Automatic luminous control for self-oscillating electronic ballast

This paper presents a simple alternative of automatic luminous control for electronic ballasts operating in self-sustained oscillating mode feeding fluorescent lamps for energy saving. The luminous flux level control is based on a signal from a lighting dependent resistor, which measures the luminous flux level. The dimming feature is obtained using switching frequency variation. Thus, the circuit interprets the measurement from the sensor to control the switching frequency in the self-oscillating gate-driver circuit automatically. Experimental results from one 40 W fluorescent lamp are presented to demonstrate the feasibility of the proposed system.