• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a circuit arrangement for operating a luminous means, comprising a pulse modulation device (14) which is designed to generate electrical pulses with an adjustable frequency, wherein the electrical pulses can be used to control the supply of the luminous means (23) with electrical energy, the Frequency can be set as a function of a predetermined brightness level for the illuminant (23).
    公开号:AT17248U1
    申请号:TGM134/2017U
    申请日:2017-06-19
    公开日:2021-10-15
    发明作者:
    申请人:Tridonic Gmbh & Co Kg；
    IPC主号:
    专利说明:

    description
    CIRCUIT ARRANGEMENT FOR OPERATING A LIGHT SOURCE
    The present invention relates to a circuit arrangement for operating a lighting means. The present invention relates in particular to a circuit arrangement which comprises a pulse modulation device in order to set a brightness level predetermined for the lighting means.
    LED light sources, such as, for example, individual LEDs and LED modules, are used in many lighting devices because they have a long service life and low energy consumption. Usually, such LED lamps cannot be operated directly with a mains voltage, such as an alternating voltage of 230-240 V, but are operated with a suitable voltage and / or via a corresponding circuit arrangement, a so-called LED converter or LED converter a suitable current.
    It is often desirable to adjust the brightness of the LED illuminant. Such a setting is also referred to as "dimming". For example, pulse width modulation (PWM, pulse width modulation) can be used in conjunction with a constant current source in order to set the brightness of the LED light source (see, for example, DE 20 2004 006 292 U1). The use of pulse width modulation can, however, lead to flickering or flickering of the LED illuminant, which can be perceived as unpleasant by a user. Furthermore, the achievable gradation in the brightness setting can be insufficiently precise.
    [0004] The object of the present invention is therefore to provide an improved control for LED lighting means, which in particular improves the brightness control of LED lighting means.
    This object is achieved according to the present invention by a circuit arrangement for operating a lighting means according to independent claim 1. The dependent claims define advantageous and / or preferred embodiments of the invention.
    According to the present invention, a circuit arrangement for operating a light source, in particular an LED light source, is provided. The circuit arrangement comprises a pulse modulation device which is able to generate electrical pulses with an adjustable frequency. A supply of the lighting means with electrical energy can be controlled by means of the electrical pulses. The frequency can be set as a function of a predetermined brightness level for the illuminant. In other words, the brightness of the light source is set using pulse frequency modulation (PFM). With pulse frequency modulation, it is not the length of the pulse that is set, but the time interval between the pulses. This makes it possible to set a length of the electrical pulses essentially independently of the desired brightness level. As a result, a ripple, a so-called ripple, on the lighting means can be reduced, whereby a flickering of the lighting module can be prevented or reduced.
    The length of the electrical pulses can be adjusted, for example, as a function of a property of the illuminant. Since different lighting means can have different properties with regard to (perceived) flickering and this flickering can be influenced by the switch-on pulse lengths, the flickering can be reduced, in particular, taking this property of the lighting means into account.
    According to one embodiment, the length of the electrical pulses is set as a function of the predetermined brightness level for the lighting means. As will be described further below, a current supplied to the lighting means can be controlled by means of the electrical pulses and filtered with the aid of a low-pass filter. In particular, the low-pass filtering can reduce a peak current which is fed to the lighting means on the basis of an electrical pulse. However, the peak current can have an effect on a
    Have the color rendering of the light source. In order to increase the peak current, it can therefore make sense, for example at lower brightness levels or brightness level ranges, to increase the length of the electrical pulse in order to ensure a constant color rendering of the illuminant. In this embodiment, both a pulse frequency modulation and a pulse width modulation are used in the control of the energy supply of the lighting means.
    In a further embodiment, the electrical pulses have a constant length. This embodiment can be implemented in a particularly simple manner.
    In a further embodiment, the frequency of the electrical pulses is also set as a function of a property of the lighting means. The different illuminants can have different properties. For example, different LED types can be used in different lighting means or different arrangements of LEDs, for example series connections or parallel connections of several LEDs, can be used in different lighting means. The different properties of the different illuminants can have an influence on a flickering behavior or a color constancy, especially in the case of a pulse-modulated control. Taking these properties into account when setting the frequency of the pulse modulation device can therefore improve the color constancy and the flickering behavior. For example, corresponding information for setting the frequency of the pulse modulation device for various lighting means properties can be determined in advance and stored in a memory of the circuit arrangement and used by the pulse modulation device.
    The property of the lighting means, for example an LED lighting means, can include, for example, a characteristic curve of the LED. The characteristic curve can include, for example, a current-voltage characteristic curve or a temperature-dependent current-voltage characteristic curve field. For example, an LED type can be determined from this.
    If the lighting means comprises a plurality of light emitting diodes, the property of the lighting means can also include an arrangement of the plurality of light emitting diodes in the lighting means, for example a parallel and / or row arrangement of the plurality of light emitting diodes.
    According to one embodiment, the circuit arrangement comprises a property determination device for determining the property of the lighting means, in particular for determining the characteristic of a light emitting diode or light emitting diode arrangement of the lighting means. Corresponding methods for detecting the characteristic curves of light emitting diodes are known, for example, from WO 2009/000475 A2. These methods can be used by the property determining device to determine the property of the luminous means. In addition, the property determination device is designed to set the frequency with which the pulse modulation device generates the electrical pulses to a measurement frequency at which at least one characteristic value of the characteristic curve can be determined. For example, a frequency can be set at which the LED lights up only very weakly or not at all in order to determine the property or characteristic of the LED without the user noticing.
    In a further embodiment, the circuit arrangement comprises a constant current source which is switched with the electrical pulses and provides a supply current for the lighting means as a function of the electrical pulses. The pulse modulation device can, for example, provide the electrical pulses as pulses with a constant voltage, which, for example, are distributed to a plurality of lighting means modules, for example LED modules, via a bus. The voltage pulses, i.e. the pulses with constant voltage, can be generated from a direct voltage, for example, by means of the pulse modulation device. A corresponding constant current source can be provided in each LED module, which provides a current matched to the light-emitting diodes present in the LED module and is controlled with the electrical pulses and supplied with electrical energy. The constant current source generates corresponding electrical current pulses with a constant current in accordance with the electrical pulses from the pulse modulation device.
    Between the constant current source and the lighting means, for example a light emitting diode or an arrangement of light emitting diodes, a low-pass filter can be arranged which filters the supply current for the lighting means. The low-pass filter can for example comprise a coil and / or a capacitor, for example a so-called LC filter. The low-pass filter can have a cut-off frequency which essentially corresponds to the frequency of the pulse modulation device at a predetermined brightness level for the lighting means of 10% of a maximum brightness level for the lighting means. The term “essentially” in this context means that the cutoff frequency of the low-pass filter corresponds, for example, in a range of +/- 20%, preferably +/- 10% of the frequency of the pulse modulation device at the predetermined brightness level for the illuminant of 10% of the maximum brightness level . For example, the frequency with which the pulse modulation device generates the electrical pulses can be 100 Hz in order to operate the lighting means with 10% of its maximum brightness level. In this case, the cutoff frequency of the low-pass filter can be selected, for example, in a range of 80-120 Hz, preferably 90-110 Hz. With such a design of the low-pass filter it is achieved that at low brightness levels the electrical current pulses of the constant current source are passed on to the illuminant essentially unfiltered, whereby the color rendering of the illuminant is improved, that is, the color of the light emitted by the illuminant changes with a change in brightness essentially not.
    According to the present invention, a method for operating a lighting means is also provided. In the process, electrical pulses are generated with an adjustable frequency. The supply of electrical energy to the illuminant is controlled by means of the electrical pulses. The frequency is set as a function of a predetermined brightness level for the light source. The method thus comprises the steps of generating electrical pulses with an adjustable frequency, the supply of electrical energy to the lighting means being controllable by means of the electrical pulses, and setting the frequency as a function of a predetermined brightness level for the lighting means.
    The present invention is explained below with reference to the figures on the basis of embodiments. In the figures, identical reference symbols denote identical elements.
    1 shows schematically a circuit arrangement for operating a lighting means.
    Fig. 2 shows schematically a voltage profile of an output voltage of a pulse modulation device and a resulting current profile through a lighting means according to an embodiment of the present invention at a predetermined brightness level of 50%.
    Fig. 3 shows schematically a voltage profile of an output voltage of a pulse modulation device and a resulting current profile through a lighting means according to an embodiment of the present invention at a predetermined brightness level of 10%.
    Fig. 4 shows schematically a voltage profile of an output voltage of a pulse modulation device and a resulting current profile through a lighting means according to an embodiment of the present invention at a predetermined brightness level of 100%.
    1 shows schematically a circuit arrangement 10 for controlling a lighting means 23. The lighting means 23 is located, for example, on an LED module 20. The circuit arrangement 10 can also control several other LED modules, for example the LED shown in FIG. Module 30. The individual LED modules 20, 30 can also have a plurality of lighting means 23 of the type shown in FIG. 1 or also of a different type.
    The circuit arrangement 10 comprises an EMC filter and rectifier device 11 which is connected to a power supply network 40, for example. The power supply network 40 can, for example, provide an alternating voltage in the range of 100-400 V.
    len. A rectifier of the device 11 generates a corresponding direct voltage from the alternating voltage. An EMC (electromagnetic compatibility) filter of the device 11 prevents electromagnetic interference from the circuit arrangement 10 from reaching the power supply network 40.
    The DC voltage of the device 11 is fed to an up-converter and power correction filter device 12. The power correction filter of the device 12 set the power factor of the power consumed by the circuit arrangement 10 to a value which is as close as possible to the amount 1, for example in a range of 0.98-1. The boost converter of the device 12 generates a defined direct voltage of 405 V, for example, from the supplied direct voltage. This defined direct voltage is fed to one or more HB-LLC devices 13.
    The HB-LLC device 13 is a DC-DC converter circuit which comprises, for example, a half bridge (HB) and an LLC resonance converter with two coils (LL) and a capacitor (C), which is controlled by the half bridge. The HB-LLC device 13 can furthermore comprise a transformer for galvanic separation of the output voltage of the HB-LLC device 13 from the defined direct voltage supplied. The output voltage of the HB-LLC device 13 can comprise a direct voltage of 24 V, for example. The output voltage of the HB-LLC device 13 is fed to a pulse modulator 14.
    The above-described generation of the direct voltage, which is fed to the pulse modulator 14, is only an exemplary arrangement which can be used, for example, in larger lighting systems, such as in business premises or production facilities. In the case of smaller lighting systems, the DC voltage fed to the pulse modulator 14 can be generated in a simpler manner, for example with a switched-mode power supply directly from the AC voltage of the power supply network 40, i.e., in particular without generating the much higher DC voltage between the devices 12 and 13.
    The pulse modulator 14 generates a sequence of voltage pulses which are output, for example, on a power supply bus 15. One or more LED modules 20, 30 can be connected to the energy supply bus 15 and be supplied with electrical energy via the energy supply bus 15. A frequency with which the voltage pulses are generated by the pulse modulator 14 is set in the pulse modulator 14 as a function of a predetermined brightness level for the connected LED modules via an input 16. The predetermined brightness level, which corresponds, for example, to a desired brightness in a room illuminated by the LED modules 20, 30, can be set via the input 16, for example, by means of a voltage corresponding to the predetermined brightness level or a digital code word corresponding to the predetermined brightness level. The pulse modulator 14 can, for example, generate voltage pulses of constant length which are output to the energy supply bus 15 at the set frequency. In this case, the pulse modulator 14 corresponds to a so-called pulse frequency modulator (PFM). In addition, the length of the voltage pulses can be variable. In this case, the pulse modulator 14 operates in a mixed mode of pulse frequency modulator and pulse width modulator (PWM). The length of the voltage pulses can be set, for example, as a function of the brightness level specified via input 16. Alternatively or additionally, the length of the voltage pulses can be set, for example, as a function of a property of the LED module 20 via a further input 17 of the pulse modulator 14. The property of the LED module can include, for example, a current-voltage characteristic curve of the light-emitting diode used in the LED module. The frequency with which the voltage pulses are generated by the pulse modulator 14 can also be set as a function of the property of the LED module 20.
    The LED module 20 comprises a constant current source 21, a low-pass filter 22, a light-emitting diode arrangement 23 and a property determining device 24. The light-emitting diode arrangement 23 can, for example, a single light-emitting diode or an arrangement of several
    Include light-emitting diodes in, for example, a parallel connection, a series connection or a combination thereof. The property determining device 24 can be configured to determine the properties of the light emitting diode arrangement 23, for example a number and arrangement of light emitting diodes in the light emitting diode arrangement 23 as well as properties of individual light emitting diodes of the light emitting diode arrangement 23, for example one type of light emitting diode. The properties of the light-emitting diode arrangement 23 can be determined, for example, via a current-voltage measurement (U1 measurement) under different operating conditions of the light-emitting diode arrangement 23. Corresponding methods are described, for example, in WO 2009/000475 A2. For example, an initial control sequence can be used, for example a certain frequency of the pulse modulator at which the light-emitting diodes appear essentially as non-luminous, and after recognizing the arrangement and / or type of light-emitting diodes, an optimal frequency or an optimal frequency band is determined for the operation of the pulse modulation device will.
    The constant current source 21 is coupled to the power supply bus 15. The voltage pulses provided by the pulse modulator 14 are received by the constant current source 21 and the constant current source 21 generates current pulses as a function of the received voltage pulses. The current pulses can, for example, have the same length as the received voltage pulses and can be generated at the same frequency as the received voltage pulses. The individual current pulses have a constant current intensity which is matched to the light-emitting diode arrangement 23. The current pulses generated by the constant current source 21 are fed to the light-emitting diode arrangement 23 via the low-pass filter 22. The low-pass filter 22 can, for example, comprise a smoothing capacitor or a combination of a capacitor and a coil, a so-called LC element. A cutoff frequency of the low-pass filter 22 can be adapted to the frequency range used by the pulse modulator. For example, the cutoff frequency of the low-pass filter 22 can correspond to the frequency which is used by the pulse modulator 14 at a predetermined brightness level of 10% of a maximum brightness level. If the pulse modulator 14 outputs the voltage pulses with a frequency of 100 Hz, for example, in order to operate the LED arrangement 23 with 10% of its maximum brightness, the low-pass filter 22 can be designed, for example, in such a way that it has a cut-off frequency of approximately 100 Hz, for example a cut-off frequency in the range of 90-110 Hz. The length of the voltage pulses can be, for example, 1 ms in this case. The mode of operation of the low-pass filter 22 designed in this way will be described schematically below with reference to FIGS. 2-4.
    Fig. 2 shows in the upper diagram schematically an output of voltage pulses from the pulse modulator 14 at a predetermined brightness level of, for example, 50% of the maximum brightness of the LED arrangement 23. The length of the individual voltage pulses is, for example, 1 ms and the frequency, with which the voltage pulses are output is approximately 500 Hz in this example. The constant current source 21 generates corresponding current pulses with a frequency of 500 Hz, ie, for example, current pulses with a length of 1 ms each. The 500 Hz are well above the cutoff frequency of the low-pass filter 22. In the lower diagram, FIG. 2 schematically shows an output of a current from the low-pass filter 22 to the light-emitting diode arrangement 23. The low-pass filter 22 essentially smoothes the current output to the light-emitting diode arrangement 23, so that a flickering or flickering of the light-emitting diode arrangement 23 can essentially be avoided despite the pulsed control.
    At a lower brightness level, the frequency of the pulse modulator is reduced accordingly.
    3 shows schematically in the upper diagram an output of voltage pulses from the pulse modulator 14 at a predetermined brightness level of, for example, 10% of the maximum brightness of the LED arrangement 23. The length of the individual voltage pulses is again, for example, 1 ms. In this case, however, the frequency with which the voltage pulses are output is only approximately 100 Hz. The 100 Hz is in the range
    the cutoff frequency of the low-pass filter 22, so that the output current from the low-pass filter 22 is significantly less smoothed.
    In the lower diagram, FIG. 3 shows schematically a corresponding output of the current from the low-pass filter 22. The peak current which is output from the low-pass filter 22 to the light-emitting diode arrangement 23 is still relatively high, for example approximately as high as the current by the light-emitting diode arrangement 23 in the 50% example of FIG. 2. Since a color rendering of the light-emitting diodes can be influenced by the drive current, a change in the color reproduced by the light-emitting diode arrangement 23 between the 50% setting in FIG. 2 and the 10% setting can Adjustment of FIG. 3 can be essentially prevented.
    At a higher brightness level, the frequency of the pulse modulator 14 is increased accordingly. In the example described above, the maximum brightness is achieved, for example, at approximately 1 kHz, since in this case the 1 ms voltage pulses are output essentially continuously and without interruption, so that a constant voltage level is output by the pulse modulator 14.
    4 shows schematically in the upper diagram such an output of closely spaced voltage pulses from the modulator 14 for a predetermined brightness level of, for example, 100%. The result is a more or less constant voltage output. The constant current source 21 accordingly also generates a continuous and constant current. In this operating case, the low-pass filter 22 therefore has essentially no influence on the current output by the constant current source 21.
    In the lower diagram, FIG. 4 schematically shows a corresponding output of the current from the low-pass filter 22, which is fed to the light-emitting diode arrangement 23 in this case.
    With the circuit arrangement 10 described above, flickering or flickering of the light emitted by the light-emitting diode arrangement 23 can be prevented or reduced, in particular at average brightness levels of more than 20 or 30% of the maximum brightness. Furthermore, in particular at low brightness levels of 20% or below, the color of the light emitted by the light-emitting diode arrangement 23 can be prevented from changing.
    The frequencies and pulse lengths used in the examples described above are only exemplary. Depending on the arrangement of light-emitting diodes used in the light-emitting diode arrangement 23 and the type of light-emitting diodes used in the light-emitting diode arrangement 23, other frequencies or frequency ranges and other pulse lengths can be used. Typical pulse lengths can be in the range from 0.1 ms to 100 ms, for example. The frequencies used can accordingly be in a range from 10 Hz to 100 kHz.
    权利要求:
    Claims (10)
    [1]
    1. Circuit arrangement for operating a light source, comprising:
    - A pulse modulation device (14) which is designed to generate electrical pulses with an adjustable frequency,
    characterized in that a supply of the illuminant (23) with electrical energy can be controlled by means of the electrical pulses, the frequency being adjustable as a function of a predetermined brightness level for the illuminant (23).
    [2]
    2, circuit arrangement according to claim 1, characterized in that the length of the electrical pulses can be adjusted as a function of a property of the illuminant (23).
    [3]
    3. Circuit arrangement according to claim 1 or claim 2, characterized in that the length of the electrical pulses can be adjusted as a function of the predetermined brightness level for the lighting means (23).
    [4]
    4. Circuit arrangement according to claim 1, characterized in that the electrical pulses have a constant length.
    [5]
    5. Circuit arrangement according to one of the preceding claims, characterized in that the frequency of the electrical pulses can also be adjusted as a function of a property of the illuminant (23).
    [6]
    6. Circuit arrangement according to claim 5, characterized in that the lighting means (23) comprises a light-emitting diode, the property of the light-emitting means comprising a characteristic curve of the light-emitting diode.
    [7]
    7. Circuit arrangement according to claim 6, further comprising: a property determination device (24) for determining the characteristic of the light-emitting diode, characterized in that the property determination device (24) is designed to set the frequency to a measurement frequency at which at least one characteristic value of the characteristic can be determined is.
    [8]
    8. Circuit arrangement according to one of claims 2 or 5-7, characterized in that the lighting means (23) comprises several light emitting diodes, the property of the lighting means (23) comprising an arrangement of the several light emitting diodes in the lighting means (23).
    [9]
    9. Circuit arrangement according to one of the preceding claims, further comprising: - a constant current source (21), characterized in that the constant current source (21) can be switched with the electrical pulses and provides a supply current for the illuminant (23) as a function of the electrical pulses .
    [10]
    10. Circuit arrangement according to one of the preceding claims, characterized in that the electrical pulses are voltage pulses which can be generated from a DC voltage by means of the pulse modulation device (14).
    In addition 3 sheets of drawings
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    DE202017002443.8U|DE202017002443U1|2017-05-08|2017-05-08|Circuit arrangement for operating a light source|
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