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 New Single-Phase Single-Stage AC-DC Stacked Flyback Converter With Active Clamp ZVS

Single-stage AC-DC converters integrate an AC-DC front-end converter with a DC-DC back-end converter. Compared with conventional two-stage AC-DC converters, single-stage AC-DC converters use less components and only one controller, which is used to regulate the output voltage. As a result, the cost, size and complexity of AC-DC converters can be reduced, but single-stage converters do not perform as well as two-stage converters, and most have drawbacks that are related to the fact that the DC bus voltage is not controlled an can become excessive. A new single-phase single-stage AC-DC converter that uses stacked flyback converters is proposed in this thesis. The proposed converter consists of two low power flyback converters stacked on top of each other and an active clamp that helps the main switches operate with ZVS. The stacked structure helps reduce the voltage stresses typical fund in many single-stage converters. In the thesis, the operation of the converter is explained, the steady-state characteristics of the converter are determined and its design is discussed. The feasibility of the new converter is confirmed with experimental results obtained from a 100VAC~220VAC worldwide input, 48V output, 100kHz switching frequency and 200 W output power prototype converter

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

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

Reductor activo de armónicos sin condensador electrolítico aplicado a lámparas LED de sustitición

XXIV Seminario Anual de Automática, Electrónica Industrial e Instrumentación 2017 (SAAEI'17), Valencia (España)De todos son conocidas las bondades de los diodos emisores de luz (Light-Emiting Diodes, LEDs) para la iluminación: alta eficiencia, larga vida útil, bajo mantenimiento, etc. Para hacer extensibles estas ventajas a toda la luminaria, el convertidor encargado de la alimentación no puede limitar sus características, y ha de ser también eficiente y duradero. Además, en el caso concreto de las lámparas LED para la sustitución de bombillas incandescentes hay que añadir más requisitos: la necesidad de reducir los costes y el cumplimiento de la normativa vigente de inyección de armónicos de baja frecuencia en la red de distribución de alterna. Por lo tanto, se exige mucho del convertidor a diseñar. A raíz de las últimas modificaciones relativas a equipos de baja potencia que ha introducido la normativa, surge la posibilidad de aplicar una solución topológica presentada en el pasado, que puede reunir todas las especificaciones requeridas. Este artículo propone los Reductores de Armónicos Activos (RA2) sin condensador electrolítico [1] para el diseño del convertidor CA/CC en este tipo de luminarias, revisando esta familia de topologías y presentando modificaciones sobre las mismas para conseguir los objetivos preestablecidos. Finalmente, esta propuesta se validará a partir de las pruebas realizadas sobre un prototipo de 24 W

Overview of Passive Light Emitting Diode Driver Circuits for Street Lighting

This paper describes the overview and comparison of various passive Light Emitting Diode (LED) driver circuits employed for street lighting applications. Passive LED driver circuits are constructed with diodes and capacitors without using any power electronic semiconductor switches which in turn eliminates the secondary supply unit for control circuits and controllers. Passive LED driver circuits are simple in construction, low cost, less maintenance and control free. 50 W LED driver circuit is identified for performance comparison and simulations are performed in matlab- simulink to get an overview of different passive LED driver circuits. The most predominant parameters such as efficiency and total harmonic distortion are compared to identify the suitiblity of the driver circuits for various applications