WO2010091707A1

WO2010091707A1 - Electrical power supply circuit

Info

Publication number: WO2010091707A1
Application number: PCT/EP2009/007799
Authority: WO
Inventors: Igor Ivanov; Bosko Papric
Original assignee: Bocom Energiespar-Technologien Gmbh
Priority date: 2009-02-11
Filing date: 2009-10-31
Publication date: 2010-08-19
Also published as: DE202009001707U1

Abstract

The present invention relates to an electrical power supply circuit (31) having a transformer (2), a rectifier (3), and a smoothing capacitor (11) connected in said sequence one after the other, wherein the power supply circuit (31) provides a smoothed direct-current voltage (U₄) at the output thereof in the case where an alternating current voltage (U₀) is applied to the input thereof, to which output a consumer (5), in particular at least one LED, is or can be connected, wherein the transformer (2) is a free-running electronic transformer and a power factor correction filter (10) is connected between the rectifier (3) and smoothing capacitor (11).

Description

DESCRIPTION

Electrical supply circuit

The present invention relates to an electrical supply circuit having a transformer, a rectifier and a smoothing capacitor, which are electrically connected in series in this sequence, wherein the supply circuit provides a smoothed DC voltage at its output in the case of an AC voltage applied to its input to which a consumer, in particular at least one LED is connected or connectable. Furthermore, the present invention relates to a luminous means with at least one LED, which is operated on a smoothed DC voltage. In addition, the present invention relates to a low-voltage lighting system comprising a dimmer, a transformer, a rectifier, at the output of which a rectified voltage is provided, followed by a smoothing capacitor providing a smoothed operating voltage, at least one LED connected to the smoothing capacitor via a control circuit adjusts the applied operating voltage to a luminous voltage with a predetermined, substantially fixed level, the dimmer is provided to vary a level of the operating voltage and the control circuit is executed, the luminous power of a LED depending on the level of the operating voltage and while maintaining the Level of the luminaire voltage to control. In addition, The present invention provides a control circuit for operating at least one LED in a low voltage lighting system, the control circuit converting an applied voltage to a lighting voltage that is a DC voltage having a predetermined, substantially fixed level and depending on the level of the applied voltage controls the luminous power of at least one LED while maintaining the level of the lamp voltage. Furthermore, the present invention relates to a low-voltage illuminant with a rectifier, a Glättunyskonderisatox and weiiiyateiis an LED for operation on a transformed low-voltage AC voltage or a low-voltage bulb with a smoothing capacitor and at least one LED for operation on a rectified voltage.

In the prior art such low-voltage lighting systems are known for example from DE 20 2008 013 638 Ul. The lighting system comprises a transformer, a rectifier with a downstream smoothing capacitor, which provide a smoothed operating voltage. This is connected via a DC-DC converter at least one LED. The DC-DC converter provides a luminous voltage of a predetermined substantially fixed level to the LED and controls the luminous power of the at least one LED depending on the level of the operating voltage when varied by a dimmer. The level of the luminaire voltage is maintained in order not to change the luminous properties of the LED. countries. The individual components can be combined in different units, for example to form low-voltage lamps or a control circuit.

The size of the low-voltage lighting system, the supply circuit, the light source is largely due to the size of the transformer. Therefore, at least the transformer of the supply circuit is often provided separately from the consumer, for example in an external power supply.

There are also known electronic transformers, which have a small design. In them voltage pulses are generated at a frequency of typically about 50 kHz from the mains voltage, whereby the actual transformer transformer can be designed very small and incurred only small magnetization losses. Low-cost self-oscillating electronic transformers have been specially developed for the use of incandescent or incandescent bulbs, which are a predominantly resistive load. However, they can not be operated with pronounced inductive or capacitative loads, such as those resulting from the use of a smoothing capacitor, since such loads cause a phase shift in the feedback of the self-oscillating electronic transformers. This disturbs the resonant circuit and the vibrations can come to a standstill. Alternatively, active clocked electronic transformers are known that do not know this problem. However, these are rarely used in practice for cost reasons.

From DE 199 37 924 Al a rectifier with center point feed is known, which can be operated in the output of a free-swinging inverter. The control of the switching transistors of the inverter is done by direct feedback of the load current, which is why a slightly inductive character of the subsequent rectifier is desired. For this purpose, the rectifier comprises a circuit with two inductors, which act both as Umschwinginduktivität as well as smoothing inductance, whereby the load is equally distributed to both inductors and they can be made small. This causes the desired power factor adjustment of the rectifier to an inductive character. However, this circuit is not suitable for adapting a load as an ohmic load.

Despite these problems, the demand for alternative and novel bulbs for use in common lamp sockets and lighting systems is increasing. This is due, on the one hand, to rising energy costs and growing environmental awareness among consumers and, on the other hand, to legal requirements, which, for example, mean that only light bulbs with low power consumption will be available in the European Union in a few years' time may be brought. The use of new bulbs would make existing electronic transformers unusable and therefore does not represent an acceptable solution.

Object of the present invention is therefore to provide a stable, small and inexpensive electrical circuit, which allows the operation of the novel, in particular LED-based bulbs in existing lighting systems. In a low-voltage lighting system, the task is to reduce the size and energy consumption.

This object is achieved in the known supply circuit and the known low-voltage lighting system in that the transformer is a free or self-oscillating electronic transformer and an active power factor correction filter is connected between the rectifier and smoothing capacitor. Accordingly, the control circuit has a smoothing capacitor and an active power factor correction filter connected upstream of it.

The basic idea of the invention is thus to convert the load by the active power factor correction filter such that it represents approximately a purely resistive load for the transformer. This stabilizes the self-oscillating electronic transformer and allows its use also for consumers who themselves are an inductive or capacitive load. such as a smoothing capacitor. Active filters are much more efficient than passive filters. Compared to passive filters, they also contain only small passive elements, so that they themselves have a smaller design. For example, they are an adequate solution for integration with consumers. In particular, the use in light sources with LEDs, which are directly usable with a conventional lamp holder in conventional lighting systems, is quite possible because of given lamp sockets and existing lamps, a size restriction for the integrated Illuminant exists. Special adjustments of the lamp or its electrical installation to the light bulb thus formed are not required.

Thus, the electrical supply circuit can be formed particularly advantageous as an integral circuit, which can be easily integrated into different devices or in lighting means by their small size. Due to the low price, use in or with inexpensive mass-produced articles is also possible because the proportion of the production costs of the electrical supply circuit to the total production costs is low.

Furthermore, a low-voltage bulb can be designed with a control circuit with power factor correction filter. If the low-voltage illuminant is operated on a low-voltage alternating voltage, the control circuit must be preceded by a rectifier. Thus, the dervoltleuchtmittel be used in conventional low-voltage lighting systems for the replacement of conventional low-voltage lighting. By using the power factor correction filter, even novel low-voltage lamps essentially act as an ohmic load, so that the self-oscillating electronic transformer does not become unstable.

In a further embodiment of the invention, the power factor correction filter is designed as a non-ideal filter with a predistortion of its current-Spannungsungskennliniε. The self-oscillating electronic transformer with the downstream power factor correction filter requires at the beginning of each half-wave slightly more power than usual in order to safely drive its switching elements at the beginning even small / low voltage in the feedback loop can. An approximately ideal filter, however, can not do this because it equalizes the current to the voltage waveform, and therefore the current decreases too much in accordance with the voltage at the beginning and end of each half cycle. If the filter is performed with predistortion, the self-oscillating electronic transformer can receive enough power for stable operation. Such a configuration of the characteristic is possible with little effort in the active filter.

The predistortion of the current-voltage characteristic can be carried out such that the characteristic at the beginning and at the At the end of the half cycle the voltage is raised and flattened in the central region, and thus is substantially constant during each voltage period. As a result, the swinging of the electronic transformer is continuously assisted and its stable operation is ensured for a whole period, with the permanent symmetry of the characteristic obtained on average the ohmic character of the load.

Alternatively or additionally, the predistortion of the current-voltage curve can be carried out in such a way that the current is raised at the beginning of each half-period of the voltage. Thus, a first ignition in the electronic transformer can be reliably performed even with small amplitudes of the applied mains voltage.

When using a luminous means with at least one LED, this can be preceded by a control circuit which regulates the brightness of the at least one LED. Thus, the at least one LED can always be operated in its ideal operating point. In addition, an effective dimming by a suitable control circuit in a known per se manner is possible, for example by a pulse width modulation.

In a further embodiment of the invention, the control circuit may comprise a control unit for carrying out a pulse width modulation and the power factor correction filter a control module, wherein the control unit inte- gral with the control module is executed. Both the filter and the pulse width modulation require an active control, which is advantageously carried out together. This simplifies the structure of the control circuit and saves costs and space.

Finally, the smoothing capacitor may be an electrolytic capacitor. These capacitors have a particularly high energy storage density, whereby the size of the supply circuit can be kept very small.

With regard to further advantageous embodiments of the invention, reference is made to the dependent claims and the following description of an embodiment with reference to the accompanying drawings. In the drawing shows:

1 shows a circuit diagram of a low-voltage lighting system with a DC voltage distribution, a dimmer and upstream and two low-voltage lamps in parallel operation,

FIG. 2 shows a circuit diagram of a control circuit according to the present invention,

FIG. 3 shows a current-voltage core line of a light-emitting diode at different temperatures T 1 and T 2, FIG. 4 shows curves of the voltages U ₀ to U ₅ in the non-dimmed state,

FIG. 5 shows curves of the voltages U ₀ to U ₅ in the dimmed state,

FIG. 6 shows a circuit diagram of a luminous means with an electrical supply circuit according to the present invention,

7 shows a circuit diagram of a low-voltage lighting system according to the present invention with an AC voltage distribution and two low-voltage illuminants connected thereto, FIG.

Figure 8 shows the circuit diagram of Figure 7 with upstream dimmer, and

9 shows a circuit diagram of a low-voltage lighting system according to the present invention with a DC voltage distribution and two low-voltage illuminants connected thereto.

FIG. 1 shows a low-voltage lighting system 1 according to the present invention. To the lighting system 1 include as individual components, a free or self-oscillating electronic transformer 2 and a rectifier 3, to which a RegelSchaltung 4 is a LED to be operated 5 is connected.

To the low-voltage lighting system 1 further includes a dimmer 6, which is connected upstream of the transformer 2. The dimmer is on the input side to a supply voltage U _0, a conventional 230V alternating voltage with a frequency of 50 Hz connected here, and provides a dimming voltage U. ₁ For this purpose, the dimmer 6 has a known phase-angle control, which reduces the effective value of the voltage U ₁ . The dimmed voltage U ₁ is less than or equal to the mains voltage U ₀ and is applied to the transformer 2 as an input voltage.

The control circuit 4 serves to provide a constant luminous voltage U ₅ for the light-emitting diode 5. The control circuit 4 is shown in detail in FIG. 2 and has on the input side a power factor correction filter 10, to which an electrolytic capacitor as a smoothing capacitor 11 is connected downstream. The power factor correction filter 10 provides an operating voltage U _{4 on the} output side, which is smoothed by the smoothing capacitor 11. On the input side, the power factor correction filter 10 performs a minimization of the reactive power, so that a phase shift of current and voltage passing through the smoothing capacitor 11 and possibly. subsequent non-resistive loads is effected, is ideally canceled at the rectifier 3

(cos (φ) = 1). Accordingly, the self-oscillating de electronic transformer 2 practically not charged with reactive power. As a result, the power factor correction filter 10 provides the operating conditions required for the self-oscillating electronic transformer 2.

For the stable operation of the self-oscillating electronic transformer 2, the power factor correction filter 10 is designed as a non-ideal filter. It shows a predistortion of its current-voltage characteristic. The self-oscillating electronic transformer 2 requires with downstream power factor correction filter 10 at the beginning of each half-wave slightly more power than usual to safely drive its switching elements at the beginning even small / low voltage in the feedback loop can. This is ensured by the special design of the filter 10. In detail, the predistortion of the current-voltage characteristic is carried out in such a way that the characteristic is raised at the beginning and at the end of the half-wave of the voltage and flattened in the central region, and thus substantially constant during each voltage period. Accordingly, the current is raised at the beginning of each half period of the voltage.

To the operating voltage U ₄ is a transducer element 12 in the form of a DC-DC converter, which is designed as a cuttlefish converter connected. The cuttlefish converter 12 sets the luminaire voltage U ₅ at a predetermined, substantially fixed level, in this case 3.5 V, and independently of the set level of the smoothed operating voltage U ₄ ready. The cuttlefish converter 12 supplies the required level of the lamp voltage U ₅ even in the case that the smoothed operating voltage U _{4 is} lower than the level of the lamp voltage U ₅ .

The sepia converter 12 comprises a switching element (not shown) for carrying out a pulse width control with which the luminaire voltage U _{5 is switched as a} function of a control signal S supplied from the outside. In addition, the cuttlefish 12 has a not crazy. Detail shown measuring device with a measuring input M. The measured value of the measuring device is used to compensate the level of the lamp voltage U ₅ .

The cuttlefish converter 12 is followed by a low-pass filter 13 consisting of a coil 14 and a capacitor 15. The low-pass filter 13 reduces voltage spikes that may occur during the switching operations of the cuttlefish converter 12.

Furthermore, the control circuit 4 has a control unit 16 which provides a control signal for controlling the pulse width modulation at the control input S of the sepia converter 12. The control unit 16 and the cuttlefish converter 12 are designed for pulse width control with pulse trains of about 300 Hz. The control unit 16 has two terminals 17, 18, which pick off the rectified voltage U ₃ to measure their level. In addition, the control unit 16 has a memory unit, not shown, in which a characteristic, not shown, is stored. The characteristic curve indicates a relationship between the smoothed operating voltage U ₄ and a luminous power of the light-emitting diode 5. In addition, the respective luminous power is assigned a pulse width with which the luminous intensity can be generated at the light-emitting diode 5.

On the output side, a measuring resistor 19 is connected to the control circuit 4. The current I flowing through the measuring resistor 19 causes a voltage drop across the measuring resistor 19, which is detected by the sepia converter 12 via a measuring connection 20 at the measuring input M.

In operation, without using the dimming function of the dimmer 6, the maximum level of the smoothed operating voltage U ₄ at the input of the control circuit 4 is initially present when the mains voltage U _{0 is} switched on. The principal voltage curves are shown in FIG. The cuttlefish converter 12 supplies on the output side the luminaire voltage U ₅ for the LED ₅ to be operated with a fixed level. The control unit 16 measures the applied rectified voltage U ₃ via the terminals 17, 18 and compares the measured value with the stored characteristic curve. Without the use of the dimming function, the maximum rectified voltage U _{3 is applied} to the control unit 16 which controls the sepia Transducer 12 controls such that it provides quasi-continuously the luminaire voltage U ₅ , and the luminous power of the LED 5 and thus the brightness is maximum.

As soon as the dimming function of the dimmer 6 is used, the level of the smoothed operating voltage U _{4 changes} . The corresponding voltage profiles are shown in principle in FIG. This change is detected by the control unit 16 via the terminals 17, 18 via the change of the rectified voltage U ₃ . The control unit 16 compares the currently applied voltage U ₃ with the characteristic in order to obtain a desired luminous power for the light-emitting diode 5. From this, the control unit 16 determines the pulse ratio corresponding to the luminous intensity for the luminaire voltage U ₅ .

The control unit 16 controls the cuttlefish converter 12 via the control signal S in such a way that this pulse sequence generates the luminaire voltage U _{5 in} accordance with the determined pulse ratio at a quasi-constant level of the luminaire voltage U ₅ . Thus, at each pulse of the luminaire voltage U _5, the typical current I specified by the manufacturer according to the diode characteristic shown in FIG. 3 is set by the light emitting diode 5. The desired luminous power results from the RMS values of current I and luminaire voltage U ₅ , which are set by the pulse ratio. In addition, the cuttlefish converter 12 varies the level of the luminaire voltage U _{5 as a} function of the voltage drop measured across the measuring resistor 19. Thus, the current I flowing through the light-emitting diode 5 is determined directly. By compensating the luminaire voltage U ₅ , the current I for each pulse can be kept at the value prescribed for the light-emitting diode 5. As a result, in particular temperature fluctuations which lead to a strong shift in the current-voltage characteristic (see FIG. 3) in the light-emitting diode 5 are compensated. Thus, the brightness and also other parameters, eg the color temperature, of the light generated by the light-emitting diode 5 are the same during each pulse. Also, the current I is limited by the light emitting diode 5 to the typical current specified by the manufacturer.

FIG. 6 shows a luminous means 30 according to the invention with an electrical supply circuit 31 according to the invention. The components used essentially correspond to those of the low-voltage lighting system 1, so that their structure and their function are only discussed if they differ from those described above.

The light-emitting means 30 is designed in a manner not shown with a standard screw base, for example E14 or E27, for direct use in a corresponding lamp socket, via which it is connected to a mains voltage U ₀ . In principle, the operation of a Dimmers possible, so that a dimmed voltage U ₁ is applied to the lamp 30.

The electrical supply circuit 31 comprises a free or self-oscillating electronic transformer 2, a rectifier 3, a power factor correction filter 10 and a smoothing capacitor 11, which are electrically connected in series, wherein the power factor correction filter 10 includes an active control electronics. The transformer 2, the rectifier 3 and the smoothing capacitor 11 are identical in construction and function to those described above. The transformer 2 represents the input side and the smoothing capacitor 11 represents the output side of the electric supply circuit 31.

The lighting means 30 further comprises a control circuit 4 'and a light-emitting diode 5, which are connected downstream of the electrical supply circuit 31. Accordingly, the control circuit 4 'is connected directly to the operating voltage U ₄ . The control circuit 4 'used here also serves to provide a luminous voltage U ₅ with a fixed predetermined level for the light-emitting diode 5. The control circuit 4 'stabilizes the luminaire voltage U ₅ in particular against fluctuations in the temperature and thereby operates the light-emitting diode 5 with a constant brightness. In a manner known per se, the control circuit 4 'can also be designed to reduce the brightness of the light-emitting diode 5 during dimming operation by means of a pulse wave transmission. modulation and perform a voltage compensation of the luminaire voltage U ₅ . By way of example, the control circuit 4 'can be designed like the previously described control circuit 4 without power factor correction filter 10 and smoothing capacitor 11, the control unit 16 detecting the level of the operating voltage U ₄ for the control of the pulse width modulation.

The operation of the luminous means 30 corresponds to that of the low-voltage lighting system 1 described above. The mains voltage U ₀ is applied to the transformer 2, which transforms the mains voltage U ₀ to a low-voltage AC voltage U ₂ . The transformer 2 is designed so that it generates a transformed voltage U ₂ of 12 V (effective) from the mains voltage U ₀ . The transformed low-voltage AC voltage U ₂ is rectified in the rectifier 3 to the voltage U ₃ , which is applied to the power factor correction filter 10. The smoothing capacitor 11 provides the operating voltage U ₄ .

The level of the operating voltage U ₄ is on the self-oscillating electronic transformer 2, the rectifier 3, the power factor correction filter 10 and the smoothing capacitor 11 of the effective value of the mains voltage U ₀ dependent. If the mains voltage U _{0 is changed,} for example, by dimming with a dimmer provided outside the luminous means 30 and a dimmed mains voltage U ₁ is applied to the transformer 2, as is shown by way of example in FIG. 1 for the low-voltage lighting system 1 is shown, the subsequent voltages U ₂ , U ₃ , U _{4 change} . The control circuit 4 'can readily detect the change in the operating voltage U ₄ at its input and adjust the luminous power of the LED 5 accordingly, with the level of the luminous voltage U _{5 is} kept constant to maintain the luminous characteristic. Alternatively, the control circuit 4 'in a manner not shown, the transformed low-voltage AC voltage U ₂ or the rectified voltage U ₃ for adjusting the luminous power of the light emitting diode 5 detect.

A low-voltage lighting system 1 according to a further embodiment of the invention is shown in FIG. Central is a self-oscillating electronic transformer 2 is provided which is connected via a common electrical distribution 40, which provides a low-voltage AC voltage U ₂ , with a plurality of low-voltage lighting means 41. Each low-voltage lighting means 41 has a rectifier 3, a power factor correction filter 10, a smoothing capacitor 11, a control circuit 4 'and a light-emitting diode 5, which are electrically connected in series and integrated. The function of the individual components is as described above. In this case, each low-voltage bulb 41 represents an approximately resistive load by the use of the power factor correction filter 10, so that the self-oscillating electronic transformer 2 is in a stable operation as a whole. A functionally identical low-voltage lighting system 1 is shown in FIG. It differs from the low-voltage lighting system 1 shown in FIG. 7 in that, in addition, a dimmer 6 is arranged centrally. Via a downstream voltage distribution 40, which provides a low-voltage alternating voltage U ₂ , a plurality of low-voltage lighting means 41 are connected for operation at a low-voltage alternating voltage. The low-voltage lighting means 41 comprise the same electrical components as the low-voltage lighting means 41 shown in FIG. 7, which, however, are combined in different assemblies. Thus, the power factor correction filter 10 and the smoothing capacitor 11 are included in the control circuit 4 in the low-voltage bulb 41 shown in Fig. 8, while singly provided as the separate components thereof in the low-voltage bulb 41 in Fig. 7.

In the low-voltage lighting system 1 shown in FIG. 9, in addition to the low-voltage lighting system 1 shown in FIG. 8, the rectifier 3 is additionally provided centrally, so that a voltage U _{3 which is} not rectified but not smoothed is provided centrally. Accordingly, low-voltage illuminants 41 'used here do not include any additional rectifier 3. Otherwise, the embodiment shown in FIG. 9 is identical to that of FIG. The low-voltage illuminants 41, 41 'according to the invention are also exchangeable with conventional low-voltage illuminants. As a result, conventional lighting systems according to the invention low-voltage lighting means 41, 41 'can be used. The operation of the conventional lighting system is not limited by the low-voltage lighting means 41, 41 'according to the invention.

Claims

claims

Electric supply circuit (31) having a transformer (2), a rectifier (3) and a smoothing capacitor (11), which are electrically connected in series in this sequence, wherein the supply circuit (31) in the case of a voltage applied to its input ( U ₀ ) provides at its output a smoothed DC voltage (U ₄ ) to which a consumer

(5), in particular at least one LED is connected or connectable, characterized in that the transformer (2) is a freewheeling or self-oscillating electronic transformer and between rectifier (3) and smoothing capacitor (11) an active power factor correction filter (10) is connected ,

Second supply circuit (31) according to claim 1, characterized in that the smoothing capacitor (11) is an electrolytic capacitor.

3. supply circuit (31) according to one of claims 1 or 2, characterized in that the self-oscillating electronic transformer (2), the rectifier (3), the power factor correction filter (10) and the smoothing capacitor (11) are formed as an integral circuit.

4. illuminant (30) with at least one LED (5) which is operated on a smoothed DC voltage (U ₅ ), characterized in that it comprises a supply circuit (31) according to one of the preceding claims and with a mains voltage (U ₀ ) connected or connectable.

5. Lamp (30) according to claim 4, characterized in that the at least one LED (5) is preceded by a control circuit (4 '), which regulates the brightness of the at least one LED (5).

6. low-voltage lighting system (1) with a dimmer (6), a transformer (2), a rectifier (3), at whose output a rectified voltage (U ₃ ) is provided, with downstream smoothing capacitor (11), the one smoothed operating voltage (U ₄ ) provides, at least one LED (5) which is connected to the smoothing condenser (11), and a control circuit (4) which the applied operating voltage (U ₄ ) to a lighting voltage (U ₅ ) is set at a predetermined, substantially fixed level, the dimmer being provided to vary a level of the operating voltage (U ₄ ) and the control circuit (4) is implemented, the luminous power of the one LED (5) depends on the level of the LED Operating voltage (U ₄ ) and while maintaining the level of the luminaire voltage (U ₅ ) to control, characterized in that the transformer (2) a freewheeling or self-oscillating electronic transformer and an active power factor correction filter (10) is provided between the rectifier (3) and the smoothing capacitor (11).

7. low-voltage lighting system (1) according to claim 6, characterized in that the control circuit (4) comprises a control unit (16) for performing a pulse width modulation and the power factor correction filter (10) comprises a control module, wherein the control unit (16) integral with the control module is.

8. control circuit (4) for the operation of at least one LED (5) in a low-voltage lighting system (1), wherein the control circuit (4) an applied voltage to a lighting voltage (U ₅ ), which is a DC voltage with a predetermined, substantially is fixed level, converts and depending on the level of the applied voltage controls the luminous efficiency of the at least one LED (5) while maintaining the level of the luminaire voltage (U ₅ ), characterized in that the control circuit (4) a smoothing capacitor (11) and a comprising this upstream active power factor correction filter (10).

9. Control circuit (4) according to claim 8, characterized in that the control circuit (4) has a control unit (16) for carrying out a pulse width modulation and the

Power factor correction filter (10) comprises a control module, wherein the control unit (16) is integral with the control module.

10. Low-voltage illuminant (41) with a rectifier (6), a smoothing capacitor (11) and at least one LED (5) for operation on a transformed low-voltage alternating voltage (U ₂ ), characterized in that the low-voltage illuminant (41) comprises a control circuit (4 ) according to one of claims 8 or 9 and a rectifier (3) connected upstream of the control circuit (4).

11. Low-voltage illuminant (41 ') with a smoothing capacitor (11) and at least one LED (5) for operation on a rectified voltage (U ₃ ), characterized in that the low-voltage illuminant (41') a control circuit (4) according to one of claims 8 or 9.

12. Low-voltage lighting system (1), supply circuit (31), control circuit (4), low-voltage lighting means (41, 41 ') or lighting means (30) according to one of the preceding claims, characterized in that the power factor correction filter (10) as a non-ideal filter with a predistortion of its current-voltage characteristic is executed.

13. Low-voltage lighting system (1), supply circuit (31), control circuit (4), low-voltage lighting means (41, 41 ') or lighting means (30) according to claim 12, characterized in that the predistortion of the current-voltage characteristic is carried out such that the ISIN line is raised at the beginning and at the end of the half wave of the voltage and flattened in the central region, and thus during each voltage period is substantially constant.

14. low-voltage lighting system (1), supply circuit (31), control circuit (4), low-voltage lighting means (41, 41 ') or lighting means (30) according to any one of claims 12 or 13, characterized in that the predistortion of the current-voltage characteristic is carried out in such a way is that the current is raised at the beginning of each half period of the voltage (U ₃ ).