A review and classification of LED ballasts

This paper presents a review on existing ballasts for light-emitting diodes (LED) with considerations to their compliance to regulations, technological challenges, and on meeting various application requirements. All existing LED ballasts, including those proposed in recent literature, have been appropriately classified and systematically organized for the discussion. The dissemination of this information and its understanding is helpful for future R&D pursuits in this area. © 2013 IEEE.published_or_final_versio

High-efficiency LED driver without electrolytic capacitor for street lighting

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 pretvarača za primjene u LED rasvjeti

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–lighting 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.Svjetleće diode s visokom razinom svjetline (HB-LED) smatraju se budućim trendom u rasvjeti zahvaljujući 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 iskorištenja prethodno spomenutih svojstava, potrebno je razviti nove, posebno osmišljene izvore napajanja. Osim toga, ponašanje im se posve razlikuje od ostalih tipova rasvjete što je potrebno uzeti u obzir pri projektiranju pretvarača za njihovo napajanje. Kao posljedica toga, mnoge su poznate topologije pretvarača optimirane ili preoblikovane posebno za primjenu u LED rasvjeti, a zadnjih nekoliko godina mnoge nove su se tek pojavile. U ovom članku objašnjena su osnovna HB-LED svojstva naglašavajući njihov utjecaj na razvoj izvora napajanja. Uz to, prikazane su osnovne topologije, od najjednostavnijih do najsloženijih, ujedno analizirajući prednosti i nedostatke pojedinih

A Survey, Classification and Critical Review of Light-Emitting Diode Drivers

Based on a survey on over 1400 commercial LED drivers and a literature review, a range of LED driver topologies are classified according to their applications, power ratings, performance and their energy storage and regulatory requirements. Both passive and active LED drivers are included in the review and their advantages and disadvantages are discussed. This paper also presents an overall view on the technical and cost aspects of the LED technology, which is useful to both researchers and engineers in the lighting industry. Some general guidelines for selecting driver topologies are included to aid design engineers to make appropriate choices.published_or_final_versio

A Family of High Frequency AC-LED Drivers Based on ZCS-QRCs

A family of dimmable AC-LED drivers fed from dc voltages, is presented in this paper based on Zero Current Switching Quasi-Resonant Converters (ZCS-QRCs). The proposed family of drivers is based on replacing the diode in conventional converter topologies (i.e. buck, boost or buck-boost) by a string of High-Brightness Light-Emitting Diodes (HB-LED). Hence, the HB-LED string will be working as the rectifier diode and the load, switching at the same frequency of the main switch. In this case, the output current, which is experimentally validated, shows a negative current peak due to the reverse-recovery effect of the HB-LEDs. In order to reduce the reverse-recovery effect on the HB-LEDs, the main switch of the proposed topologies is replaced with a full-wave resonant switch, which makes possible to reduce the di/dt during the turn-off of the HB-LED string, therefore the reverse recovery effect is eliminated. Moreover, the dimming of the HB-LEDs is done by means of changing the switching frequency of the converter, by varying the turn-off while keeping a constant turn-on time. In order to validate the analysis, the proposed topologies have been experimentally tested on a constructed prototype with an output power of 7.5

Técnicas de control robusto basado en modelo de referencia e inyección de la corriente de carga aplicadas a rectificadores monofásicos con corrección activa del factor de potencia

La proliferación en los últimos años de equipos electrónicos conectados a redes de distribución eléctrica, ha provocado la aparición de standards internacionales, como por ejemplo la norma EN 68000-3-2, que regulan la distorsión armónica 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 más adecuadas para reducir la distorsión armónica de la corriente consumida de la red eléctrica. En su versión monofásica y cuando no se requiere devolver energía a la red, los rectificadores con alto factor de potencia suelen implementarse mediante la asociación en cascada de un rectificador pasivo (diodos) y un convertidor dc-dc de tipo boost. Un lazo de regulación de corriente se encarga de mantener la distorsión de la corriente de entrada próxima a cero, recibiendo una señal de consigna de un lazo de regulación de la tensión de salida. Este último lazo se encarga de mantener la tensión de salida cercana a un cierto valor de referencia. El problema más documentado en la literatura al respecto es la pobre respuesta dinámica del lazo de regulación de tensión, debido a que dicho lazo debe ser extremadamente lento para no producir distorsión en la corriente de entrada. En esta tesis se propone la aplicación de las técnicas de control Robust Model Following (RMF) y Load Injection Current (LI2) al diseño del lazo de regulación de la tensión de salida. Dichas técnicas permiten reducir considerablemente la impedancia de salida del convertidor en lazo cerrado, sin que se requiera aumentar la velocidad de respuesta del lazo de tensión. En consecuencia, mejoran de forma notable la respuesta dinámica del convertidor sin distorsionar la corriente de entrada. Una ventaja adicional de las técnicas propuestas es su bajo coste de implementación, lo que las convierte en una alternativa muy interesante para ser implementadas en equipos industriales.Benavent García, JM. (2010). Técnicas de control robusto basado en modelo de referencia e inyección de la corriente de carga aplicadas a rectificadores monofásicos con corrección activa del factor de potencia [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8684Palanci