A Dynamic Pspice Model for High-Frequency Fluorescent Lamp with Continuous-Dimming Operation

Fluorescent lamps were first introduced to the world in the 1939 World’s Fair. They are low-pressure mercury discharge lamps. Since then, the fluorescent lamps have been the mainly lighting source due to their merits of high color rendering, soft-visualization, long life, and energy-saving. Unfortunately, however, all gas discharge lamps cannot directly connect to a voltage source and require a so-called “ballast” circuitry for normal operation due to the very distinctive electrical characteristic of the lamps. The gas discharge lamps behave as nonlinear time-varying power resistors and the instantaneous values are influenced by the source voltage variation, the ballast circuit characteristics, and the internal physical processes within the arc discharge themselves [1]. There are interactions within the lamp-ballast systems, which great affect lamp performances. To properly design lamp-ballast systems, it is important to accurately characterize the lamp electrical model. Many studies have been reported in the literature to establish mathematical modes for the gas discharge lamps [116]. However, some models are based on the physical discharge phenomena of lamps and generally far too complicated to be suitable for circuit design applications. Other models use curve-fitting method to simulate lamp’s terminal V-I characteristic and are more suitable for circuit simulations. However some of them need complex model parameter derivation procedures and most models cannot be applied for dimming ballast simulation, especially for low dimming levels such as less than 10% of dimming level where the lamps show severe capacitive features. This paper presents a curve-fitting model for fluorescent lamps, which include the capacitive feature of the lamps. The presented model has advantages of good agreement with both of static and dynamic response of dimming lamps.