5792 IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 30, NO. 10, OCTOBER 2015 Ultralow-Loss Passive T5 Fluorescent Lamp Ballasts for Subzero Temperature Operation Wai Man Ng, Member, IEEE, and S. Y. R. Hui, Fellow, IEEE Abstract—Ultralow-loss passive ballasts for T5 fluorescent lamps have previously been proven to be more energy efficient than their electronic counterparts at room temperature operation. The ab- sence of electrolytic capacitor, switched-mode circuit, and control integrated circuit makes them particularly suitable for extreme temperature conditions. This paper first describes the challenges required for low-temperature operation and frequent ignition of T5 high-efficiency lamps. Then, the design of passive inductive– capacitive (LC) ballast for T5 28-W lamps based on a physical discharge lamp model is illustrated. To reduce the blackening ef- fects of the filaments, a bypass resistor is incorporated to each filament to avoid local hot spot formation. Frequent ignition tests have been conducted for the proposed ballast and electronic ballast to confirm the effectiveness of the bypass resistors in protecting the filaments. Index Terms—Lighting control, low-temperature operation, sus- tainable lighting technology. I. INTRODUCTION D ESIGNING lighting equipment for extreme temperature has always been challenging, as reported by a group of Canadian researchers from different companies [1]. Such lighting equipment is needed for outdoor applications in low- temperature areas, large freezer rooms, and containers. Outdoor lighting may be subject to subzero temperature (e.g., below −10 °C) for long duration in the winter in some areas in Canada, Russia, and China. The choices of ballast topologies and their associate components are, therefore, critical because it will af- fect the reliability and lifetime of such products. Since 1940s, magnetic ballasts have been the dominant ballast type for T8 and T12 fluorescent lamps [2]. Magnetic ballasts have a long history of reliability and robustness against extreme weather conditions. However, the emergence of electronic ballasts in the last two decades for T8 lamps has somewhat eroded the market of magnetic ballasts because of the high energy efficiency of the electronic ballasts for T8 lamps. The dominance of electronic ballasts continues when T5 lamps were developed. However, the rapid expansion of electronic ballasts has led to the electronic waste issue [3] and the effects of electronic wastes have been addressed in [4] and [5]. Manuscript received October 21, 2014; accepted November 20, 2014. Date of publication December 12, 2014; date of current version May 22, 2015. This work was supported by the Hong Kong Research Grant Council under Theme-based Research Grant T22-715/12N. Recommended for publication by Associate Editor M. Ponce-Silva. W. M. Ng is with the Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong (e-mail: wmng@eee.hku.hk). S. Y. R. Hui is with the Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, and also with the Imperial College London, London SW72AZ, U.K. (e-mail: ronhui@eee.hku.hk). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TPEL.2014.2379956 Fig. 1. Schematic of an ultralow-loss LC ballast system based on an LC circuit for the ULL ballast driven system [8]. For discharge lamps such as fluorescent lamps, low- temperature operations involve several challenges. First, the low-temperature plasma inside the lamp tube requires a higher voltage for ignition. Second, for outdoor applications that re- quire frequent ON/OFF operation, protection of the filaments is needed in order to avoid rapid degradation of the filaments’ lifetime. An example of such application is the motion-senor- controlled fluorescent lamps used in corridors and stairs of factory buildings. Finally, circuit components must be robust against extreme low temperature for long period of time. Unlike T8 lamps, T5 lamps are high-voltage lamps. The nom- inal on-state lamp voltage of T8 36-W lamps is about 100 V and that of T5-HE 28-W lamps is about 175 V, which is close to the 220–240 V mains voltage. This may give a false impression that the lamp arc of a T5 28-W lamp may not be able to sustain when it is used with traditional magnetic ballast. This misun- derstanding has been dispelled in [6]. The inductive–capacitive (LC) ballasts previously proposed in countries with low ac mains voltage of 110 V [7] have offered a good solution to overcome the high lamp arc voltage problem because the capacitive voltage has an opposite polarity of the inductor voltage and, therefore, cancels a part of the voltage drop across the inductor. Against the traditional thinking, the ultralow-loss (ULL) LC ballast (see Fig. 1) has been practically proven in [8] to be more energy efficient than electronic ballasts for T5 lamps. In this paper, the design of passive LC ballast suitable for prolonged low-temperature operation and frequent ignition is presented. This passive ballast has been proven to be more en- ergy efficient than its electronic counterparts for T5 HE lamps at room temperature of 25 °C [8]. In order to meet the three challenges mentioned earlier for the low-temperature (subzero) operation, a physical fluorescent lamp model with tube wall temperature effect that has previously been used for accurate prediction of discharge lamp performance, has been adopted for the performance prediction of various designs of passive ballast- driven T5 lamp systems for subzero temperature (at −15 °C) 0885-8993 © 2014 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. 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