Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
  • H05B41/14—Circuit arrangements
  • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
  • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
  • H05B41/295—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps
  • H05B41/298—Arrangements for protecting lamps or circuits against abnormal operating conditions
  • H05B41/2981—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the circuit against abnormal operating conditions
  • H05B41/2985—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the circuit against abnormal operating conditions against abnormal lamp operating conditions

Definitions

• the invention relates to a ballast circuit, specifically a ballast circuit for running multiple fluorescent lamps.
• ballast topologies with multiple parallel load circuits for running plural fluorescent lamps the element tolerances of the resonance circuit generally cause unbalanced resonance characteristics in the circuit. Also different load situations (e.g. a broken lamp) will cause severe imbalance in the ballast topologies. This results overload conditions, which are critical for conventional halfbridge switches and thus demand for a solution of high rate components.
• the object of the invention is to provide an arrangement of ballast topologies for running multiple fluorescent lamps, in which no unbalance occurs even one of the fluorescent lamps is broken.
• sequence start capacitors for multiple lamps operation is well known in the ail. However taking advantage of those sequence start capacitors to solve the unbalance caused by asymmetric LC resonance in
• the multiple fluorescent lamps are connected in series and divided into groups of every two lamps- comprising: LC resonance circuits for igniting respective groups of the two fluorescent lamps, each of the resonance circuits is formed with a resonance capacitor and a coil and connected between the corresponding group of the lamps and ground; a DC block capacitor for conducting the electric current from the resonance capacitor to ground, wherein the ballast circuit further comprising sequence start capacitors (C3, C4) that are connected through the filaments between both LC resonance circuits when there are two fluorescent lamps, or connected from each LC resonance circuit to the connection point of the other group of lamps when there are more than two fluorescent lamps, for limiting the electric voltage generated on the respective resonance capacitor when one of the lamps is broken in a corresponding group of
• the sequence start capacitors in parallel between LC resonance circuits are connected to other LC resonance circuit in a multiple lamp operation.
• the problem of asymmetric LC resonance in parallel circuit is solved and the multiple lamp operation is implemented.
• FIG. 1 shows an embodiment of the invention, in which a ballast circuit runs two lamps;
• Fig. 2 shows another embodiment of the invention, in which a ballast circuit runs four lamps.
• Fig. 1 shows an embodiment of the invention, in which a ballast circuit runs two lamps.
• the ballast circuit is labeled by 2*L3 ⁇ W circuit.
• Lamp 1 and Lamp 2 indicate two lamps connected in series.
• Capacitors Cl and C2 arc ignition capacitors.
• C4 are sequence start capacitors, and a capacitor CS is a DC block capacitor.
• Coils L 1 and L2 have a function as a lamp choke respectively.
• the capacitors C3 and C4 are connected through the filaments between both LC resonance circuits. When a lamp Lamp 1, is broken, the coil Ll and capacitor Cl will generate a very high ignition voltage due to an asymmetric circuit load.
• the sequence start capacitors C3 and C4 some of the current from the capacitor Cl is bypassed to the capacitor C5, the voltage of the capacitor Cl thus is decreased and limited, and the asymmetric resonance in the circuit is eliminated
• FIg. 2 shows another embodiment of the invention, in which the ballast circuit runs four lamps.
• the ballast circuit is labeled by 4*L18W circuit.
• Lamp 1, Lamp 2, Lamp 3 and Lamp 4 indicate four lamps connected in series.
• Capacitors Cl and C2 in respective LC resonance circuits are ignition capacitors.
• Capacitors C3 and C4 are
• a capacitor CS is a DC block capacitor.
• Colls Ll and L2 in respective LC resonance circuits have a function as a lamp choke respectively.
• the four lamps are divided into two groups, one group comprises lamps Lamp 1 and Lamp 2, the other comprises lamps Lamp 3 and Lamp 4.
• the four lamps are connected in series, while the respective LC resonance circuits of each group are connected in parallel.
• the connection of the capacitors C3 and C4 is in a way extended from that shown in Fig. 1.
• the capacitors C3 and C4 are connected to every other lamps, i.e. the capacitor C3 is connected across lamps Lamp 2 and
• Lamp 4 and capacitor C4 is connected across lamps Lamp 1 and Lamp 3.
• the sequence start capacitors C3 and C4 are connected from each LC resonance circuit to the series connection point of the other group of lamps.
• the sequence start capacitors C3 and C4 are connected from each LC resonance circuit to the series connection point of the other group of lamps.
• the ballast topologies further comprise two switches U l and U2 for connecting the resonance circuits to a power supply.
• the capacitance values range of the sequence start capacitors C3 and C4 is from 14OpF to 4.9nF
• the capacitance values range of the resonance capacitors C l and C2 in the LC resonance circuits can be selected from 90OpF to 16nF
• the induction values range of the coils Ll and L2 in the resonance circuits is from 950 ⁇ H to 8.4mH.
• the intended capacitance values range of the sequence start capacitors C3 and C4 is from 2OpF to 90OpF
• the intended capacitance values range of the resonance capacitors C l and C2 in the LC resonance circuits can be selected from 20OpF to B. ⁇ nF
• the intended induction values range of the coils L l and L2 in the resonance circuits is from l 90 ⁇ H to 1.6mH.
• the number of the lamps in the topologies is not limited to the above-mentioned embodiments.
• the principle of the invention can be used for any other type of fluorescent lamps and also can be extended to any number of parallel resonance circuits.
• a person skilled in the art could change or modify the circuit arrangement without exceeding the essence of the invention.
• the changes and modifications belong to the range of the invention as set forth in claims.

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• Circuit Arrangements For Discharge Lamps (AREA)
• Discharge Heating (AREA)

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Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

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Cited By (1)

Citations (3)

• 2007
  • 2007-10-30 CN CN2007101657190A patent/CN101426322B/zh not_active Expired - Fee Related
• 2008
  • 2008-10-09 EP EP08845841A patent/EP2206414B1/de not_active Not-in-force
  • 2008-10-09 PL PL08845841T patent/PL2206414T3/pl unknown
  • 2008-10-09 WO PCT/EP2008/063565 patent/WO2009056431A2/en active Application Filing
  • 2008-10-09 AT AT08845841T patent/ATE538625T1/de active

Patent Citations (3)

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