A single-stage electronic ballast with emergency lighting features

This paper presents a single-stage electronic ballast with emergency lighting features. The ballast can function as a regular ballast, emergency ballast, battery charger or discharger and power failure detector, achieving regular and emergency lighting features. The single-stage converter used in the ballast is an integration of a bidirectional flyback converter and two half-bridge series-resonant parallel-loaded inverters. Derivation and operating principle of the proposed converter is first presented and an application to regular and emergency lighting is then developed. With the proposed converter and a single-chip microcontroller (EM78P458), a low cost, multifeature electronic ballast can be readily implemented and installed. Simulation results and hardware measurements have verified its feasibility and the desired features.