Efficiency Improvement of Emergency Lighting Circuit by Separately Excited One Transistor Inverter

Abstract

Efficiency improvement of a fluorescent lamp driving inverter for emergency lighting use is described. a separately excited one transistor inverter is applied to the 36% luminous flux system of a 20 watt lamp. A Darlington circuit was bridged with a coil to reduce the switching and driving losses in the transistor switch circuit. For effective use of battery energy, the input power to the lamp is kept constant by controlling the switching duty cycle against the change of source voltage. Two kinds of load circuits, direct current type and capacitance ballast type are studied.
Consequently, an efficiency better than 83% and constant power characteristics are achieved in the prototype circuits.