METHOD FOR DRIVING A VALVE FOR REGULATING THE FLOW RATE OF FUEL GAS TOWARDS A BURNER, IN PARTICULAR FOR CONDENSATION BOILERS HAVING HIGH POWER MODULATION

Method for driving a device for modulating a valve (1) regulating the flow rate of gas towards a burner (3), in particular of a condensation boiler having high power modulation, the valve together with the associated closure member thereof being designed so as to operate with a predetermined characteristic curve, the flow rate (Qgas) delivered being proportionally related to the strength of a first current signal (Imod) sent to the modulator such that the flow rate can be modulated, using said characteristic of proportionality, within a range of modulation between a maximum flow rate (Qgas_max) and a minimum flow rate (Qgas_min), and, so as to deliver controlled gas flow rates that are below said minimum flow rate (Qgas_min), thereby extending the range of modulation into minimum deliverable flow rate values, provision being made to drive the modulator with a second PWM voltage signal capable of generating a particular second PWM current signal (Imod'), so as to move the closure member of the valve according to the second signal. Furthermore, the terms first (Ta) and second (Tb) time interval being given to the successive durations of the high signal and the low signal, respectively, the sum of which is equal to the period (T) of the second signal, with a duty cycle (dc) equal to the relationship Ta/T, the strength of the second current signal (Imod') is modulated: - by amplitude modulation of the second signal (Imod'), leaving the duty cycle constant, so as to vary the flow rate accordingly, or - by modulation of the duty cycle in the period (T), keeping a preset amplitude of the second signal constant relative to the first time interval, so as to vary the flow rate delivered accordingly. L'invention concerne un procédé d'entraînement d'un dispositif pour moduler une soupape (1) régulant le débit d'un gaz vers un brûleur (3), en particulier d'une chaudière à condensation ayant une modulation de puissance élevée, la soupape et son élément de fermeture associé étant conçus de manière : à fonctionner avec une courbe de caractéristique prédéterminée, le débit (Qgaz) distribué étant proportionnellement lié à la puissance d'un premier signal de courant (Imod) envoyé au modulateur de telle sorte que le débit peut être modulé, à l'aide de ladite caractéristique de proportionnalité, dans une plage de modulation entre un débit maximal (Qgaz_max) et un débit minimal (Qgaz_min) ; et à distribuer des débits de gaz régulés qui sont inférieurs audit débit minimal (Qgaz_