Abstract The metal halide lamp is one of high-intensity discharge lamps. It has many advantages such as good color rendering, high efficacy and a variety of color presentations. However, the problems of acoustic resonance, a long transition period of cold starting, and an extremely high ignition voltage for hot restarting should be overcome. The investigation of the thesis is focused on the electrical characteristics of the metal halide lamp operating at high-frequency. Included are the acoustic resonance, starting transient and steady state operation. Various ballast circuits incorporating with ignitors are designed to drive several 70-W metal halide lamps. The operating frequency ranges with acoustic resonance, the ignition voltages for both cold starting and hot restarting, the transition period, the dimming performance, and the lamp equivalent resistance during the lamp life are measured and analyzed. Based on the investigated results, a useful guideline can be provided for the operation and design of the electronic ballast for metal halide lamps. Key words : Metal halide lamp, electronic ballast, acoustic resonance, hot restarting.

A robust design utilizing consecutive orthogonal arrays algorithm is proposed for designing electronic ballasts of fluorescent lamps. By this design method, the variation in the lamp power can be less than 10% under different operating conditions. In the manipulation of the consecutive orthogonal arrays, component values of the ballast circuit and DC-link voltage are used as controllable variables for inner orthogonal arrays; while manufacturers, ambient temperature, used hours, and variation in DC-link voltage are treated as uncontrollable variables for outer orthogonal arrays. The average effects of the output power for each controllable variable are calculated from simulation results, which are served as indexes to find the combination of circuit parameters with a better solution. With consecutive orthogonal arrays, the target values of the circuit parameters are approached step by step. In addition, the effect of the DC-link voltage on the lamp power can be understood from the uncontrollable variable of outer orthogonal arrays. The proposed design tool is implemented on the design of an electronic ballast for a 40W fluorescent lamp. The test results show that the designed electronic ballast can be adopted for the lamps from different manufacturers, with different used hours, and under variation in a wide range of ambient temperature.

Fluorescent lamps are nowadays the most important light sources in industrial, commercial, and domestic applications. To drive fluorescent lamps, electronic ballasts with high-frequency resonant inverter, instead of the electromagnetic ones, are increasingly used due to the benefits of lightweight, small size, high luminous efficiency, and long lamp life. Recently, efforts are concentrated on how to reduce the product cost as well as to improve the circuit performances. To further curtail the product cost, the power-factor-correction circuit is integrated into the ballast circuit as single-stage high-power-factor electronic ballast. On the other hand, the unit cost per lamp can be substantially reduced by developing a ballast circuit which is capable of driving multiple lamps. For convenient use, the user may turn on the desired number of the lamps in accordance with the expected luminosity. A starting-aid circuit is added to eliminate the glow current during preheating. In addition, a protection circuit will be included in the multi-lamp electronic ballast. In case of operating partial lamps, a high power factor at the line input will be always retained. In this thesis, the feasible circuit configuration is developed and design equations are derived. Accordingly, design guidelines for determining circuit parameters are provided. The laboratory circuits are built and tested to verify the computer simulations and analytical predictions.

A new starting profile, instead of ANSI C82.11, is defined to illustrate the starting transient of rapid-start fluorescent lamps driven by high-frequency electronic ballasts. By scrutinizing the lamp voltage and current waveforms, the starting transient can be classified into preheating, glow, and glow-to-arc stages. By the new definition, the starting characteristics of all ballast-lamp circuits can be well interpreted. To investigate the starting performance, a test system is set up. Experimental results show that the time required for glow and glow-to-arc stage is significantly affected by the starting voltage, the filament preheating and the environment temperature. On the basis of the in-depth analysis on the investigated results, the starting characteristics of rapid-start fluorescent lamps are well understood, providing useful information for designing the starting scenario for the ballast.

A high-frequency electronic ballast with auto-tracking control was proposed to operate the metal halide lamps at a specific frequency free from acoustic resonance. In case the acoustic resonance should happen, the operating frequency is changed step by step with the auto-tracking control, until the lamp is operated at a frequency with stable operation. The electrical characteristics of the lamps are first investigated. Based on the investigated results, a detection circuit is designed to identify the occurrence of acoustic resonance. With the auto-tracking control, the Class-D half-bridge series-resonant inverter can be adopted for the high-frequency electronic ballast to achieve high efficiency and high power density. The control strategy of auto-tracking is practically realized by a single-chip microprocessor. The proposed approach is implemented on a 70 W test lamp with an operating frequency range from 20 kHz to 30 kHz. To regulate the lamp power at its rated value, a buck-boost converter is used as a pre-regulator, which serves also as a power-factor-corrector to achieve a high power factor at the input line.

This thesis presents a single-stage high-power-factor electronic ballast for metal halide lamps. The proposed ballast integrates a buck-boost converter, a buck converter and a full-bridge inverter into a single power conversion circuit. The buck-boost converter is designed to be operated at the discontinuous conduction mode (DCM) with a constant duty ratio at a fixed switching frequency to provide a constant lamp power and to achieve a high power factor for a given ac input voltage. The full-bridge inverter supplies a square-wave current for the lamp at a low frequency the same as the line frequency to avoid acoustic resonance. For the universal input voltage ranged from 90 V to 264 V, the lamp remains at the rated power by controlling the duty-ratio of the buck converter. The circuit operation is analyzed in detail to derive the design equations. An electronic ballast for 70 W lamps is designed and tested. Computer simulations and experimental measurements are provided to verify that the proposed ballast has the merits of a nearly unity input power factor, a high efficiency greater than 82 % and can drive the lamp at a constant power.

Design and realisation of electronic regulated ballast with USB interface. The ballast has three functions: constant I, constant U and constant R. This device is intended for example to measure discharge curves of accumulators.

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Small size, light weight, high efficacy, longer lifetime and controllable output are the main advantages of high-frequency electronic ballasts for gas discharge lamps. However, power line quality and electromagnetic interference (EMI) issues arise when a simple peak rectifying circuit is used. To suppress harmonic currents and improve power factor, input-current-shaping (ICS) or power-factor-correction (PFC) techniques are necessary. This dissertation addresses advanced high-frequency electronic ballasting techniques by using a single-stage PFC approach. The proposed techniques include single-stage boost-derived PFC electronic ballasts with voltage-divider-rectifier front ends, single-stage PFC electronic ballasts with wide range dimming controls, single-stage charge-pump PFC electronic ballasts with lamp voltage feedback, and self-oscillating single-stage PFC electronic ballasts. Single-stage boost-derived PFC electronic ballasts with voltage-divider-rectifier front ends are developed to solve the problem imposed by the high boost conversion ratio required by commonly used boost-derived PFC electronic ballast. Two circuit implementations are proposed, analyzed and verified by experimental results. Due to the interaction between the PFC stage and the inverter stage, extremely high bus-voltage stress may exist during dimming operation. To reduce the bus voltage and achieve a wide-range dimming control, a novel PFC electronic ballast with asymmetrical duty-ratio control is proposed. Experimental results show that wide stable dimming operation is achieved with constant switching frequency. Charge-pump (CP) PFC techniques utilize a high-frequency current source (CS) or voltage source (VS) or both to charge and discharge the so-called charge-pump capacitor in order to achieve PFC. The bulky DCM boost inductor is eliminated so that this family of PFC circuits has the potential for low cost and small size. A family of CPPFC electronic ballasts is investigated. A novel VSCS-CPPFC electronic ballast with lamp-voltage feedback is proposed to reduce the bus-voltage stress. This family of CPPFC electronic ballasts are implemented and evaluated, and verified by experimental results. To further reduce the cost and size, a self-oscillating technique is applied to the CPPFC electronic ballast. Novel winding voltage modulation and current injection concepts are proposed to modulate the switching frequency. Experimental results show that the self-oscillating CS-CPPFC electronic ballast with current injection offers a more cost-effective solution for non-dimming electronic ballast applications. / Ph. D.

The dissertation investigates the starting transient behaviors of metal halide lamps driven by constant currents and constant powers, respectively. Based on the investigation results, three starting scenarios are proposed for shortening the starting time, and an identification strategy is figured out for designing an electronic ballast being capable of driving three small-wattage lamps rated at different powers. A laboratory electronic ballast is designed to drive small-wattage metal halide lamps with a programmable low-frequency square-wave current. Experiments are conducted to examine the effects of the starting current on variations of the light output as well as the lamp voltage and power. From the effects of the applied current on the generated luminance, three starting scenarios are attempted to accelerate the starting transient stage. Experimental evidence shows that the starting time can be effectively shortened by increasing the lamp current during glow-to-arc and warm-up stages. A short interval of over-power operation during the warm-up stage enables the lamp to further enhance the producing of luminance quickly, and hence greatly reduce the starting transient period. According to the starting transient characteristics of metal halide lamps, an identification strategy is figured out to recognize three small-wattage metal halide lamps rated at powers of 20-W, 35-W and 70-W from three world-wide prominent brands, GE, OSRAM and PHILIPS. An electronic ballast is designed to drive the metal halide lamps with the multi-stage constant-power starting scenario. Experimental results evidence that the electronic ballast with the proposed identification strategy can recognize three lamps¡¦ rated powers correctly during the starting transition, and drive the lamp to its rated power before entering the steady-state.