A Behavioral SPICE Compatible Model of an Electrodeless Fluorescent Lamp Sam Ben-Yaakov *1 , Moshe Shvartsas 1 and Jim Lester 2 * Corresponding author 1 Power Electronics Laboratory Department of Electrical and Computer Engineering Ben-Gurion University of the Negev P. O. Box 653 Beer-Sheva 84105, ISRAEL Phone: +972-8-646-1561; Fax: +972-8-647-2949; Email: sby@ee.bgu.ac.il Website: www.ee.bgu.ac.il/~pel 2 Central Research & Services Laboratories Fluorescent Systems Laboratory OSRAM SYLVANIA 71 Cherry Hill Dr. Beverly, MA 01915 USA Phone: 1-978-750-1605 FAX: 1-978-750-1790 EMAIL: jim.lester@sylvania.com Abstract- A behavioral, SPICE compatible, model was developed for an electrodeless fluorescent lamp (OSRAM SYLVANIA ICETRON/ENDURA 150W). The model emulates the static and dynamic behavior of the lamp when driven at high frequency. The model was tested under various experimental conditions: at steady state for different power levels, with an AM modulated drive, and under transient changes. Good agreement was found between the simulation runs and experimental results. However, the effect of temperature on the lamp’s behavior may require a tighter fit of the model to the temperature dependence in cases where large changes in operating condition need to be simulated. I. INTRODUCTION Fluorescent lamps are simply constructed light sources consisting of a glass vessel coated inside with light emitting phosphor. Inside the vessel is a combination of inert gas and Mercury gas. During operation, the Mercury is energized and produces UV, which activates the phosphor and produces light. In an electroded lamp, the Mercury is energized by the current delivered through the electrodes [1]. In an electrodeless lamp, power must be delivered to the lamp either inductively or capacitively. Most commercial electrodeless lighting products today use inductive coupling and low operating frequencies where power conversion is most efficient. There are many shapes used in electrodeless lamps [2, 3]. Each shape offers a different optical or efficiency advantage. Some lamps are spherical in shape with the inductive coupling coil inside the lamp protected by a glass re-entrant cavity. Some spherical lamps have the coil surrounding the lamp. This paper will examine the oval or racetrack shaped lamp shown in Fig. 1, which uses two inductive coupling coils connected in parallel. The physics of this lamp has been discussed in recent papers [4 - 7]. This paper will examine a PSPICE circuit model for the lamp construction of Fig, 1, which can be used in circuit simulations. The results can be applied to other electrodeless lamp shapes. The objective of this study was to develop a SPICE compatible model that will exhibit two major electrical features of an electrodeless fluorescent lamp operated at HF: the dependence of the lamp's resistance on power level and its dynamic response to changes in electrical excitation. Based on an earlier methodology, which relies on experimental observations as well as some physics based reasoning, a behavioral model was developed to emulate the electrical response of the electrodeless fluorescent lamp. Once developed, the model was calibrated against experimental data and then verified by independent measurements. II. THE BEHAVIORAL MODEL OF ELECTRODELESS FLUORESCENT LAMP The proposed model is based on the assumption that the fundamental behavior of an electrodeless fluorescent lamp is similar to the behavior of a lamp with hot electrodes. The only difference being the way the electrical energy is coupled to the plasma. In the case of the lamp with electrodes, coupling is via wires. In the case of the electrodeless lamp of the ICETRON/ENDURA type, coupling is by magnetic induction. It was thus assumed that the model concept developed earlier [8] will fit the case of the electrodeless lamp. As reported in an earlier study [9], the impedance of a fluorescent lamp operated at high frequency is, to a first order approximation, resistive. That is, at any given operation point, the current of the lamp’s arc tube can be expressed as: eq lamp lamp R V I = (1) 0-7803-7405-3/02/$17.00 (C) 2002 IEEE