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The objective of this work is to study the influence of a pulsed power supply on the energy efficiency of high-intensity discharge lamps in comparison with a pseudo-continuous ballast. The results presented in this paper concern the dynamic behaviour of discharges in mercury vapour doped with thallium iodide. The acquisition of the arc current, arc voltage and spectral radiation enables us to investigate the influence of the pulsed power supply on the electrical characteristics of the lamp such as the behaviour of the lamp conductance and spectral radiance. The analysis of the 577 nm mercury line's response to the current pulse excitation allowed us to identify several phases. Good agreement has been found between simulation and experimental results. [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]

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]

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 wattage-independent (7–18 W) compact fluorescent lamp (CFL) model has been developed in Matlab-Simulink and validated in low-frequency (50 Hz) operation in our earlier work. In this paper, the same lamp model is simulated for high-frequency operation and then validated experimentally with a 9 W test CFL driven by a compatible electronic ballast (e-ballast). Simulation results have shown a maximum 6.4% deviation compared to the measured data. Thereafter, the developed model is applied to obtain the arc resistance versus power and power versus frequency characteristics of CFLs required to design dimmable e-ballasts. An algorithm is developed to compute design parameters of a dimmable e-ballast based on voltage-fed series-parallel resonant inverter topology. The electrical performance of the designed e-ballast is simulated at three different power levels (100%, 75% and 50%) using Matlab-Simulink. [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 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]

In this paper, the dimming effects on the photometric and electric characteristics of high intensity discharge lamps supplied by a low frequency square waveform are evaluated. For this evaluation an electronic ballast is presented. The ballast consists of a current source, AC/DC converter and a full-bridge inverter. The electronic supply provides to the lamp a different form of current excitation (square waves with variable short drops). Dimming control and the characteristics of low frequency operated high intensity discharge lamps are described. The lamp is represented in a simulation by its conductance model and coupled to its electronic power supply. Experimental results are shown and compared with the simulation. A dimming range from 100% to about 60% has been achieved. [ABSTRACT FROM AUTHOR]

The main advantages of high-frequency electronic ballasts for high-intensity discharge lamps are high luminous efficacy, small size, lightweight and longer lifetime. This is why high-intensity discharge lamps operating at high frequency are widely used. This paper proposes an approach for designing resonant circuit electronic ballasts controlled by frequency variation for high-intensity discharge lamps. The proposed technique including an AC/DC rectifier, a power factor correction circuit and a DC/AC half bridge inverter. These electronic ballasts offer a wide range of dimming controls and can avoid acoustic resonance. However, under dimming, the electric and photometric characteristics of the lamp change. In order to study these effects under the process of dimming, this work studies the lamp properties by varying both lamp power and operating frequency. [ABSTRACT FROM AUTHOR]

This paper proposes a novel single stage single switch resonant inverter with high power factor for electronic ballast. The power factor correction circuit is at the input side. It is designed to operate at discontinuous conduction mode. The lamp power is controlled by adjusting the duty ratio of the active switch of the power factor correction circuit. The circuit operation is analyzed in detail to derive the design equations. Circuit parameters are designed based on design considerations. Finally, prototype electronic ballast for a 40-W compact fluorescent lamp is built and tested. The efficiency and the performance of the proposed converter are verified for the designed prototype. Copyright © 2016 John Wiley & Sons, Ltd. [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]

This paper proposes a way to quantify the emissions of mercury (Hg) and CO2 associated with the manufacture and operation of compact fluorescent lamps with integrated ballasts (CFLis), as well as the economic cost of using them under different operating cycles. The main purpose of this paper is to find simple criteria for reducing the polluting emissions under consideration and the economic cost of CFLi to a minimum. A lifetime model is proposed that allows the emissions and costs to be described as a function of degradation from turning CFLi on and their continuous operation. An idealized model of a CFLi is defined that combines characteristics stated by different manufacturers. In addition, two CFLi models representing poor-quality products are analyzed. It was found that the emissions and costs per unit of time of operation of the CFLi depend linearly on the number of times per unit of time it is turned on and the time of continuous operation. The optimal conditions (lowest emissions and costs) depend on the place of manufacture, the place of operation and the quality of the components of the lamp/ballast. Finally, it was also found that for each lamp, there are intervals when it is turned off during which emissions of pollutants and costs are identical regardless of how often the lamp is turned on or the time it remains on. For CO2 emissions, the lamp must be off up to 5 minutes; for the cost, up to 7 minutes and for Hg emissions, up to 43 minutes. It is advisable not to turn on a CFLi sooner than 43 minutes from the last time it was turned off. [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 proposes a method for predicting fluorescent lamp lifetimes based on a minimum number of accelerated life tests. This prediction allows the life of the lamp in continuous operation to be estimated without having to know the nominal lifetime. This paper evaluates the possibility of making this prediction based on two accelerated tests, and finds that this is not generally to be recommended. It also evaluates the advisability of making the prediction based on three accelerated tests and fitting the results by a non-analytical iterative method. We conclude that under certain conditions, this method makes reasonable life predictions for fluorescent lamps associated with specific ballasts. [ABSTRACT FROM AUTHOR]

A novel single-stage single-switch electronic ballast topology with a unity power factor is presented in this paper. The proposed circuit consists of an integrated buck–boost stage that operates in the discontinuous conduction mode to provide a high power factor and a single-switch current-fed resonant inverter to stabilize the lamp current. The proposed topology presents a low cost and compact electronic ballast design method. The detailed descriptions of the circuit's operating principles are provided in this paper. The design equations and mathematical analysis regarding the proposed circuit are discussed in this paper. The proposed ballast has been tested with an 18-W compact fluorescent lamp, and the experimental results confirmed that a very high power factor of 0.995 and an efficiency of 83.4% have been achieved. [ABSTRACT FROM PUBLISHER]

High-intensity discharge (HID) lamps are becoming popular substitutes for halogen lamps in automotive headlamps because of the high lumen/watt ratio and the color of the light. In this paper, a ballast (integrated with a voltage multiplier circuit in the secondary winding of the de converter transformer) with dimming control is presented. The proposed circuit not only eliminates one auxiliary winding but also reduces the voltage across the switch on the primary side and consequently permits the selection of switches with a lower rating. A brief review of the HID circuits is done and compared with the proposed circuit. Experimental results from the prototype are presented. This paper also presents different methods of dimming the automotive HID lamps based on analog and digital control and discusses the relative merits of each of the methods. The dimming control is implemented using both the methods, and experimental results are presented. It is envisaged that the dimming control will provide some flexibility to drivers in the control of HID lamps to suit the driving conditions in the modern cities that are very well lit at night. This paper investigates the merits of each method and discusses the practical issues for implementing such controls. [ABSTRACT FROM AUTHOR]

The threat of an asteroid or comet impacting the Earth has been receiving more attention in recent years, due in part to the discovery of the Apophis asteroid, which was at one time projected to have a significant probability of impacting the Earth in the year 2029. Although a later analysis of the Apophis trajectory precluded this impact, the threat has brought a lot of attention to the dangers posed by asteroids. Many ideas have been put forward for mitigating such threats. This paper presents one such technique: the attachment of a long tether and ballast mass to change the orbit of an Earth-threatening asteroid or comet. Specifically, for this paper, a parametric study was conducted to determine to what degree the trajectory of an asteroid or comet could be altered by attaching a tether and ballast for various values of orbital semimajor axis and eccentricity and for various tether lengths and ballast mass sizes. The results show that a long tether and ballast mass could be effective for such a diversion. It was found that the technique was most effective using longer tethers and larger ballast masses on asteroids or comets with smaller, more eccentric, orbits. [ABSTRACT FROM AUTHOR]

Railway ballast is a granular material with a complex stress-strain relationship under monotonic loading. The discrete element method has been widely used to investigate the mechanical behaviour for the behaviour of granular materials. In this paper, discrete element modelling has been used to capture the essential mechanical features of railway ballast. The effects of particle shape and interparticle friction have been studied. Parallel bonds have also been introduced in the simulations to simulate the interlocking of small-scale asperities, so that the correct stress-strain relationship for ballast can be modelled. Asperity breakage has been modelled by using small balls bonded at the edges of the main body of a particle. A range of confining pressures have been applied to the assembly of particles. The simulations demonstrate the validity of numerical modelling of railway ballast. In particular, the unique contribution of this paper is to show that the monotonic shearing behaviour of railway ballast can be correctly modelled under a range of confining pressures, providing micromechanical insight into the behaviour. [ABSTRACT FROM AUTHOR]

This paper describes a novel light sensor-based information transmission system for indoor positioning and navigation with particular benefits for mobile and wearable computers. It can seamlessly extend outdoor GPS tracking to the indoor environment. In a novel manner, fluorescent light is used as the medium to transmit information, which is encoded by using a pulse-frequency modulation technique. The user receives the encoded light information through a photo-receiver. The information is passed into the wearable or mobile computer after the data is decoded. This information allows positioning information to be given to indoor mobile and wearable computers. We design an economical transmitter circuit by adding few components to a commercial electronic ballast circuit for fluorescent lamps with price of less than US $10. The propose system can be used in indoor guidance and navigation applications. Exemplary applications are included in the paper, with experimented results detailed. [ABSTRACT FROM AUTHOR]

This paper proposes a two-stage low-frequency square-wave (LFSW) electronic ballast with digital control. The first stage of the ballast is a power factor correction (PFC) stage, and the second is a full-bridge (FB) converter used for both lamp ignition and LFSW drive. As a novelty for LFSW ballasts, ignition is achieved without an additional igniter circuit by operating the FB during start-up as a high-frequency resonant inverter. After ignition, the converter operates as an LFSW inverter to avoid exciting acoustic resonances by controlling the FB as a buck con- verter and regulating alternately positive or negative current to the lamp. Lamp power is regulated by adjusting the average current supplied by the PFC stage. Another contribution of this paper is to utilize digital control as a simple solution to achieve multimode control, including resonant lamp ignition, LFSW transitions, and lamp current and power regulation. [ABSTRACT FROM AUTHOR]

This paper presents the piezoelectric transformer (PT)-based continuous-conduction-mode (CCM) current source (CS) charge-pump (CP) power-factor-correction (PFC) electronic ballast. The main drawbacks of the PT-based dc-side discontinuous-conduction-mode (DCM) CS CP-PFC electronic ballast include high di/dt, high current stress and high switching losses. In order to solve these problems that are caused by DCM operation, and to reduce the components count, the PT-based bridgeless CCM CS CP-PFC electronic ballast is proposed in this paper. The experimental results show that the electronic ballast proposed in this paper not only can achieve high power factor and low total harmonic distortion, but also the switches can operate under a zero-voltage-switching condition without requiring a series inductor in front of the employed PT. [ABSTRACT FROM AUTHOR]

Over the past few decades, ultraviolet (UV) water treatment has become widely recognized and accepted by regulatory agencies as a proven disinfection process. With the increased awareness of health concerns and water quality, UV disinfection is quickly gaining popularity in the consumer market as a safe, effective, and economical approach to disinfection. In order to disinfect properly, conventional UV water-treatment systems keep their light intensity at maximum level regardless of the operating condition; this will result in unnecessary energy waste along with lamp-life-span reduction. In this paper, a new design of high- power-factor low-cost electronic ballast with intelligent control for UV water-treatment system is proposed. For the purposes of energy saving, an intelligent-control algorithm is proposed to dim the luminance of the UV lamp according to the measured water flow rate and UV light intensity. Accurate knowledge of the characteristics of the UV lamps is essential for the ballast design. Therefore, an automatic identification system is also proposed in this paper to obtain the characteristic parameters, which are the dynamic and steady-state profiles of the UV lamps. Systematic design procedures are then presented accordingly. The proposed UV water-treatment system boasts the advantages, such as compactness, low cost, and energy saving, and is suitable for residential users. According to the experimental results, the energy-saving capability of the proposed system is better than 50%. [ABSTRACT FROM AUTHOR]

There is a common misconception that energy saving is always equivalent to environmental protection. Compared with electromagnetic ballasts, electronic ballasts have a much shorter lifetime and are not recyclable. This prompts new concerns about their environmental impacts due to the accumulation of a huge amount of toxic and/or nonbiodegradable electronic waste components and materials. In this paper, the combined use of a central dimming system with low-loss electromagnetic ballasts is compared with electronic ballasts. Experimental results have confirmed that the use of a central dimming system for large electromagnetic-ballast-driven lighting systems can be as energy efficient as electronic ballasts. Considering the long lifetime (> 30 years) of electromagnetic ballasts and the recyclability of their magnetic chokes, this paper shows that such combined technology can provide an improved environmentally friendly and energy-saving solution for large-scale electric-lighting systems, particularly for lighting systems in large public areas. Due to the elimination of many electronic ballasts, this proposed technology has the potential of drastically reducing a huge amount of electronic waste. With the positive results obtained in this paper, it is hoped that international regulatory organizations would reconsider their current policies and promote lighting technology that is both environmentally friend!y and energy saving. [ABSTRACT FROM AUTHOR]

Railway ballast particles undergo significant amount of breakage under repeated train load. Breakage of ballast particles, especially highly angular fresh ones, causes an increase in settlement, contributing to track degradation. The quantitative analysis of the influence of breakage on the stress-strain properties of ballast can be performed either experimentally or numerically. Numerical modeling has the advantage of simulating ballast breakage subject to various types of loading and different boundary conditions for a range of material properties. In this paper, ballast breakage under cyclic loading is simulated using a 2D discrete element method (DEM) utilizing the software PFC2D. A new subroutine is developed and incorporated in the PFC2D analysis to study ballast breakage and to quantify breakage in relation to particle size distribution. The influence of confining pressure on both breakage and permanent deformation is also studied and compared with laboratory observations. The findings of this paper provide an insight into the true ballast behavior under cyclic loading and are expected to assist railway practitioners in developing suitable design criteria for track stability. [ABSTRACT FROM AUTHOR]

This paper presents a new methodology for the adjustment of the preheating process and steady-state operation of electronic ballasts intended for hot-cathode fluorescent lamps. The classical series-resonant parallel-loaded half-bridge inverter is the power stage analyzed in this paper. In addition, the preheating process is based on the imposition of a constant rms current through the electrodes, in order to provide a proper value of the Rh /Rc ratio before the lamp start. According to the proposed methodology, it is possible to set suitable operating points for the electronic ballast, considering optimal conditions for the lamps electrodes. Therefore, the proposed methodology for setting the preheating and steady-state operation is a complete platform to the design of electronic ballasts for hot-cathode fluorescent lamps. [ABSTRACT FROM AUTHOR]

This paper proposes high-power-factor electronic ballast for fluorescent lamps. The converter offers a high input power factor and a high-frequency supply to the lamp using a single switch. Besides the simple circuit configuration, the excellent performances of high power factor for ac input side and low lamp crest factor for lamp are included in this paper. The conventional electronic ballast circuit has larger conduction losses because its power flow path of power factor correction (PFC) circuit always includes two diode losses from the front-end bridge rectifier and one power switch loss. The PFC power flow path of the proposed circuit has three semiconductor conduction drops when the active switch is on and two semiconductor conduction drops when the active switch is off. Therefore, it can provide lower conduction loss than the conventional one. The design equations are derived from the analyzed results based on fundamental approximation, and then an easy-to-use design tool is provided accordingly under considerations of filament heating and ignition. A prototype circuit that operates at 40-kHz switching frequency and 110-V line voltage for one 40.W fluorescent lamp is built and tested to verify the analytical predictions. [ABSTRACT FROM AUTHOR]

This paper presents active current-equalization (CE) techniques for equalizing the lamp currents of multi-lamp electronic ballasts. Multi-lamp products, such as the backlighting for liquid crystal display (LCD) panels, have to be capable of equalizing luminance. Due to the deviations of lamps and ballasts, the currents flowing through the lamps are not equal, which causes poor-quality backlight sources for LCD panels. Additionally, since the size of thin-film transistor LCD (TFT-LCD) monitors is becoming larger, a multi-lamp drive system must provide higher levels of voltage and current and more power for longer length lamps and more lamps. Since the number of lamps that can be driven by one inverter is limited, distributed multi-ballast drive systems are becoming popular. In order to achieve current equalization for distributed multi-ballast drive systems, the active CE technique is proposed to equalize every output current of the ballast. In this paper, the three-ballast drive system, for distributed single-lamp inverters, is implemented with the active CE technique. In addition, the CE ability in dimming range is demonstrated by experiments in order to verify the performance of the proposed active CE circuit scheme. [ABSTRACT FROM AUTHOR]

A novel simple control strategy to improve the ignition behavior of a cold cathode fluorescent lamp (CCFL) in digital-dimming mode is proposed in this paper. Due to restriking manipulation in the digital-dimming mode, the lamp life of CCFL is reduced substantially. For extending the lamp life, a digital-dimming controller with current spikes elimination technique is realized to reduce the high ignition voltage and eliminate the ignition current spike. The half-bridge resonant inverter is employed in the presented backlight system to assess the system performance. Complete analysis and design considerations are discussed in detail in this paper. Experimental results agree with the theoretical prediction. The overall efficiency of the system achieved at the rated power is over 84.9%. The ignition voltage is reduced about 30% without any lamp current spike that occurred under digital-dimming operation. [ABSTRACT FROM AUTHOR]

A non-resonant electronic ballast based on one power switch and on one reactive element-one inductance-is described in this paper. The special current mode control implementation provides an intrinsic short-circuit protection and a very simple control circuitry. Filament heating time, current during the heating period, and protection against broken tube can be easily implemented with the proposed circuitry. A greenhouse application with a 120-V dc bus power distribution is presented in this paper. The dc bus voltage is easily obtained (in this particular application) from a classical series-connected 12-pulse rectifier in combination with a transformer with two secondary windings (one in Wye connection and other one in Delta connection). An additional advantage of this configuration is the high power factor obtained at the input stage. [ABSTRACT FROM AUTHOR]

This paper proposes a phase-locked loop (PLL) control scheme for the electronic ballast employing a parallel-serial resonant tank (PSRT), in which the resonant frequency of the circuit is continuously tracked, in order to drive the fluorescent lamps even with low equivalent resistance at steady-state. Compared with the conventional PLL control of the electronic ballasts for cold cathode fluorescent lamps, the proposed PLL control scheme, by sensing the phase signals at the both ends of the resonant inductor, is able to have resonant frequency tracked for the electronic ballasts, where the equivalent resistance of the fluorescent lamps is even equal to hundreds of ohms or lower at steady-state. By employing the current regulator circuit, the proposed PLL controller regulates the values of the lamp's current by adjusting the operating frequency from the resonant frequency as a reference frequency point, the lamp's current is accurately controlled. The analysis of the proposed PLL control scheme will be presented in this paper. Finally, the implementation of a prototype circuit is provided to demonstrate the performance of the proposed PLL control scheme by associating with a current regulator circuit. [ABSTRACT FROM AUTHOR]

The paper proposes an electronic ballast in which the resonant frequency of the circuit is continuously tracked by the phase-locked loop (PLL). This electronic ballast, which employs PLL control, has a high tolerance for the variations that exist in the equivalent resistance of a lamp. At present, the PLL control is used to drive cold-cathode fluorescent lamps (CCFLs), in which variations in equivalent resistance between ignition and the steady state are small, so that phase differences at the resonant frequency are almost fixed; thus the resonant frequency can be tracked continuously by the operating frequency. However, if variations in equivalent resistance are large, the phase difference at the resonant frequency may be not fixed, and thus the resonant frequency may be not continuously tracked by the operating frequency. The paper proposes the electronic ballast for fluorescent lamps with large variations in equivalent resistance between ignition and the steady state. According to the phase characteristics of various resonant tanks and an optimum design of the resonant tank, the circuit's resonant frequency is continuously tracked by the PLL. Since the current regulator circuit limits the value of the lamp current as the operating frequency increases from the resonant frequency, the lamp current is accurately controlled, regardless of variations in the load. The paper discusses the implementation of the proposed ballast with PLL control, which offers high tolerance for the variations of the equivalent resistance in the lamp. [ABSTRACT FROM AUTHOR]

To determine the causes of poor track geometry, a trackbed investigation should comprise a full assessment of ballast, sub-ballast and formation condition. If information about any of these layers is omitted, the true cause of poor formation sites cannot be ascertained satisfactorily and consequently appropriate ground improvement schemes may not be implemented. This has been observed in the UK rail network with examples of a lack of detailed site investigation and subsequent expensive remedial work being carried out without eliminating the initial cause of the problem. This paper summarises the trackbed investigation performed at a site requiring high maintenance, suspected as being caused by poor formation. The paper concludes with an analysis of ground conditions and possible choice of remedial schemes. [Copyright &y& Elsevier]

This paper presents the analysis, design, and experimental results of a new integrated electronic ballast based on the half-bridge boost rectifier followed by the half-bridge series resonant parallel loaded inverter. The electronic ballast features a high power factor and low harmonics input current. The involved converters share the power switches, reducing costs significantly. The input stage of the ballast works in discontinuous inductor current mode with constant duty cycle and variable switching frequency. It is important to maintain this operating condition in order to get a high power factor. Integrating the power stages results in higher complexity in the control design because a close relationship still exists between the power stages. Within the paper, the operating characteristic is established in order to obtain a design method for the ballast. The obtained method is used to design a laboratory prototype for a 26-watt fluorescent lamp. Some experimental results are included. [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]

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]

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]

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]

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]

Ballasted track is the most common form of construction used in railway transportation due to a number of benefits in comparison with other solutions such as slab track. However, the degradation of the ballast particles and the layer settlement lead to important maintenance costs. Thus, diverse research has been carried out to develop new materials with the aim of increasing the service life of the track. To this end, the present paper focuses on the use of crumb rubber (from end-of-life tires) as elastic aggregates mixed with ballast particles, which could reduce ballast degradation and consumption of natural aggregates. At the same time, an abundant waste source is reused and the use of raw binders (proposed technique employed to bond elastic particles to ballast particles) is not necessary, which potentially reduces costs and consumption of raw materials. For this reason, the influence of different percentages of crumb rubber was studied in the laboratory using a ballast box. In addition, once the optimal quantity of rubber had been determined, its effect on ballast behaviour under high stress level was analysed. Results show that the use of 10% of crumb rubber (by volume) could reduce ballast degradation and at the same time as the capacity of the ballast layer to dissipate energy is increased and its stiffness is reduced. Additionally, based on the present laboratory study, the track settlement could be reduced with 10% rubber particles used as elastic aggregates. [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]

Thermal stability is one of several important performance requirements for RF power amplifier modules used for cellular applications. In this work, the conditions for thermal instability in an HBT array for shared and individual ballast configurations are evaluated using experimental results from RF biased life test (RFHTOL) and ADS simulations. The instability is modest under nominal operating conditions, but becomes more severe at elevated temperatures which are frequently used in accelerated reliability tests such as RFHTOL. Thermally unstable power cells exhibit current crowding where one or two cells hog most of the current, resulting in localized hot spots from increased power dissipation density. This paper discusses the link between reliability failures during RFHTOL reliability testing and the thermal stability of HBT arrays used in a power amplifier. Shared ballast arrays are shown to be less thermally stable than individually ballasted arrays and thus have more failures during RFHTOL testing. Electro-thermal results indicate the layout aspects of power amplifier module also play an important role in determining junction temperatures for various stages. [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]

Although manufacturers recommend light-emitting diode technology for all types of urban lighting, it is likely that high-pressure sodium lamps will be used for roadway lighting for many years. The purpose of this paper is to establish whether electronic ballasts represent a better solution for such lamps than electromagnetic ballasts. Special attention was devoted to the fact that electronic ballasts allow considerably higher voltage drops. However, taking into account the earth-fault protection demands, it is shown that electronic ballasts provide only a modest possibility to increase the length of the street lighting section. The techo-economic analysis showed that, owing to the high prices and shorter life of electronic ballasts, conventional electromagnetic control gear still represents a better choice from the financial point of view. [ABSTRACT FROM PUBLISHER]

Environmental impacts of light sources and control gears have been analysed in several life cycle assessments (LCAs). In contrast, this paper analyses the environmental impacts of an entire fluorescent lamp/luminaire combination. The environmental impacts of a fluorescent lamp luminaire with two T5 lamps and an electronic ballast are analysed in a variety of potential environmental impacts. The results show that the energy consumption during use dominates the total environmental impacts by 93% on the average, while manufacturing accounts for 7% and end-of-life less than 1%. The importance of energy consumption is dependent of the used energy source. Compared to a previous LCA of fluorescent lamp luminaire, the division of the results into life cycle stages is similar but there are differences in the numerical results. [ABSTRACT FROM PUBLISHER]

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]