Simple HPS lamp circuital model for both line‐frequency and high‐frequency operations

Abstract

A novel high pressure sodium (HPS) lamp model is proposed. The proposed model is particularised for 150 W HPS lamps, providing a powerful tool for simulating the behaviour of such lamps operating with low-frequency electromagnetic ballasts or high-frequency switching electronic ballasts. Simulations and experimental results are provided for verification of the model. The model can be easily extended to other rated wattages and kinds of discharge lamps.Introduction: High pressure sodium (HPS) lamps are very complex devices, with a high number of physical, electrical and thermal parameters that must be considered when designing a lighting system. HPS lamps present good chromatic rendering, long lifetime and high luminous efficiency (Lm/W) [1]. However, due to the behaviour of the plasma discharge, they need to be supplied by means of current sources. Thus, in order to connect discharge lamps to the mains facility, a special circuit (ballast) is needed.Practical and useful design tools are needed to predict the behaviour of HPS lamps. A number of models for HPS lamps have been presented in the technical literature. In [2], a very complex HPS lamp model is presented based on electro-and thermo-physical parameters, which are difficult to obtain. In [3,4], HPS lamp models for high-frequency (HF) operation are presented. These models implement the lamp behaviour by means of a pure resistor, but they are valid only for HF operation. In [5], a model based on energy balance equations including the dynamic electrode voltage drop is given. This model presents also high complexity, and the needed real parameters of the lamp are not easy to obtain. In this Letter, we propose a practical, simple 150 W HPS lamp model that allows the prediction of the behaviour of the lamp operating with low-frequency (LF) (50 Hz) electromagnetic ballast or HF (tens or hundreds of kHz) electronic ballasts. Simulations and experimental results validate the proposed model.