HID lamp acoustic resonance detection: A simple current-based method using sample-hold circuits

Acoustic resonance phenomenon influences the functioning of high intensity discharge lamps driven by electronic ballasts since it causes fluctuation in plasma temperature and pressure so distorting the arc discharge. To avoid acoustic resonance several solutions have been proposed and most of them monitor the electrical parameters of the lamp. In this paper the authors propose a simple method using a sample-hold circuit to identify the occurrences of the acoustic resonance sensing the variation in the lamp current. The results of the laboratory tests on a 400W Metal Halide HID lamp confirm the effectiveness of the proposed current-based method.