BALLAST CIRCUIT FOR GASEOUS-DISCHARGE LAMP Russian patent published in 2002 - IPC

FIELD: electrical engineering. SUBSTANCE: ballast circuit for gaseous-discharge lamp incorporates network of resonance load including gaseous-discharge lamp, resonant inductance and resonant capacitor. Direct current-to-alternating current converter induces alternating current in network of resonance load. Converter loop has first and second switches placed in series between conductor of D C bus and reference conductor and which are tied up together in one unit through which alternating current of load passes. Each first and second switch includes control unit and reference unit, voltage between these units determines state of conductance of corresponding switch. Control units of first and second switches are interconnected. Reference units of first and second switches are tied up together in one common unit. Gate unblanking circuit regeneratively controls first and second switches and includes enabling choke connected to mentioned resonant choke so that voltage proportional to momentary rate of change of alternating current of load is induced in it. Unblanking choke is placed between common unit and control units. Second choke is connected in series with enabling choke. Unblanking and second chokes connected in series are placed between common unit and control units. Bi-directional voltage limiter is placed between common unit and control units to limit positive and negative surges of voltage across control units relative to common unit. EFFECT: raised reliability of firing of gaseous-discharge lamp. 12 cl, 10 dwg