DE102019215592A1 - Circuit arrangement and method for controlling semiconductor light sources - Google Patents

Abstract

The invention relates to a circuit arrangement and a method for controlling semiconductor light sources from a rectified mains voltage, with a semiconductor light source chain, the semiconductor light source chain forming at least two segments, an energy store which is connected in parallel to more than one segment, the circuit arrangement being set up as a function of the instantaneous value the mains voltage to apply the rectified mains voltage to predetermined segments of the semiconductor light source chain, and the circuit arrangement is set up to operate the semiconductor light sources with three different operating phases depending on the current mains voltage and the voltage at the energy storage device: - in a first phase, the circuit arrangement is configured so that it provides the entire power for the semiconductor light sources from the mains voltage, - in a second phase, the circuit arrangement is configured so that it provides part of the power device for the semiconductor light sources from the mains voltage, and provides part of the power for the semiconductor light sources from the energy store, - in a third phase, the circuit arrangement is configured so that it provides the entire power for the semiconductor light sources from the energy store.

Description

Technical area

The invention concerns circuits for controlling semiconductor light sources by means of an alternating voltage, the alternating voltage being applied directly to the semiconductor light sources without interposing a voltage converter.

background

The invention is based on a circuit arrangement for controlling semiconductor light sources according to the preamble of the main claim.
Circuit arrangements are known which can operate a plurality of LEDs connected in series without an energy storage device directly on an AC mains voltage.

1 shows such a circuit arrangement in which a semiconductor light source chain consisting of light-emitting diodes connected in series is operated directly on a rectified AC voltage. For this purpose, a current control is connected in series with the semiconductor light source chain. Switches that can short-circuit these LED segments are arranged parallel to the LED segments. In the example in 1 is the semiconductor light source chain in three LED segments N ₁ , N ₂ and N ₃ divided. A short-circuit switch, which can short-circuit this branch in a controlled manner, is arranged over two of the three LED segments. As a result, the forward voltage of the semiconductor light source chain can be adapted to the instantaneous voltage of the mains input voltage. This means that, depending on the current mains voltage, a different number of serially connected light-emitting diodes is active and contributes to the generation of light.

2 shows a similar known circuit arrangement with switches arranged overlapping in parallel. With this arrangement, just as many sub-strings can be controlled as with the serial arrangement of short-circuit switches. However, only one of the switches has to be controlled, which can, depending on the circuit topology, bring advantages in the control.

The disadvantage of both variants, however, is a gap in the current through the semiconductor light sources, since when the mains voltage crosses zero, the forward voltage of the smallest sub-string is above the input voltage, and thus no current flows. Another disadvantage is that the total number of series-connected semiconductor light sources must be adapted to the mains input voltage. With a mains input voltage of e.g. 230V, a large number of individual semiconductor light sources are necessary, which is undesirable in many applications today.

task

It is the object of the invention to provide a circuit arrangement for controlling semiconductor light sources which no longer has the aforementioned disadvantages.

Presentation of the invention

The object is achieved according to the invention with a circuit arrangement for controlling semiconductor light sources, having a mains input for inputting a mains voltage, and a rectifier for rectifying the mains voltage; a semiconductor light source chain which is a series circuit of at least a part of the semiconductor light sources, the semiconductor light source chain forming at least two LED segments; an energy storage device connected in parallel to more than one LED segment; The circuit arrangement is set up to apply the rectified line voltage to predetermined LED segments of the semiconductor light source chain as a function of the instantaneous value of the line voltage, and the circuit arrangement is set up to operate the semiconductor light sources with three different operating phases as a function of the instantaneous value of the line voltage and the voltage at the energy store , wherein in a first phase the circuit arrangement is configured in such a way that it provides the entire power for the semiconductor light sources from the mains voltage, in a second phase the circuit arrangement is configured in such a way that it provides part of the power for the semiconductor light sources from the mains voltage, and provides part of the power for the semiconductor light sources from the energy store, in a third phase the circuit arrangement is configured in such a way that it provides the entire power for the semiconductor light sources from the energy store b provided. With this measure, a uniform current flow in is advantageous the semiconductor light sources and thus a uniform light output over a network half-wave, since these three phases are all active one after the other in a network half-wave.

In a preferred embodiment, a multipole network is coupled to the semiconductor light source chain and to the rectified mains voltage. This multipole network can contain one or more advantageous functionalities.

In another preferred embodiment, the rectified mains voltage in at least one LED segment is passed via a decoupling diode, the decoupling diode being part of the multipole network. The decoupling diode advantageously ensures that the energy store cannot be discharged without operating the semiconductor light sources.

Switches are preferably provided in the multipole network which apply the rectified mains voltage to a connection point between two LED segments in accordance with the instantaneous value of the mains voltage. This advantageously ensures the best possible adaptation of the forward voltage of the semiconductor light source chain to the instantaneous value of the mains voltage.

The rectified mains voltage is particularly preferably applied to a connection point between two LED segments via a respective decoupling diode, each decoupling diode being part of the multipole network. This facial expression is a particularly simple advantageous embodiment of the adaptation of the forward voltage of the semiconductor light source chain to the instantaneous value of the mains voltage.

It is also a preferred embodiment that a first connection of the switches is each connected to a decoupling diode, and a second connection of the switches is connected to a common reference potential. This topology ensures a simple and inexpensive construction of the circuit with a central control unit such as a microcontroller or a control IC, which adjusts the forward voltage of the semiconductor light source chain to the instantaneous value of the mains voltage.

Another preferred embodiment is that a first connection of a first switch is coupled to the rectified mains voltage, and a second connection of the first switch is connected to a connection point between two LED segments via a decoupling diode, and the first switch is a second switch and all other switches form a series circuit, the connection points of which are each connected to a decoupling diode, the second connection of the last switch being coupled to the rectified mains voltage. This topology can be set up particularly cost-effectively with a simple analog circuit for controlling the switches.

Another embodiment is that the energy store is connected in parallel to the semiconductor light source chain. The energy store can thus be charged in parallel to the semiconductor light source chain and discharged in parallel into the semiconductor light source chain, which corresponds to a particularly simple structure of the arrangement.

Another embodiment is that the switches are designed as current-controlled switches. Such a current control can advantageously be implemented in an analog manner and ensures a particularly uniform flow of current through the semiconductor light source chain over a network half-wave.

The invention also relates to a method for controlling semiconductor light sources, with a circuit arrangement having a mains input for inputting a mains voltage, and a rectifier ( 10 ) to rectify the mains voltage; a semiconductor light source chain which is a series circuit of at least a part of the semiconductor light sources, the semiconductor light source chain forming at least two LED segments; an energy storage device in parallel with more than one segment; depending on the instantaneous value of the line voltage, the rectified line voltage is applied to predetermined LED segments of the semiconductor light source chain, the entire power for the semiconductor light sources from the line voltage in a first phase, which is dependent on the instantaneous value of the line voltage and the voltage at the energy store is provided, wherein in a second phase, which is dependent on the instantaneous value of the mains voltage and on the voltage at the energy store, part of the power for the semiconductor light sources is provided from the mains voltage, and part of the power for the semiconductor light sources is provided from the energy store, wherein in a third phase, which is dependent on the instantaneous value of the mains voltage and on the voltage at the energy store, the entire power for the semiconductor light sources is provided from the energy store. This measure has the advantage that, when the network crosses zero, the charge on the storage capacitor is discharged into the semiconductor light source chain, so that a continuous current flow through the semiconductor light source chain and thus a continuous light output over the entire network half-wave is given. The high light modulation that is feared in these circuits can be significantly reduced.

Further advantageous developments and configurations of the circuit arrangement according to the invention and the method according to the invention for controlling semiconductor light sources emerge from further dependent claims and from the following description.

Figure list

• 1 eine bekannte Schaltungsanordnung mit einer Halbleiterlichtquellenkette von in Serie geschalteten Leuchtdioden, wobei Teilstücke der Halbleiterlichtquellenkette von gesteuerten Schaltern überbrückt werden können, und die Schalter seriell zueinander angeordnet sind.
• 2 eine bekannte Schaltungsanordnung mit einer Halbleiterlichtquellenkette von in Serie geschalteten Leuchtdioden, wobei Teilstücke der Halbleiterlichtquellenkette von gesteuerten Schaltern überbrückt werden können, und die Schalter parallel zueinander angeordnet sind.
• 3a eine Schaltungsanordnung in einer ersten Ausführungsform mit einer Halbleiterlichtquellenkette von in Serie geschalteten Leuchtdioden, wobei Teilstücke der Halbleiterlichtquellenkette über gesteuerte Schalter und über Entkoppelungsdioden mit der gleichgerichteten Netzspannung verbunden werden können, und die Schalter seriell angeordnet sind, und parallel zur Halbleiterlichtquellenkette ein Speicherkondensator angeordnet ist.
• 3b eine Zustandstabelle zur Schaltungsanordnung gemäß der ersten Ausführungsform. (1=Schalter geschlossen, 0=Schalter offen) 3c eine Spannung UG über der Zeit mit den in der Zustandstabelle eingetragenen Zeitpunkten t₁..t₆.
• 4a die Schaltungsanordnung in einer zweiten Ausführungsform mit einer Halbleiterlichtquellenkette von in Serie geschalteten Leuchtdioden, wobei Teilstücke der Halbleiterlichtquellenkette über gesteuerte Schalter und über Entkoppelungsdioden mit der gleichgerichteten Netzspannung verbunden werden können, und die Schalter auf ein gemeinsames Potential bezogen sind, und parallel zur Halbleiterlichtquellenkette ein Speicherkondensator angeordnet ist.
• 4b eine Zustandstabelle zur Schaltungsanordnung gemäß der zweiten Ausführungsform.
• 5a die Schaltungsanordnung in einer dritten Ausführungsform mit einer Halbleiterlichtquellenkette von in Serie geschalteten Leuchtdioden, wobei Teilstücke der Halbleiterlichtquellenkette über gesteuerte Schalter und über Entkoppelungsdioden mit der gleichgerichteten Netzspannung verbunden werden können, und die Schalter seriell zueinander angeordnet sind, und parallel zur Halbleiterlichtquellenkette ein Speicherkondensator angeordnet ist.
• 5b eine Zustandstabelle zur Schaltungsanordnung gemäß der dritten Ausführungsform.
• 6a die Schaltungsanordnung in einer vierten Ausführungsform mit einer Halbleiterlichtquellenkette von in Serie geschalteten Leuchtdioden, wobei Teilstücke der Halbleiterlichtquellenkette über gesteuerte Schalter und über Entkoppelungsdioden mit der gleichgerichteten Netzspannung verbunden werden können, und die Schalter auf ein gemeinsames Potential bezogen sind, und parallel zur Halbleiterlichtquellenkette ein Speicherkondensator angeordnet ist.
• 6b eine Zustandstabelle zur Schaltungsanordnung gemäß der vierten Ausführungsform.
• 7a die Schaltungsanordnung in einer fünften Ausführungsform mit einer Halbleiterlichtquellenkette von in Serie geschalteten Leuchtdioden, wobei Teilstücke der Halbleiterlichtquellenkette über gesteuerte Schalter und über Entkoppelungsdioden mit der gleichgerichteten Netzspannung verbunden werden können, und die Schalter seriell angeordnet sind, und parallel zur Halbleiterlichtquellenkette ein Speicherkondensator angeordnet ist, und parallel zu einem Teil der in Serie geschalteten Leuchtdioden eine gesteuerte Stromquelle angeordnet ist.
• 7b eine Zustandstabelle zur Schaltungsanordnung gemäß der fünften Ausführungsform.
• 8 die Schaltungsanordnung der zweiten Ausführungsform, wobei die gesteuerten Schalter durch eine reale Anordnung aus Bipolartransistoren ersetzt sind,
• 9 die Schaltungsanordnung in einer erfindungsgemäßen sechsten Ausführungsform, die ähnlich der dritten Ausführungsform ist, wobei der Speicherkondensator jedoch nicht fest parallel zum LED-Segment geschaltet ist, sondern über Entkoppeldioden in Serie zum LED-Segment geladen wird und parallel zum LED-Segment entladen wird
• 10 die Schaltungsanordnung in einer erfindungsgemäßen siebten Ausführungsform, die ähnlich der sechsten Ausführungsform ist, wobei die optionalen Entkoppeldioden weggelassen wurden,
• 11 die Schaltungsanordnung in einer erfindungsgemäßen achten Ausführungsform, die ähnlich der sechsten Ausführungsform ist, wobei die Entkoppeldioden in Serie zum LED-Segment geschaltet sind,
• 12 die Ausgestaltung der Schaltungsanordnung in einer erfindungsgemäßen achten Ausführungsform als analoge Schaltung mit einer Halbleiterlichtquellenkette von in Serie geschalteten Leuchtdioden und einem Speicherkondensator, bei der der Speicherkondensator in Serie zum LED-Segment geladen wird und parallel zum LED-Segment entladen wird, wobei die gesteuerten Schalter durch eine reale Anordnung aus Bipolartransistoren ersetzt sind.

Further advantages, features and details of the invention emerge from the following description of exemplary embodiments and from the drawings, in which identical or functionally identical elements are provided with identical reference symbols. Show:

• 1 a known circuit arrangement with a semiconductor light source chain of series-connected light-emitting diodes, parts of the semiconductor light source chain can be bridged by controlled switches, and the switches are arranged in series with one another.
• 2 a known circuit arrangement with a semiconductor light source chain of series-connected light-emitting diodes, parts of the semiconductor light source chain can be bridged by controlled switches, and the switches are arranged parallel to one another.
• 3a a circuit arrangement in a first embodiment with a semiconductor light source chain of series-connected light-emitting diodes, parts of the semiconductor light source chain can be connected to the rectified mains voltage via controlled switches and decoupling diodes, and the switches are arranged in series, and a storage capacitor is arranged parallel to the semiconductor light source chain.
• 3b a status table for the circuit arrangement according to the first embodiment. (1 = switch closed, 0 = switch open) 3c a tension Basement over time with the times t ₁ .. _{t 6} entered in the status table.
• 4a the circuit arrangement in a second embodiment with a semiconductor light source chain of series-connected light-emitting diodes, parts of the semiconductor light source chain can be connected to the rectified mains voltage via controlled switches and decoupling diodes, and the switches are related to a common potential, and a storage capacitor is arranged parallel to the semiconductor light source chain is.
• 4b a status table for the circuit arrangement according to the second embodiment.
• 5a the circuit arrangement in a third embodiment with a semiconductor light source chain of series-connected light-emitting diodes, parts of the semiconductor light source chain can be connected to the rectified mains voltage via controlled switches and decoupling diodes, and the switches are arranged in series with one another, and a storage capacitor is arranged parallel to the semiconductor light source chain.
• 5b a status table for the circuit arrangement according to the third embodiment.
• 6a the circuit arrangement in a fourth embodiment with a semiconductor light source chain of series-connected light-emitting diodes, parts of the semiconductor light source chain can be connected to the rectified mains voltage via controlled switches and decoupling diodes, and the switches are related to a common potential, and a storage capacitor is arranged parallel to the semiconductor light source chain is.
• 6b a status table for the circuit arrangement according to the fourth embodiment.
• 7a the circuit arrangement in a fifth embodiment with a semiconductor light source chain of series-connected light-emitting diodes, parts of the semiconductor light source chain can be connected to the rectified mains voltage via controlled switches and decoupling diodes, and the switches are arranged in series, and a storage capacitor is arranged parallel to the semiconductor light source chain, and a controlled current source is arranged parallel to a part of the series-connected light-emitting diodes.
• 7b a status table for the circuit arrangement according to the fifth embodiment.
• 8th the circuit arrangement of the second embodiment, the controlled switches being replaced by a real arrangement of bipolar transistors,
• 9 the circuit arrangement in a sixth embodiment according to the invention, which is similar to the third embodiment, but the storage capacitor is not permanently connected in parallel to the LED segment, but is charged via decoupling diodes in series with the LED segment and is discharged parallel to the LED segment
• 10 the circuit arrangement in a seventh embodiment according to the invention, which is similar to the sixth embodiment, wherein the optional decoupling diodes have been omitted,
• 11 the circuit arrangement in an eighth embodiment according to the invention, which is similar to the sixth embodiment, wherein the decoupling diodes are connected in series with the LED segment,
• 12th the design of the circuit arrangement in an eighth embodiment according to the invention as an analog circuit with a semiconductor light source chain of light-emitting diodes connected in series and a storage capacitor, in which the storage capacitor is charged in series with the LED segment and is discharged parallel to the LED segment, with the controlled switch through a real arrangement of bipolar transistors are replaced.

Preferred embodiment of the invention

A semiconductor light source chain comprises several LED segments N ₁ , N ₂ , N ₃ connected in series with each other. If necessary, further components can be arranged between the LED segments. Every LED segment N ₁ to N ₃ can use a variety of LEDs 5 which are connected in series with one another. The LED segments N ₁ , N ₂ , N ₃ are also referred to below as segments, sub-strings or LED strings N ₁ , N ₂ , N ₃ designated.

A mains voltage U _in denotes an alternating voltage such as is provided by an electrical supply network, for example. The mains voltage can be converted into rectified mains voltage half-waves via a rectifier U _G (also referred to as “half-waves” or “rectified mains voltage”). The rectifier 10 can be designed as a one-way or a two-way rectifier.

Combinational possibilities of the forward voltages corresponding to the LED segments are used to control the series-connected LED segments. According to the number of LEDs connected in series in a segment, a forward voltage results as the sum of the forward voltages of all LEDs. A different number of LEDs connected in series can result in different forward voltages for different LED segments.

It should be noted here that different LEDs 5 same or different types (e.g. different LED modules and / or LEDs 5 with different colors) can be connected in series. It is also possible that individual LEDs 5 comprise a parallel connection of at least two semiconductor light-emitting elements.

One or more storage capacitors is / are connected in parallel to the semiconductor light source chain or in parallel to the respective LED segment.

wobei U_i(l) eine Gesamtspannung der nicht überbrückten LEDs für den Schaltzustand t_i bei einem Strom I ist.Parallel to at least one LED segment N ₁ ..N _n , in particular parallel to several LED segments, electronic switches can be provided which short-circuit the supply path from the rectifier via individual or several LED segments, but do not change the current path for the storage capacitor due to decoupling diodes. By controlling the electronic switches, it can be achieved that the voltage of the LED segments U _LED (t) effective for the supply path from the mains rectifier of the rectified mains voltage U _G (t) (i.e. the above half-waves) follows (or is tracked): $${\text{U}}_{\text{LED}}\left(\text{t}\right)={\text{U}}_{\text{LED}}\left({\text{t}}_{\text{i}},\text{I.}\right)={\text{U}}_{\text{i}}\left(\text{I.}\right),$$

where U _i (l) is a total voltage of the non-bridged LEDs for the switching state t _i at a current I.

Here, the LED segments can be designed differently, ie they can have forward voltages that are at least partially different from one another. In particular, at least two of the LED segments can have different numbers and / or types of LEDs. In other words, not all LED segments have to be equipped with the same number of LEDs of the same type with the same interconnection. 3a shows a circuit arrangement in a first embodiment with a semiconductor light source chain of light-emitting diodes connected in series. The semiconductor light source chain is in segments N ₁ , N ₂ and N ₃ split, with segments N ₁ , N ₂ , N ₃ the semiconductor light source chain of controlled switches via decoupling diodes D ₁ , D ₂ and D ₃ can be supplied. The semiconductor light source chain is via the first decoupling diode D ₁ and through a current control circuit 3 to the rectified mains voltage U _G connected. The rectified line voltage U _G is to the anode of the decoupling diode D ₁ and connected to the terminal of the current regulating circuit which is not connected to the semiconductor light source chain. The cathode of the last LED in the segment N ₃ is with the current control circuit 3 connected, while the anode of the first light-emitting diode of the segment N ₁ with the cathode of the decoupling diode D ₁ connected is. The decoupling diode D ₁ is therefore arranged lying on top. A first switch S ₁ is with its first connection with the anode of the decoupling diode D ₁ connected, its second terminal is connected to the anode of the second decoupling diode D ₂ . The cathode of the decoupling diode D ₂ is at the connection point between the segment N ₁ and segment N ₂ connected.

A second switch S ₂ is between the anode of the decoupling diode D ₂ and the connection point between segment N ₂ and segment N ₃ switched. Between the second switch S ₂ and the connection point between segment N ₂ and segment N ₃ a third decoupling diode D ₃ can also be inserted. A third switch S ₃ is one connector with the second switch S ₂ connected, while the other connector to the connection point between the third segment N ₃ and the current regulating circuit 3 connected is.

A storage capacitor C ₁ is connected to both ends of the semiconductor light source chain. The decoupling diodes are necessary because real LEDs can have an anti-parallel protective diode and because they have a low reverse voltage.

ti

den Schaltzustand,

Sm

mit m=1 bis 3 den Schalter,

0

einen offenen Schalter,

1

einen geschlossenen Schalter,

U_N1(I) bis U_N3(I) eine Vorwärtsspannung der netzseitig nicht überbrückten LEDs bei dem Strom I für das LED-Segment 1 bis 3 bezeichnen. I S₁ S₂ S₃ U_i(I) t₁ 1 1 1 t₂ 1 1 0 U_N3(I) t₃ 1 0 0 U_N2(I) + U_N3(I) t₄ 0 0 0 U_N1(I) + U_N2(I) + U_N3(I) t₅ 1 0 0 U_N2(I) + U_N3(I) t₆ 1 1 0 U_N3(I) t₁ 1 1 1 The following table shows examples of possible combinations with an arrangement with three LED segments N ₁ , N ₂ , N ₃ , in which

ti

the switching status,

Sm

with m = 1 to 3 the switch,

0

an open switch,

1

a closed switch,

U _N1 (I) to U _N3 (I) a forward voltage of the LEDs not bridged on the mains side at the current I for the LED segment 1 to 3 describe. I. S ₁ S ₂ S ₃ U _i (I) t ₁ 1 1 1 t ₂ 1 1 0 U _N3 (I) t ₃ 1 0 0 U _N2 (I) + U _N3 (I) t ₄ 0 0 0 U _N1 (I) + U _N2 (I) + U _N3 (I) t ₅ 1 0 0 U _N2 (I) + U _N3 (I) t ₆ 1 1 0 U _N3 (I) t ₁ 1 1 1

fällt an dem Stromregler 3 ab. Mit einer Mehrzahl von LED-Segmenten mit unterschiedlich (vielen) in Reihe geschalteten LEDs lassen sich eine Mehrzahl verschiedener Gesamt-Vorwärtsspannungen für die mit dem Netz verbundene Teil-LED-Stränge realisieren, so dass diese Gesamtspannung der aktuellen Netzspannung sehr nahe kommt. Die Restspannung U_G (t) - U_LED(t) ist damit im Vergleich zur gleichgerichteten Netzspannung U_G (t) klein.The residual tension $${\text{U}}_{\text{G}}\left(\text{t}\right)-{\text{U}}_{\text{LED}}\left(\text{t}\right)$$

falls on the current regulator 3 from. With a plurality of LED segments with different (many) LEDs connected in series, a plurality of different total forward voltages can be implemented for the partial LED strings connected to the network, so that this total voltage comes very close to the current network voltage. The residual tension U _G (t) - U _LED (t) is compared to the rectified mains voltage U _G (t) small.

Because of this low residual voltage, the current regulator can be designed, for example, as a linear regulator that is simple and inexpensive to implement. The current regulator can also be designed so that the current (almost) ideally follows the mains voltage, so that a power factor (mains power factor) of the circuit is close to 1.0 and no (noteworthy) harmonics occur.

In extreme cases, the current regulator can even be omitted, e.g. if the dynamics of the LED characteristic curve with a limited current modulation is sufficient to fill the gaps between the switching stages.

In the following, the function of the circuit arrangement is based on 3a to 3c explained. 3b shows a switching table analogous to the table above for the three switches S ₁ , S ₂ and S ₃ at different times of the half-wave of the rectified mains voltage U _G . The 3c shows the rectified line voltage U _G over time. The times t ₁ to t _{6 of} the switching table are in the 3c registered.

At time t ₁ , the line voltage is in the zero crossing and the rectified line voltage is accordingly zero. It is assumed below that the storage capacitor C ₁ is empty. All three switches S ₁ to S ₃ are closed and no current flows from the rectifier. A current then begins from the rectifier via the switches S ₁ to S ₃ and the current control circuit 3 to flow.

The switches are at time t ₂ S ₁ and S ₂ closed while the switch S ₃ is open. As a result, the current driven by the rectified instantaneous mains voltage flows through the closed switches S ₁ and S ₂ and the decoupling diode D ₃ through the segment N ₃ . The current control circuit 3 regulates this current to a value that is optimal _{for operation at time t 2.} This current can, for example, be proportional to the current mains voltage in order to achieve a power factor close to 1.0. A charging current can be applied via the decoupling diode D ₁ through the storage capacitor C ₁ to the current control circuit 3 flow and the storage capacitor C ₁ charge. The switch is at time t ₃ S ₁ closed, and the switch S ₂ and S ₃ open. The current from the rectifier now flows through the switch S ₁ , the decoupling diode D ₂ and the two segments N ₂ and N ₃ to the current control circuit 3 which in turn regulates to an optimal current strength. A charging current can be applied via the decoupling diode D ₁ through the storage capacitor C ₁ to the current control circuit 3 flow and the storage capacitor C ₁ charge.

At time t ₄ , the mains voltage has reached its peak value, and so have all switches S ₁ to S ₃ are opened. The current from the rectifier flows through the decoupling diode D ₁ through all segments N ₁ to N ₃ and through the storage capacitor connected in parallel C ₁ which is charged by it. At time t ₅ , the line voltage has dropped again, and so does the switch S ₁ is closed again. The mains current flows from the rectifier 10 over the switch S ₁ through the decoupling diode D ₂ and through the segments N ₂ and N ₃ to the current control circuit 3 . Another partial current flows from the charged storage capacitor C ₁ through the segments N ₁ to N ₃ . This partial current does not flow via the current regulating circuit, so that the current is solely via the voltage on the storage capacitor C ₁ and yields the forward voltage of all series-connected LEDs of the semiconductor light source chain.

At time t ₆ , the line voltage has dropped further, and so do the switches S ₁ and S ₂ are closed. The desk S ₃ is still open. The mains current flows from the rectifier 10 over the switch S ₁ and S ₂ through the decoupling diode D ₃ and through the segment N ₃ to the current control circuit 3 . Another partial current flows from the charged storage capacitor C ₁ through the segments N ₁ to N ₃ . This partial current does not flow via the current regulating circuit, so that the current is solely via the voltage on the storage capacitor C ₁ and yields the forward voltage of all series-connected LEDs of the semiconductor light source chain.

At the next point in time t ₁ , the mains voltage is again in the next zero crossing, and no current flows into the segments from the rectifier N ₁ , N ₂ or N ₃ . However, a current can still flow from the storage capacitor C ₁ into the segments N ₁ , N ₂ or N ₃ flow, provided that the forward voltage of the segments is even lower than the voltage on the storage capacitor. Because the forward voltage drops as the current through the LEDs decreases, a current through the LEDs and thus a light output of the LED chain can be maintained for a long time when the mains voltage crosses zero. This is also aided by the fact that the forward voltage of the LEDs is caused by the total current of the mains current and the discharge current through the capacitor C ₁ is determined and therefore the discharge current through the capacitor near the mains zero crossing C ₁ can increase again, as the forward voltage of the LEDs also decreases due to the falling mains current.

At the following times t ₂ and t ₃ , in addition to the above-described current from the rectifier, a current from the storage capacitor can continue C ₁ flow into the segments. The current flows in the process from the storage capacitor, due to the topology, always through all segments N ₁ , N ₂ and N ₃ , i.e. through the entire semiconductor light source chain.

The decoupling diodes D ₁ , D ₂ and D ₃ prevent the current from flowing out of the storage capacitor C ₁ through the switch S ₁ , S ₂ or S ₃ can flow, and the switches the storage capacitor C ₁ can partially or fully short-circuit. The decoupling diode D ₁ is absolutely necessary, the decoupling diodes D ₂ and D ₃ are optional.

The 4a and b show a second embodiment of the circuit arrangement. The second embodiment is similar to the first embodiment. Therefore, only the differences from the first embodiment will be explained.

In the second embodiment, the switches are S ₁ to S ₃ all related to a common potential. The second connections of each switch are to the connection point between the cathode of the decoupling diode D ₁ and the current regulating circuit 3 connected. The first connections of each switch are in each case via the decoupling diodes D ₂ and D ₃ with a connection point between the segments N ₁ , N ₂ and N ₃ or between the connection point of the segment N ₁ and coupled to the rectifier. The first connection of the switch S ₁ is to the anode of the first LED of the segment N ₁ connected. The first connection of the switch S ₂ is connected to the cathode of the decoupling diode D ₃ , the anode of which in turn is connected to the connection point between the segment N ₁ and N ₂ connected is. The first connection of the switch S ₃ is connected to the cathode of the decoupling diode D ₂ , the anode of which in turn is connected to the connection point between the segment N ₂ and N ₃ connected is. The cathode of the decoupling diode D ₁ is the switch with the second connections S ₁ to S ₃ connected, the anode of the decoupling diode D ₁ is with the cathode of the last LED in the LED segment N ₃ connected. The current control circuit 3 is with the cathode of the decoupling diode D ₁ connected. The diodes D ₁ to D ₃ and the switches S ₁ to S ₃ are to the multipole network V _N1 summarized, which is also referred to below as a network V _N1 referred to as.

4b FIG. 13 shows the status table of the second embodiment in FIG 4a . The times t ₁ to t ₆ as a function of the instantaneous voltage Basement (t) correspond to those of 3c .

At time t ₁ , all switches are on S ₁ to S ₃ closed. The desk S ₁ it short-circuits the entire semiconductor light source chain, the switches S ₂ and S ₃ are actually not necessary at this point and could just as well be open.

The switches are at time t ₂ S ₂ and S ₃ closed, the switch S ₁ open. A current flows from the rectifier 10 through the LED segment N ₁ over the switch S ₂ to the current control circuit 3 . Part of the current flows through the storage capacitor C ₁ and the decoupling diode D ₁ to the current control circuit 3 and charges the storage capacitor C ₁ on. The desk S ₃ has no effect at this point and could also be open.

The two switches are at time t ₃ S ₁ and S ₂ open, the switch S ₃ is closed. The current flows from the rectifier 10 via the LED segments N ₁ and N ₂ , the decoupling diode D ₂ and the switch S ₃ to the current control circuit 3 . Part of the current flows through the storage capacitor C ₁ and the decoupling diode D ₁ to the current control circuit 3 and charges the storage capacitor C ₁ further on.

At time t ₄ , the sinusoidal half-wave of the mains voltage is at its apex, and all of them are switches S ₁ to S ₃ open. The current flows from the rectifier 10 via the semiconductor light source chain from the LED segments N ₁ to N ₃ to the current control circuit 3 . Part of the current flows through the storage capacitor C ₁ and the decoupling diode D ₁ to the current control circuit 3 and charges the storage capacitor C ₁ to the peak tension of U _G on.

The switch is at time t ₅ S ₃ closed again, a current flows from the rectifier 10 via the LED segments N ₁ and N ₂ , the decoupling diode D ₂ and the switch S ₃ to the current control circuit 3 . A partial current flows from the charged storage capacitor C ₁ through the LED segments N ₁ to N ₃ back to the condenser.

The switches are at time t ₆ S ₂ and S ₃ closed, the switch S ₁ is open. The desk S ₃ is ineffective and could be open as well. A current flows from the rectifier 10 via the LED segment N ₁ , the decoupling diode D ₃ and the switch S ₂ to the current control circuit 3 . A partial current flows from the charged storage capacitor C ₁ through the LED segments N ₁ to N ₃ back to the condenser.

At the next point in time t ₁ , all switches are closed. Because the switch S ₁ the two switches S ₂ and S ₃ bridged, their state is irrelevant. They could also be open. At time t ₁ , the mains voltage is in its zero crossing, the voltage U _G is therefore also 0V. Therefore no current can come from the rectifier 10 flow. However, a current flows from the storage capacitor that is still charged C ₁ through the semiconductor light source chain, i.e. the segments N ₁ to N ₃ . The storage capacitor thus maintains a current through the LEDs even when the mains voltage crosses zero. This means that the light modulation that is otherwise always present is significantly weakened due to the frequency of the mains voltage.

The circuit arrangement of the 5a does not differ significantly from the circuit arrangement of the 3a . It is therefore only on the differences to the circuit arrangement of the 3a received.

In the circuit arrangement of the 5a are the anodes of the decoupling diodes D ₁ to D _{3 are} connected to the corresponding connection points between the LED segments, and the cathodes of the decoupling diodes D ₁ to D ₃ are connected to the connection points between the switches connected in series. This will provide the supply for the LED segment N ₁ now from the switch S ₁ shorted out the supply for the segment N ₂ from the switch S ₂ shorted, and the supply for the LED segment N ₃ from the switch S ₃ shorted. The decoupling diode D ₁ is absolutely necessary so that the storage capacitor connected in parallel to the semiconductor light source chain C ₁ not through the switch S ₁ to S ₃ can be short-circuited. The mains current through the LED segment always flows through the decoupling diode D ₁ .

5b FIG. 13 shows the switching table of the third embodiment of the circuit arrangement according to FIG 5a . The times t ₁ to t ₆ as a function of the instantaneous voltage U _G (t) correspond to those of 3c .

Here, too, the mains input voltage _{is at time t 1 of the zero crossing} Uin , in which also the rectified mains voltage U _G equals zero, all switches are closed.

At time t ₄ , at which the peak value of the mains input voltage Uin or the rectified mains voltage U _G occurs, all switches are open. The mode of operation otherwise corresponds to the function of the circuit arrangement according to FIG 3a .

The circuit arrangement of the 6a does not differ significantly from the circuit arrangement of the 4a . It is therefore only on the differences to the circuit arrangement of the 4a received.

In the circuit arrangement of the 6a are the switches S ₁ to S ₃ as in the circuit arrangement of the 4a all related to a common potential. The second connections of each switch are to the connection point between the anode of the decoupling diode D ₁ and the rectifier 10 connected. The first connections of each switch are in each case via the decoupling diodes D ₂ and D ₃ with a connection point between the segments N ₁ , N ₂ and N ₃ or between the connection point of the segment N ₃ and the current regulating circuit 3 coupled. The first connection of the switch S ₁ is to the cathode of the last LED of the segment N ₃ connected. The first connection of the switch S ₂ is connected to the anode of the decoupling diode D ₃ , its cathode in turn to the connection point between the segment N ₂ and N ₃ connected is. The first connection of the switch S ₃ is connected to the anode of the decoupling diode D ₂ , the cathode of which in turn is connected to the connection point between the segment N ₁ and N ₂ connected is. The cathode of the decoupling diode D ₁ is with the connection point between the anode of the first diode of the LED segment N ₁ and the storage capacitor C ₁ connected. The anode of the decoupling diode D ₁ is with the rectifier 10 connected. The decoupling diode D ₁ is absolutely necessary so that the storage capacitor connected in parallel to the semiconductor light source chain C ₁ not through the switch S ₁ to S ₃ can be short-circuited.

6b FIG. 13 shows the switching table of the fourth embodiment of the circuit arrangement according to FIG 6a . The times t ₁ to t ₆ as a function of the instantaneous voltage U _G (t) correspond to those of 3c .

Here, too, at time t _{1 of} the zero crossing of the mains input voltage Uin, in which the rectified mains voltage is also present U _G equals zero, all switches are closed.

At time t ₄ , at which the peak value of the line input voltage Uin or the rectified line voltage U _G occurs, all switches are open. The mode of operation otherwise corresponds to the function of the circuit arrangement according to FIG 4a .

The 7a and b show a fifth embodiment of the circuit arrangement according to the invention. The fifth embodiment is similar to the first embodiment. Therefore, only the differences from the first embodiment will be explained.

The fifth embodiment corresponds to the first embodiment, with only two switches S ₁ and S ₂ . That means that in the zero crossing the LED segment N ₃ is always active and is not short-circuited.

The fifth embodiment differs from the first embodiment in that some of the LEDs of the LED segment N ₁ can be partially short-circuited. The short circuit is not necessarily to be viewed as a low-resistance shunt, but can also only carry part of the current through the LED segment. The shunt is made in the fifth embodiment by an arrangement Z realized with a transistor. The collector of a bipolar transistor T ₁ is connected to the connection point between the cathode of the decoupling diode D ₁ and anode of the top diode of the LED segment N ₁ connected. The emitter of the bipolar transistor T ₁ is via an emitter resistor R ₃ with a connection point of two LEDs of the LED segment N ₁ connected. The LEDs between the collector of T ₁ and the emitter resistor R ₃ can therefore be partially bridged. A voltage divider consisting of the resistors R ₁ and R ₂ is between the collector of the bipolar transistor T ₁ and the connection point between the current regulating circuit 3 and the rectifier 10 switched. The base of the bipolar transistor T ₁ is connected to this voltage divider.

The circuit can now be dimensioned so that a current flows through the LED segment for a very long time, even if the storage capacitor is C ₁ is discharged in its voltage lower than the actual forward voltage of the semiconductor light source chain. If this occurs, the transistor T _{1 has a} lower resistance and the voltage U _CE across the transistor drops. As a result, the forward voltage of the entire LED segment also drops, and the semiconductor light source chain can continue to be operated.

7b FIG. 11 shows the switching table of the circuit arrangement according to FIG 7a . The times t ₁ to t ₆ as a function of the instantaneous voltage U _G (t) correspond to those of 3c .

8th shows a possible simple analog implementation of the switches including the control. The circuit arrangement itself corresponds to the circuit arrangement of the second embodiment of FIG 4a . The switches S ₁ to S ₃ correspond to the transistors T ₁ to T ₃ . The resistors R ₁ to R ₃ are shunt resistors which are connected as emitter resistors and which _{switch on the transistors T 1} to T ₃ one after the other due to the current flow through the LED segment. The following condition is essential for the circuit to work:
R ₃ <R ₂ <R ₁ ;

The shunts R ₁ , R ₂ , R ₃ are thus chosen such that the transistors T ₁ , T ₂ , T ₃ each switch on and off at a certain current through the semiconductor light source chain. The transistors are thus arranged as current-controlled switches. The circuit is arranged in such a way that the transistors are switched on at low currents and switch off when a certain current threshold is reached. Due to the small resistance of the shunt R ₃ , the transistor T _{3 is} only switched off at relatively high currents. If the voltage drops after it has passed its peak value, transistor T _{3 is} thus the first to be switched on again at time t _5. The circuit is based on the knowledge that at a high driving voltage U _G the resulting current through the semiconductor light source chain is also higher. By switching on the transistor T ₃ , the semiconductor light source chain is shortened, and the forward voltage of the still active semiconductor light source chain is reduced as a result. If the input voltage continues to fall U _G the switching threshold of transistor T _{2 is} reached at time t ₆ , and this switches on. As a result, the forward voltage of the semiconductor light source chain decreases further, and the current through the remaining active semiconductor light source chain increases again for a short time. With decreasing tension U _G this decreases also again and falls at time t _1, the switching threshold for the transistor T. ₁ The driving voltage for the semiconductor light source chain is then so low that it can no longer drive any current through the chain. In reverse order, the transistors are switched off again, therefore, at the time t ₂ of the transistor T _1, the time t ₃ of the transistor T ₂ and the time t _4, the transistor _T3.

The current-regulated switches SI1 to SI3 can be supplied by a tap in the lowest LED segment. 8th is to be understood here only as a principle circuit diagram. As soon as the transistor T _{3 is} switched on, the supply must be maintained, for example by means of a buffer capacitor.

9 shows the circuit arrangement in a sixth embodiment, which is similar to the third embodiment, but the storage capacitor is not permanently connected in parallel to the semiconductor light source chain, but is charged in series with the semiconductor light source chain and is discharged parallel to the semiconductor light source chain. In principle, this procedure has the advantage that the circuit arrangement manages with fewer LEDs connected in series, because the capacitor, which can be charged to half the network voltage in the course of a network half-cycle, is arranged in the charging path. This advantage should not be underestimated, as LED technology has made such progress that many LEDs are no longer required in modern light sources, as a single LED now has a significantly higher light output than it did a few years ago. This embodiment is therefore particularly suitable especially for lamps and LED modules with smaller light packages. The circuit that switches the storage capacitor from parallel operation to serial operation consists of a diode D8, a diode D9 and a switch S _1A . In serial operation, switch S _{1A is} switched off and the storage capacitor is switched off C ₁ is connected in series to the semiconductor light source chain. The storage capacitor charges as the system half-cycle rises C ₁ according to the current in the increasingly on. As the network half-wave falls, the point in time at which the voltage from the network is no longer sufficient and is lower than the forward voltage of the semiconductor light source chain, so that a current could no longer be maintained through it. Before this point in time, the switch S _{1A is} switched on. This results in a current path from the connection of the storage capacitor C ₁ , which is connected to the switch S _1A , via the switch S _1A to the cathode of the diode D9 through the semiconductor light source chain via the diode D8 for connecting the storage capacitor C ₁ connected to the anode of diode D9. The diode D9 is used for decoupling, so that the switch S _{1A is} the storage capacitor C ₁ can no longer short-circuit. With this measure, a current can be maintained through the semiconductor light source chain during the voltage zero crossing of the mains voltage, and thus a low light modulation over the mains half-wave can be achieved. The control of the circuit via a half-wave of the mains input voltage Uin is as described above for the third embodiment.

10 shows the circuit arrangement in a seventh embodiment, which is similar to the sixth embodiment, with the optional decoupling diodes D ₁ , D ₂ , D _{3 have been} omitted. This allows the switching states of the switches S ₂ and S ₃ As already described for the mains voltage, the falling voltage on the storage capacitor C ₁ follow and one of the LED strands N ₁ or N ₂ bridge in order to still be able to use smaller voltages with a more heavily discharged capacitor. However, it must be taken into account that the switching states of the switches S ₁ to S ₃ must continue to be chosen so that a current draw from the rectifier can be maintained for as long as possible.

11 shows the circuit arrangement in an eighth embodiment, which is similar to the sixth embodiment, wherein the decoupling diodes are connected in series with the LED segment. Due to the serial connection to the LED segment, further storage capacitors C _N1 and C _N2 can be used, which can improve the light modulation even further over the mains half-wave. The storage capacitors C _N1 and C _N2 are parallel to the respective LED segment N ₁ respectively N ₂ switched. The associated switches S ₂ for the LED segment N ₂ and S ₃ for the LED segment N ₁ are parallel to the series connection of the LED segment N ₂ and the decoupling diode D ₂ or the LED segment N ₁ and the decoupling diode D ₁ switched. With these measures, the switches S ₂ and S ₃ the storage capacitors C _N1 and C _N2 do not discharge. The control of the circuit via a half-wave of the mains input voltage Uin is as described above for the sixth embodiment. When the mains voltage is sufficient, switch S _{1A is} open and the storage capacitor is open C ₁ thus in series with the LED segments N ₁ and N ₂ switched. If the mains voltage is lower than the forward voltage of the switched-on LED segment N ₁ or N ₂ , then switch S _{1A is} closed and the storage capacitor C ₁ is parallel to the LED segments N ₁ and N ₂ switched. The current flows from the storage capacitor C ₁ via switch S _1A to the cathode of decoupling diode D9, then through the LED strings N ₁ and N ₂ (or the switches S ₂ , S ₃ if switched on) through the decoupling diode D ₁ and the decoupling diode D8 back to the storage capacitor C ₁ . An alternative embodiment can provide that the current path from the LED segment N ₁ directly to the decoupling diode D ₈ (dashed line) flows because this is the decoupling diode D ₁ is not needed.

12th shows the circuit arrangement in a ninth embodiment with a semiconductor _{light source chain N 1} + N ₂ of light-emitting diodes connected in series and a storage capacitor C ₁ , in which the storage capacitor is charged in series with the LED segment and discharged in parallel with the LED segment. The charging current path in the ninth embodiment goes from the rectifier 10 away via the storage capacitor C ₁ and the LED segments N ₁ and N ₂ to the current control circuit 3 and back to the rectifier 10 . As soon as the instantaneous value of the mains voltage falls below a certain value, the transistor T ₁ becomes conductive. This opens up a discharge current path from the storage capacitor C ₁ via the transistor T ₁ to the LED segments N ₁ and N ₂ and from there via the resistor R ₁₂ and the decoupling diode D8 back to the storage capacitor C ₁ . The transistors T ₆ and T ₈ are dependent on the voltage applied to the LED segments, similar to FIG 9 controlled as described. The switches close depending on the total voltage across the LED segments N ₁ and N ₂ and ensure the most continuous flow of electricity possible. The excess voltage drops on the linear regulator 3 which keeps the current in a favorable range.

List of reference symbols

1

Circuit arrangement

3

Current control circuit, current control circuit

5

Light emitting diodes

10

Rectifier

11, 12

Power input

13th

positive rectifier output

14th

negative rectifier output

N1..N3

LED segments

Uin

Mains voltage

Basement

rectified mains voltage

C1

Storage capacitor

D1

Decoupling diode

D8

Decoupling diode

VN1

Multipole network

S1, S2, S3

counter

Z

arrangement

Uin

Mains voltage

Basement

rectified mains voltage

P12, P23

Nodes

Claims (10)

Circuit arrangement for controlling semiconductor light sources (5), comprising: - a mains input (11, 12) for inputting a mains voltage (Uin), and a rectifier (10) for rectifying the mains voltage; - A semiconductor light source chain which is a series circuit of at least some of the semiconductor light sources, the semiconductor light source chain forming at least two LED segments (N ₁ , N ₂ , N ₃ ); - An energy store (C ₁ ) which is connected in parallel to more than one LED segment (N ₁ , N ₂ , N ₃ ); The circuit arrangement is set up to apply the rectified line voltage (U _G ) to predetermined LED segments of the semiconductor light source chain as a function of the instantaneous value of the line voltage (Uin), and the circuit arrangement is set up as a function of the instantaneous value of the line voltage (Uin) and the voltage operate the semiconductor light sources (5) on the energy store with three different operating phases: - in a first phase, the circuit arrangement is configured in such a way that it provides the entire power for the semiconductor light sources (5) from the mains voltage (Uin), - is in a second phase the circuit arrangement is configured in such a way that it provides part of the power for the semiconductor light sources (5) from the mains voltage (Uin), and provides part of the power for the semiconductor light sources (5) from the energy store (C ₁ ), In a third phase, the circuit arrangement is configured in such a way that it provides all of the power for the semiconductor light sources (5) from the energy store (C ₁ ). Circuit arrangement for controlling semiconductor light sources (5) according to Claim 1 , characterized in that a multipole network (V _N1 ) is coupled to the semiconductor light source chain and to the rectified mains voltage. Circuit arrangement for controlling semiconductor light sources (5) according to Claim 2 , characterized in that - the rectified mains voltage (U _G ) in at least one LED segment (N ₁ ) is passed through a decoupling diode (D ₁ ), the decoupling _{diode (D 1} ) being part of the multipole network (V _N1 ). Circuit arrangement for controlling semiconductor light sources (5) according to one of the Claims 1 to 3 , characterized in that switches (S ₁ , S ₂ , S ₃ ) are provided in the multipole network (V _N1 ) which apply the rectified mains voltage (U _G ) to a connection point between two LED segments in accordance with the instantaneous value of the mains voltage (Uin) . Circuit arrangement for controlling semiconductor light sources (5) according to Claim 3 or 4th , characterized in that the rectified mains voltage (U _G ) is applied via a decoupling diode (D ₁ , D ₂ , D ₃ ) to a connection point between two LED segments, each decoupling diode being part of the multipole network (V _N1 ) . Circuit arrangement for controlling semiconductor light sources (5) according to one of the Claims 4 or 5 , characterized in that a first connection of the switches is each connected to a decoupling diode (D ₁ , D ₂ , D ₃ ), and a second connection of the switches is connected to a common reference potential. Circuit arrangement for controlling semiconductor light sources (5) according to one of the Claims 4 or 5 , characterized in that a first connection of a first switch _{is coupled to the rectified mains voltage (U G} ), and a second connection of the first switch is connected to a connection point between two segments via a decoupling diode, and the first switch, a second switch and all further switches form a series circuit, the connection points of which are each connected to a decoupling diode, the second connection of the last switch being _{coupled to the rectified mains voltage (U G} ). Circuit arrangement for controlling semiconductor light sources (5) according to one of the preceding claims, characterized in that the energy store (C ₁ ) is connected in parallel to the semiconductor light source chain. Circuit arrangement for controlling semiconductor light sources according to one of the preceding claims, characterized in that the switches (S ₁ , S ₂ , S ₃ ) are designed as current-controlled switches (SI1, S12, SI3). Method for controlling semiconductor light sources (5), with a circuit arrangement having: - a mains input for inputting a mains voltage (Uin), and a rectifier (10) for rectifying the mains voltage; - A semiconductor light source chain which is a series circuit of at least some of the semiconductor light sources (5), the semiconductor light source chain forming at least two LED segments (N ₁ , N ₂ , N ₃ ); - An energy store (C ₁ ) parallel to more than one LED segment (N ₁ , N ₂ , N ₃ ); depending on the instantaneous value of the line voltage (Uin), the rectified line voltage (U _G ) is applied to predetermined LED segments of the semiconductor light source chain (5), in a first phase that depends on the instantaneous value of the line voltage (Uin) and the voltage on the energy store (C ₁ ), the entire power for the semiconductor light sources (5) is provided from the mains voltage (Uin), - in a second phase, which depends on the instantaneous value of the mains voltage (Uin) and on the voltage at the energy store ( C ₁ ), part of the power for the semiconductor light sources (5) from the mains voltage (U _in ), and part of the power for the semiconductor _{light sources (5) from the energy store (C 1} ) is provided, wherein in a third phase, which is dependent on the instantaneous value of the mains voltage (Uin) and on the voltage at the energy store (C ₁ ), the entire power for the semiconductor light sources (5) is provided from the energy store (C ₁ ).

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