between dimmer and power amplifier. A typical dimmer, which can be used in conjunction with the circuit according to the invention, is connected to a supply network (for example 230 V) and supplies at its output a phase angle signal. This is typically based on the alternating current supplied by the supply network, wherein, depending on the dimming factor, different portions of the beginning of the respective half-waves are cut away in accordance with the dimming rate.

• einen Dimmereingang, einen Lampenausgang sowie einen zwischen diese geschalteten Widerstand,
• einen Komparator zum Vergleichen einer am Widerstand anliegenden Messspannung mit einer Komparatorspannung, um in Abhängigkeit vom Ergebnis des Vergleiches die Endstufe zu aktivieren, sowie
• eine Kontrolleinheit, die dazu eingerichtet ist, nachdem die Endstufe durch den Komparator aktiviert wurde, die Aktivierung unabhängig von der Messspannung aufrecht zu erhalten bis zu einem Freigabe-Zeitpunkt, der vor einem erwarteten Nulldurchgang der Messspannung liegt.

The control circuit comprises the following components:

• a dimmer input, a lamp output and a resistor connected between them,
• a comparator for comparing a measuring voltage applied to the resistor with a comparator voltage to activate the output stage depending on the result of the comparison;
• a control unit, which is set up after the output stage has been activated by the comparator, to maintain the activation independent of the measuring voltage up to a release time which is before an expected zero crossing of the measuring voltage.

The dimmer input is intended for connection to the dimmer. This can then be used to receive the phase-angle signal of the dimmer. In practice, the dimmer input can be given for example by a socket into which a dimmer-side plug is inserted. Also, the connection to the dimmer may be given by a solder joint or the like. It is also conceivable that a single continuous line runs from the dimmer to the resistor, whereby the dimmer input can be seen at any point of the line. Accordingly, the lamp output is provided for connection to the lamp unit. With regard to the physical design of the lamp output, the options shown for the dimmer input apply. The dimmer with one or more power additives can also be implemented as an embedded system.

The resistor is connected between the dimmer input and the lamp output. Thus, with the dimmer and lamp unit connected, the resistance between the dimmer and the load is switched so that the control current flowing from the dimmer to the lamp unit (or at least a part thereof, if any components are connected in parallel with the resistor) flows through the resistor. The resistor is typically designed as an ohmic resistor (although, as is known, certain inductive and capacitive components of reality can not be ruled out), preferably as a high-impedance resistor.

The comparator is set up to compare a measuring voltage applied to the resistor with a comparator voltage. In this case, the measuring voltage is the voltage which is applied to the resistor (or drops there) while it is being passed through by the control current. The measurement voltage is thus proportional to the current flowing through the resistor between the dimmer and the lamp unit and to the value of the resistor. As is known, a comparator has two inputs. While the measuring voltage is applied to one input of the comparator, the comparator voltage to which the measuring voltage is compared is applied to the other input. By means of this circuit arrangement, without having to use a microcontroller, it can be determined in a particularly sensitive manner whether a current flows through the resistor, which is the case after the phase gating has taken place. Ideally, it is possible to set the comparator voltage to a value that is close to zero or, in any case, considerably smaller than an expected peak value of the measuring voltage. The output of the comparator is provided for connection to the output stage. The output voltage of the comparator assumes one of two extreme values (logic "1" and "0"), depending on whether the measuring voltage or the comparator voltage is greater. By applying the appropriate voltage to a dedicated input of the power amplifier, this can be activated. An output of the output stage is here connected to the lamp unit and supplies this after activation of the power amplifier with power. An evaluation of the dimmer signal, whether the output stage of the lamp unit is to be controlled or not, is thus purely circuit technology executable in this concept. This is the quasi spontaneous reaction in the control of the power amplifier justified.

In the presence of a non-continuous current through the load, the voltage applied to the resistor voltage may be subject to certain fluctuations, which could lead to a faulty control of the power amplifier. Due to the described fluctuations of the measuring voltage, it could happen that the falling below the threshold voltage, the output stage is already deactivated before the actual end of a half-wave. In order to avoid this, a control unit according to the invention is provided which, for example, can be realized by a microcontroller. After the output stage has been activated by the comparator, which the control unit can ascertain, for example, by tapping the output voltage of the comparator, the control unit maintains the activation of the output stage independently of the applied measuring voltage. This means that even if the measuring voltage falls below the threshold due to unexpected fluctuations, the power amplifier remains forcibly activated by the control unit. This forced activation maintains the control unit up to a release time which is before or at the expected zero crossing of the measurement voltage. Such a zero crossing of the measuring voltage corresponds to the end of a half-wave and thus to the point at which the control of the output stage is to take place again on the basis of the described voltage comparison by the comparator. The release time can be determined in different ways. These algorithms are well known.

By the inventive concept, in which a comparator and a control unit are combined, both a high degree of speed and reliability can be achieved. The control of the power amplifier is herewith practically possible synchronously with the dimmer. In addition, even the smallest measuring voltages can be detected.

According to one embodiment of the invention, the control unit is configured to maintain the activation by changing the comparator voltage so that a comparison with the measurement voltage results in the comparator holding the final stage activated. In this case, the input of the comparator for the comparator voltage is connected to the control unit. For example, if positive values are to be expected for the measuring voltage, the control unit may set the comparator voltage to a negative one Set the value so that even with unexpected fluctuations of the measuring voltage in the area of the zero point, the measuring voltage is still recognized as the larger one. Thus, a comparison of the two voltages always leads to an activation of the power amplifier.

According to an alternative embodiment, the control unit is adapted to maintain the activation by directly controlling the output stage. This can happen, for example, in that the control unit interrupts the connection between the output of the comparator and the output stage and instead feeds its own control signals via a corresponding connection to the output stage.

The release date can be set in different ways. One possibility for this is, for example, that the control unit for determining the release time is set up from a measurement of the phase-angle signal. The phase-angle signal may in this case be e.g. be controlled via the measuring voltage applied to the resistor. Of course, there are other possibilities, for example that the control unit is connected in a similar way to the resistor between the dimmer input and the lamp output. By measuring the time course of the phase-angle signal (namely a voltage corresponding to this), the expected zero crossing can be extrapolated to a certain extent. This is at least approximately possible, so that a (short) before release date can be determined.

Alternatively or in combination with this, it is possible to determine the release time with the aid of previously stored information about the phase-angle signal. These may e.g. Information about the frequency of the signal and the sinusoidal course of the half-waves include. The control unit can here also include the observations from past half-waves, which can be based in particular on voltage measurements. The information can be evaluated alone or in combination with current measured values by means of suitable algorithms in order to determine an expected value for the next zero crossing.

In an advantageous embodiment of the invention, the comparator with provided a hysteresis. Such a comparator, which is also referred to as Schmitt trigger, changes the voltage at its output only when the difference of the two input voltages exceeds a certain threshold. If, for example, the measuring voltage exceeds a certain value relative to the comparator voltage, the output voltage changes its level (for example, from "0" to "1"); If the measuring voltage then drops again, the level does not change immediately, but only with a certain delay. The purpose of this embodiment is to avoid swinging the control signal of the dimmer. This can occur when the output stage is activated, since in typical applications it is supplied via the same network as the dimmer and the additional, parallel current path given by the output stage can lead to a drop in the control current at least in the short term, which in turn leads to the comparator could react back to the final stage. A resulting vibration behavior of the entire system can be prevented by the described hysteresis.

The comparator and the control unit in the context of the present invention represent functionally different units. Physically, however, these can advantageously be designed as a single component. In this case, the comparator and the control unit form parts of an integrated circuit. Since the control unit usually has a much higher complexity than the comparator, one could also say that the comparator is integrated in the control unit.

The resistor used advantageously has a relatively high value, so that even at low currents a sufficiently large measuring voltage is present, which can be easily evaluated by the comparator. In order to avoid or reduce the power loss to be accepted in such an embodiment, means for limiting the measuring voltage are provided according to an embodiment. Preferably, such means comprise at least one diode. For example. In this case, diodes can be connected in parallel to the resistor. From a certain voltage these diodes act as a kind of bypass for the resistor, which limits the power loss. In this case, the measuring voltage applied to the resistor is no longer continuously proportional to the control current. A proportionality is given for small voltages, for large values limits Forward voltage of the diodes the measuring voltage. However, there is also an increase in the voltage during phase control, which is sufficient for activating the output stage by the comparator.

The circuit according to the invention can be supplemented by an output stage, which is connected to the control by the control circuit with this. In particular, in this case, the entire circuit including the power amplifier can be installed within a housing as an additional power, which can be integrated into existing systems with a dimmer and a lamp unit.

Furthermore, the circuit is supplemented when used as intended by a dimmer connected to the dimmer input and connected to the lamp output and the power amplifier lamp unit.

It is also conceivable that the circuit comprises a plurality of control circuits and power amplifiers, wherein in each case a control circuit is associated with an output stage. In this case, the respective control circuits may be connected in series with respect to the output from the dimmer control current, so that the lamp output of a first control circuit is not directly connected to the lamp unit, but to the dimmer input of a second control circuit and from there via the resistor and lamp output finally to the lamp unit , Accordingly, in this embodiment, the dimmer input of the second control circuit is not directly connected to the dimmer but indirectly via the first control circuit.

• der Dimmer ein Phasenanschnitt-Signal liefert,
• ein Komparator eine am Widerstand abfallende Messspannung mit einer Komparatorspannung vergleicht und in Abhängigkeit vom Vergleich die Endstufe aktiviert und
• eine Kontrolleinheit, nachdem die Endstufe durch den Komparator aktiviert wurde, die Endstufe unabhängig von der Messspannung aktiviert hält bis zu einem Freigabe-Zeitpunkt, der vor einem erwarteten Nulldurchgang der Messspannung liegt.

The invention further provides a method of operating an AC-operable lamp unit having an output stage connected to the lamp unit and a resistor connected between a dimmer and the lamp unit

• the dimmer provides a phase gating signal,
• a comparator compares a measuring voltage drop across the resistor with a comparator voltage and, depending on the comparison, activates the final stage and
• a control unit, after the output stage has been activated by the comparator, keeps the output stage activated independent of the measuring voltage until a release time which is before an expected zero crossing of the measuring voltage.

Preferred embodiments of the method correspond to the above-described embodiments of the circuit according to the invention. Therefore, the relevant statements apply in a corresponding manner for the claimed method. According to one embodiment, the control unit keeps the output stage activated by changing the reference voltage in such a way that a comparison with the measurement voltage results in the comparator holding the output stage activated. According to an alternative embodiment, the control unit keeps the output stage activated by directly controlling the output stage.

The control unit preferably determines the release time from a measurement of the phase-angle signal. Alternatively or additionally, it is preferred that the control unit determines the release time with the aid of previously stored information about the phase gating signal.

Fig. 1:

eine Schaltskizze nach Art eines Blockschaltbildes einer Ausführungsform einer erfindungsgemäßen Schaltung einschließlich eines Dimmers und einer Lampeneinheit;

Fig. 2:

ein Blockdiagramm einer ersten Ausführungsform einer Steuerschaltung sowie einer Endstufe sowie

Fig. 3:

ein Blockdiagramm einer zweiten Ausführungsform einer Steuerschaltung sowie einer Endstufe.

Further advantages and embodiments of the invention will be explained below with reference to embodiments with reference to the figures. Hereby shows:

Fig. 1:

a circuit diagram in the manner of a block diagram of an embodiment of a circuit according to the invention including a dimmer and a lamp unit;

Fig. 2:

a block diagram of a first embodiment of a control circuit and a power amplifier and

3:

a block diagram of a second embodiment of a control circuit and a power amplifier.

FIG. 1 shows an embodiment of a circuit 1 according to the invention for operating a lamp unit 50. The lamp unit 50, the here simplified as a single light source is shown, may well include, for example, several tens or hundreds of LEDs. The power of the lamp unit 50 is to be controlled by means of a dimmer 40 which is connected to phase 60 and neutral 61 of a supply network. At a dimmer output 41, the dimmer 40 provides a phase gating signal.

The circuit 1 further comprises two power supplements 10, 30, in which the phase-angle signal is fed successively and which are connected in series between dimmer output 41 and lamp unit 50 in this regard. Since the two power supplements 10, 30 are designed the same here, only the first power supplement 10 will be described in detail below. These statements apply equally to the performance supplement 30. As in FIG. 1 can be seen, the power addition 10 has a network connection 14 for the phase 60 of the supply network and a supply terminal 15 for the lamp unit 50 to which a phase control signal is to be provided, the power amplified and synchronized as possible to that at the dimmer output 41 should.

The basic structure of the power addition 10 is shown in the block diagram in FIG. 2 seen. As from the synopsis of FIG. 1 and FIG. 2 becomes clear, the power supplement 10 has a dimmer input 11 which is connected to the dimmer output 41. Between this dimmer input 11 and a lamp output 12, a resistor 13 is connected. The lamp output 12 is in turn connected to the lamp unit 50 via the second power addition 30. Therefore, the control current flows between the dimmer output 41 and the lamp unit 50 through the resistor 13, where a measurement voltage drops there. The measuring voltage is applied to a first input 17 of a comparator 16 provided with a hysteresis, whose second input 18 is connected to a microcontroller 20.

The dimmer input 11, the lamp output 12, the resistor 13, the comparator 16 and the microcontroller 20 form the essential components of a control circuit 2. A comparator output 19 is for controlling an output stage 21 with a control input provided there 22 connected. The output stage is further connected to the mains terminal 14, via which it is supplied with voltage, as well as to the supply terminal 15, where it is to provide the power-enhanced phase gating signal.

The operation of the control circuit 2 will be described below. First, before a phase angle, the microcontroller 20, which is also connected via not shown connections to the supply network, the second input 18 of the comparator 16 with a comparator voltage, which is just above 0 V. Since initially virtually no current flows between the dimmer input 11 and the lamp output 12, no measuring voltage is present at the resistor 13. The difference between the measuring voltage and comparator voltage is below a threshold given by the hysteresis, which is why a voltage - corresponding to logic "0" - is applied to the comparator output 19, by which the output stage 21 is not activated. With the phase angle of the current flowing through the resistor 13 increases significantly and thus the voltage applied to the resistor 13 measurement voltage. The difference between this and the comparator voltage exceeds the threshold given by the hysteresis, whereby the voltage applied to the comparator output 19 changes the level - to logical "1" - and the output stage 21 is activated. The purely hardware-based activation of the output stage 21 takes place here extremely fast compared to an activation that would be based on operations of the microcontroller 20. Due to the intended hysteresis causes a falling below the threshold no immediate falling back of the voltage applied to the comparator output voltage 19 to logic "0".

Via a connection, not shown in the figure, the microcontroller 20 picks up the voltage applied to the comparator output 19 and thus determines the activation of the output stage 21. It maintains this activation by significantly reducing the comparator voltage applied to the second input 18 in this embodiment, so that even with fluctuations in the measuring voltage, this is always always greater than the comparator voltage. For example, the comparator voltage can be set to a value that is below the measurement voltage that occurs when no current flows. At the same time the microcontroller 20 via connections also not shown the course of the measurement voltage and extrapolated by means of an internally predetermined algorithm the probable next zero crossing. At a release time, which is before the calculated zero crossing, the microcontroller 20 raises the comparator voltage again to the initial value (slightly above 0 V), whereby the control of the output stage 21 is again based effectively on an evaluation of the measurement voltage at the resistor 13.

An alternative embodiment of an additional power 10a is shown in FIG FIG. 3 shown. This can alternatively take place in the FIG. 2 shown power supplement 10 can be used. Its structure corresponds essentially to that of performance supplement 10, which is why only the differences are to be explained below. In this embodiment, the comparator 16a, which picks up the measuring voltage applied to the resistor 13, integrated in a microcontroller 20a. The first phase of the control of the output stage 21 is the same here as in the reference to FIG FIG. 2 described embodiment, wherein the comparator 16a is applied to the control input 22 via a comparator output 19a. Has in this case, however, the microcontroller 20a detects the activation of the output stage 21, it interrupts the connection between the comparator output 19a and the control input 22 of the power amplifier and provides a not shown here circuit at the control input 22 a - logic "1" corresponding - ready, through which the power amplifier 21 remains activated. After the release time, the microcontroller 20a restores the connection between the comparator output 19a and the control input 22.

Another difference between the control circuit 2a shown in the figure with respect to the control circuit 2 is that it comprises, in addition to the resistor 13, two diodes 23, 24 which are connected in anti-parallel to each other and parallel to the resistor 13. As a result, care is taken that the voltage applied to the resistor 13 and the associated power loss is not too large. This circuit used for limiting the power loss can equally be realized in the control circuit 2.

In the in FIG. 1 1, two power supplements 10, 30 are used, each of which comprises a control circuit 2, 2a according to the invention and an output stage 21. It is understood that, depending on the power consumption of the lamp unit 50, a single power addition 10, 30 could be used in conjunction with the dimmer 40.

LIST OF REFERENCE NUMBERS

1

circuit

2, 2a

control circuit

10, 10a

power booster

11

dimmer input

12

lamp output

13

resistance

14

mains connection

15

supply terminal

16, 16a

comparator

17

entrance

18

entrance

19, 19a

comparator output

20, 20a

microcontrollers

21

final stage

22

control input

23

diode

24

diode

30

power booster

50

lamp unit

60

phase

61

neutral

Claims (10)

1. Circuit for operating a lamp unit (50) which can be operated with alternating current, having a control circuit (2, 2a) for receiving a leading-edge signal of a dimmer (40) of a power amplifier (21), an output (15) of the power amplifier (21) being connected to the lamp unit (50) for driving the lamp unit (50) in accordance with the leading-edge signal, which control circuit (2, 2a) comprises the following components:

   - A dimmer input (11) for connection to the dimmer (40), a lamp output (12) for connection to the lamp unit (50) as well as a resistor (13) interposed between the dimmer input (1) and the lamp output (12),

   - A comparator (16, 16a) to compare a measuring voltage at the resistor (13) with a comparator voltage, wherein one output (19, 19a) of the comparator (16, 16a) is linked to the power amplifier (21), in order to activate the power amplifier (21) depending on the result of the comparison,
   characterized by the fact that the control circuit (2, 2a) additionally

   - comprises a control unit (20, 20a), adapted to determine, by tapping the output voltage of the comparator, whether the power amplifier (21) has been activated by the comparator (16, 16a), and to maintain the activation of the power amplifier (21) independent of the measuring voltage up until a release time determined based on the leading-edge signal which is before an expected zero crossing of the measuring voltage.
2. Circuit in accordance with Claim 1, characterized by the fact that the control unit (20) is disposed to change the comparator voltage in a way that the activation is maintained so that a comparison with the measuring voltage makes that the comparator (16) keeps the power amplifier (21) activated.
3. Circuit in accordance with one of the previous Claims, characterized by the fact that the control unit (20, 20a) is disposed to determine the release time by measuring the leading-edge signal.
4. Circuit in accordance with one of the previous Claims, characterized by the fact that the comparator (16, 16a) has a hysteresis.
5. Circuit in accordance with one of the previous Claims, characterized by the fact that the comparator (16a) and the control unit (20a) are designed as parts of an integrated circuit.
6. Circuit in accordance with one of the previous Claims, characterized by the fact that means (23, 24) for limitation of the measuring voltage are provided, which means (23, 24) preferably comprise at least one diode.
7. Process for operating a lamp unit (50) which can be operated with alternating current, with a power amplifier (21) connected to the lamp unit (50) and a resistor (13) of a control unit (2, 2a) which is interposed between a dimmer input (11) of the control circuit (2, 2a) and the lamp unit (50), wherein the process comprises the following steps:

   - Receiving a leading-edge signal from the dimmer (40),

   - Comparing a decreasing measuring voltage at the resistor (13) with a comparator voltage by means of a comparator (16, 16a),

   - Activating the power amplifier (21) depending on the comparison,

   - By means of a control unit (20, 20a) after the power amplifier (21) has been activated: determining whether the power amplifier (21) is activated by tapping the output voltage of the comparator (16, 16a) of the control circuit (2, 2a),

   - Maintaining the activation of the power amplifier (21) independent of the measuring voltage up until a release time determined based on the leading-edge signal, which release time is before an expected zero crossing of the measuring voltage.
8. Process in accordance with Claim 7, characterized by the fact that the step of maintaining the activation comprises the step: changing the comparator voltage to keep the power amplifier (21) activated.
9. Process in accordance with any of Claims 7 or 8, characterized by the fact that the release time is determined by measuring the leading-edge signal.
10. Process in accordance with any of Claims 7 to 9, characterized by the fact that the release time is determined by pre-stored information via the leading-edge signal.

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