Éléments de conception d’un générateur électrique pour l’alimentation d’un dispositif à décharge à barrière diélectrique (DBD)

Ce travail traite de la conception de générateur alimentant une lampe DBD destinée à la production de rayonnement UV. Cette alimentation doit permettre un contrôle efficace du rayonnement, grâce aux degrés de liberté apportés par le contrôle du générateur (fréquence, amplitude du courant injecté dans la lampe). Le modèle électrique de la lampe est utilisé pour prédire l’impact des caractéristiques du générateur sur le rayonnement UV produit. Une synthèse des interrupteurs de puissance du convertisseur statique permettant le contrôle du courant injecté est proposée et des solutions d’implémentation sont étudiées. Une démarche de conception en vue de l’optimisation du transformateur haute tension est proposée, notamment en ce qui concerne la valeur de ses éléments parasites. L’ensemble de ces travaux est étayé par des réalisations expérimentales. ABSTRACT : This work presents the concept of a generator supplying a DBD lamp for UV radiation production purpose. This supply permits effective control of radiation based on degree-of-freedom provided by generator control system (lamp current frequency and ampli-tude). Lamp electrical model is used to predict the impact of power source characteristics on the produced UV radiation. A synthesis of the switching devices of power converter for current lamp control is pro-posed and the implemented solutions are studied. A design procedure for high voltage transformer optimization is proposed in particular concerning parasitic elements. The entire work is supported by experimentations

The synthesis of conceptual elements for an electrical generator of dielectric barrier discharge (DBD) device supply system

Ce travail traite de la conception de générateur alimentant une lampe DBD destinée à la production de rayonnement UV. Cette alimentation doit permettre un contrôle efficace du rayonnement, grâce aux degrés de liberté apportés par le contrôle du générateur (fréquence, amplitude du courant injecté dans la lampe). Le modèle électrique de la lampe est utilisé pour prédire l’impact des caractéristiques du générateur sur le rayonnement UV produit. Une synthèse des interrupteurs de puissance du convertisseur statique permettant le contrôle du courant injecté est proposée et des solutions d’implémentation sont étudiées. Une démarche de conception en vue de l’optimisation du transformateur haute tension est proposée, notamment en ce qui concerne la valeur de ses éléments parasites. L’ensemble de ces travaux est étayé par des réalisations expérimentales.This work presents the concept of a generator supplying a DBD lamp for UV radiation production purpose. This supply permits effective control of radiation based on degree-of-freedom provided by generator control system (lamp current frequency and ampli-tude). Lamp electrical model is used to predict the impact of power source characteristics on the produced UV radiation. A synthesis of the switching devices of power converter for current lamp control is pro-posed and the implemented solutions are studied. A design procedure for high voltage transformer optimization is proposed in particular concerning parasitic elements. The entire work is supported by experimentations

Current Source Power Supply for DBD Excilamps

International audienceThe electrical power delivered to the gas in a XeCl Dielectric Barrier Discharge exciplex lamp, is analyzed, applying causality criteria based on an equivalent circuit model of the DBD; this power is shown to be controllable by the current supplied to the lamp. This highly desired property is obtained by means of a specific power supply topology, which concepts and design are discussed. Experimental prototype of a current-mode converter operating in discontinuous current mode around 50 kHz is presented and its capability to control the amount of energy transferred during each current pulse is shown. The capability of this power supply to sustain specific operating conditions for the DBD lamp, with a very stable behavior, (even with a very low current, thus obtaining a single discharge channel) is illustrated. The results concerning the coupling of this converter with a XeCl excilamp are presented and the influence of the supply parameters on the 308nm emission of a Xenon/Chlorine excilamp is analyzed. The shape of the pulsed UV power radiated by the lamp is experimentally shown to be very similar to the one of the current which actually flows into the gas mixture. The UV radiation is demonstrated to be tightly correlated to the current injected into the gas and controllable by means of the available degrees of freedom offered by the control of the power supply. Measurements of the output characteristics and performances of the system are discussed

Time resolved imaging of a dielectric barrier discharge by using pulsed power supply

International audienceShort exposure images of the Ultraviolet (UV) and both the visible and UV emission from a Xenon/Chlorine Dielectric Barrier Discharge (DBD), have been recorded to investigate the discharge structure for a pulsed power supply for various frequencies. The images from the pulsed discharge have shown that the plasma is essentially concentrated on the active electrode area. From the results obtained, it is indicated that the exciplexes formation area is drastically different, which depends on the power supply waveforms

High Speed UV Imaging of a Dielectric Barrier Discharge Excilamp Pumped by Various Waveforms

International audienceExcilamps are potentially powerful and efficient UV sources but their properties are strongly linked to their power supply mode. One of the most efficient ways to supply Dielectric Barrier Discharge (DBD) excilamps is a high voltage (some kilovolts) pulsed voltage waveform at some hundreds of kilohertz, with a pulse width around one microsecond. This can be either achieved by high voltage switching, which leads to costly and poorly efficient power converters, or by low voltage switching followed by a step-up transformer. In this latter case, the coupling between the inductive properties of the transformer and the capacitive behavior of the DBD excilamp leads unexpected ringings in the waveforms. Time resolved UV imaging of a DBD excilamp in a Xenon/Chlorine mixture are presented to analyze the mechanisms involved in the production of exciplexes for various power supply modes

Control of the UV flux of a XeCl dielectric barrier discharge excilamp through its current variation

International audienceThe efficiency of the electrical power transfer to the gas mixture of a XeCl dielectric barrier discharge (DBD) exciplex lamp is analysed. An equivalent circuit model of the DBD is considered. It is shown that the excilamp power can be controlled by applying current to the lamp. This highly desired property is ensured by means of a specific power supply topology, whose concepts and design are discussed. The experimental prototype of a current-mode converter operating in the pulsed regime at pulse repetition rate of 50 kHz is presented and its capability to control the amount of energy transferred during each current pulse is demonstrated. The capability of this power supply to maintain specific operating conditions for the DBD lamp, with a very stable behaviour (even at a very low current, in the regime of a single discharge channel), is illustrated. The experimental results of a combined use of this converter and a XeCl excilamp are presented. The influence of the supply parameters on the 308-nm XeCl excilamp is analysed. The shape of the UV pulse of the lamp is experimentally shown to be similar to that of the current, which actually flows into the gas mixture. The UV radiation power is demonstrated to be tightly correlated to the current injected into the gas and controlled by the available degrees of freedom offered by the power supply. The measured UV output characteristics and performance of the system are discussed. Time resolved UV imaging of a XeCl DBD excilamp is used to analyse the mechanisms involved in the production of exciplexes at various power supply regimes. It is shown that a pulsed voltage source leads to formation of short high intensity UV peaks, while current pulses lead to formation of sustained discharge filaments. Based on the results of modelling of the above-mentioned operation conditions, the two power supply regimes are compared and analysed from the point of view of the UV power and radiative control