Study on high efficiency method of HID lamp control circuit by means of a variable resonance frequency inverter

Abstract

For the power control method of discharge lamp by electronic ballasts, the impedance variation with frequency changing can be thought. But as the frequency increased the swiching loss should be larger and the circuit efficiency becomes decrease. If zero voltage or zero current switching is done on the semiconductor devices, the losses may be decrease. This paper describes a high efficiency HID lamp operating circuit which has a high frequency inverter with an equivalent variable capacitance controlled by means of “ON TIME CONTROL METHOD”. The operational characteristics of the circuit are analyzed by simulation, and it is clarified a region of the circuit constants to suit for HID lamp operation. The experiment of 100 W metal halide lamp based on above results shows the circuit efficiency is about 80 %, and the variation of the circuit efficiency bounded within 10 % at controlling the output power from 100 % to 60 %.