EPE Association: EPE 2009 - Subtopic 16-2 - LS: 'Power Supplies - Electronic Ballasts and Solid State Lighting'

EPE 2009 - Subtopic 16-2 - LS: 'Power Supplies - Electronic Ballasts and Solid State Lighting'
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2009 - Conference > EPE 2009 - Topic 16: 'Power Supplies' > EPE 2009 - Subtopic 16-2 - LS: 'Power Supplies - Electronic Ballasts and Solid State Lighting'

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   A novel low-cost current-sharing method for automotive LED-lighting systems
By Werner THOMAS, Johannes PFORR [View]
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Abstract: A novel low cost and passive current-sharing method for parallel connected LEDs is presented. The current-balancing concept is based on discontinuous inductor currents. An analysis has been performed and a prototype converter has been built and tested. The prototype converter drives 36 high-brightness LEDs consisting of six parallel strings with six high-brightness LEDs connected in series. The converter is designed for an automotive head-light system operating directly from the 14V electrical automotive power net. Experimental results are in good correlation with theoretical predictions and demonstrate the good current-balancing performance.

   HPS ELECTRONIC BALLAST WITH MODULATION INDEX CONTROL
By Lenin MORAIS, Pedro DONOSO-GARCIA, Seleme SELEME JR, Porfirio CORTIZO [View]
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Abstract: Acoustic resonance in HPS lamps can be avoided by using a controlled PWM inverter and third harmonic injection. The crest factor can also be reduced by harmonic injection. This paper proposes to use of the modulation index adjustment as a method of eliminating the transformer at the output of the ballast as well as maintaining the lamp nominal power during its lifetime. An ignitor for high-intensity discharge lamps based on forced oscillation via an external periodic voltage square wave supplied by a digitally controlled inverter is also presented.

   Overview of mercury migration mechanisms in cold cathode fluorescent lamps caused by asymmetrical driver waveforms
By Peter TANT, Frank VAN DER SCHANS, Michel DE JONGH, Johan DRIESEN, Geert DECONINCK [View]
[Download]

Abstract: Certain CCFL driver topologies produce an asymmetrical output voltage which causes migration of the mercury to one side of the CCFL tube. It is known that a DC voltage component across the CCFL leads to this effect. However, even when no DC component is present across the lamp, migration takes place if the voltage is asymmetrical. Eventually, in the absence of a series ballast capacitor, a DC current starts to flow through the CCFL, due to the interaction between the non-linear lamp characteristic and the voltage asymmetry. The direction of this external DC current is opposite to the direction of internal ion displacement (migration direction). This paper summarizes the mechanisms causing these effects. Different circuit configurations are investigated experimentally. A DC servo circuit is introduced, regulating the residual DC voltage across the lamp to zero. It is shown that a series ballast capacitor effectively eliminates the DC lamp current, but, under certain conditions, allows for a relatively high DC voltage to build up across the lamp terminals again leading to migration.

EPE 2009 - Subtopic 16-2 - LS: 'Power Supplies - Electronic Ballasts and Solid State Lighting'
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2009 - Conference > EPE 2009 - Topic 16: 'Power Supplies' > EPE 2009 - Subtopic 16-2 - LS: 'Power Supplies - Electronic Ballasts and Solid State Lighting'
	[return to parent folder]

	A novel low-cost current-sharing method for automotive LED-lighting systems By Werner THOMAS, Johannes PFORR	[View] [Download]
Abstract: A novel low cost and passive current-sharing method for parallel connected LEDs is presented. The current-balancing concept is based on discontinuous inductor currents. An analysis has been performed and a prototype converter has been built and tested. The prototype converter drives 36 high-brightness LEDs consisting of six parallel strings with six high-brightness LEDs connected in series. The converter is designed for an automotive head-light system operating directly from the 14V electrical automotive power net. Experimental results are in good correlation with theoretical predictions and demonstrate the good current-balancing performance.

	HPS ELECTRONIC BALLAST WITH MODULATION INDEX CONTROL By Lenin MORAIS, Pedro DONOSO-GARCIA, Seleme SELEME JR, Porfirio CORTIZO	[View] [Download]
Abstract: Acoustic resonance in HPS lamps can be avoided by using a controlled PWM inverter and third harmonic injection. The crest factor can also be reduced by harmonic injection. This paper proposes to use of the modulation index adjustment as a method of eliminating the transformer at the output of the ballast as well as maintaining the lamp nominal power during its lifetime. An ignitor for high-intensity discharge lamps based on forced oscillation via an external periodic voltage square wave supplied by a digitally controlled inverter is also presented.

	Overview of mercury migration mechanisms in cold cathode fluorescent lamps caused by asymmetrical driver waveforms By Peter TANT, Frank VAN DER SCHANS, Michel DE JONGH, Johan DRIESEN, Geert DECONINCK	[View] [Download]
Abstract: Certain CCFL driver topologies produce an asymmetrical output voltage which causes migration of the mercury to one side of the CCFL tube. It is known that a DC voltage component across the CCFL leads to this effect. However, even when no DC component is present across the lamp, migration takes place if the voltage is asymmetrical. Eventually, in the absence of a series ballast capacitor, a DC current starts to flow through the CCFL, due to the interaction between the non-linear lamp characteristic and the voltage asymmetry. The direction of this external DC current is opposite to the direction of internal ion displacement (migration direction). This paper summarizes the mechanisms causing these effects. Different circuit configurations are investigated experimentally. A DC servo circuit is introduced, regulating the residual DC voltage across the lamp to zero. It is shown that a series ballast capacitor effectively eliminates the DC lamp current, but, under certain conditions, allows for a relatively high DC voltage to build up across the lamp terminals again leading to migration.