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This paper presents a feasibility analysis of vertical wake steering for floating turbines by differential ballast control. This new concept is based on the idea of pitching the floater with respect to the water surface, thereby achieving a desired tilt of the turbine rotor disk. The pitch attitude is controlled by moving water ballast among the columns of the floater. This study considers the application of differential ballast control to a conceptual 10MW wind turbine installed on two platforms, differing in size, weight, and geometry. The analysis considers the following: (a) the aerodynamic effects caused by rotor tilt on the power capture of the wake-steering turbine and at various downstream distances in its wake; (b) the effects of tilting on fatigue and ultimate loads, limitedly to one of the two turbine-platform layouts; and (c) for both configurations, the necessary amount of water movement, the time to achieve a desired attitude, and the associated energy expenditure. Results indicate that - in accordance with previous research - steering the wake towards the sea surface leads to larger power gains than steering it towards the sky. Limitedly to the structural analysis conducted on one of the turbine-platform configurations, it appears that these gains can be obtained with only minor effects on loads, assuming a cautious application of vertical steering only in benign ambient conditions. Additionally, it is found that rotor tilt can be achieved on the order of minutes for the lighter of the two configurations, with reasonable water ballast movements. Although the analysis is preliminary and limited to the specific cases considered here, results seem to suggest that the concept is not unrealistic and should be further investigated as a possible means to achieve variable tilt control for vertical wake steering in floating turbines. [ABSTRACT FROM AUTHOR]

In this paper, a wireless ballastless lighting system for fluorescent lamps is proposed and implement-ted. The key is to utilize magnetic resonant coupling to achieve wireless power transfer (WPT) while igniting the fluorescent lamp without using any magnetic or electronic ballast. Meanwhile, series-parallel compensation is identified to be more suitable for this WPT system. Also, burst firing control is utilized to achieve efficient light dimming. In order to achieve the fully wireless feature, remote lighting control via Bluetooth is realized by a smart phone. As an example, an experimental setup, which can light up an 8 W fluorescent lamp with illuminance of 2330 lx, has been designed and developed. In particular, it can achieve the transmission efficiency of 57% and the operating frequency of 51 kHz, with distance up to 56 cm. Both theoretical analyses and experimental results are given to validate the feasibility and flexibility of the proposed system. [ABSTRACT FROM AUTHOR]

An improved vehicle-track coupled dynamics model that takes into account the differential ballast settlement is presented in this paper. Central to this formulation is an iterative method for acquiring the mapping relationship between the ballast settlement and the deflection of rail and sleepers. The proposed method is validated by comparing the results obtained with those of the finite element method (FEM) and the equilibrium state calculated for the track with the ballast settlement. Using the proposed method and dynamic model, numerical analyses have been performed for the static deflection of the rail and sleepers and for the dynamic response of the vehicle-track coupled system. The results indicate that the upper track structure will settle along with the ballast bed, and sleepers are likely to become unsupported when the settlement amplitude is large or when the settlement wavelength is small. The contact between the sleeper and the ballast bed changes dynamically when the vehicle passes through the settlement area. The ballast settlement has a significant effect on the deformation of the track and sleepers, thereby deteriorating the running safety and ride comfort of the vehicle. [ABSTRACT FROM AUTHOR]

In nature, metal ores such as iron, lead, aluminum and others are found in an impure state, sometimes oxidized and mixed with silicates of other metals. During casting, when the ore is exposed to high temperatures, these impurities are separated from the molten metal and can be removed. The mass formed by these compounds is slag. Slag is the co-product of the smelting of ore to purify metals. It may be considered a mixture of metal oxides, but may also contain metal sulphites and metal atoms in their elemental form. After it is reprocessed to separate the metals contained, the co-products of this process can be used in cement, rail ballast, road paving and various other purposes. The objective of this research work is the presentation of the chemical and mineralogical characterization tests of the silicon-manganese iron slag with the purpose of reusing the co-product as rail ballast. X-ray diffraction tests, quantitative chemical analyzes, scanning electron microscopy and free lime content were prepared for these characterizations. The results of these tests showed the technical feasibility of using slag as rail ballast. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study and compare the temperature profile and energy performance of traditional and Vegetative Roofs (VRs) during winter season in Lebanon, a country in the Middle East. Three roof mockups were installed on the rooftop of the Chemical Engineering Department at the University of Balamand: a Traditional Gravel Ballasted Roof (TGBR) and two Extensive Green Roofs (EGRs) with different substrate depth and composition. Each minute, the temperature of air, on TGBR surface, and at different depths of EGR was recorded. The daily cooling and heating demands were also calculated. Results confirmed that VRs protect the roof membrane from high temperature fluctuations and decrease air temperature by a factor of one and a half during sunny winter days ( T airmax = 32 ° C ). Findings of this study also showed that the total cooling demand of EGR decreased by 90% compared to TGBR. [ABSTRACT FROM AUTHOR]

Electronic ballasts are implemented for obtaining a high power factor and a good operation of the lamp; these goals are reached traditionally by implementing multiple stages. On the first stage, a unity power factor is obtained and the second stage is designed in order to feed properly the lamp. Different topologies have been studied not only for decreasing the number of employed controllers and stages, but also reducing the number of components and active switches. Electronic ballasts, which are based on the “Z” and “qZ” source inverters, are considered in this paper, where the proposed systems have a single stage. Two topologies are illustrated: the first one for the fluorescent lamps and the second one for the high intensity discharge lamps, where electronic ballasts with a high power factor are obtained. The operation, analysis, and experimental results are shown. [ABSTRACT FROM PUBLISHER]

This paper deals with the design, modeling, analysis and implementation of unity power factor (UPF) based electronic ballast for a fluorescent lamp (FL). The proposed electronic ballast uses a boost AC-DC converter as a power factor corrector (PFC) to improve the power quality at the input ac mains. In this single-stage UPF based electronic ballast, boost PFC converter and a half bridge series resonant inverter (HBSRI) share a common power switch. Thus one power switch is reduced as compared to the conventional two-stage approach. The design, modeling, analysis and implementation of this topology were carried out in MATLAB-Simulink environment for a T8 36 W, 220 V, 50 Hz fluorescent lamp. The switching frequency was kept more than the resonant frequency of the inverter, to ensure the zero voltage switching (ZVS) operation of both power switches. This resulted in reduction of high frequency switching losses. The power quality parameters such as displacement power factor (DPF), distortion factor (DF), power factor (PF), crest factor (CF) and total harmonic distortion of ac mains current (THD) were evaluated to analyze the performance of proposed electronic ballast. Test results on a developed prototype of PFC electronic ballast were included to validate the design and simulated results. [ABSTRACT FROM AUTHOR]

In this paper, we investigate multilayer tubular conductor for multi-MHz Wireless Power Transfer systems high- Q (quality factor) resonators. The conductor layers’ thicknesses and current sharing between them are optimized at 13.56 MHz, showing significant reduction in conductor ac resistance R{AC}. Capacitive ballast is used as a practical method for current sharing between layers and operation of coil near resonance. A two-layer conductor is designed, fabricated, and characterized at 27.93 MHz, showing 18.1% and 12.8% reduction in R{AC}, compared with an identical conductor without capacitive ballast and a same size solid conductor, respectively. [ABSTRACT FROM PUBLISHER]

This paper presents a design methodology for an electronic ballast applied to ultraviolet radiation (UV) lamps for a drinking water purifier, providing adjustable UV dose in order to ensure the inactivation of microorganisms’ reproduction, commonly found in untreated water, which can be harmful to human health. The design methodology is based on the multiple segment summation source model, used for defining the UV dose applied to penstock purifiers, considering immersed lamps on a water slide enclosure, which in combination with its hydraulic behavior, provide a good performance for the microorganisms UV absorption along the entire purifier structure ducts. Thus, the water purifier was designed using hydrostatic simulations, in order to ensure compliance with the NSF/ANSI Standard 55, for commercial and residential applications. Thereby, an electronic ballast that guarantees a controlled preheating process for the UV lamp electrodes before its ignition and sets the nominal power point on the steady state, was implemented in order to guarantee the designed UV dose. Furthermore, the ballast incorporates a power factor correction flyback input rectifier stage, in discontinuous conduction mode, with universal input voltage range (90 V \text{rms}–240 V \text{rms}), attending the limits imposed by IEC 61000-3-2 Standard, for class-C devices. [ABSTRACT FROM PUBLISHER]

This paper presents an interleaved half-wave rectifier circuit, which constitutes an electronic ballast with high open-voltage gain and current doubler. It is suitable for applications in short-arc xenon lamp needing high open-circuit voltage and low operating voltage. By integrating interleaved half-wave rectifier with LCC resonant circuit, the electronic ballast can provide a low arc-sustaining current dc power source with low ripple and dimmable capability along with starting current suppression feature. Finally, a 25-A 500-W short-arc xenon lamp electronic ballast is developed to possess full load efficiency as high as 91.32% along with dimming range falling between 7.6% and 100% and peak starting current being as low as 16 A. [ABSTRACT FROM AUTHOR]

An LED driver compatible with various electronic ballasts that are currently commercially used is newly proposed, which adopts a variable switched capacitor by controlling the switching duty cycle for LED power regulation. The resonant frequency of an LC resonant tank of electronic ballasts can be changed, which makes the proposed LED driver versatile for electronic ballasts for various switching frequencies. In this way, the fluorescent lamp is replaced with an LED lamp, where the electronic ballast in the lighting infrastructure remains unchanged. The zero voltage switching is applied for the variable switched capacitor in the electronic ballast, operating at a frequency of 30–60 kHz. Neither an inductor nor a transformer is introduced in the proposed LED driver, which leads to compact size and high efficiency. Furthermore, no electrolytic capacitor is used, which is beneficial for the long lifetime of LED drivers. A prototype LED driver of 16 W was implemented and verified for the three types of electronic ballasts that are most popular in markets. The LED power was well regulated for a wide range of the source voltage variations between 180 and 270 V, and the power efficiencies of the proposed LED driver were 95.8%, 96.1%, and 94.1% for the instant start, rapid start, and programmed start types of the electronic ballasts, respectively. [ABSTRACT FROM PUBLISHER]

In this paper, a new technique to equalize light-emitting diode (LED) currents in multiarray LED lamps is proposed. The current through the LEDs is controlled by changing the inductance of a variable inductor. The proposed technique can be employed to control the current through each LED branch independently. The operation principle of this technique and a design example of the proposed system are presented in detail in this paper. As an example, a forward converter has been selected to supply the LED branches, which can be designed to operate with one or several outputs. The component values of the converter as well as the LED current control circuit are also calculated as a design example. A prototype of the circuit has been implemented. The experimental results obtained at the laboratory are satisfactory and in accordance to the proposed design methodology. The proposed technique can prove to be very cost-effective for LED drivers in the range of 100 W and beyond with multiple independent LED arrays. [ABSTRACT FROM AUTHOR]

Current-controlled variable inductors adjust the inductance of an alternating current (ac) coil by applying a controlled dc current to saturate the iron cores of the ac coil. The controlled dc current has to be maintained during operation, which results in increased power losses. This paper presents a new stress-based variable inductor to control inductance using the inverse magnetostrictive effect of a magnetostrictive material. The stress can be applied by a piezoelectrical material, and thus a voltage-controlled variable inductor can be realized with zero-power consumption. The new stress-based variable inductor concept is validated using a 3-D finite-element analysis. A prototype was manufactured, and the experimental results are presented. A linear relationship between inductance and applied stress can be achieved. [ABSTRACT FROM AUTHOR]

The emissions of polychlorinated biphenyl (PCB) congeners from thirteen caulk samples were tested in a micro-chamber system. Twelve samples were from PCB-contaminated buildings and one was prepared in the laboratory. Nineteen light ballasts collected from buildings that represent 13 different models from five manufacturers were tested in 53-L environmental chambers. The rates of PCB congener emissions from caulking materials and light ballasts were determined. Several factors that may have affected the emission rates were evaluated. The experimentally determined emission factors showed that, for a given PCB congener, there is a linear correlation between the emission factor and the concentration of the PCB congener in the source. Furthermore, the test results showed that an excellent log-linear correlation exists between the normalized emission factor and the vapor pressure (coefficient of determination, r 2 ⩾ 0.8846). The PCB congener emissions from ballasts at or near room temperature were relatively low with or without electrical load. However, the PCB congener emission rates increased significantly as the temperature increased. The results of this research provide new data and models for ranking the primary sources of PCBs and supports the development and refinement of exposure assessment models for PCBs. [ABSTRACT FROM AUTHOR]

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 absence 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 effects 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. [ABSTRACT FROM AUTHOR]

This paper presents the current stabilization technique that uses high-frequency voltage pulses to supply discharge lamps and takes advantage of the resistivity of the plasma to limit the current through the lamp. A computational model that regards the chemical and physical discharge characteristics for high-pressure sodium lamp was implemented in MATLAB to validate the proposed power supply. A 150-W prototype was implemented to confirm the current stabilization technique. [ABSTRACT FROM PUBLISHER]

This study deals with the design, modelling and implementation of unity power factor (UPF) boundary conduction mode (BCM)-based electronic ballast for a T8, 36 W fluorescent lamp. In low power applications, BCMbased boost converter is widely used because of the low inductor value, however, because of zero crossover distortion, achieving a total harmonic distortion of <10% is difficult for universal AC mains. In proposed electronic ballast, UPF has been achieved at universal AC mains by using a boost power factor corrected converter operating in BCM with constant on time control. The achieved constant DC-link voltage is converted into high frequency AC voltage using a quasi-half bridge series resonant inverter to initiate the discharge and also to drive the fluorescent lamp with constant current. The modelling and simulation of the proposed topology have been performed using sim power system tool-boxes in MATLAB-Simulink environment. The switching losses have been reduced by achieving zero voltage switching at an operating switching frequency of 46 kHz. Different evaluated parameters have been found as per the international standard IEC61000-3-2 of class C regulations. [ABSTRACT FROM AUTHOR]

Lighting is one of the major energy end uses, which accounts for approximately 20–30% of electricity consumption in buildings. In fact, the fluorescent lamp is the most employed lamp in a lighting system for both inside and outside the building. The ballast is one of the major components of fluorescent lamps; it exists commercially as an electromagnetic ballast, a low loss ballast and an electronic ballast. To reduce energy consumption in a lighting system, the electronic ballast has already been introduced for profit in terms of its peak demand reduction and energy conservation in the building. However, when the electronic ballast functions, harmonics will be generated. Hence, this paper investigates energy savings and the generation of harmonics when using a fluorescent T5 lamp with electronic ballast in a building. The efficiency indices in terms of illumination, energy savings, and harmonics are also evaluated and compared with the fluorescent T8 lamp operating with a low watt loss electromagnetic ballast, which is also widely used. The obtained results are useful for the design and decision to install a fluorescent T5 lamp with electronic ballast in building lighting system to conserve energy and/or reduce energy consumption for the future of the country. [ABSTRACT FROM AUTHOR]

This paper presents a comparative investigation, design and development issues about six different single-stage topologies, applied as electronic ballasts, for electrodeless fluorescent lamps. The ballast is intended to feed a 100 W lamp at 250 kHz, with dimming feature. The proposed topologies use different converters for the power factor correction (PFC) stage: Buck-Boost, SEPIC, Zeta, Cúk, Flyback, and Boost. All of them operate in discontinuous conduction mode. A resonant half-bridge inverter is used as lamp power control (PC) stage. The integration of both stages (PFC and PC) is proposed in this paper. In this way, it is possible to reduce the number of active switches, as well as simplify the required driving and control circuitry. Experimental results demonstrate the feasibility of the proposed dimming technique that achieved around 56% lamp power dimming, from 100 W down to 44 W. The implemented topologies attained high average power factor (>0.98), and low line current average total harmonic distortion (<;15.3%). A comparison among all the proposed topologies in terms of power factor, harmonic distortion, efficiency and number of components is presented. Finally, a comparison between an integrated and a nonintegrated SEPIC half-bridge converter is also performed. [ABSTRACT FROM AUTHOR]

A detailed controller design for indirect constant power regulation of high intensity discharge (HID) electronic ballast and the experimental implementation of an adaptive passivity-based constant power (PBC) controller has been extensively studied through simulation and the findings are reported in this paper. An indirect method to regulate the inductor current to ensure the lamp constant output power is proposed in order to overcome the difficulties in measuring the output power of the HID ballast. The controller is derived using passivity theory which guarantees global stability and asymptotic convergence of all state errors. The simulation and controller design are based on an average model using the Euler-Lagrange (EL) equations of the system. As the lamp resistance will inevitably change with ageing, an adaptive method is used to compensate for the lamp performance as the lamp ages. This equips the controller the power to adapt to load variations and there is no need to tune the design parameters values each time manually. Another interconnection and damping assignment (IDA)-PBC method is analyzed and simulation results are provided for comparison. Computer simulation and hardware implementation are carried out to verify the system model and to demonstrate the controller is robust. [ABSTRACT FROM AUTHOR]

This paper presents a comparative analysis of the performance characteristics among different dimming methods for electronic ballasts using the self-oscillating half-bridge (HB) inverter with a power factor correction (PFC) stage. Initially, a review of common dimming methods presented in the literature is presented, and a general analysis of each dimming method is carried out. Furthermore, the operation of the dimmable self-oscillating electronic ballast with a PFC stage is analyzed in order to evaluate the performance of each different dimming methods used. Finally, a comparison among the different dimming methods implemented with the self-oscillating HB inverter and PFC stage is carried out. [ABSTRACT FROM AUTHOR]

In this study, for application of 36 W/220 Vrms/50 Hz fluorescent lamp, a high performance of high-power-factor and low line input current harmonics of electronic ballast is proposed. The proposed ballast has a structure based on a combination of charged pump and valley fill circuit. By adding paralleled capacitors to each power switch and setting the circuit parameters, operation modes of the inverter can be modified from single-stage conventional class D to a class DE. Consequently, duty ratio can be reduced by up to 25% so that the voltage stress at power switch is lower when compared with the conventional class D inverter. Furthermore, switching power loss and dv/dt can also be reduced because of zero voltage switching condition. Details of design and circuit operation are described. The experimental results of prototype circuit, operated around 50 kHz of switching frequency at full power output, show that the proposed ballast has 94.48% of efficiency, 4.30% of THDi, 0.996 of input power factor and 1.38 of lamp current crest factor. [ABSTRACT FROM AUTHOR]

In the past, only governments and large corporations could afford the high cost of earth observation and atmospheric data collection. A high-altitude balloon system called ValBal flies for days at a time at a cost under $1,000, putting it within reach of start-ups and even hobbyists. [ABSTRACT FROM AUTHOR]

This paper proposes a novel single-stage electronic ballast with high power factor (HPF) for supplying fluorescent lamps. The presented electronic ballast integrates a dual boost converter with coupled inductors and a half-bridge series-resonant parallel-loaded inverter into a single-stage power conversion topology. The features of the ballast are cost-effectiveness, HPF (\PF > 0.98), high circuit efficiency ( $ > $90%), low input current total harmonic distortion (\THD < 7\%), low level of crest factor (\CF < 1.4), and zero-voltage switching obtained on both two power switches. Operational principles, design equations, and experimental results of one T5-type fluorescent lamp with a rated power of 21 W operating at 50 kHz switching frequency with 110 V-RMS line input voltage are presented. Satisfactory results demonstrate the feasibilities of the proposed ballast. [ABSTRACT FROM PUBLISHER]

Utility voltage fluctuations not compensated by the low-frequency voltage loop of the power factor correction (PFC) stage cause a perceptible variation in the light emitted by lamps, unpleasant for the human eye and known as flicker effect. A novel extension of the digital control for PFC stages analyses the input voltage, detects the fluctuations in the range of human flicker sensitivity and modifies the PFC output voltage controller to avoid their propagation to the DC bus. The purpose of the controller is to make the PFC compatible with any second stage lamp driver, assuring the mitigation of the lamp light variation caused by utility disturbances in consistent with the human eye perception. The controller is implemented in a field programmable gate array. A constant lamp luminance is achieved with this digital controller with no dependence on the next ballast stage. [ABSTRACT FROM AUTHOR]

In the paper, a novel pulse ignition circuit is proposed for electronic ballast with the zero-voltage-switching quasi-square wave (ZVS-QSW) converter; the voltage pulse of the proposed igniting circuit contains both a high frequency part and a low frequency part; the high frequency part made it easy to exit the gas in the ionization conduction state in the high-intensity discharge lamp, and the low frequency part makes it easy to lower the igniting potential and provides the continuous pulse energy. The circuit is with few components, low costs, high reliability, and easy to control. The circuit model is analyzed in detail and the influence of the circuit parameters on the pulse amplitude and width is given in this paper. The peak current is limited and the amplitude variation caused by the deviation of the parasitic capacitor for the transformer is restricted by the auxiliary inductor. The auxiliary inductor and the transformer parasitic capacitor form another resonant circuit. As a result, an igniting pulse sequence with two different frequencies is applied to the lamp and both pulse amplitude and width are guaranteed. In the laboratory, the circuit is used in a 70-W metal halide lamp electronic ballast with the ZVS-QSW converter, and the lamp can be ignited reliably. [ABSTRACT FROM AUTHOR]

Electronic ballasts for high-pressure sodium lamps based on an ac-chopper topology are proposed as a cheaper and less complex alternative to the industry-standard low-frequency square-wave ballasts. In this paper, the design process of the ac-chopper ballast is reviewed, and the design tradeoffs caused by the single-stage topology are discussed. The analytical and simulation results are verified with measurements of a 250-W prototype system, including a detailed list of the losses for the different circuit components and electromagnetic compatibility measurements. Due to the disadvantages of the single-stage topology, a comparison to a two-stage ballast using the inverter stage of the ac-chopper ballast with a separate power factor correction stage is provided. [ABSTRACT FROM PUBLISHER]

Experimental tests of metal extraction from stones sampled from artificially contaminated railway ballasts are presented and discussed. Metal extraction was performed by washing with aqueous solutions of disodium ethylenediaminetetraacetate (EDTA), at selected concentrations. The effectiveness of the remediation process was evaluated using leaching tests. The results indicate that the washing technology represents a successful and affordable solution for the implementation of an on-site treatment aimed at a reuse process. Adopting a 0.05 M EDTA solution, extraction yields in the range between 40% and 70% were achieved, depending on contact time and pH of the washing solution. [ABSTRACT FROM AUTHOR]

Abstract: Approximately, 20% of the electricity consumed in the world is spent for lighting. More efficient utilization of the sun, as a natural source of light, for lighting would save electricity used for lighting. The aim of this study is to illuminate a windowless room via a light-pipe and dimmable electronic ballasts. Light-pipe is used for the illumination of the space during the daytime. In case of inadequate daylight, artificial lighting is made via dimmable electronic ballasts and fluorescence lamps. Artificial lighting is supervised by a fuzzy logic control system to keep the illumination level at 350lux. When there is a motion in the room, the system works with the message of the motion sensor, which, thereby, enables energy saving. Additionally, dimming the lamps result in conversation of the electrical energy used for illumination. After the experimental studies, 350lux value targeted in the work plane is achieved with ±10lux error. [Copyright &y& Elsevier]

An LED lamp driver with its input compatible with high- and low-frequency sources is proposed. It can be powered by the ac mains, low-frequency electromagnetic ballast, or high-frequency electronic ballast. Its input impedance is controlled to meet the operational requirements and conditions of different sources and its output is controlled to deliver the required power to the LED array. When the driver is powered by a low-frequency source, like ac mains or low-frequency electromagnetic ballast, it is configured as an active power factor corrector. Its input current follows the wave shape of the source voltage. When the driver is powered by a high-frequency source, like electronic ballast, it is configured as a phase-shifted resonant converter with controllable input resistance and susceptance. Moreover, the driver has a startup mechanism that emulates the ignition process of a fluorescent lamp. Such a wide source compatibility of the driver enables the lamp be applied in new lighting installations or retrofitting fluorescent lamps with LED lamps without modification of existing ballasts and/or lighting infrastructure. A 20-W prototype, which is designed to retrofit a 36-W T8 fluorescent lamp, has been built and evaluated with different sources, including ac mains (110 V/60 Hz, 220 V/50 Hz), electromagnetic ballast, and electronic ballast. [ABSTRACT FROM AUTHOR]

This paper proposes a high-power-factor electronic ballast for metal-halide (MH) lamps. In the proposed circuit, two buck-boost converters and a buck converter are integrated with a full-bridge inverter by sharing the four active switches of the full-bridge inverter. Two active switches are switched at high frequencies, while the other two are switched at lower frequencies. The buck converter is used to step down the DC-link voltage of the full-bridge inverter and filter out the high-frequency components to drive lamps with a low-frequency square-wave (LFSW) current. The buck-boost converters are operated at discontinuous-conduction mode to perform the function of power-factor correction (PFC) to ensure almost unity power factor at the input line. By tactful arrangement of diodes, the DC-link capacitors are discharged in parallel; this helps to operate the high-frequency active switches at a high duty ratio, achieving a small peak value of the PFC-converter current and correspondingly smaller conduction losses. Detailed operation modes and the design equations are provided. A prototype electronic ballast for a 70 W MH lamp is built and tested. Experimental measurements have proven that the proposed electronic ballast has the advantages of high-power factor and being free of acoustic resonance. By integrating the active switches of the converters and the inverter, the proposed electronic ballast is advantageous in terms of cost-effectiveness and high energy-conversion efficiency. [ABSTRACT FROM AUTHOR]

This study presents a single-stage electronic ballast for the high-intensity-discharge (HID) lamp with high-power factor. The presented ballast consists of a discontinuous-conduction-mode operated dual-boost converter to achieve input current shaping, and a high-frequency combined with a low-frequency square-wave-driven half-bridge-type inverter for supplying the HID lamp with low-frequency square-wave sources. The attractive features of the proposed ballast are highpower factor (> 0.99), low total harmonic distortion of input utility-line current (< 10%), high efficiency (> 90%), costeffectiveness and freedom from acoustic resonance. The operational principles, design guidelines and a design example are included in this paper. A prototype ballast circuit has been successfully implemented and tested for supplying three different brands of 70W HID lamps operating with 110 V-root-mean-square input utility-line voltage. Satisfactory experimental results demonstrate the functionalities of the proposed ballast. [ABSTRACT FROM AUTHOR]

The use of continuous welded rails (CWR) is increasingly common and is particularly important when it comes to high-speed ballasted tracks. As the longitudinal displacements are restricted in CWR tracks, a considerable rise in temperature induces compressive stresses in the rails that can lead to track buckling. Given the nonlinear behavior of the ballast, usually represented by a linear plastic model, the problem of snap-through buckling may occur, for which only a few nonlinear analysis methods can trace the full response of the track structure. However, these methods fail to yield convergent solutions for problems with thermal loads when implemented in their conventional algorithm. For this reason, a new methodology is presented allowing the calculation of the safe temperature. In addition, some analytical results are also derived for comparison with the numerical results, obtained using three-dimensional finite element beam models provided by ANSYS. [ABSTRACT FROM AUTHOR]

New mathematical models of L-complementary self-oscillating class D inverter with output voltage clamping in the steady state and during starting are proposed in this paper. The proposed models are very useful for predicting the converter operation and optimizing the circuit design. Experimental results for a 42-W spiral compact fluorescent lamp electronic ballast are presented to validate the analysis. [ABSTRACT FROM AUTHOR]

This paper presents an electronic ballast for driving high intensity discharge (HID) lamps with low frequency square waveform from a dc supply. From the dc source (e.g., PFC rail), a flyback arrangement is inserted into a switching structure whose output provides low frequency voltage yet avoiding instability issues. Proposal's main advantage is the use of one single choke of simple assembly and only two active switches for current control and inversion. Converter design for DCM is presented in this work, besides an equivalent circuit from a control point of view. Small signal ac model is obtained and a feedback control loop is designed, based upon frequency response stability and performance analysis. HID dynamics is inserted into converter model, with feedback directly implemented. A prototype is presented and described in detail, consisting of a complete power and sensing circuit fully referenced to the switches common ground proposal. For design conformity, experimental and simulation results from Matlab and PSIM are presented, as well as discussions about the converter feasibility. [ABSTRACT FROM AUTHOR]

This paper presents an approach to reduce the size of low-frequency square-wave (LFSW) ballasts by using a single stage for resonant ignition and LFSW operation together with soft-saturation magnetic material and digital control techniques. Inductor design constraints are developed to leverage the nonlinear inductor behavior and achieve both size reduction and desirable performance in lamp ignition, warm-up, and normal operation modes. The digital controller provides multiple functions, including 1) a phase-controlled resonant sweep to achieve reliable lamp ignition and device protection with zero-voltage switching despite the nonlinear tank inductance, 2) lamp ignition detection and rapid transition to LFSW mode for lamp warm-up, 3) fast LFSW polarity transitions with optimal timing control for acoustic resonance free operation, and 4) two-loop feedback control. A fast current control loop limits and stabilizes the lamp current and rejects large ripple from the power factor correction (PFC) stage in order to reduce the size of the PFC output capacitor. A slow power control loop rejects variations in the lamp characteristics during warm-up and lamp aging. Experimental results are presented showing successful ignition and operation of a 150-W high-intensity discharge lamp. [ABSTRACT FROM AUTHOR]

CuO is doped into (Na0.5K0.5)NbO3 (NKN) ceramics to improve the piezoelectric properties and thus obtain a piezoelectric transformer (PT) with high output power. In X-ray diffraction patterns, the diffraction angles of the CuO-doped NKN ceramics shift to lower values because of an expansion of the lattice volume, thus inducing oxygen vacancies and enhancing the mechanical quality factor. A homogeneous microstructure is obtained when NKN is subjected to CuO doping, leading to improved electrical properties. PTs with different electrode areas are fabricated using the CuO-doped NKN ceramics. Considering the efficiency, voltage gain, and temperature rise of PTs at a load resistance of 1 kΩ, PTs with an electrode with an inner diameter of 15 mm are combined with the circuit design for driving a 13-W T5 fluorescent lamp. A temperature rise of 6°C and a total efficiency of 82.4% (PT and circuit) are obtained using the present PTs. [ABSTRACT FROM PUBLISHER]

This paper presents the analysis, design, simulation and experimental results of a digital control strategy applied to an electronic ballast to supply a 70-W high-pressure-sodium lamp. The electronic ballast consists of a single-stage converter that integrates a buck converter to provide power factor correction and two flyback converters to supply the lamp, with low frequency square waveform, in order to avoid the acoustic resonance phenomenon occurrence. The proposed digital control strategy is composed of three control loops: voltage loop for lamp ignition and warm-up, an inner current loop for steady state, and a slow outer power loop to maintain the lamp power constant during its useful life. The lamp dynamic model is included to the ac model of the converter, so the effects of its right-half-plane zero are considered to design the digital control system. Fixed-point simulation is presented using Q base number format, where the exact variable values employed in the microcontroller code are used. Experimental results are included to demonstrate the performance of the proposed digital control strategy. [ABSTRACT FROM PUBLISHER]

The incorporation of a ballast resistor layer underneath field emitters can improve the reliability and stability of field emission cathodes. However, it has not been successfully demonstrated in carbon-nanotube (CNT)-based field emitters. In this paper, we introduce a fabrication process of a low-density vertically aligned CNT array with a ballast resistor layer. Furthermore, an X-ray tube prototype based on this cathode is demonstrated. [ABSTRACT FROM AUTHOR]

Light sources as LEDs are with high efficacy and have possibility of light dimming. A microprocessor controlled photo sensor array enables automatic measurement process of obtaining photometrical and electrical parameters, for preliminary testing of developed luminaries, existing products and analyzing data to evaluate lighting dimming process efficiency at different dimming levels. [ABSTRACT FROM AUTHOR]

Public lighting applications, including street and pedestrian lighting provide crucial services for human safety, productivity and comfort in the modern urban and suburban landscape. However, energy charges for these lighting applications represent the largest part of all expenses for public lighting. The increasing price of electricity is, by itself, responsible for the majority of the increase in streetlight operation budgets. Telemanagement systems that control public lighting networks offer a significant opportunity to save energy and decrease the impact of artificial lighting on the environment. When high intensity discharge lamps are used regulation of light flux can be achieved using either step-dimming or continuous dimming ballasts (1-10V, DALI). This paper presents the variation of electrical parameters of two lighting solutions due to continuous dimming of light output. The first solution consists of a high pressure sodium SON-T 150W lamp and the electronic DynaVision SON ballast. The ceramic metal halide CDO-TT 150W lamp and the electronic DynaVision CDO ballast represent the second studied solution. Both solutions use the 1-10V analogic protocol technology for continuous dimming of lamp light flux. The results are presented as a comparison of the influence of light output dimming on the electrical parameters of the two solutions. This comparison is defined in terms of active and reactive power consumption, current harmonics and power factor values. [ABSTRACT FROM AUTHOR]

This research paper presents a practical approach in terms of using the technology found in CFL lighting devices for controlling the new types of high power light emitting diodes, (LED). Advantages, like good reliability and cost efficiency of the electronic ballasts found in CFL, which can be used in future LED based lighting devices are representing a very good prospect for research but also good opportunity in terms of high mass implementation. This unified technology will be presented in this paper by means of practical measurements and Orcad/PSpice simulations. [ABSTRACT FROM AUTHOR]

A novel ballast control IC is presented, which fully satisfies specific needs of hot cathode fluorescent lamp and significantly simplifies the external circuit design with the great reliability, generality and practicability. Integrated with a simple multi-frequency oscillator, the IC obtains adjustable preheat-time by controlling frequency changing rate with an external capacitor, and adjusts the minimum frequency by controlling minimum charging current with an external resistor. And a steady dead-time can also be achieved. Based on 0.5 μm BCD process, the HSPICE simulation was done with 14 V voltage supply. While a 1 μF capacitor and a 100 kΩ resistor are utilized in the external circuit, this IC gives out a preheating frequency up to 175 kHz and the minimum working frequency is 75 kHz. A high frequency preheating time of 1 s and a steady dead-time of 2 μS can also be achieved. [ABSTRACT FROM AUTHOR]

This paper presents a new model for electrodes of fluorescent lamps with constant RMS voltage heating, in order to predict the electrodes' characteristic ratio of hot-to-cold resistance (RH/RC) during the preheating phase, which is related to both the preheating time and the RMS value of voltage across the lamp electrodes. In developing this model, we first analyzed a simple test platform, to obtain a functional fit to the measured data, and then verified the model using a prototype laboratory ballast. The experimental results presented here demonstrate the validity of the analysis and confirm its potential as an effective tool for the design of electronic ballasts. [ABSTRACT FROM AUTHOR]

This paper presents the development of a universal electronic ballast for TL5 lamps. The intent is to efficiently operate the maximum number of TL5 lamps with different power ratings at nominal power, using a resonant variable inductance, provided by a magnetic regulator, while maintaining the switching frequency constant. A microcontroller and additional digital circuitry are used to command a dc-dc buck converter to supply the necessary dc control current to the magnetic regulator and to regulate the switching frequency of the half-bridge resonant inverter that supplies the lamp. The selection of the resonant capacitance is done in order to comply with the SoS limits established for each lamp. Experimental results with lamps ranging from 14 to 49 W, operating with high efficiency and high output, are presented in this paper. [ABSTRACT FROM AUTHOR]

This paper presents the analysis and design of the self-oscillating full-bridge electronic ballast for the metal halide lamp at 2.65-MHz operating frequency. In order to avoid the acoustic-resonance problem of the metal halide lamp and meet the electromagnetic interference limitation by International Electrotechnical Commission (IEC) regulation, the self-oscillating full-bridge electronic ballast is operated at 2.65-MHz radio frequency (RF). However, the effect caused by the gate-to-source capacitor Cgs of the mosfets on the self-oscillating gate-drive network becomes significant to influence the design of the operating frequency at RF. Therefore, the gate-to-source capacitor Cgs of the mosfets is considered to derive the design equation of the magnetizing inductor for the current transformer in the self-oscillating gate-drive network. Finally, based on the prototype circuit of a 35-W self-oscillating full-bridge electronic ballast with constant-lamp-current control and no-lamp-protection scheme at 2.65-MHz operating frequency, the SIMPLIS simulation and experimental results are used to validate the effect from gate-to-source capacitor Cgs, the proposed design equation, and the design criteria. [ABSTRACT FROM AUTHOR]

Compact fluorescent lamps (CFLs) incorporating electronic ballasts are widely used in lighting. In many cases, the ability to dim the lamp is a requirement. Dimming can be achieved by varying the switching frequency of the inverter or by changing the voltage supplied to the inverter. The effect of dimming by both approaches on the power losses in the inverter is studied in this work. The lamp and associated inverter has been modeled in Pspice, using a behavioral model for the CFL. Predicted losses are in good agreement with experimental data obtained from calorimetry. After verification, the model was then used to determine the distribution of losses within the inverter, enabling a comparison of the effects of the two dimming methods to be made. [ABSTRACT FROM AUTHOR]