A constant power controller of DC-AC electronic ballast inverter for HID lamps

This paper presents a constant power controller for use in the DC-AC inverter of an electronic ballast for high-intensity-discharging (HID) lamps. The proposed DC-AC inversing stage is a high-frequency combined with low-frequency square-wave-driven half-bridge-type inverter with a constant lamp power control scheme; it supplies the HID lamp with low-frequency square-wave sources to avoid acoustic resonance and to sense the lamp feedback voltage and current in order to keep the lamp power constant throughout aging. The features of the proposed inverter for driving HID lamps are cost-effectiveness, constant lamp power, and lack of acoustic resonance. This paper describes the operational principles and experimental results of the proposed constant-power-controlled inverter of an electronic ballast, for one 70 W HID lamp operating with an input DC-linked bus voltage of 400 V.