EP1209954A1 - Réglage de l'intensité d'un starter électronique - Google Patents

Réglage de l'intensité d'un starter électronique Download PDF

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Publication number
EP1209954A1
EP1209954A1 EP00310431A EP00310431A EP1209954A1 EP 1209954 A1 EP1209954 A1 EP 1209954A1 EP 00310431 A EP00310431 A EP 00310431A EP 00310431 A EP00310431 A EP 00310431A EP 1209954 A1 EP1209954 A1 EP 1209954A1
Authority
EP
European Patent Office
Prior art keywords
converter
power
ballast
electronic ballast
power supply
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
EP00310431A
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German (de)
English (en)
Other versions
EP1209954A4 (fr
Inventor
Shu-Yuen Ron Hui
Shu-Hung Henry Flat A 19th Floor Chung
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City University of Hong Kong CityU
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City University of Hong Kong CityU
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Publication date
Application filed by City University of Hong Kong CityU filed Critical City University of Hong Kong CityU
Priority to EP00310431A priority Critical patent/EP1209954A1/fr
Publication of EP1209954A4 publication Critical patent/EP1209954A4/fr
Publication of EP1209954A1 publication Critical patent/EP1209954A1/fr
Ceased legal-status Critical Current

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    • 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
    • H05B41/282—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
    • 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
    • H05B41/36—Controlling
    • H05B41/38—Controlling the intensity of light
    • H05B41/39—Controlling the intensity of light continuously
    • H05B41/392—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor
    • H05B41/3921—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations
    • H05B41/3927—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations by pulse width modulation

Definitions

  • This invention relates to an apparatus and method for the dimming control of an electronic ballast for a fluorescent lamp.
  • the invention relates to an apparatus and method for such dimming control that generates low electromagnetic interference and low switching stress.
  • Electronic ballasts for the high-frequency operation of fluorescent lamps have been increasingly adopted as an energy efficient solution in residential, commercial and industrial lighting applications.
  • Electronic ballasts have a number of advantages including improved efficiency of the overall system, higher lumen output per watt and longer lifetime of the fluorescent lamps.
  • Electronic ballasts are in effect switched mode power electronic circuits, and most modern electronic ballast designs employ series resonant converters as the power circuits for driving the lamps.
  • Fig.1 shows a conventional electronic ballast design.
  • the basic concept of this design is to use the resonant voltage across the resonant capacitor C r to cause the lamp arc to strike at high frequency, typically from 25kHz to 50kHz. Because of the high frequency of the excitation voltage the lamp Is essentially in a continuous on-state, which provides high-quality illumination without any unwanted flickering effect.
  • Fig.2 shows a conventional implementation of a half-bridge series resonant inverter for an electronic ballast application.
  • the two switches S1 and S2 are complementary switches (ie when S1 is on S2 is off, and vice versa). If the potential at point Y is taken as the zero voltage reference point, then voltage V xy will have the values ⁇ V dc /2 where V dc is the DC voltage applied to the ballast circuit either by an AC-DC converter if the power source is AC or by a DC-DC converter if the power source is DC.
  • V dc is the DC voltage applied to the ballast circuit either by an AC-DC converter if the power source is AC or by a DC-DC converter if the power source is DC.
  • the two capacitors C are much larger than the resonant capacitor C r and provide a stable DC voltage nominally at V dc /2 at the point Y.
  • the switching frequency f sw of S1 and S2 slightly higher than the resonant frequency f r of inductor L r and capacitor C r the resonant load becomes inductive. If the current ( i Lr ) in the inductor L r is continuous, S1 and S2 can be turned on under zero-voltage. This zero-voltage switching is desirable because it reduces turn-on switching loss and minimises the electromagnetic interference (EMI) from the power switches. If additional small capacitors Cs1 and Cs2 are added as shown in Fig.2, switches S1 and S2 can also be turned off under zero-voltage as long as the inductor current ( i Lr ) is continuous.
  • EMI electromagnetic interference
  • the first method of dimming control is by control of the duty cycle ( d ) of the two switches S1 and S2.
  • the ideal duty cycle is 0.5 but in practice the maximum d should be slightly less than 0.5 so that a small deadtime when both switches are off is provided to avoid shoot-through in S1 and S2.
  • Fig.3 shows typical waveforms of the gating signals of S1 and S2.
  • a major advantage of the circuit of Fig.2 is that the switches can be turned on and off under zero-voltage conditions which substantially reduces EMI emission and switching stress in the power switches.
  • the duty cycle is too small the inductor current may become discontinuous and the zero-voltage switching conditions will be lost and the switches will suffer switching stress, leading to reduced reliability and increased EMI emission.
  • Fig.4(a) shows a first stage in which switch S1 is ON while switch S2 is OFF and the main current path is highlighted in bold.
  • a second stage shown in Fig.4(b) the two switches are OFF while Cs1 is charged up to V DC and Cs2 is discharged.
  • Cs2 is discharged the anti-parallel diode of S2 will start to conduct.
  • Fig.4(c) shows this third stage in which the two switches S1 and S2 are both still OFF and the anti-parallel diode is conducting clamping the voltage across S2 to almost 0V and when the switch S2 is later turned on again it is turned on under this zero-voltage condition.
  • dimming control by duty cycle variation it is also known to provide dimming control by varying the switching frequency. If the switching frequency is increased, the inductor impedance is increased and thus the inductor current is reduced, This allows the output of a fluorescent lamp to be controlled by varying the switching frequency and Fig.5 shows the power of a 4-ft 40W fluorescent lamp plotted against switching frequency. It can be seen that the lamp power, and therefore the intensity of the emitted light, decreases with increasing switching frequency.
  • the present invention provides apparatus for controlling the power output of a fluorescent lamp comprising, an electronic ballast for driving said fluorescent lamp, power supply means for providing DC power input to said electronic ballast, and means for varying the voltage of said DC power input to said electronic ballast.
  • the power supply may comprise an AC power input followed by an AC-DC converter capable of providing a (i) power factor correction and (ii) variable DC output.
  • Such converters may comprise a diode bridge followed by one of (a) a flyback converter, (b) a Cuk converter, (c) a SEPIC converter, (d) a Shepherd-Taylor converter, and (e) a boost converter.
  • this front end converter uses soft-switching.
  • the power supply may comprise a DC power input followed by a DC-DC converter capable of providing a variable DC output.
  • the converter may be a step-down or a step-up/step-down converter.
  • the electronic ballast comprises a half-bridge series resonant inverter.
  • the ballast preferably comprises two switches soft-switched at a constant frequency slightly higher than the resonant frequency of an inductor-capacitor tank of the ballast.
  • the switches are preferably switched at a constant duty-cycle, preferably as close as possible to 0.5 while providing a short deadtime therebetween to prevent shoot-through.
  • the present invention provides a method for controlling the power output of a fluorescent lamp driven by means of an electronic ballast in the form of a half-bridge resonant inverter, comprising operating said ballast at a constant duty cycle and a constant frequency and providing a variable DC power input to said ballast.
  • dimming control is achieved by the use of a variable converter DC voltage as the means to provide a smooth and desirable dimming control for a fluorescent lamp system.
  • a power converter is inserted between the input power supply and the half-bridge circuit with the power converter being able to produce a variable V DC output to the half-bridge circuit.
  • Fig.6 assumes that the power supply is AC and so the converter is an AC-DC converter, but as shown in Fig.7 the same principle can apply when the input power supply is DC by providing a front-end DC-DC converter with control of the output DC voltage,
  • the output DC voltage V DC of the front-end converter is controlled in order to control the lamp power.
  • a constant duty-cycle (nearly 0.5) is used for the switching of the half-bridge inverter in order to ensure a wide power range of continuous inductor current operation and thus soft-switching operation. This has the further advantage of making switching control simple.
  • a constant switching frequency is used in the converter so that the resonant L-C circuit can be optimised for any given type of lamp.
  • the front end converter must naturally be an AC-Dc converter.
  • suitable AC DC converters include (a) a diode bridge followed by a flyback converter, (b) a diode bridge followed by a Cuk converter, (c) a diode bridge followed by a Sepic converter, (d) a diode bridge followed by a Shepherd-Taylor converter, and (e) a diode bridge followed by a boost converter.
  • These five AC-DC converters can provide input power factor correction in order to reduce voltage harmonics and current harmonics in the AC power supply.
  • soft-switching is preferably incorporated into the front-end converter. This may be achieved by adding an auxiliary circuit to the front-end converter.
  • a significant advantage of controlling V DC to provide dimming control is that lamp power decreases smoothly and almost linearly with decreasing V DC .
  • Fig.7 shows simulated and measured lamp power values as a function of V DC for a 4-ft 40W lamp under a constant duty cycle and constant switching frequency. From Fig.7 it can be seen that there is a substantially linear relationship between lamp power and V DC which makes dimming control very easy and convenient.
  • Fig.9 illustrates an embodiment comprising a front-end SEPIC (single-ended-primary-inductance-converter).
  • the half-bridge resonant electronic ballast can be considered as the load.
  • the SEPIC comprises one controlled switch S and one uncontrolled switch D.
  • the controlled switch S can be a MOSFET, BJT, IGBT or the like and its conduction state is determined by the gate signal v gate .
  • the converter is operated in continuous conduction mode where two circuit topologies are switched alternately in one cycle. These topologies are shown in Fig.10.
  • the input current of the SEPIC is controlled to follow the full-rectified waveform of the sinusoidal input voltage v g by pulse-width modulation (PWM) control.
  • PWM pulse-width modulation
  • the reference signal i ref for the current-shaping feedback loop is proportional to v g .
  • the input current is sensed and compared to the reference signal and an identified error signal is amplified by a current loop amplifier A 1 the output of which is compared to a ramp function.
  • the duty ratio of S may be adjusted in order to minimize the error between the reference current and the sensed line current.
  • the output voltage is in fact controlled by adjusting the reference current i ref .
  • an error amplifier K e such as a proportional-plus-integral controller, is used to process the error between the output voltage v out and a reference voltage v ref to give a necessary signal to one of the multiplier inputs so that v out will follow the desired magnitude of v ref .
  • Fig.11 illustrates an alternative embodiment with an AC-DC front-end converter.
  • the front-end converter comprises an AC-DC flyback converter.
  • the input voltage to the flyback converter (enclosed in the dashed box) is the rectified version of the AC input voltage v s , and if the flyback converter is switched so that the flyback inductor current i L is discontinuous, the envelope of the current pulses will follow the shape of the rectified voltage waveform.
  • the input L-C filter reduces the current ripple and thus the input phase current i s is sinusoidal as shown in Fig.12. If the switching frequency is high, say 20kHz to 100kHz, the current ripple becomes negligible.
  • the AC-DC converter shapes the current into a sinusoidal curve so as to achieve a unitary power factor (ie current is sinusoidal and in phase with the input voltage).
  • the magnitude of the input AC voltage may be fixed by the mains supply (220V say) but the input current magnitude can be controlled and thus the output of the AC-DC converter may be controlled by controlling the magnitude of the input AC current.
  • Fig.13 shows a possible step-down (buck) converter
  • Fig.14 shows a flyback converter that may be either a step-up or step-down converter.
  • the present invention provides a ballast comprising a front-end converter that can provide a variable DC voltage output.
  • the front-end converter can be a power-factor-corrected AC-DC converter (preferably with soft-switching) if the input supply is AC, and a DC-DC converter if the input supply is DC.
  • the DC output voltage of the front-end converter is fed to a soft-switched half-bridge inverter with an inductor-capacitor resonant circuit.
  • the fluorescent lamp is connected across the resonant capacitor.
  • the two switches in the half-bridge inverter are switched at a constant frequency slightly higher than the resonant frequency of the inductor-capacitor tank.
  • the two inverter switches are switched in a complementary manner with a large constant duty cycle in order to achieve soft-switching in the half-bridge inverter over a wide power range.
  • the lamp power is simply controlled by varying the DC output voltage of the front-end converter.
  • This allows the inverter bridge to operate under continuous inductor current mode regardless of the power output of the lamp, ie from nominal DC voltage for full lamp power down to very low DC voltage for low lamp power, thereby reducing EMI emissions from the inverter bridge over a wide power range.
  • the present invention allows the entire ballast system to have low conducted and radiated EMI emission, low switching losses and stress, and thus high reliability.
  • the present invention may also be applied to single or multi-lamp systems.
EP00310431A 2000-11-24 2000-11-24 Réglage de l'intensité d'un starter électronique Ceased EP1209954A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP00310431A EP1209954A1 (fr) 2000-11-24 2000-11-24 Réglage de l'intensité d'un starter électronique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP00310431A EP1209954A1 (fr) 2000-11-24 2000-11-24 Réglage de l'intensité d'un starter électronique

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EP1209954A4 EP1209954A4 (fr) 2001-02-19
EP1209954A1 true EP1209954A1 (fr) 2002-05-29

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004008815A1 (fr) * 2002-07-15 2004-01-22 Koninklijke Philips Electronics N.V. Procede et dispositif permettant d'identifier le type de lampe a decharge
EP1438880A1 (fr) * 2001-09-28 2004-07-21 Sono-Eclair (Sa) Ballast electronique a puissance constante
US6969955B2 (en) 2004-01-29 2005-11-29 Axis Technologies, Inc. Method and apparatus for dimming control of electronic ballasts
WO2006037265A1 (fr) * 2004-10-01 2006-04-13 E. Energy Double Tree Limited Systeme d'eclairage reglable
WO2006065831A1 (fr) * 2004-12-14 2006-06-22 Lutron Electronics Co., Inc. Regulateur d'eclairage comportant a convertisseur elevateur de tension avec command marche/arret et procede de fonctionnement de regulateur
US7304439B2 (en) 2001-09-06 2007-12-04 E. Energy Technology Limited Phase-controlled dimmable electronic ballasts for fluorescent lamps with very wide dimming range
CN101587677A (zh) * 2008-05-23 2009-11-25 双叶电子工业株式会社 荧光显示器的驱动电路
WO2010054454A2 (fr) * 2008-11-13 2010-05-20 Ufsc- Universidade Federal De Santa Catarina Ballast électronique pour lampes à vapeur de métal utilisant des techniques d'intégration pour corriger le facteur de puissance et éliminer la résonance acoustique

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1133579A (fr) * 1978-05-08 1982-10-12 Carlile R. Stevens Bloc d'alimentation pour lampe a decharge ou fluorescente a haute intensite
US5289083A (en) * 1989-04-03 1994-02-22 Etta Industries, Inc. Resonant inverter circuitry for effecting fundamental or harmonic resonance mode starting of a gas discharge lamp
US5488269A (en) * 1995-02-10 1996-01-30 General Electric Company Multi-resonant boost high power factor circuit
WO2000048433A1 (fr) * 1999-02-08 2000-08-17 Koninklijke Philips Electronics N.V. Regulateur d'ampoule electronique a correction du facteur de puissance

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1133579A (fr) * 1978-05-08 1982-10-12 Carlile R. Stevens Bloc d'alimentation pour lampe a decharge ou fluorescente a haute intensite
US5289083A (en) * 1989-04-03 1994-02-22 Etta Industries, Inc. Resonant inverter circuitry for effecting fundamental or harmonic resonance mode starting of a gas discharge lamp
US5488269A (en) * 1995-02-10 1996-01-30 General Electric Company Multi-resonant boost high power factor circuit
WO2000048433A1 (fr) * 1999-02-08 2000-08-17 Koninklijke Philips Electronics N.V. Regulateur d'ampoule electronique a correction du facteur de puissance

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7304439B2 (en) 2001-09-06 2007-12-04 E. Energy Technology Limited Phase-controlled dimmable electronic ballasts for fluorescent lamps with very wide dimming range
EP1438880A1 (fr) * 2001-09-28 2004-07-21 Sono-Eclair (Sa) Ballast electronique a puissance constante
WO2004008815A1 (fr) * 2002-07-15 2004-01-22 Koninklijke Philips Electronics N.V. Procede et dispositif permettant d'identifier le type de lampe a decharge
US6969955B2 (en) 2004-01-29 2005-11-29 Axis Technologies, Inc. Method and apparatus for dimming control of electronic ballasts
WO2006037265A1 (fr) * 2004-10-01 2006-04-13 E. Energy Double Tree Limited Systeme d'eclairage reglable
CN101044800B (zh) * 2004-10-01 2011-06-08 研能双树有限公司 可调光照明系统
AU2005316610B2 (en) * 2004-12-14 2009-11-12 Lutron Electronics Co., Inc. Lighting ballast having boost converter with on/off control and method of ballast operation
AU2005316610C1 (en) * 2004-12-14 2010-07-01 Lutron Electronics Co., Inc. Lighting ballast having boost converter with on/off control and method of ballast operation
WO2006065831A1 (fr) * 2004-12-14 2006-06-22 Lutron Electronics Co., Inc. Regulateur d'eclairage comportant a convertisseur elevateur de tension avec command marche/arret et procede de fonctionnement de regulateur
CN101099417B (zh) * 2004-12-14 2011-11-09 路创电子公司 具有通断控制的升压转换器的照明镇流器及镇流器操作方法
CN101587677A (zh) * 2008-05-23 2009-11-25 双叶电子工业株式会社 荧光显示器的驱动电路
CN101587677B (zh) * 2008-05-23 2013-07-31 双叶电子工业株式会社 荧光显示器的驱动电路
WO2010054454A2 (fr) * 2008-11-13 2010-05-20 Ufsc- Universidade Federal De Santa Catarina Ballast électronique pour lampes à vapeur de métal utilisant des techniques d'intégration pour corriger le facteur de puissance et éliminer la résonance acoustique
WO2010054454A3 (fr) * 2008-11-13 2010-12-02 Ufsc- Universidade Federal De Santa Catarina Ballast électronique pour lampes à vapeur de métal utilisant des techniques d'intégration pour corriger le facteur de puissance et éliminer la résonance acoustique

Also Published As

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