4 research outputs found

    High-efficiency LED driver without electrolytic capacitor for street lighting

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    High-Brightness Light Emitting Diodes (HB-LEDs) are considered as a remarkable lighting device due to their high reliability, chromatic variety and increasing efficiency. As a consequence, a high number of solutions for supplying LED strings are coming out. One-stage solutions are cost-effective, but their efficiency is low as they have to fulfill several purposes with only one converter: Power Factor Correction (PFC), galvanic isolation (in some cases) and current regulation. Two-stage and three-stage solutions have higher efficiency as each stage is optimized for just one or two tasks and they are the preferred option when supplying several strings at the same time. Nevertheless, due to their higher cost in comparison to one-stage solutions, they are used when high-efficiency, high-performance and the possibility of supplying several strings are the main concerns. Besides, they are also used when high reliability is needed and electrolytic capacitors cannot be used. In this paper, a three-stage solution and its complete design guideline for LED-based applications is proposed. PFC is achieved by a Boost converter while the galvanic isolation is provided by an Electronic Transformer (second stage). The third stages (one for each LED string) are designed following the TIBuck schematic, but taking advantage of the load characteristics (i.e., the high value of the LED string knee voltage, approximately equal to half the string nominal voltage). Besides, a variation of the analog driving technique is also proposed. Experimental results obtained with a 160-W prototype show an efficiency as high as 93% for the whole topology and 95% for the cascade connection of the second and third stage

    Pregled AC-DC i DC-DC pretvara膷a za primjene u LED rasvjeti

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    High-Brightness Light Emitting Diodes (HB-LEDs) are considered the future trend in lighting not only due to their high efficiency and high reliability, but also due to their other outstanding characteristics: chromatic variety, shock and vibration resistance, etc. Nevertheless, they need the development of new power supplies especially designed for boosting and taking advantage of their aforementioned characteristics. Besides, their behaviour is completely different from the rest of lighting devices and, consequently, it should be also taken into account in the design of the converters used to drive them. As a result, many well-known topologies have been optimized or redesigned in order to be used in LED鈥搇ighting applications and many new topologies have come up in the recent years with the same purpose. In this paper, the main HB-LED characteristics will be explained, highlighting how they influence the design of their power supplies. After, the main topologies will be presented from the simplest to the most complex ones, analysing their advantages and disadvantages.Svjetle膰e diode s visokom razinom svjetline (HB-LED) smatraju se budu膰im trendom u rasvjeti zahvaljuju膰i ne samo visokom stupnju efikasnosti i pouzdanosti, nego i njihovim izvanrednim svojstvima: raznolikost boja, otpornost na udarce i vibracije i sl. Ipak, s ciljem potpunog iskori拧tenja prethodno spomenutih svojstava, potrebno je razviti nove, posebno osmi拧ljene izvore napajanja. Osim toga, pona拧anje im se posve razlikuje od ostalih tipova rasvjete 拧to je potrebno uzeti u obzir pri projektiranju pretvara膷a za njihovo napajanje. Kao posljedica toga, mnoge su poznate topologije pretvara膷a optimirane ili preoblikovane posebno za primjenu u LED rasvjeti, a zadnjih nekoliko godina mnoge nove su se tek pojavile. U ovom 膷lanku obja拧njena su osnovna HB-LED svojstva nagla拧avaju膰i njihov utjecaj na razvoj izvora napajanja. Uz to, prikazane su osnovne topologije, od najjednostavnijih do najslo啪enijih, ujedno analiziraju膰i prednosti i nedostatke pojedinih

    T茅cnicas de control robusto basado en modelo de referencia e inyecci贸n de la corriente de carga aplicadas a rectificadores monof谩sicos con correcci贸n activa del factor de potencia

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    La proliferaci贸n en los 煤ltimos a帽os de equipos electr贸nicos conectados a redes de distribuci贸n el茅ctrica, ha provocado la aparici贸n de standards internacionales, como por ejemplo la norma EN 68000-3-2, que regulan la distorsi贸n arm贸nica de baja frecuencia que dichos equipos pueden introducir en la red. En este contexto, los rectificadores con alto factor de potencia constituyen una de las soluciones m谩s adecuadas para reducir la distorsi贸n arm贸nica de la corriente consumida de la red el茅ctrica. En su versi贸n monof谩sica y cuando no se requiere devolver energ铆a a la red, los rectificadores con alto factor de potencia suelen implementarse mediante la asociaci贸n en cascada de un rectificador pasivo (diodos) y un convertidor dc-dc de tipo boost. Un lazo de regulaci贸n de corriente se encarga de mantener la distorsi贸n de la corriente de entrada pr贸xima a cero, recibiendo una se帽al de consigna de un lazo de regulaci贸n de la tensi贸n de salida. Este 煤ltimo lazo se encarga de mantener la tensi贸n de salida cercana a un cierto valor de referencia. El problema m谩s documentado en la literatura al respecto es la pobre respuesta din谩mica del lazo de regulaci贸n de tensi贸n, debido a que dicho lazo debe ser extremadamente lento para no producir distorsi贸n en la corriente de entrada. En esta tesis se propone la aplicaci贸n de las t茅cnicas de control Robust Model Following (RMF) y Load Injection Current (LI2) al dise帽o del lazo de regulaci贸n de la tensi贸n de salida. Dichas t茅cnicas permiten reducir considerablemente la impedancia de salida del convertidor en lazo cerrado, sin que se requiera aumentar la velocidad de respuesta del lazo de tensi贸n. En consecuencia, mejoran de forma notable la respuesta din谩mica del convertidor sin distorsionar la corriente de entrada. Una ventaja adicional de las t茅cnicas propuestas es su bajo coste de implementaci贸n, lo que las convierte en una alternativa muy interesante para ser implementadas en equipos industriales.Benavent Garc铆a, JM. (2010). T茅cnicas de control robusto basado en modelo de referencia e inyecci贸n de la corriente de carga aplicadas a rectificadores monof谩sicos con correcci贸n activa del factor de potencia [Tesis doctoral no publicada]. Universitat Polit猫cnica de Val猫ncia. https://doi.org/10.4995/Thesis/10251/8684Palanci
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