Efficiency improvement of electronic ballast

A novel approach is presented that reduces losses of a half bridge inverter which is widely used as electronic ballast for discharge lamps. Most losses of electronic ballast are generated in semiconductor switches and ballast inductor. A loss of the inverter is, therefore, assumed to consist of the one of the switches and of the inductor. The requirement that the sum of these losses becomes minimum is determined. We applied the result to an experimental circuit, and obtained the efficiency of 98.6%. An operation point of the inverter block optimally designed in efficiency is not statically made stable. We presented one of the control methods, that input DC voltage of the inverter was controlled to regulate a lamp current to be the rated amount. The entire circuit, including a rectifier, a pre-regulator, the inverter and the control circuit showed the efficiency of 94.6%