DE102019207182A1 - LED DRIVERS WITH SAFETY LOW VOLTAGE AND MEANS TO PREVENT GLIMING EFFECTS - Google Patents

Abstract

Electronic operating device (1) for converting an electrical input variable which can be applied to an input connection (2) into a predeterminable electrical operating variable which can be provided at an output connection (8) and has a predeterminable maximum value for operating an electronic operating unit (15), in particular a light-emitting diode as the main load , having a rectifier (4) for rectifying the input variable, a device for galvanic decoupling (5) between the input connection (2) and the output connection (8) with a primary side (6) and a secondary side (7), and an interference suppression capacitor (9) with a first connection (A) and a second connection (B), is characterized in that the interference suppression capacitor (9) with its first connection (A), viewed in the direction of the input connection (2), is in front of the rectifier ( 4), is connected to the input connection (2) and with its second connection (B) on the secondary side (7) of the galvanis Chen decoupling (5) is connected to a circuit (5b) to which the operating unit (15) can be connected.

Description

Technical area

The present invention relates to an operating device designed for operation with safety extra-low voltage for light-emitting diodes as an operating unit, in particular for installation in luminaires of protection class II, with the ability to avoid glowing effects.

A light diode (LED) or an LED module can be voltage-operated or current-operated. For operation, however, a limitation to an ideal value for the light-emitting diode is necessary in each case. Otherwise, the light-emitting diode could flicker or, in particular when operating on a voltage supply, fail with increasing power consumption due to the associated thermal load. So-called electronic ballasts (EVG) have proven to be useful for setting the corresponding operating parameters, especially for current limitation. Electronic ballasts for light diodes are also known as LED drivers.

For lights and all other electrical equipment, three protection classes are specified in EN 61140, in which it is described whether and how a protective conductor (PE) is to be connected in each case. Luminaires of protection class II (PC II luminaires) have reinforced or double insulation between the mains circuit and the output voltage or the metal housing (VDE 0100 part 410, 412.1). They usually do not have a connection to a protective conductor. If cables with a protective conductor are used, this must not be connected to the housing.

Safety extra-low voltage (SELV) refers to an electrical voltage that, due to its low level and its insulation against circuits of higher voltage, e.g. by means of safety isolating transformers, offers special protection against electric shock (EN 61558; IEC 61558 safety of transformers). If the nominal voltage is less than 25V AC or 60V DC, a protective conductor to protect against direct contact can be dispensed with when operating a device with safety extra-low voltage.

State of the art

Electronic devices must comply with limit values for the emission of interference signals and meet minimum requirements for susceptibility to interference. A Y capacitor is usually used for radio interference suppression of electronic ballasts with safety extra-low voltage. This is an interference suppression capacitor or safety capacitor that enables electromagnetic interference to be reduced.

1 shows an electronic ballast 101 with radio interference suppression according to the state of the art. As shown, it essentially comprises an input connection 102 , a circuit part 103 , a bridge rectifier 104 , a SELV transformer 105 with a primary side 106 and a secondary side 107 , and an output terminal 108 with the terminals LED + and LED- for connection to an LED operating unit (not shown), eg an LED module. There is also a Y capacitor 109 provided with a port A and a port B.

With the known ballast 101 is connection A with a SELV transformer 105 assigned circuit part 105a that is behind the rectifier 104 on the primary side 106 is connected. "Behind" in this context means into one of the input connection 102 groundbreaking and to the output terminal 109 indicative direction. Connection B is located in one of the SELV transformers 105 assigned circuit part 105b on the secondary side 107 . Where is the Y capacitor 109 usually, as in 1 shown, with connection A to the GND connection of the rectifier 104 and connected with connector B to the output LED-.

This arrangement results in a leakage current from the mains connection 102 via connection A via the Y capacitor 109 via connection B via the output terminals LED-, LED + of the electronic ballast 101 to the connected LED module and thus via its capacitive coupling (parasitic capacitance) to earth or to the PE conductor (or the N conductor, which is usually connected to the PE conductor at the building feed or at the installation node ). The leakage current partially flows through the LEDs on the LED module and stimulates them to a glow effect ("glow effect"), ie to a weak glow or glow.

In standby mode of the electronic ballast 101 , ie if the ballast is connected to the mains but switched off via the interface or dimmed to very low light values, a high alternating voltage is generated. At 230V AC, for example, a peak-peak voltage of 150 to 330V arises from the output (LED + or LED-) of the ballast 101 to N potential or PE potential. This alternating voltage is a common mode alternating voltage on LED + and LED- compared to N potential or PE potential. This means that the alternating voltage at LED + and LED- is similarly high, so that the voltage between LED + and LED- for the glow effect is only one plays a subordinate role. The polarity of the mains plug does not play a role in the connection of the Y capacitor according to the prior art described above. The alternating voltage is therefore always similarly high regardless of the polarity, so that the glowing effect described occurs with glow-sensitive lights.

This glowing effect is disruptive for the application, since the glowing is also present when the electronic ballast is at a very small level via its communication interface (DALI-BUS, radio interface, wireless communication, 1-10V interface, etc.) Light level is dimmed or switched off. In this case, the LED module emits more light than it should because the light-emitting diodes on the LED module glow even though the ballast itself or the light is switched off via the interface. The annoying glow occurs primarily with glow-sensitive lights that tend to glow. Such lights are characterized in that they have a high capacitive coupling from the LED module to earth or to PE or N and / or are equipped with light-emitting diodes that visibly glow even at low capacitive leakage currents.

To avoid the undesired glow effect, an additional PE connection terminal with a suitable circuit of a Y capacitor has been used so far, the Y capacitor between the PE connection and the secondary circuit part e.g. connected to LED-. For this, however, a PE connection terminal must be available on the electronic ballast. However, this is disadvantageous, in particular because the user has to do additional cabling to the PE connection in order to connect the device, there is little or no space available for a PE terminal on the housing in the case of compact electronic ballasts, and because this is the case with SKII luminaires PE connection is usually not available anyway, since there is no PE connection from the outside to the luminaire.

As usual, the term PE conductor ("protective earth") denotes the protective conductor, i.e. an electrical conductor for safety, in particular for protection against electric shock, in the event of a fault in the electrical system. Accordingly, PE connection denotes the connection for the PE conductor or the PE conductor.

As usual, the term N conductor denotes the neutral conductor, i.e. a conductor that is connected to the neutral point in the low-voltage network and is intended to carry electricity.

The term L-conductor (line conductor) describes the outer conductor (phase), which is live in normal operation and is intended to carry current.

The grounding serves to divert electrical currents into the ground in order to establish a defined reference potential or equipotential bonding. The term earth accordingly describes the electrical potential of the conductive earth.

The term GND ("chassis ground") or ground refers to a conductive body to which the reference potential 0V is usually assigned.

Presentation of the invention

Based on the prior art described above, the invention is based on the object of providing an electronic operating device, in particular for light-emitting diodes, which can be easily connected or installed by the user, which can be used without restriction in protection class II (SKII) lights, and / or with which an undesirable glow effect can be prevented.

These objects are achieved by an operating device according to claim 1.

Accordingly, the operating device for converting an electrical input variable which can be applied to an input connection into a predeterminable electrical operating variable which can be provided at an output connection and has a predeterminable maximum value for the operation of an electronic operating unit comprises a rectifier for rectifying the electrical input variable, a device for galvanic decoupling between the input connection and the output connection with a primary side and a secondary side, and an interference suppression capacitor. The interference suppression capacitor is connected with its first connection A in the direction of the input connection in front of the rectifier with the input connection, and with its second connection B on the secondary side of the galvanic decoupling with a circuit to which the operating unit can be connected.

The input terminal of the operating device can be connected to a voltage source or a current source. The input variable is thus an alternating voltage or an alternating current.

The rectifier is connected to the input connection on the one hand and to the primary side of the galvanic isolating device on the other hand. The rectifier is preferably designed as a mains rectifier, particularly preferably as a bridge rectifier circuit known per se, with a first connection node for alternating voltage (AC) or a first AC connection node and a second AC connection node for converting AC voltage into DC voltage.

The output connection is connected to the secondary side of the galvanic isolating device and preferably has a first output terminal (LED-) and a second output terminal (LED +) for connecting a load.

The operating device is preferably set up to operate light-emitting diodes as the main load. The operating device is particularly preferably set up to operate lights of protection class II, in particular for LED modules. Accordingly, the operating device preferably does not include a PE terminal or an equipotential terminal for connection to a lamp housing. The operating device according to the invention is preferably a so-called LED driver.

The operating device preferably additionally has an input-side circuit which is upstream of the rectifier and with which functional features such as e.g. a line filter, an overvoltage protection device, etc., can be implemented in a known manner.

The operating device preferably comprises further functional elements, in particular power stages or converter stages, such as e.g. a PFC stage, flyback stage, LLC stage, LCC stage, buck stage, which are implemented in a known manner.

The interference suppression capacitor or safety capacitor is used to block and attenuate interference signals. This is preferably a Y capacitor according to IEC 60384-1.

Preferably the first terminal A of the interference suppression capacitor is connected to the input terminal in such a way, e.g. connected to the preferred input-side circuit that a connection point of the first connection A in the standby mode of the operating device has a low peak-peak alternating voltage to one of the two input terminals. The connection A is thus advantageously closely coupled to one of the two input terminals with regard to the alternating voltage difference (alternating potential distance). Preferably only a small alternating voltage occurs between connection A and the corresponding input terminal. It does not matter which of the two input terminals connection A is closely coupled to.

The close coupling is preferably designed such that the said peak-peak alternating voltage is in the range from 0V to 50V, in particular in the range from 0V to 20V.

The first connection A is preferably directly connected to one of the two AC connection nodes of the power rectifier. Or the first connection A is connected to a connection point on a supply line that leads from the respective input terminal to the corresponding AC connection node, the first connection A being particularly preferably connected to the input terminal via a mains fuse and a line filter choke connected in series.

The device for galvanic decoupling is preferably an isolating transformer, in particular an SELV transformer, which is integrated into the operating device in such a way that the operating device is isolating from the input connection to the output connection via the isolating transformer. The operating device is particularly preferably set up in such a way that a safety extra-low voltage can be provided at the output connection or that the output connection is an SELV output.

It is particularly advantageous in this embodiment that the voltage divider effect ensures a low alternating voltage. The reason for this is that due to the galvanic isolation of the interference suppression capacitor in the case of a connection according to the invention with a low alternating voltage between connection A and N potential, an otherwise high common mode alternating voltage between the output terminals and earth or PE or N potential is reduced to low Values can decrease. This happens because the interference suppression capacitor is at N potential and the coupling capacitance of the galvanic isolation (e.g. implemented by the SELV transformer) is small compared to the capacitance of the interference suppression capacitor. The interference suppression capacitor reduces the alternating voltage by means of a capacitive voltage divider effect.

A marking is preferably provided (e.g. on the ECG housing) which shows an operator which of the input terminals is connected to the interference suppression capacitor or which of the two mains input terminals must be connected to the N conductor in order to avoid the undesired glowing Avoid effect.

Through a targeted connection of the input terminal connected to the interference suppression capacitor to the N conductor of the power supply, due to the inventive design of the operating device in standby mode, a correspondingly small alternating voltage is generated (with 230V AC, for example, a peak-peak voltage of only 0 ... 50V) from the output connection (LED + or LED-) to N potential or PE potential. This alternating voltage is so low that there is no glow effect even with very glow-sensitive luminaires or only a very weak glow effect no longer occurs is disturbing. In other words, through the targeted connection of the interference suppression capacitor, an anti-glow function can be activated or used, with which an undesired glow effect can essentially be prevented in the stand-by mode. The advantage here is that in principle it does not matter which of the two input terminals is the selected terminal.

It is preferably explained in a corresponding description (in the data sheet or manual of the control gear) that the marked connection terminal should be connected to N in the event that the anti-glow function is to be used during the luminaire installation.

Incidentally, where exactly on the secondary side the connection B is connected does not play a significant role with regard to the glow effect, since this does not play a role in the level of the leakage currents that cause the glow effect in standby.

The operating device can preferably be controlled analog or digitally or via radio via a separate interface (i.e. not phase control or phase control), i.e. dimmable and switchable on and off.

The operating device can preferably be dimmed or switched off down to 0% light.

The design of the operating device according to the invention also enables the operating device to be connected to the mains connections L, N with any connection of the input terminals. The control gear allows the connection to L or N to be freely selected, i.e. to swap. Preferably a label is provided, e.g. a “∼” symbol on the mains terminals, and the lack of lettering N, L on the mains terminals, which indicates to an operator that the input terminals can be freely selected or connected to L or N at will.

This is particularly advantageous because the anti-glow feature is only required for lights that are sensitive to glow. In this respect, in the case of the operating device according to the invention, in the normal case, i.e. In the case of luminaires that are not sensitive to glow, the luminaire can be connected without considering the assignment of L and N, which considerably simplifies installation. The operating device according to the invention is therefore also suitable for portable (i.e. mobile) lights or for lights without a fixed connection (to N, L). With this type of luminaire, the control gear is designed in such a way that the polarity direction of the mains plug (which can be turned at random by the user) is irrelevant for the safety and operation of the luminaire, because both polarity directions are permitted without restriction.

The operating device according to the invention is therefore a universal device with the option of ( 1 ) a free assignment or ( 2 ) a specific connection when using the anti-glow function.

The interference suppression capacitor preferably has a capacity so that even when the interference suppression capacitor is connected to the L-network conductor (e.g. by accidentally turning the power plug on portable lights) the safety-relevant contact leakage currents via the interference suppression capacitor are below the for SELV devices allow limit for the leakage current if the SELV output is touched. At the same time, however, the interference suppression capacitor must be at least large enough to reduce the alternating voltage transmitted via the coupling capacitance of the galvanic separation (from the output terminal to earth or PE or N) to small values through the voltage divider effect described.

The interference suppression capacitor preferably has a capacitance of 100 pF to 10 nF, particularly preferably 300 pF to 4.7 nF.

It is preferably provided that the contact leakage current via the interference suppression capacitor at the output of the operating device is in the range <0.7 mA peak, preferably <2 mA peak, particularly preferably <2 mA effective to 3.5 mA effective.

In summary, the disruptive glow effect can be prevented with a corresponding connection with the operating device according to the invention. The LEDs can therefore be dimmed to a real 0%. Normally, however, when the glow effect function is not required, the operating device can in principle be freely connected. Furthermore, the operating device according to the invention can be designed without a PE terminal. This saves costs, enables a more compact housing and saves the user the otherwise necessary PE connection. The operating device according to the invention can thus be used without restriction for SKII lights.

Further advantages, features and details of the invention emerge from the claims, the following description of preferred embodiments and on the basis of the drawings.

Figure list

• 1 einen Schaltplan eines aus dem Stand der Technik bekannten elektronischen Vorschaltgeräts;
• 2 einen Schaltplan eines LED-Treibers gemäß der Erfindung mit angeschlossenem LED-Modul;
• 3 einen Schaltplan eines LED-Treibers gemäß einem bevorzugten Ausführungsbeispiel der Erfindung.

Show it:

• 1 a circuit diagram of an electronic ballast known from the prior art;
• 2 a circuit diagram of an LED driver according to the invention with a connected LED module;
• 3 a circuit diagram of an LED driver according to a preferred embodiment of the invention.

Preferred embodiment of the invention

2 shows an operating device according to the invention in a basic embodiment 1 for converting an electrical input variable into an electrical operating variable, in particular for LEDs as the main load, as well as an input to the operating device 1 connected LED module 15th .

The control gear 1 has an input port 2 , preferably an input circuit 3 , a power rectifier 4th , a device for galvanic isolation 5 with a primary side 6th and a secondary side 7th , and an output terminal 8th on. Furthermore, the operating device 1 an interference suppression capacitor, in particular a Y capacitor 9 , with a first port A and a second port B.

The input connector 2 serves to connect the electrical supply, in this case mains voltage (AC voltage), and has a first and second input terminal 2a and 2 B for connection to the voltage source (not shown).

The input circuit 3 includes functional features, such as a line filter, an overvoltage protection device, etc., which circuitry can be implemented in a known manner.

The power rectifier 4th is designed as a bridge rectifier circuit designed in the usual way, each with two pairs of diodes connected in parallel. This has a first and a second AC connection node 11a , 11b and a negative output terminal 12a and a positive output terminal 12b on. The first AC connection node 11a is about the circuit part 3 with the input terminal 2 B connected. The second AC connection node 11b is about the circuit part 3 with the input terminal 2a connected. The output signals are via the output connection nodes 12a , 12b with the primary side 6th galvanic isolation 5 connected.

The device for galvanic isolation 5 is designed as a SELV transformer, for example. This has one of its primary side 6th assigned circuit part or a primary circuit 5a as well as one of its secondary 7th assigned circuit part or a secondary circuit 5b on.

The output connector 8th is with the secondary side 7th connected and has a first output terminal 8a (or LED-) and a second output terminal 8b (or LED +) for connection to the LED module 15th on.

The Y capacitor 9 is according to the invention with its first connection A before the power rectifier 4th connected. “Before the mains rectifier” means that the first connection A is principally connected to the input side of the mains rectifier 4th connected is. The first connection A is preferably connected to the input circuit 3 connected or integrated. A connection point is designated as connection A, which is in the standby mode of the control gear 1 a low peak-peak alternating voltage to one of the two input terminals 2a , 2 B having. The first terminal A of the Y capacitor 9 is, for example, close to the first input terminal with regard to the alternating voltage difference (alternating potential distance) 2a coupled. The peak-peak alternating voltage is preferably in the range from 0 V to 20V.

The Y capacitor 9 is with its second connection B, as known from the prior art, on the secondary side 7th of the isolating transformer 5 with the circuit 5b galvanically connected to the LED module 15th connected is. Where exactly on the secondary side 7th the second connection B is connected does not play an essential role with regard to the glow effect, since this does not play an essential role for the level of the leakage currents that cause the undesired glow effect in standby.

3 shows a preferred embodiment of the operating device according to the invention 1 . The control gear 1 is basically like in 2 shown and accordingly has the features described above. According to the preferred embodiment 3 is the Y capacitor 9 with its first connection A via a mains fuse 13 and a line filter choke connected in series for this purpose 14th with the first input terminal 2a connected. In addition, the first connection A is connected to the second AC connection node 12b of the power rectifier 4th connected. The second connection B of the Y capacitor 9 is with the output connector 8th , especially with the first output terminal 8a or with the connection "LED-".

The exemplary embodiments described above represent special embodiments of the invention. The invention is not limited to these embodiments; rather, each individual partial feature of the / each exemplary embodiment is also detached from all other partial features described in connection therewith on its own and also in combination with any other features Embodiment for the subject matter of the invention of importance. The invention also includes all embodiments that have the same effect within the meaning of the invention. Furthermore, the invention has not yet been restricted to the combination of features defined in the independent claims, but can also be defined by any other combination of specific features of all of the individual features disclosed. This means that in principle each individual feature of the independent claim can be omitted or replaced by at least one individual feature disclosed elsewhere in the application.

List of reference symbols

1

Control gear

2

Input connector

2a

First input terminal

2 B

Second input terminal

3

Input circuit

4th

Power rectifier

5

Device for galvanic decoupling

5a

Primary circuit

5b

Secondary circuit

6

Primary side

7th

Secondary side

8th

Output connector

8a

First output terminal (LED-)

8b

Second output terminal (LED +)

9

Suppression capacitor

11a

First AC connection

11b

Second AC connection

12a

Negative output connection

12b

Positive output connection

13th

resistance

14th

Inductance

15th

LED module

101

State-of-the-art electronic ballast

102

Input connector

103

Input circuit

104

Bridge rectifier circuit

105

SELV transformer

105a

Primary circuit

105b

Secondary circuit

106

Primary side

107

Secondary side

108

Output connector

109

Suppression capacitor

Claims (15)

Electronic operating device (1) for converting an electrical input variable which can be applied to an input connection (2) into a predeterminable electrical operating variable which can be provided at an output connection (8) and has a predeterminable maximum value for the operation of an electronic operating unit (15), in particular a light-emitting diode as the main load , having a rectifier (4) for rectifying the input variable, a device for galvanic decoupling (5) between the input connection (2) and the output connection (8) with a primary side (6) and a secondary side (7), and an interference suppression capacitor (9) with a first connection (A) and a second connection (B), characterized in that the interference suppression capacitor (9) with its first connection (A), viewed in the direction of the input connection (2), is in front of the rectifier (4 ), is connected to the input connection (2) and with its second connection (B) on the secondary side (7) the galvanic n decoupling (5) is connected to a circuit (5b) to which the operating unit (15) can be connected. Electronic control gear (1) according to Claim 1 , characterized in that the effective coupling capacitance of the device for galvanic decoupling (5) is small compared to the capacitance of the interference suppression capacitor (9), so that the interference suppression capacitor (9) with a small AC voltage between connection (A) and N. -Potential an otherwise high common-mode alternating voltage between an output terminal (8a, 8b) of the output connection (8) and ground or PE potential or N potential can be reduced to small values, preferably to a peak-peak alternating voltage in Range 0V to 50V, in particular in the range 0V to 20V, can be reduced. Electronic operating device (1) according to one of the preceding claims, characterized in that the first connection (A) of the interference suppression capacitor (9) is closely coupled to exactly one input terminal (2a, 2b) of the input connection (2) with respect to the AC voltage. Electronic control gear (1) according to Claim 3 , characterized in that a small alternating voltage, preferably a peak-peak alternating voltage in the range 0V to 50V, in particular in the range 0V to 20V, occurs between the first connection (A) and exactly one of the two input terminals (2a, 2b) . Electronic operating device (1) according to one of the preceding claims, characterized in that the rectifier (4) is a mains rectifier, preferably a bridge rectifier circuit (4), with a first AC connection node (11a) and a second AC connection node (11b). Electronic control gear (1) according to Claim 5 with reference to Claim 3 or 4th , characterized in that the first connection (A) is directly connected to one of the two AC connection nodes (11a, 11b) of the mains rectifier (4), or to a connection point on a supply line that leads from the input terminal (2a, 2b), is preferably connected via a mains fuse (13) and / or one or more mains filter choke (s) (14) to the respective AC connection node (11a, 11b). Electronic operating device (1) according to one of the preceding claims, characterized in that the device for galvanic decoupling (5) is an isolating transformer (5), in particular an SELV transformer, the operating device (1) from the input connection (2) to is insulating to the output connection (8) via the isolating transformer (5), so that a safety extra-low voltage can be provided at the output connection (8) of the operating device (1). Electronic operating device (1) according to one of the preceding claims, characterized in that the operating device (1) can be controlled, in particular dimmed, and switched on and off via a separate interface. Electronic operating device (1) according to one of the preceding claims, characterized in that the operating device (1) can be dimmed down to 0% light or can be switched off. Electronic operating device (1) according to one of the preceding claims, characterized in that the operating device (1) is set up to operate a lamp of protection class II or to operate an operating unit (15), in particular an LED module, having at least one lamp of protection class II or is intended for installation in luminaires of protection class II. Electronic operating device (1) according to one of the preceding claims, characterized in that the operating device (1) can be used with any connection of the input terminals (2a, 2b) of the input connection (2) to the network connections (L, N), preferably with an identification is provided, which indicates to an operator that when connecting the input terminals (2a, 2b) the connection to L or N can be freely selected. Electronic operating device (1) according to one of the preceding claims, characterized in that there is an identification of the input terminals (2a, 2b) and / or a description in the technical documentation for the operating device (1) which describes which input terminal (2a, 2b) ) must be connected to the mains connection (N) so that the first connection (A) of the interference suppression capacitor (9) is closely connected to the N conductor of the power supply so that the device can be operated without annoying glowing. Electronic operating device (1) according to one of the preceding claims, characterized in that when the input terminal (2a, 2b), which is closely coupled to the first connection (A) of the interference suppression capacitor (9), is connected to the N conductor of the voltage supply, a glow- Effect in stand-by mode can be prevented. Electronic operating device (1) according to one of the preceding claims, characterized in that the interference suppression capacitor (9) has a capacitance of 100 pF to 10 nF, preferably of 300 pF to 4.7 nF. Electronic control gear (1) according to Claim 14 , characterized in that a contact leakage current via the interference suppression capacitor (9) at the output (8) of the operating device (1) in the range <0.7 mA peak, preferably <2 mA peak, particularly preferably <2 mA effective to 3.5 mA effective , lies.

Images