DE102010000203A1 - Electronic ballast for high pressure gas discharge lamp, has igniter attached to lamp circuit, and capacitor attached to power line and lamp circuit by bypassing input circuit, direct voltage intermediate circuit, inverter and igniter - Google Patents

Abstract

The ballast (1) has an inverter (5) attached to a direct voltage intermediate circuit (7) for supplying operating power to the inverter, and a lamp circuit (20) attached to the inverter for feeding the operating power for a gas discharge lamp (2) present in the lamp circuit. An igniter (6) is attached to the lamp circuit for supplying ignition pulses for igniting the gas discharge lamp, and a capacitor (31) is attached to a power line (3) and the lamp circuit by bypassing an input circuit (4), the intermediate circuit, the inverter and the igniter.

Description

The invention relates to a ballast for gas discharge lamps, in particular high-pressure gas discharge lamps, but also low-pressure gas discharge lamps, each with or without phosphor.

As is known, gas discharge lamps are operated because of their negative internal resistance to ballasts that set or at least limit the lamp current. Electronic ballasts use an inverter to provide the lamp current, which usually operates at a switching frequency significantly higher than the mains frequency. Existing steep switching edges of existing in the inverter electronic switches can lead to significant radio interference. It is desirable to reduce such interference. Various measures have already been proposed for this:
The DE 199 25 795 A1 discloses an arrangement with an electronic ballast, an ignitor and the associated gas discharge lamp, in particular for operation in motor vehicles. The document proposes to arrange a current-compensated choke between the unit formed by the ignitor and the lamp and the electronic ballast. This should in particular suppress electromagnetic interference. The interference from the ignition pulses is thus limited to the unit formed by the gas discharge lamp and the ignitor and is not delayed to the optionally longer leads leading to the electronic ballast.

This approach is not suitable for the provision of electronic ballasts, which are intended for general lighting purposes, because there ignition device and ballast must be integrated in a device that is optionally connected via longer, unshielded, lines with the gas discharge lamp. The laying of the cables and thus their effectiveness with regard to the emission of interference pulses largely eludes the sphere of influence of the ECG manufacturer. Nevertheless, this must ensure that when using its ECGs predetermined Störgrenzen be exceeded. This requirement is difficult to meet especially for the frequency range from 30 MHz to 300 MHz.

The above-mentioned use of suitable filters for interference suppression is also proposed by a whole series of other publications. For example, the DE 10 2007 012 413 A1 in a ballast for fluorescent lamps, to provide in the lamp circuit inductive Entstorbauelemente. These are intended to keep disturbances from the inverter away from the lamp circuit. Another inductive suppression device is to be connected in series with the electronic switch, which is part of a provided for feeding the DC intermediate circuit boost converter.

To avoid interference propagation in electrical circuits proposes the DE 199 51 114 A1 corresponding LC filters with π structure before. These π filters are in turn arranged between the ballast and an ignition device. They serve to prevent the propagation of ignition pulses as interference over longer lines.

Also from the DE 198 03 855 A1 is the suppression of a lamp circuit via LC filter known. A similar way follows the DE 196 45 752 A1 , At the lamp output of the ballast an LC filter is provided there to suppress the propagation of disturbances on the lamp leads. The LC filter must be designed with regard to the dielectric strength on the ignition pulses occurring and must not be too limited, so as not to degrade the ignition of the lamp there.

Furthermore, routine standard measures include the provision of electronic ballasts on the network side with filters. An example of this shows the DE 195 07 553 A1 , which is upstream of the input side Graetz bridge a line filter. The same is also the case DE 44 18 886 A1 to be found, which also proposes to connect a branch of the transformer-powered lamp circuit via capacitors with the positive operating voltage of the DC link.

The measures mentioned reach their limits, in particular, when very steep switching edges occur in the electronic ballast, if the radiation, in particular of very high frequencies, is to be severely limited and / or if the connected lamps have a high power requirement.

In practice, it is also known to limit disturbances emanating from a step-up converter by a capacitor, preferably in the range of one nanofarad (nF), which bridges the series connection of inductor and diode of the boost converter. As is known, this capacitor can also be connected in series with an ohmic resistor. In addition, a ceramic capacitor may be connected in parallel with the electrolytic capacitor of the boost converter in order to reduce the HF ripple of the applied DC voltage.

The measures known in the art for suppression often aim to attenuate the resulting interference only.

It is an object of the invention to provide an effective concept for suppression of electronic ballasts.

This object is achieved with the ballast according to claim 1:
The ballast according to the invention has an input circuit for converting the mains AC voltage into a DC voltage, from which an inverter is fed. A lamp circuit is connected to the inverter; which contains a gas discharge lamp. In addition, the gas discharge lamp is associated with an ignition device to supply the lamp at the start of operation with ignition pulses. According to the invention, at least one capacitor is provided for suppression of the circuit, which is connected by bridging the input circuit, the DC voltage intermediate circuit and the inverter and the ignition on the one hand to the power supply line and on the other hand to the lamp circuit. It can be seen that with this measure it is possible in particular to effectively suppress disturbances which are in the frequency range from 30 MHz to 300 MHz. The capacitor prevents the transmission of interference pulses of said frequency range from the inverter to the leading to the gas discharge lamp, often unshielded misplaced line of the lamp circuit and the emission of glitches from this line. The present invention is based essentially on the finding that instead of or in addition to the attenuation of the interference, the targeted derivation of the interference to defined interference current paths leads to improvements of the radio interference suppression.

Preferably, the capacitor has a capacitance between 100 picofarads (pF) and 5 nanofarads (nF). It creates a capacitive bridge between the lamp circuit and the power line. The power line here comprises at least two, in many cases three lines, of which at least one is connected to the capacitor in question. The power line can act, for example, a live conductor L, a zero-voltage-carrying conductor N and possibly a protective conductor E.

Preferably, the capacitor is disposed within the ballast. He thus picks up the voltage to be dissipated from the device end of the lamp circuit. In addition, it at least largely prevents the formation of an RF-radiation-capable Dipolantennenartigen structure with lamp circuit and power line and interposed ballast.

The said suppression measure is particularly suitable for use in ballasts for gas discharge lamps, which are ignited by means of voltage pulse, such as HID gas discharge lamps (high-pressure gas discharge lamps). On the one hand, the lamp ignition pulses to be taken here must not deteriorate and, on the other hand, they must suppress any interference voltages which may occur. Lamp ignition pulses have a high edge steepness and a high voltage. If the slew rate or peak voltage suffers, the ignition of the gas discharge lamp may be affected. The inventively proposed measures the capacitive bridging of the ballast by an effective between the lamp circuit and the power line capacitor allows Störspannungsableitung with very low capacity, so that the ignition of the gas discharge lamp is little or not affected.

In particular, it is proposed to leave the potential of a line of the lamp circuit largely unchanged upon ignition of the lamp and to conduct the ignition pulse via the respective other line to the gas discharge lamp. It is further considered advantageous to connect the suppression capacitor to that line of the lamp circuit whose potential remains largely unchanged during ignition. In this way, ignition pulses are passed unhindered to the gas discharge lamp. Nevertheless, there is a good interference suppression effect during operation of the gas discharge lamp.

In principle, the capacitor other components, such as ohmic resistors, non-linear resistors, inductors or the like, can be connected in series or in parallel. However, it is considered advantageous to form the connection between the lamp circuit and the power line exclusively via a capacitor without series or parallel connection of other components. However, should additional components be provided in series with the capacitor, their impedance for the frequency range from 30 MHz to 300 MHz should not be greater than the impedance of the capacitor provided for the suppression, that is, for example, not exceed the value of 1 to 10 Ω.

Further details of advantageous embodiments of the invention will become apparent from the drawings, the description or subclaims. Show it:

1 an inventive ballast, in a schematic representation;

2 a mains rectifier of the ballast after 1 ;

3 a boost converter of the ballast after 1 ;

4 an inverter of the ballast after 1 ;

5 and 6 Ignition devices of the ballast after 1 ;

7 an alternative embodiment of an inverter for the ballast after 1 and

8th - 25 different configurations of ballasts with suppression capacitor.

In 1 is a ballast 1 with a connected gas discharge lamp 2 illustrated by the ballast 1 is supplied with operating power. The gas discharge lamp 2 may be a high pressure gas discharge lamp or a low pressure gas discharge lamp with heated or unheated electrodes. In the preferred application, the gas discharge lamp 2 to a high pressure gas discharge lamp as it comes under the name HID increasingly in use. It has unheated electrodes and is ignited by high voltage pulses.

The ballast 1 is an input side connected to a power supply network, for example in the form of a public power grid. In that regard, the ballast 1 , in particular for stationary operation, provided for general lighting purposes, for example, room lighting, shop window lighting or the like. The ballast 1 is connected to a power line 3 connected. The power line 3 comprises at least one live conductor L, another, for example, zero voltage carrying conductor N and at least optionally a protective conductor E.

The ballast 1 includes several assemblies, including an input circuit 4 , an inverter 5 and an igniter 6 belong. The input circuit 4 serves to the low frequency mains voltage of for example 50 Hz or 60 Hz in a DC voltage of a DC intermediate circuit 7 implement. For this purpose, the input circuit 4 on the input side, for example, the in 2 illustrated rectifier 8th and the in 3 schematically illustrated boost converter 9 on. It should be noted that for the rectifier 8th and the boost converter 9 in the 2 and 3 in each case the basic circuits are specified. Other components, such as interference suppression capacitors on the diodes of the rectifier 8th and freewheeling diodes or buffer capacitors on the boost converter 9 according to 3 , of course, can be provided. The main elements of the boost converter 9 are the throttle 10 , an electronic controlled switch 11 , a diode 12 and a capacitor 13 , This can be designed as an electrolytic capacitor. Preferably, a not further illustrated ceramic capacitor is connected in parallel.

The electronic controlled switch 11 may be a MOSFET, an IGBT or the like. Its control electrode is connected to a not further illustrated drive circuit. The boost converter 9 generated at its output 14 a DC link voltage of preferably several 100 V to supply the DC link 7 ,

The control circuit of the switch 11 Controls the switching frequency and / or the duty cycle for switching the switch on and off 11 so that of the rectifier 8th absorbed current as close as possible to a sinusoidal shape.

At or in the input circuit 4 Suppressors may be provided, such as a line filter 15 , this in 8th as an assembly and part of the ballast 1 is provided. As a net filter, all known filter configurations, including Y capacitors, chokes, current-compensated chokes or the like can be used.

For further construction of the ballast 1 illustrates 4 a possible embodiment of the inverter 5 , This can be used as a full bridge inverter with four electronic switches 16 . 17 . 18 . 19 be educated. The electronic switches 16 to 19 may be MOSFETs, IGBTs or the like. The inverter 5 is to the DC voltage intermediate circuit 7 connected. The switches 16 to 19 Freewheeling diodes can be connected in parallel. The bridge diagonal branch coming out of the switches 16 to 19 formed bridge circuit containing the lamp circuit 20 with the gas discharge lamp 2 , In the lamp circuit, the ignition device 6 be provided.

The ignition device 6 comprises at least one pulse generating element 21 and preferably has predominantly inductive character. It can thus serve as a throttle for limiting the lamp current. Alternatively, in the lamp circuit 20 another current limiting reactor in series with the gas discharge lamp 2 be provided. In addition, the series connection of the igniter 6 and the gas discharge lamp 2 through a buffer capacitor 22 be bridged.

The switches 16 to 19 are connected to a control circuit which regulates their operation and the switching on and off of the switches 16 to 19 controls. For example, the switches 16 and 18 with a low operating frequency and the switches 17 and 19 operated at a high operating frequency. Alternatively, the switches 18 . 19 with a low and the switches 16 . 17 be operated at a high operating frequency. The low operating frequency is used to reverse the operating current in the gas discharge lamp 2 , The high operating frequency is used with the inductive component 21 the ignition device 6 or a separate coil, the operating current of the gas discharge lamp 2 to regulate.

The pulse generating element 21 can according to 5 be educated. It can be through a coil 23 be formed with the gas discharge lamp 2 connected in series and a tap 24 having. To this can be connected via a control circuit, a not further illustrated resonant capacitor to a high ignition voltage of preferably several 1000 V at the gas discharge lamp 2 to create. Alternatively, other circuit means may be provided to enter the tap 24 to feed appropriate ignition pulses.

An alternative of out 6 to be taken pulse generating element 21 ' contains a coil 23 with a transformer coupling coil 25 in turn, ignition pulses into the lamp circuit 20 can be fed.

The inverter 5 may alternatively be formed as a half-bridge inverter, such as 7 shows. The inverter illustrated there 5 ' again contains two electronic switches 16 . 17 , to the example of the ignition device 21 a line 26 of the lamp circle 20 connected. Another line 27 of the lamp circle 20 is connected to a mid-potential at a node 28 is tapped. The middle potential 28 is for example a capacitive voltage divider with two capacitors 29 . 30 and optionally not widely illustrated balancing resistors provided. Alternatives are possible. For example, instead of the node 28 Ground potential can be used when the boost converter 9 provides balanced positive and negative operating voltages.

In the present embodiment, the ignition device 21 between the electronic switches 16 . 17 and the gas discharge lamp 2 intended. With regard to the ignition pulses thus forms the line 26 the "hot" line during the pipe 27 the "cold" line forms, because it leads no ignition pulses. Alternatively, the ignition device 21 but also at the knot 28 be connected. In this case, the line becomes 27 to the hot wire while the wire 26 then represents the cold line with respect to the ignition pulses.

In the 2 to 7 illustrated assemblies can be according to the scheme of 1 arbitrarily combine with each other. In any case, the lamp circle 20 from the igniter 21 with ignition pulses and after igniting the lamp from the inverter 5 (respectively. 5 ' ) supplied with operating current.

1 is as well as those discussed below 8th to 25 show various measures for suppression of the ballast 1 always on a capacitive coupling of the lamp circle 20 with the power line 3 based.

How out 1 can be seen, is the lamp circuit 20 via one of the suppression capacitor 31 with the power line 3 connected. The capacitor 31 bridges the input circuit 4 , the inverter 5 and also the ignition device 6 , The capacitor 31 is with a first connection to one of the lines 26 . 27 of the lamp circle 20 and with its other connection to a conductor of the power line 3 connected. Preferably, the capacitor 31 thereby to the cold line 27 and to the conductor L, N or E of the power line 3 connected.

The capacitor 31 is preferably in the immediate vicinity of the connection of the power line 3 arranged. Preferably, the connections of the lines 26 . 27 and the power line 3 on the housing 16 arranged adjacent to each other. In this case, the capacitor can 31 connect the adjacent lines directly to each other. In this and in all other embodiments, the capacitor is preferably (but not necessarily) designed as an SMD component.

Irrespective of the internal structure of the ballast 1 can the capacitor 31 in the most different ways between the lamp circle 20 and the power line 3 be switched. 8th illustrates a variant similar 1 in which the capacitor 31 between the conductor L and the line 27 is arranged. At the exit of the lamp circle 20 is between the inverter 5 and the capacitor 31 a noise filter 32 arranged. 9 illustrates a corresponding variant, which differs from the ballast 1 to 8th only different in that the capacitor 31 is connected to the zero voltage carrying conductor N. Otherwise, the previous description applies accordingly.

10 illustrates a further variant, which differs from the embodiments 8th and 9 only different in that the capacitor 31 against the protective conductor E of the power line 3 is switched. Again, the previous description otherwise applies accordingly.

While the capacitor 31 in the embodiments according to 8th to 10 between the noise filter 32 and the lamp 2 connected, the show 11 to 16 Embodiments in which the capacitor 31 between a noise filter 33 and the inverter 5 is arranged. With regard to the anti-interference filter 33 all apply to the noise filter 32 made statements accordingly. The capacitor 31 like doing that 11 to 13 show, with one end to the hot line 26 be connected. With his other end he can go to the ladder 11 ( 11 ) the conductor N ( 12 ) or to the conductor E ( 13 ).

As the 14 to 16 show, the capacitor can 31 also to the cold pipe 27 again between the noise filter 33 and the inverter 5 be connected. The other end of the capacitor 31 can contact the leader 11 ( 14 ), the conductor N ( 15 ) or the conductor E ( 16 ).

As the 17 to 22 show, the lamp circle can 20 also two noise filters each 32 . 33 contained in series. The capacitor 31 Can it to the hot line 26 ( 17 to 19 ) or to the cold line 27 ( 20 to 22 ). The other end of the capacitor 31 can with the conductor L ( 17 ), with the conductor N ( 18 ) or the conductor E ( 19 ). The same applies to the 20 to 22 , where the capacitor 31 there with the cold pipe 27 connected is.

The 23 to 25 exemplify different configurations for the noise filter 32 and / or the noise filter 33 , The filter configurations described below can be used for both suppression filters 32 . 33 Find application.

For example, the noise filter 32 or 33 in the form of a single coil 34 be trained in the line 26 or alternatively in the line 27 is arranged. The capacitor 31 can, as shown, be connected to the conductor E, but alternatively also to the conductor N or the conductor L. The capacitor 31 can from the perspective of the gas discharge lamp 2 in front of or behind the coil 34 with the line 26 or alternatively with the line 27 be connected.

As 22 shows, as a filter 32 and or 33 also a current-compensated choke 35 be provided. This is wrapped up so that its two coils 36 . 37 those from the streams of the pipes 26 . 27 are flowing through, generate opposing magnetic fluxes, so that the magnetic fields of the two coils 35 . 36 in the core of the throttle 37 cancel each other out. The current-compensated choke 35 serves the common mode rejection of interfering signals. The capacitor 31 can turn to the hot line 26 or alternatively to the cold line 27 be connected. It can be connected at its other end to one of the lines L, N or E.

For the noise filter 32 and or 33 More costly filter concepts are also suitable. For example, the lines 26 . 27 before and / or behind the throttle 35 by interference suppression capacitors 38 and or 39 be interconnected. The capacitor 31 can turn with a connection with the cold line 27 or the hot line 26 be connected. The other end may alternatively be connected to one of the lines L, N or E.

With the presented embodiments are variants of a suppression concept for a ballast 1 for a gas discharge lamp 2 which a capacitor causing the filtering has been presented 31 is common, the lamp circle 20 with the power line 3 combines. This concept allows for the efficient dissipation of spurious signals so that they do not exceed the tolerable levels of the lines 26 . 27 of the lamp circle 20 be radiated.

LIST OF REFERENCE NUMBERS

1

ballast

2

Gas discharge lamp

L

ladder

N

Zero voltage conductor

e

protective conductor

3

power line

4

Input switching circuit

5

Inverters, 5 '

6

detonator

7

Dc link

8th

rectifier

9

Boost converter

10

throttle

11

switch

12

diode

13

buffer capacitor

14

output

15

Line filter

16

switch

17

switch

18

switch

19

switch

20

lamp circuit

21

Pulse generating element

22

buffer capacitor

23

Kitchen sink, 23 '

24

tap

25

Kitchen sink

26

hot line

27

cold pipe

28

node

29

first capacitor of a capacitive voltage divider

30

second capacitor of the capacitive voltage divider

31

Capacitor for filtering

32

Noise Filter

33

Noise Filter

34

Kitchen sink

35

current-compensated choke

36

Winding in the pipe 26

37

Winding in the pipe 27

38

suppression capacitor

39

suppression capacitor

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19925795 A1 [0002]
• DE 102007012413 A1 [0004]
• DE 19951114 A1 [0005]
• DE 19803855 A1 [0006]
• DE 19645752 A1 [0006]
• DE 19507553 A1 [0007]
• DE 4418886 A1 [0007]

Claims (12)

Ballast ( 1 ) for gas discharge lamps ( 2 ), with an input circuit ( 4 ), the input side of power lines ( 3 ) and the output side to a DC voltage intermediate circuit ( 7 ) and is set up to convert an AC line voltage into a DC link voltage, with an inverter ( 5 ) connected to the DC link voltage ( 7 ), in order to be supplied by the latter with operating power, with a lamp circuit ( 20 ) connected to the inverter ( 5 ) is connected and from this with operating power for at least one in the lamp circuit ( 20 ) existing gas discharge lamp ( 2 ), with an ignition device ( 6 ) connected to the lamp circle ( 20 ) is connected to this for igniting the gas discharge lamp ( 2 ) with ignition pulses, with at least one capacitor ( 31 ), bridging the input circuit ( 4 ), the DC intermediate circuit ( 7 ), the inverter ( 5 ) and the ignition device ( 6 ) on the one hand to the power line ( 3 ) and on the other hand to the lamp circle ( 20 ) connected. Ballast according to claim 1, characterized in that the capacitor ( 31 ) has a capacity between 100 pF and 5 nF. Ballast according to claim 1, characterized in that the inverter ( 5 ) a bridge circuit having at least two electronic switches ( 16 . 17 ), the lamp circuit ( 20 ) is arranged in the diagonal branch of the bridge circuit. Ballast according to claim 1, characterized in that the ignition device ( 6 ) an ignition transformer ( 21 . 21 ' ), with a winding ( 23 ) in the lamp circle ( 20 ) in series with the gas discharge lamp ( 2 ) is arranged. Ballast according to claim 4, characterized in that parallel to the series circuit of the ignition transformer ( 21 . 21 ' ) and the gas discharge lamp ( 2 ) a buffer capacitor ( 22 ) is provided. Ballast according to claim 1, characterized in that the lamp circuit ( 20 ) two to the gas charge lamp ( 2 ) leading lamp lines ( 26 . 27 ), wherein one of the lamp lines ( 26 ) to the ignition device ( 6 ) and wherein the capacitor ( 31 ) to the other of the two lamp leads ( 26 . 27 ) not connected to the ignition device ( 6 ) leads. Ballast according to claim 1, characterized in that between the capacitor ( 31 ) and the inverter ( 5 ) a filter ( 32 ) is provided. Ballast according to claim 1, characterized in that between the gas discharge lamp ( 2 ) and the capacitor ( 31 ) a filter ( 33 ) is provided. Ballast according to claim 7 or 8, characterized in that the filter ( 32 . 33 ) a throttle ( 34 . 35 ) contains. Ballast according to claim 7 or 8, characterized in that the capacitor ( 31 ) is connected to a mains voltage leading line (L, N). Ballast according to claim 7 or 8, characterized in that the capacitor ( 31 ) is connected to the protective conductor (E). Ballast according to one of the preceding claims, characterized in that the capacitor ( 31 ) is arranged on the printed circuit board in the immediate vicinity of the terminals.

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