Characterization of Acoustic Resonance in a High Pressure Sodium Lamp

With the last decades, the high pressure sodium (HPS) lamp has been supplied in high frequency in order to increase the efficacy of the lamp/ballast system. However, at some given frequencies, standing acoustic waves, namely acoustic resonance (AR), might develop in the burner and cause lamp luminous fluctuation, extinction and destruction in the most serious case. As we seek for a control method to detect and avoid the lamp AR some main characteristics of the acoustic resonances in a 150W HPS lamp are presented in this paper,. The first one is the characteristic of the lamp AR threshold power, the second one is the differences between forward and backward frequency scanning effects during lamp open loop operation. Thirdly, lamp AR behaviour in closed loop operation with an LCC half bridge inverter will be presented and leads to a new point of view and a change in the choice of the AR detection method. These characteristics allow us to further understand the AR and to better control the lamp

Economic development as design: Insight and guidance through the PSI framework

Economic development is aimed at improving the lives of people in the developing world, and needs to be carried out with design at its heart, but this has often not been the case. This paper first reviews dominant approaches to economic development including the use of subsidies or the creation of markets and demand and the testing of initiatives using randomized control trials. It then introduces ‘development engineering’ as a representative engineering design approach to engineering and technology in development before presenting the view that successful development needs to involve continual learning through innovation in context. The PSI (problem social institutional) framework is presented as a basis for guiding such development as a design activity, and its application is illustrated using examples from India of the unsuccessful introduction of new cooking stoves and then both successful and unsuccessful approaches to rural electrification. A 2-level approach to PSI is taken, in which the lower level represents daily operation of communities and the 2nd level represents the development project including addressing misalignments between the different PSI spaces and levels

Active input current shaper without an electrolytic capacitor for retrofit lamps applications

The evolution of solid-state lighting technology has transformed traditional solutions in lighting. High-brightness light-emitting diodes (HB-LEDs) have become very attractive light sources due to their excellent characteristics, namely high efficiency, a long lifetime, and low maintenance. It is evident that HB-LED drivers must be durable and efficient in order to enjoy these advantages. Moreover, to replace incandescent bulbs, the ac-to-dc HB-LED driver must be simple and have low size and comply with international regulations (i.e., injecting low-frequency harmonics into the mains supply). With the last modifications regarding low-power lighting equipment (i.e., < 25 W), the authors have traditionally focused their efforts on increasing efficiency by sacrificing sinusoidal input current, yet all their solutions obviate the suppression of the traditional electrolytic capacitor of ac-to-dc converters, highlighting that this is the price to pay for a simple and low-size solution. This paper, however, puts forward the design of a simple and low-size ac-to-dc HB-LED driver for retrofit lamps without an electrolytic capacitor in order to extend its lifetime. The solution proposed here derives from a well-known technique used in the past, the active input current shaper (AICS), but without an electrolytic capacitor in this case. If the electrolytic capacitor of an AICS is removed, then low-frequency ripple arises at its intermediate dc bus, adding some distortion in the line input current over the proper natural one of an AICS. However, this addition is slight in comparison to the proper natural distortion of AICSs. Moreover, the low-frequency ripple at the intermediate bus is not transferred to the output with the help of the rapid output dynamic response of the AICS, which prevents flicker. This paper presents a theoretical analysis that guarantees a compromise between compliance with international regulations and the use of capacitor technologies other than the electrolytic design. Finally, a 24-W experimental prototype has been built and tested to validate the theoretical results presented in this paper.This work was supported by the Spanish Ministry of Education and Science under Project MINECO-13-DPI2013-47176-C2-2-R, by the Government of the Principality of Asturias under Project FC-15-GRUPIN14-143, and by European Regional Development Fund grants

A Single-Stage LED Driver Based on ZCDS Class-E Current-Driven Rectifier as a PFC for Street-Lighting Applications

This paper presents a light-emitting diode (LED) driver for street-lighting applications that uses a resonant rectifier as a power-factor corrector (PFC). The PFC semistage is based on a zero-current and zero-derivative-switching (ZCDS) Class-E current-driven rectifier, and the LED driver semistage is based on a zero-voltage-switching (ZVS) Class-D LLC resonant converter that is integrated into a single-stage topology. To increase the conduction angle of the bridge-rectifier diodes current and to decrease the current harmonics that are injected in the utility line, the ZCDS Class-E rectifier is placed between the bridge-rectifier and a dc-link capacitor. The ZCDS Class-E rectifieris driven by a high-frequency current source, which is obtained from a square-wave output voltage of the ZVS Class-D LLC resonant converter using a matching network. Additionally, the proposed converter has a soft-switching characteristic that reduces switching losses and switching noise. A prototype for a 150-W LED street light has been developed and tested to evaluate the performance of the proposed approach. The proposed LED driver had a high efficiency (>91%), a high PF (>0.99), and a low total harmonic distortion (THD i <; 8%) under variation of the utility-line input voltage from 180 to 250 V rms . These experimental results demonstrate the feasibility of the proposed LED scheme

Sources d'Alimentation Électrique pour l'Étude et l'Utilisation Efficace des Lampes Excimer DBD

Avec l'objectif d'améliorer le rendement des lampes à excimères (Excilampe) à décharge à barrière diélectrique (DBD), un convertisseur en mode de courant, qui permet un ajustement précis de la puissance électrique injectée dans ce type des lampes, à été conçu et mis en oeuvre. Ce convertisseur fournit à la lampe un courant de forme d'onde carrée contrôlé au moyen de trois paramètres: l'amplitude, la fréquence et le rapport cyclique, pour obtenir un contrôle total de l'énergie électrique transmise à l'excilampe DBD. La mise en oeuvre intègre un transformateur élévateur comme interface entre la lampe et un commutateur. Les expériences démontrent le principe de fonctionnement de ce convertisseur, y compris les mesures de puissance du rayonnement UV. Les degrés de liberté du convertisseur sont utilisées pour analyser le comportement de la lampe sous différentes combinaisons de ces trois paramètres, et sont utilisés pour déterminer le point de fonctionnement optimal de la lampe. Ensuite, un convertisseur à résonance du type onduleur série, est proposé pour alimenter la lampe avec une grande efficacité électrique. Afin de contrôler effectivement la puissance de la lampe, le mode de fonctionnement de ce convertisseur utilise le mode de conduction discontinue et la commutation douce (ZCS), avec lequel on obtient aussi de faibles émissions électromagnétiques et l'on réduit les pertes de commutation. Les relations mathématiques obtenus à partir de l'analyse du diagramme de phase, ont été validées par des simulations et avec des résultats expérimentaux. Enfin, différentes topologies d'alimentations pour DBD sont comparées analytiquement et expérimentalement pour évaluer objectivement les avantages de chaque approche. Une des perspectives de ce travail est l'application de l'alimentation en créneaux pour l'étude de la performance d'autres types de réacteurs et d'excilampes DBD. ABSTRACT : With the aim to provide a scientific tool for the enhancement of the Dielectric Barrier Discharge (DBD) Excimer Lamps (Excilamp) performance, a current-mode converter that allows an accurate adjustment of the electrical power injected into one of those lamps, is designed and implemented. With the proposed converter, the current supplied to the lamp has a square shape, controlled by means of three parameters: amplitude, duty cycle and frequency, which provides full control of the lamp electrical power. Implementation is made considering a step-up transformer interfacing the high-voltage lamp with the converter. Experiments demonstrate the operating principle of this converter, including UV power measurements for a DBD XeCl Excilamp. The capabilities of the converter are used to analyze the lamp behavior under different combinations of these three parameters, illustrating its capabilities for finding the optimal operating point. Then a series-resonant inverter for the supply of DBD) excilamp is proposed. In order to effectively control the lamp power, the operating mode of this converter combines discontinuous current-mode and soft-commutation (ZCS), obtaining as well low electromagnetic emissions, and reduced switching losses. The mathematical relationships obtained from state plane analysis, are validated with simulations and experimental results. Finally, several topologies of DBDs power supplies are compared analytical and experimentally to elucidate the advantages of each approach. After this work, one of the perspectives is the application of the square-shape supply in the performance study of other types of DBD excilamps and DBD reactors

Impact of Voltage Variation on Domestic and Commercial Loads

This Thesis studies the impact of variations in supply voltage on various loads representing different types of loads. The scope of Thesis is analysis of active and reactive power used by appliances at different supply voltages varying from 90% up to 110% of rated value, as well as other factors that these variations influence. Previous studies showed that power consumption of certain device varies with changing of supply voltage, but most of them were dealing with 120V networks, and the other ones are outdated. This study provides ZIP models (polynomial of 2nd power with coefficients Z, I and P standing for constant impedance, current and power correspondingly) for typical house appliances, also results of induction motor heating test and analysis of typical household appliances mix. Results show, which of appliances can withstand voltage variations better, as well as give an idea what is power-voltage curve of the household and what is the percentage of economical losses. Also studies show that almost every device is able to maintain its operation during critical voltage deviations of 10% Using that data, it is possible to optimize energy usage and decrease losses. The results encourage continuing further investigation of devices with higher power and show the necessity of dynamic seasonal household model

Carbon Free Boston: Technical Summary

Part of a series of reports that includes: Carbon Free Boston: Summary Report; Carbon Free Boston: Social Equity Report; Carbon Free Boston: Buildings Technical Report; Carbon Free Boston: Transportation Technical Report; Carbon Free Boston: Waste Technical Report; Carbon Free Boston: Energy Technical Report; Carbon Free Boston: Offsets Technical Report; Available at http://sites.bu.edu/cfb/OVERVIEW: This technical summary is intended to argument the rest of the Carbon Free Boston technical reports that seek to achieve this goal of deep mitigation. This document provides below: a rationale for carbon neutrality, a high level description of Carbon Free Boston’s analytical approach; a summary of crosssector strategies; a high level analysis of air quality impacts; and, a brief analysis of off-road and street light emissions.Published versio

Controlled Ecological Life Support Systems (CELSS) conceptual design option study

Results are given of a study to explore options for the development of a Controlled Ecological Life Support System (CELSS) for a future Space Station. In addition, study results will benefit the design of other facilities such as the Life Sciences Research Facility, a ground-based CELSS demonstrator, and will be useful in planning longer range missions such as a lunar base or manned Mars mission. The objectives were to develop weight and cost estimates for one CELSS module selected from a set of preliminary plant growth unit (PGU) design options. Eleven Space Station CELSS module conceptual PGU designs were reviewed, components and subsystems identified and a sensitivity analysis performed. Areas where insufficient data is available were identified and divided into the categories of biological research, engineering research, and technology development. Topics which receive significant attention are lighting systems for the PGU, the use of automation within the CELSS system, and electric power requirements. Other areas examined include plant harvesting and processing, crop mix analysis, air circulation and atmosphere contaminant flow subsystems, thermal control considerations, utility routing including accessibility and maintenance, and nutrient subsystem design