WO2005006820A1 - Ballast electronique - Google Patents

Ballast electronique Download PDF

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Publication number
WO2005006820A1
WO2005006820A1 PCT/US2004/018884 US2004018884W WO2005006820A1 WO 2005006820 A1 WO2005006820 A1 WO 2005006820A1 US 2004018884 W US2004018884 W US 2004018884W WO 2005006820 A1 WO2005006820 A1 WO 2005006820A1
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WO
WIPO (PCT)
Prior art keywords
lamp
circuit
voltage
inverter
fault
Prior art date
Application number
PCT/US2004/018884
Other languages
English (en)
Inventor
Bijoy Kumar Dash
Original Assignee
Ictel, Llc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ictel, Llc filed Critical Ictel, Llc
Publication of WO2005006820A1 publication Critical patent/WO2005006820A1/fr

Links

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
    • H05B41/2988—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the lamp against abnormal operating conditions

Definitions

  • the present invention relates generally to a high power electronic ballast for gas discharge lamps driven by a series resonant inverter and having a soft start clamp circuit and a fault detection circuit.
  • Various protection circuits are known to avoid hazardous high voltages and damaging currents.
  • One type of current protection uses an electro-mechanical thermal switch to remove the bias voltage of the inverter transistor. In many known gas discharge lamp ballasts, a high voltage is suddenly applied to the fluorescent lamp. This is responsible for shortening the service life of the lamps.
  • a breakdown of the inverter circuit occurs due to the variation of the fluorescent lamp impedance during start-up and continuous operation.
  • Initial start-up current is extremely high because of the very low impedance of the series resonant circuit before ignition. This condition occurs because of an open circuit in the resonant network.
  • a loose connection, a deactivated lamp, or an open lamp cause similar situations wherein abnormal current is drawn from the inverter which may damage the inverter transistors.
  • Electronic ballasts are currently used in high power gas discharge lamps for street illumination, plant growth, sun tanning beds, advertising signs etc. These ballasts suffer from problems of poor reliability, lack of protection from excessively high voltages, lack of fault indication, ultra-violet leakage radiation and low efficiency.
  • the present invention generally provides a high power electronic ballast for use with gas discharge lamps.
  • the ballast includes a series resonant inverter, a soft start clamp circuit and a fault detection circuit.
  • FIG. 5 is a perspective view of an ozone generator according to the principles of the present invention.
  • an electronic ballast circuit according to one embodiment of the invention includes an AC input 10 which feeds AC power to a line filter 12 which filters out high frequencies for suppression of radio frequency interference.
  • the output of line filter 12 is coupled to a bridge rectifier 14, which converts the AC input to a DC voltage.
  • the rectified DC voltage is supplied to input terminals of a high frequency, series resonant mode inverter 16 as is further described below, the output of which is provided to a lamp load 18 which, for example, is a fluorescent lamp or any of a variety of other gas discharge lamps.
  • a start circuit 20 is also connected to the DC supply at the output of rectifier 14 to provide starting pulses to series resonant inverter 16 during starting of the ballast circuit as is further described below.
  • the lamp ignition voltage is limited by a soft start clamp 22 which is coupled to inverter 16.
  • Soft start clamp 22 insures that the inverter output voltage does not exceed a predetermined level, thereby inhibiting damage to lamp 18 and prolonging the lamp life.
  • the ballast circuit may further include a high frequency feedback from inverter 16 to a power factor improving circuit 23 which has an output to soft start clamp 22.
  • the output of rectifier 14 is also coupled to a low voltage power supply 24 which supplies operating voltage to the control portions of the circuit as is fruther described below.
  • An output of soft start circuit 22 is used to detect faults in the operation of lamp 18 and is connected to an input of an overload comparator 26, which compares the level from soft start circuit 22 to a reference level generated by a reference generator 28 to determine if a fault has occurred in lamp 18.
  • the overload comparator 26 emits a fault signal to an indicator 30 to indicate the presence of a fault.
  • the fault signal is also transmitted to inverter 16 which is disabled until the fault is corrected and manually acknowledged.
  • a further feature of the present invention is that ultraviolet (UN) emissions from lamp 18 may be sensed by an ultraviolet sensor 32, the output of which is compared by a UN comparator 34 to a reference level generated by the reference generator 28.
  • UN comparator 34 If the ultraviolet leakage radiation emissions from lamp 18 are above a predetermined level, UN comparator 34 emits a high UN signal which is transmitted to an indicator 36 and inverter 16. Upon receipt of this high UN signal, inverter 16 is disabled so that power is no longer supplied to lamp 18. In an alternative embodiment, an ionizer 37 is added at the output of the inverter 16 to provide ionization of the gas in the vicinity of lamp 18. A further option and depending upon the type of lamp 18 used, a filament energizer 38 and indicator 39 may be provided as is further described below. In Figure 2 is shown the detailed circuit which performs the functions discussed above and shown in Figure 1.
  • Power input leads, or terminals, L (line), ⁇ (neutral), and E (earth or ground) are provided for the connection of an AC power supply, such as 220 volts, 60 hertz AC power.
  • an AC power supply such as 220 volts, 60 hertz AC power.
  • a fuse 40 which is in a preferred embodiment a 3 Ampere fuse, is connected in series with the AC line terminal L to protect the circuit from component breakdown.
  • a thermal switch 42 is connected in series with the AC input terminal ⁇ to protect components of the circuit, such as inverter transistors (described below) from thermal runaway or from any heat build up in the components.
  • a surge absorber 44 is connected across the AC input terminals L and N after fuse 40 and thermal switch 42 to protect the circuit from surges, spikes, or transients at the mains input terminals L and N.
  • Capacitors 46, 48, 50 and 52 and inductors 54 and 56 form a high frequency line filter for radio interference suppression so that the ballast circuit operates in conformity with VDE 0875, Part 2.
  • Diodes 58, 60, 62 and 64 form bridge rectifier 14 to convert power from the AC source into DC power.
  • Bridge rectifier 14 has output terminals D and G which are the DC power input terminals of high frequency inverter 16.
  • Inverter 16 is constructed to form a series resonant mode inverter, in which two switching elements 66 and 68, also termed inverter transistors, are switched alternately to a conducting state by positive feedback.
  • Inverter 16 operates, in a preferred embodiment, at a frequency range of 20-30 KHz.
  • Switching elements 66 and 68 are FETs which, in a preferred embodiment are isolated FETs, Model No. MTA 4N60.
  • the positive feedback is produced by a transformer 70 that is preferably a toroidal transformer having three windings 70a, 70b and 70c.
  • the resonant frequency of inverter 16 is determined by an inductor 72, a capacitor 74 and switching delay of transformer 70.
  • Inductor 72 is a tapped inductor which is used in the soft start function, the fault determination and in adapting the circuit for single pin or bi-pin lamps, as will be described herein.
  • Capacitor 74 has a high frequency sine wave voltage there across during operation of inverter 16 in the resonant mode.
  • a gas discharge lamp load 76 (referred to as lamp 18 in Figure 1), which in this instance is a single pin fluorescent lamp, is connected across capacitor 74 at terminals A and B. Lamp current to lamp load 76 is limited by inductor 72 at the resonating frequency.
  • Soft start element 22 avoids the drastic increases in the voltage across the resonating capacitor before ignition of lamp 76 which occurs in the known ballasts circuits because of the reduced loading by the lamp.
  • This high voltage in the known devices causes very heavy current flow through the resonating network, and even though this characteristic is useful to ignite the gas discharge lamps, it may be harmful since excessive high voltage damages or deactivates the gas discharge lamps quickly.
  • the network consisting of resistors 86 and 88, a capacitor 90 and a DIAC 92 provides starting pulses for FET 68 and, thus, make up starting circuit 20 of Figure 1.
  • the power factor of the ballast circuit is improved by high frequency positive feedback from the inverter 16. For example, in one embodiment the power factor is improved by up to a factor of 0.9.
  • capacitor 94 is the main filter capacitor, and always remains charged by high frequency available from the tap of inductor 72 via diode 78.
  • Capacitor 94 is, in a preferred embodiment, an electrolytic 100/ F capacitor and is the power factor improving block 23 of Figure 1.
  • Capacitors 96 and 98 are of very low capacitance value, i.e. l ⁇ F.
  • Low voltage power supply 24 of Figure 1 is formed in the circuit of Figure 2 by a voltage dropping resistor 100, capacitors 102 and 104 and a small, three pin voltage regulator 106 to provide low voltage DC power for electronic control circuit portions.
  • a zener diode 108 is only used for input over voltage protection of a regulator 106, while the capacitor 102 provides filtering.
  • Regulator 106 of a preferred embodiment is a 12 volt regulator, model 78L12.
  • Reference voltages for both comparators 26 and 34 shown in Figure 1 are derived from the voltage divider formed of resistors 110 and 112, the intermediate connection node being connected to the input of a buffer 114, thereby forming the reference generator 28 of Figure 1.
  • the buffered reference voltage is fed to a non- inverting input of a comparator 116 of overload comparator circuit 26.
  • the reference voltage is approximately half of the operating voltage established by low voltage supply 24.
  • the gas discharge lamp is connected across the resonating capacitor via both filaments.
  • temporary illumination of LED 122 indicates a fault in the lamp system.
  • the fault indication by illuminated LED 128 is continuously provided by triggering an SCR 124 via a diode 126 and a resistor 128 until the mains supply is available.
  • SCR 124 turns off the FET switching element 68 by removing its bias voltage via a diode 129, SCR 124 also removes the inverter starting pulses via a diode 130. Accordingly, inverter 16 is disabled immediately and until the fault is manually acknowledged.
  • the ballast is protected, in accordance with NDE 0712, part 201, requirements, from deactivated lamps, open lamps, broken lamps and loose connection of the lamp terminals through the high voltage clamp with delayed overload sensing. Power is cut-off upon the occurrence of any of the following events: (1) excessive power consumption due to aging, (2) electrodes being deactivated on two sides, (3) gas loss, electrode burn-up, or rectifier failure due to the electrodes being deactivated on two sides, or (4) gas loss, electrode burn-up, or rectifier failure due to the electrodes being deactivated on one side.
  • NDE 0712, part 201 provides that the starting voltage should not exceed an upper limit value of three kilo volts, which the present circuit meets.
  • Ultra-violet tanning beds are widely used in body tanning applications, particularly in cold countries. Beauticians or attendants, who are always in proximity of the ultra-violet rays emitted from the lamps, may be exposed to some radiation through leakage. This exposure to ultra-violet rays is undesireable. Therefore, according to a development of the present invention, ultra-violet leakage radiation from the lamp is detected. An ultra-violet radiation leakage sensor stops ballast operation, by providing annunciation after ultra-violet radiation leakage exceeds the preset level.
  • ultra-violet sensor 132 ( Figure 2), which is, in a preferred embodiment, a Gl 115 photodiode.
  • the detected amount of radiation is compared by the comparator 134 to a preset level set by resistors 136, 138 and resistor 140, which is a pre-set carbon resistor, in a voltage divider network.
  • the voltage for the divider network is obtained from reference voltage generator 28, as described above. If the ultraviolet radiation as detected by the sensor 132 is above the preset level, then comparator 134 output changes to a high level and an LED 142 indicates that a high level of ultra-violet radiation has been detected.
  • ballast inverter 16 is permanently disabled by triggering SCR 124 via a diode 144 and resistor 128. Just as when a fault is detected, SCR 124 turns off FET switching element 68 by removing its bias voltage through diode 129 and removing its starting pulses by diode 130.
  • Two modes of operation are possible with the present ballast circuit, namely single pin instant start operation, as shown in Figure 2, or bi-pin preheat rapid start lamp operation, as shown in Figure 3. Bi-pin rapid start lamps with filament heaters or single pin instant start lamps without heaters can operate without any damage to the present ballast.
  • existing electronic ballasts are not recommended for single pin instant start lamp operation because the ballast lack a protection circuit.
  • FIG. 3 shows a circuit for multi-lamp operation with a common protection circuit and the same inverter as shown in Figure 2.
  • the circuit of Figure 3 also includes initial filament heating and selective lamp switching for intensity control.
  • the circuit of Figure 3 is connected to the circuit of Figure 2 at the connection locations A, C, H and I.
  • the protection circuit as described above is the same common protection circuit that is used in the multi-lamp operation by the circuit arrangement of diodes 150, 152, 154, 156, 158, 160, 162 and 164 connecting I and H terminals of Figure 3 to I and H terminals of Figure 2.
  • any one or all lamps 168, 170, 172 and 174 develop an excessive voltage across the common resistor 82 and turns off inverter 16, as described above in connection with Figure 2, to protect from heavy current damage.
  • the lamp is connected across the resonating capacitor via both filaments. Current always flows through both filaments and unnecessarily consumes electrical energy after ignition. Filament energization is not desirable after ignition because it quickly deactivates the lamp.
  • the present circuit arrangement by contrast, only energizes lamp filaments 168 F i, and 168 K before ignition.
  • a silicon bi-directional switch 176 which is a SIDAC, is connected in series with a current limiting resistor 178.
  • the firing voltage of SIDAC 176 is selected so that it fires only when the voltage across corresponding lamp 168 is higher than the normal lamp operating voltage.
  • lamp ignition takes place.
  • the voltage across lamp 168 drops down and disables the flow of current to the filament circuit due to the high resistance path offered by SIDAC 176. This saves energy, prevents quick deactivation of the lamps and increases life of the lamps.
  • An LED 180 and a series resistor 182 are connected across filament current limiting resistor 178. Every time the mains power supply is switched on, LED 180 indicates that the filament circuit is intact and denotes the duration of filament heating.
  • a fused or open filament circuit is monitored by no indication from LED 180.
  • Each of the remaining lamps 170, 172 and 174 in Figure 3 has a similar circuit, which each correspond to indicator 39 of Figure 1.
  • I-n many known ballast circuits for high power lamp ballast applications such as in tanning beds, required exposure of ultra-violet is controllable only by means of time duration because intensity control of all these high power lamps is very costly.
  • the present invention allows such light sources to be fitted with a common ultraviolet diffuser for multiple lamps such as indicated in Figure 3. Selective switching of lamps can then be made by series switches 184, 186, 188 and 190 to control the intensity in evenly distributed order, thereby achieving dimming of the lamps.
  • the multi-lamp circuit of Figure 3 also includes tapped inductors 192, 194,
  • Figure 4 shows circuit for ozone and negative ion generation by multiplying the high frequency voltage available from inverter 16 as indicated by ionizer block 37 of Figure 1.
  • high voltage DC is used to generate ozone and/or negative ions.
  • the ozone layer acts as a barrier to inhibit passage of the ultra-violet rays.
  • Terminals A, B and E of the circuit of Figure 4 are connected to the corresponding terminals A, B and E shown in Figure 2, where terminals A and B carry the high frequency AC source and terminal E is the earth or ground terminal.
  • High frequency AC voltage is coupled to the multiplier circuit by a step-up transformer 200 having a primary to secondary ratio of 1:2.
  • FIG. 238 and 240 form a multiplier circuit.
  • Pointed needles 242 are connected to, for example, a -4KN current limited high voltage terminal J at the output of the multiplier circuit, and are placed near a grounding sheet for air ionization.
  • a very high value resistor 244, i.e., 200 Mohm, is connected between the multiplier and the terminal J to protect against shock hazards.
  • Figure 5 shows an example of mechanical components of an ozone generator or air ionization apparatus.
  • An aluminum base plate or sheet 250 is provided with a series of openings 252. Base plate 250 is connected to ground.
  • a printed circuit board 254 with spacers in which are mounted a plurality of pins 256 (same as needles 242 of Figure 4) corresponding in number and arrangement to openings 252.
  • the high voltage applied to pins 256 by the multiplier circuit of Figure 4 causes ionization of the gases between pins 256 and base plate 250.
  • the ionization arrangement is located in or near the lamp fixture to generate a cloud of ozone or ionized gas about the lamp fixture to inhibit pasage of the ultraviolet radiation.

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  • Circuit Arrangements For Discharge Lamps (AREA)

Abstract

L'invention concerne un circuit de ballast de lampes, destiné à des lampes à décharge gazeuse haute puissance, comprenant : un circuit résonnant en série servant à commander la lampe, un circuit d'amorçage progressif servant à empêcher l'application d'une tension élevée à la lampe durant l'amorçage, et un circuit de détection de défaillance ou de surcharge. Selon l'invention, un indicateur de surcharge est mis en marche et le circuit onduleur est désactivé lorsqu'une condition de défaillance est détectée. Lorsque des niveaux de rayonnements ultraviolets excessifs sont détectés, un indicateur est déclenché tandis que l'onduleur est désactivé. D'autres modes de réalisation permettent le fonctionnement de plusieurs lampes. Dans un autre mode de réalisation, de l'ozone est produit autour du dispositif d'éclairage pour protéger les utilisateurs contre les rayonnements ultraviolets.
PCT/US2004/018884 2003-06-13 2004-06-10 Ballast electronique WO2005006820A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IN622/MUM/2003 2003-06-13
IN622MU2003 2003-06-13

Publications (1)

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WO2005006820A1 true WO2005006820A1 (fr) 2005-01-20

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007121824A1 (fr) * 2006-04-21 2007-11-01 Tridonicatco Gmbh & Co. Kg Appareil d'allumage à superposition pour lampes à décharge haute pression
US7414369B2 (en) 2005-04-18 2008-08-19 Marvell World Trade Ltd. Control system for fluorescent light fixture
US7560866B2 (en) 2005-04-18 2009-07-14 Marvell World Trade Ltd. Control system for fluorescent light fixture
US8354418B2 (en) 2006-04-06 2013-01-15 Boehringer Ingelheim International Gmbh Thiazolyl-dihydro-quinazolines

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4554487A (en) * 1983-05-17 1985-11-19 Nilssen Ole K Electronic fluorescent lamp ballast with overload protection
US4855860A (en) * 1982-08-30 1989-08-08 Nilssen Ole K Ground-fault protected ballast
US5138234A (en) * 1991-05-28 1992-08-11 Motorola, Inc. Circuit for driving a gas discharge lamp load
GB2300253A (en) * 1995-04-28 1996-10-30 Hazlitt Nominees Limited Sunbeds
WO2001015202A2 (fr) * 1999-08-23 2001-03-01 Bausch & Lomb Incorporated Procedes et systeme de commande en boucle fermee de lampes fluorescentes

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4855860A (en) * 1982-08-30 1989-08-08 Nilssen Ole K Ground-fault protected ballast
US4554487A (en) * 1983-05-17 1985-11-19 Nilssen Ole K Electronic fluorescent lamp ballast with overload protection
US5138234A (en) * 1991-05-28 1992-08-11 Motorola, Inc. Circuit for driving a gas discharge lamp load
GB2300253A (en) * 1995-04-28 1996-10-30 Hazlitt Nominees Limited Sunbeds
WO2001015202A2 (fr) * 1999-08-23 2001-03-01 Bausch & Lomb Incorporated Procedes et systeme de commande en boucle fermee de lampes fluorescentes

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7414369B2 (en) 2005-04-18 2008-08-19 Marvell World Trade Ltd. Control system for fluorescent light fixture
US7560866B2 (en) 2005-04-18 2009-07-14 Marvell World Trade Ltd. Control system for fluorescent light fixture
US8120286B2 (en) 2005-04-18 2012-02-21 Marvell World Trade Ltd. Control system for fluorescent light fixture
US8531107B2 (en) 2005-04-18 2013-09-10 Marvell World Trade Ltd Control system for fluorescent light fixture
US8354418B2 (en) 2006-04-06 2013-01-15 Boehringer Ingelheim International Gmbh Thiazolyl-dihydro-quinazolines
WO2007121824A1 (fr) * 2006-04-21 2007-11-01 Tridonicatco Gmbh & Co. Kg Appareil d'allumage à superposition pour lampes à décharge haute pression

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