Self-oscillating electronic ballast with universal input voltage range

This paper presents a simple alternative of electronic ballast operating in self-sustained oscillating mode with possibility of universal input voltage (90V-240V) supplying fluorescent lamps. The proximally constant lamp power is obtained by changing the resonant filter gain through frequency modulation in according to the input voltage. A voltage divisor supplies a control signal from the bus voltage to a control circuit. Thus, this additional circuit interprets the bus voltage value, controlling the self-oscillating gate-driver circuit switching frequency. Experimental results from one 40 W fluorescent lamp are presented to demonstrate the performance and the feasibility of the proposed system.