A Generalized Dynamic Conductance Model for High Intensity Discharge Lamps and its Prospective Application to Design Dimmable Electronic Ballast

Abstract

A generalized model for high intensity discharge (HID) lamp is developed based on the Francis-Damelincourt dynamic conductance model of electric discharge by replacing the model constants A, B, C, D with four experimentally determined coefficient functions of rated lamp power and root mean square supply voltage. Experimental validation of this model is done, which shows a maximum deviation of about 5 %. Moreover, sensitivity analysis for the model coefficients is also performed, results of which conform to the physical behaviour of high pressure sodium (HPS) and metal halide (MH) lamps. This model is capable to simulate electrical characteristics of HPS and MH lamps of wide range of commercially available rated power (70–400) W fed by a wide range of supply voltage (180–250) V, 50 Hz. As a prospective application, the model is applied to design dimmable low frequency square wave electronic ballast for HID lamps. A design algorithm is proposed for this purpose. Performance analysis of the designed ballast is conducted in Matlab-Simulink environment, which shows fairly good performance of the circuit in terms of dimming accuracy (maximum deviation 2.64 %), lamp power factor (≥ 0.993), and lamp current crest factor (equal to 1.0). The model can also be utilized for designing electronic ballasts of other topologies.