EP3262901B1

EP3262901B1 - Operating device for an illuminant

Info

Publication number: EP3262901B1
Application number: EP15882940.8A
Authority: EP
Inventors: Quentin LIN
Original assignee: Tridonic GmbH and Co KG
Current assignee: Tridonic GmbH and Co KG
Priority date: 2015-02-26
Filing date: 2015-02-26
Publication date: 2022-09-14
Anticipated expiration: 2035-02-26
Also published as: EP3262901A1; WO2016134502A1; EP3262901A4

Description

The present invention relates to an operating device for an illuminant according to the pre-characterizing part of claim 1 and relates to a method for compensating excessive high voltages at output terminals of an operating device according to the pre-characterizing part of claim 10.
An operating device in which a driving circuitry for driving the illuminant comprises a rectifier for rectifying an input AC voltage to a DC voltage and a converter for converting the DC voltage output by the rectifier into a working voltage for the illuminant is disclosed in WO 2014/085837 A2 .
In WO 2014/085837 A2 , the output terminals of the operating device are galvanically isolated from the input terminals via a transformer, wherein a radio interference suppression capacitor is connected to the primary winding and the secondary winding of the transformer.
The document US 2014/368124 A1 discloses drivers for driving light circuits with light emitting diodes, comprising isolation circuits with primary and secondary parts and guiding circuits for guiding common mode surge signals to reference potentials. Thereby, the isolation circuits may be designed to guide first parts of the common mode surge signals away from the light circuits and the guiding circuits may be designed to guide second parts of the common mode surge signals away from the light circuits, the second parts being smaller than the first parts.
The document JP 2010 080381 discloses an LED lighting device and a lighting fixture including the LED lighting device that prevent the propagation of noise to a power line without grounding a lighting unit, in which a light emitting diode is deposed.
In such operating device or other devices including an isolated switching mode power supply converter, voltage surges of, for example, up to two kilo Volt at the input terminals of the operating device caused by, for example, power outages, lightning strikes or inductive spikes, may result in excessive high voltages at output terminals of the operating device when measured against the ground potential/protective earth. This risk is particular high when LEDs mounted on a Metal Core Printed Circuit Board (MCPCB) are connected to the operating device.
It is an object of the present invention to provide an operating device and a lighting device with which excessive high voltages at output terminals of the operating device can be prevented.
This object is achieved by an operating device and a lighting device according to the enclosed independent claims. Advantageous features of the present invention are defined in the corresponding subclaims.
According to the present invention, the operating device for an illuminant comprises input terminals for being supplied with an AC voltage, output terminals, a driving circuitry for driving the illuminant, when connected to the output terminals, wherein bypass means that comprise at least one capacitor are provided to bypass a current from one of the output terminals to protective earth or a neutral terminal of the input terminals.
The operating device comprises a rectifier for rectifying the AC voltage to output a DC voltage, a converter for converting DC voltage output by the rectifier into a working voltage for the illuminant, a first capacitor connected between an output terminal of the rectifier and the protective earth and, preferably, adapted to compensate needle pulses generated by the rectifier, and a second capacitor connected between an output terminal of the rectifier and the one of the output terminals.
Alternatively or in addition, the converter can be an isolated switching mode power supply converter. Preferably, the isolated switching mode power supply converter is a LED converter.
Alternatively or in addition, the bypass means can be connected in parallel to the second capacitor, wherein the capacity of the capacitor of the bypass means is greater than the capacity of the second capacitor.
Alternatively, the bypass means can be connected in parallel to a serial connection of the first capacitor and the second capacitor, wherein the capacity of the capacitor of the bypass means is greater than the capacity of the second capacitor.
Preferably, the bypass means is adapted to bypass the current when the voltage between the one of the output terminals and the protective earth and/or the neutral terminal exceeds a certain value.
Alternatively or in addition, the bypass means can comprise at least one of a gas discharge tube, Zener diode, Transient Voltage Suppression diode and voltage-dependent resistor.
According to the present invention, a lighting device comprises the operating device described above and at least one illuminant connected to the output terminals of the operating device.
For example, in a method for compensating excessive high voltages at output terminals of an operating device for an illuminant due to voltage surges at input terminals of the operating device, a current from one of the output terminals is bypassed to protective earth and/or a neutral terminal of the input terminals in order to compensate the excessive high
voltages. The method can be performed by the operating device described above.
The invention is to be explained more detailed in the following with reference to the accompanying drawing, wherein:

FIG. 1 shows, in schematic form, a first embodiment of the lighting device according to the present invention;
FIG. 2 shows, in schematic form, a second embodiment of the lighting device according to the present invention;
FIG. 3 shows, in schematic form, a third embodiment of the lighting device according to the present invention; and
FIG. 4 shows the operating device of the lighting device shown in FIG. 2 more detailed.

In the figures 1 to 4, same reference signs refer to the same or analogous elements. In the first embodiment represented in FIG. 1, the lighting device according to the present invention, which is represented in a simplified manner, comprises input terminals L, N for being supplied with an AC voltage, output terminals X1, X2, a rectifier 1 for rectifying the AC voltage to output a DC voltage, a converter 2 for converting DC voltage output by the rectifier 1 into a working voltage for the illuminant 3 connected to the output terminals X1, X2 and a bypass 4 formed of a capacitor C and connected to the output terminal X2 and the protective earth at the terminal PE. Alternatively, the bypass 4 can be connected to the output terminal X1 instead of terminal X2 and, if neutral conductor is earthed, the bypass 4 can be connected to the input terminal N instead of terminal PE.
The rectifier 1 and the converter 2 can be combined in a driving circuitry, wherein the input terminals L, N, the output terminals X1, X2, the driving circuitry and the bypass 4 form an operating device according to the present invention.
With the bypass 4 shown in FIG. 1, the output side (output terminals X1, X2) is connected to the protective earth via the capacitor C. When the voltage between the output terminals X1, X2 and the ground potential/protective earth increases due to surges at the input terminals L, N, a current is fed through the capacitor C to the terminal PE, i.e., a current output from the output terminal X2 is bypassed to the terminal PE, so that excessive high voltages between the output terminals X1, X2 of the operating device and the ground potential/protective earth may be suppressed.
FIG. 2 shows a second embodiment of the lighting device according to the present invention. In FIG. 2, in order to improve Electromagnetic Compatibility (EMC) of the lighting device, a first capacitor C1 and a second capacitor C2 are provided for compensating needle pulses generated by the rectifier 1 and for interference suppression, respectively. The first capacitor C1 is connected between the output terminal X3 of the rectifier 1 and the terminal PE and the second capacitor C2 is connected between the output terminal X3 and the output terminal X2 of the converter 2. As shown in FIG. 2, the capacitor C of the bypass 4 is connected in parallel to the second capacitor C2. The capacity of the capacitor C of the bypass means 4 is greater than the second capacitor C2 having a capacity of, for example, around 4,7nF, in order to compensate an excessive high voltage between the output terminal X2 and the terminal PE.
FIG. 3 shows a third embodiment of the lighting device according to the present invention. In FIG. 3, the capacitor C of the bypass 4 is connected between the terminal PE and the output terminal X2, i.e., the capacitor C of the bypass means 4 is connected in parallel to the serial connection of the first capacitor C1 and the second capacitor C2. Also here, the capacity of the capacitor C of the bypass means is greater than the capacity of the second capacitor C2 and, when the voltage between the output terminal X2 and the terminal PE increases strongly due to surges at the input terminals L, N, a current output from the output terminal X2 is bypassed to the terminal PE, so that excessive high voltages between the output terminal X2 and the terminal PE is suppressed.
Since the bypass 4 only must be activated in the case of excessive high voltages between the output terminal X2 and the terminal PE and usually activation is necessary only for a short period of time, switching or blocking means can be integrated in the bypass 4 that blocks or switchesoff the bypass 4 during normal operation of the lighting device in which no excessive high voltage is present.
With the switching or blocking means, losses due to the leakage current of the potentially very big capacitor C during normal operation can be avoided. The switching/blocking means 5 can be integrated in the bypass 4 in each of the first, second and third embodiments of the lighting device shown in Figs. 1, 2 and 3, respectively, wherein the capacitor C and a switching/blocking means 5 indicated by the dotted line in Figs. 1, 2 and 3 are connected in series.
The switching/blocking means 5 can be implemented by using two Zener diodes, two Transient Voltage Suppression (TVS) diodes, voltage-dependent resistor (VDR), gas discharge tube (gas arrester) or combinations thereof and is configured to open the bypass, when the voltage between the output terminal X2 and the terminal PE exceeds a certain value or predetermined value, so that a current output from the output terminal X2 is bypassed to the terminal PE. In the normal operation mode of the lighting device in which no excessive high voltage is present, the switching/blocking means 5 prevents extensive DC currents flowing across the capacitor C of the bypass 4. This improves the electromagnetic compatibility (EMC).
FIG. 4 shows an embodiment of the operating device according to the present invention. All components of the circuit shown in FIG. 4, including the rectifier 1, the converter 2, the first capacitor C1, the second capacitor C2 and the bypass 4 composed of the capacitor C and the switching/blocking means 5 formed of two Zener diodes ZD10 can be mounted on a single compact printed circuit board (not shown).
As shown in FIG. 4, the rectifier 1 comprises capacitor CX2 connected in parallel to the input terminals L and N, a full-wave rectifier B connected to the input terminals L and N via inductors L1 and L2, respectively, and a smoothing capacitor C10 connected to the output of the full-wave rectifier B. The converter 2 comprises an isolated transformer T, diodes D90 and D91 connected in parallel and a capacitor C92 connected parallel to the output terminals X1 and X2. The secondary winding of the isolated transformer T is connected to the terminal X2 and the diodes D90 and D91. One end of the primary winding of the isolated transformer T is connected to the full-wave rectifier B and the other end of the primary winding is connected to the terminal X3 via the switch S. In FIG. 4, the first capacitor C1 is connected between the terminal PE and the output terminal X3 of the rectifier 1, the second capacitor C2 is connected between the output terminal X3 and the output terminal X2 of the converter 2 and a serial connection of the capacitor C and the Zener diodes ZD10 is connected in parallel to the second capacitor C2.
As indicated by the dotted line in FIG. 4, the rectifier 1 and the converter 2 shown in Figs. 1 to 3 can be built up as shown in FIG. 4. Further, the rectifier 1 and the converter 2, the input terminals L, N, the output terminals X1, X2, and the bypass 4 shown in Figs. 1 to 3 form a operating device according to the present invention.

Claims

An operating device for an illuminant comprising
input terminals (L, N) for being supplied with an AC voltage;

output terminals (X1, X2);

a driving circuitry (1, 2) for driving the illuminant (3), when connected to the output terminals (X1, X2), wherein

bypass means (4) are provided to bypass a current from one of the output terminals (X1, X2) to protective earth (PE) or a neutral terminal (N) of the input terminals (L, N), wherein
the bypass means (4) comprise at least one capacitor (C); and wherein the driving circuitry (1, 2) comprises

a rectifier (1) for rectifying the AC voltage to output a DC voltage;

a converter (2) for converting DC voltage output by the rectifier (1) into a working voltage for the illuminant (3); and

a first capacitor (C1) connected between an output terminal (X3) of the rectifier (1) and the protective earth (PE);

characterized in that

the driving circuitry (1, 2) comprises a second capacitor (C2) connected between the output terminal (X3) of the rectifier and the one of the output terminals (X1, X2) .
The operating device according to claim 1, wherein
the converter (2) is an isolated switching mode power supply converter.
The operating device according to claim 2, wherein
the isolated switching mode power supply converter is a LED converter.
The operating device according to claim 1, 2 or 3, wherein
in case the bypass means (4) are provided to bypass the current from the one of the output terminals (X1, X2) to the neutral terminal (N), the bypass means (4) is connected in parallel to the second capacitor (C2) and the capacity of the capacitor (C) of the bypass means (4) is greater than the capacity of the second capacitor (C2).
The operating device according to claim 1, 2 or 3, wherein
in case the bypass means (4) are provided to bypass the current from the one of the output terminals (X1, X2) to the protective earth (PE), the bypass means (4) is connected in parallel to a serial connection of the first capacitor (C1) and the second capacitor (C2) and the capacity of the capacitor (C) of the bypass means (4) is greater than the capacity of the second capacitor (C2).
The operating device according to anyone of claims 1 to 3 or 5, wherein
switching or blocking means (5) are integrated in the bypass means (4) that are configured to block or switchoff the bypass means (4) during normal operation of the illuminant, wherein

in case the bypass means (4) are provided to bypass the current from the one of the output terminals (X1, X2) to the protective earth (PE), the bypass means (4) is adapted to bypass the current when the voltage between the one of the output terminals (X1, X2) and the protective earth (PE) exceeds a certain value.
The operating device according to claim 6, wherein
the bypass means (4) comprise at least one of a gas discharge tube, Zener diode, Transient Voltage Suppression diode and voltage-dependent resistor.
A lighting device comprising
the operating device according to anyone of claims 1 to 7; and

at least one illuminant (3) connected to the output terminals (X1, X2) of the operating device.