Electronic ballast for low-pressure discharge lamp

摘要

An electronic ballast for a DC- or AC-mains powered, low-pressure discharge lamp uses a half bridge rectifier feeding at least one lamp through a parallel capacitance and a series inductance. There is an electronic harmonic filter, also with capacitance and inductance, with a control unit. The electronic switches, ie, transistors, t1, t2 of the inverter 1 are controlled through feedback coupling with a current-saturable transformer l3 which has a high magnetic permeability and a very narrow B-H curve with a very steep rise. The transformer has a low Q-factor. The primary winding n1 is joined to a point between the transistors. The inductance l1 and the secondary windings n2 are joined to the transistor bases.