Editorial

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4 pages, 182 KiB

Open AccessEditorial

Latest Developments in LED Drivers

by Diego G. Lamar

Electronics 2020, 9(4), 619; https://doi.org/10.3390/electronics9040619 - 07 Apr 2020

Cited by 8 | Viewed by 2163

Abstract

Although the phenomenon of electroluminescence was discovered by H [...] Full article

(This article belongs to the Special Issue Latest Developments in LED Drivers)

Research

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19 pages, 3642 KiB

Open AccessFeature PaperArticle

Adapting Techniques to Improve Efficiency in Radio Frequency Power Amplifiers for Visible Light Communications

by Daniel G. Aller, Diego G. Lamar, Juan Rodriguez, Pablo F. Miaja, Valentin Francisco Romero, Jose Mendiolagoitia and Javier Sebastian

Electronics 2020, 9(1), 131; https://doi.org/10.3390/electronics9010131 - 10 Jan 2020

Cited by 3 | Viewed by 3748

Abstract

It is well known that modern wireless communications systems need linear, wide bandwidth, efficient Radio Frequency Power Amplifiers (RFPAs). However, conventional configurations of RFPAs based on Class A, Class B, and Class AB exhibit extremely low efficiencies when they manage signals with a [...] Read more.

It is well known that modern wireless communications systems need linear, wide bandwidth, efficient Radio Frequency Power Amplifiers (RFPAs). However, conventional configurations of RFPAs based on Class A, Class B, and Class AB exhibit extremely low efficiencies when they manage signals with a high Peak-to-Average Power Ratio (PAPR). Traditionally, a number of techniques have been proposed either to achieve linearity in the case of efficient Switching-Mode RFPAs or to improve the efficiency of linear RFPAs. There are two categories in the application of aforementioned techniques. First, techniques based on the use of Switching-Mode DC–DC converters with a very-fast-output response (faster than 1 µs). Second, techniques based on the interaction of several RFPAs. The current expansion of these techniques is mainly due to their application in cellphone networks, but they can also be applied in other promising wireless communications systems such as Visible Light Communication (VLC). The main contribution of this paper is to show how Envelope Tracking (ET), Envelope and Elimination (EER), Outphasing, and Doherty techniques can be helpful in developing more efficient VLC transmitters capable of reaching high bit-rates (higher than 1 Mbps) by using advance modulation schemes. Finally, two examples based on the application of the Outphasing technique and the use of a Linear-Assisted Envelope Amplifier (EA) to VLC are presented and experimentally verified. Full article

(This article belongs to the Special Issue Latest Developments in LED Drivers)

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13 pages, 4288 KiB

Open AccessArticle

Two-Phase Resonant Converter to Drive High-Power LED Lamps

by Christian Brañas, Rosario Casanueva, Francisco J. Díaz and Francisco J. Azcondo

Electronics 2020, 9(1), 53; https://doi.org/10.3390/electronics9010053 - 30 Dec 2019

Cited by 1 | Viewed by 2394

Abstract

This paper presents the design and modeling of a two-phase resonant converter that drives a LED lamp with a high-frequency pulsed current free of instabilities and flicker effect, fulfilling the recommendations of the IEEE PAR 1789-2015, so that it enables visible light-based communication [...] Read more.

This paper presents the design and modeling of a two-phase resonant converter that drives a LED lamp with a high-frequency pulsed current free of instabilities and flicker effect, fulfilling the recommendations of the IEEE PAR 1789-2015, so that it enables visible light-based communication at a 10 kB/s bit rate. The dynamic study of the converter takes into consideration the effect of the reflected impedance of the output filter on the AC side. In order to evaluate the dynamic response of the converter, a Spice model is defined. A 120 W prototype intended for street lighting applications has been built to validate the analysis and modeling. Full article

(This article belongs to the Special Issue Latest Developments in LED Drivers)

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22 pages, 12660 KiB

Open AccessArticle

Design and Implementation of 150 W AC/DC LED Driver with Unity Power Factor, Low THD, and Dimming Capability

by Ngo Thanh Tung, Nguyen Dinh Tuyen, Nguyen Minh Huy, Nguyen Hoai Phong, Ngo Cao Cuong and Le Minh Phuong

Electronics 2020, 9(1), 52; https://doi.org/10.3390/electronics9010052 - 29 Dec 2019

Cited by 9 | Viewed by 6648

Abstract

This paper presents the implementation of a two-stage light-emitting diode (LED) driver based on commercial integrated circuits (IC). The presented LED driver circuit topology, which is designed to drive a 150 W LED module, consists of two stages: AC-DC power factor correction (PFC) [...] Read more.

This paper presents the implementation of a two-stage light-emitting diode (LED) driver based on commercial integrated circuits (IC). The presented LED driver circuit topology, which is designed to drive a 150 W LED module, consists of two stages: AC-DC power factor correction (PFC) stage and DC/DC power converter stage. The implementation of the PFC stage uses IC NCP1608, which uses the critical conduction mode to guarantee a unity input power factor with a wide range of input voltages. The DC/DC power converter with soft-switching characteristics for the entire load range uses IC FLS2100XS. Furthermore, the design of an electromagnetic interference (EMI) filter for the LED driver and the dimming control circuit are discussed in detail. The hardware prototype, an LED lighting system, with a rated power of 150 W/32 V from a nominal 220 V/50 Hz AC voltage supply was tested to show the effectiveness of the design. The presented LED driver was tested for street lighting, and the experimental results show that the power factor (PF) was higher than 0.97, the total harmonics distortion (THD) was lower than 7%, and the efficiency was 91.7% at full load. The results prove that the performance of the presented LED driver complies with the standards: IEC61000-3-2 and CIRSP 15:2009. Full article

(This article belongs to the Special Issue Latest Developments in LED Drivers)

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22 pages, 10663 KiB

Open AccessArticle

Closed Loop Control of a Series Class-E Voltage-Clamped Resonant Converter for LED Supply with Dimming Capability

by Javier Ribas, Pablo J. Quintana, Jesus Cardesin, Antonio J. Calleja and Juan M. Lopera

Electronics 2019, 8(12), 1380; https://doi.org/10.3390/electronics8121380 - 21 Nov 2019

Cited by 3 | Viewed by 3173

Abstract

In this work, a new closed-loop control system is applied to a class-E resonant DC–DC converter with voltage clamp used for light-emitting diode (LED) supply. The proposed power topology was first described by Ribas et al. in a recent work. In the present [...] Read more.

In this work, a new closed-loop control system is applied to a class-E resonant DC–DC converter with voltage clamp used for light-emitting diode (LED) supply. The proposed power topology was first described by Ribas et al. in a recent work. In the present paper, the LED current is sensed and used to implement a feedback control loop instead of the simplified feedforward scheme used in this previous reference. To design the control, a novel, simplified small-signal model is presented. This model is used to analyze the converter behavior as a function of the output power. The proposed approximation is significantly simpler than the multifrequency averaging technique normally used to analyze resonant converters. The feedback control loop is designed to reduce the LED low frequency current ripple while providing dimming control. Both the model and the control are verified by simulation and laboratory experimentation and the results obtained are in good accordance with the expected values. Full article

(This article belongs to the Special Issue Latest Developments in LED Drivers)

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12 pages, 10845 KiB

Open AccessArticle

An Efficient Method for LED Light Sources Characterization

by Sara Raggiunto, Alberto Belli, Lorenzo Palma, Piergiovanni Ceregioli, Massimo Gattari and Paola Pierleoni

Electronics 2019, 8(10), 1089; https://doi.org/10.3390/electronics8101089 - 25 Sep 2019

Cited by 11 | Viewed by 3386

Abstract

Digital LED drivers capable of blending the spectrum of two LED fixtures with different Correlated Color Temperatures through the LEDs’ power supply control are widespread. However, the digital control of lighting systems is possible only after a careful study of the LED’s response, [...] Read more.

Digital LED drivers capable of blending the spectrum of two LED fixtures with different Correlated Color Temperatures through the LEDs’ power supply control are widespread. However, the digital control of lighting systems is possible only after a careful study of the LED’s response, in terms of illuminance and Correlated Color Temperature. The proposed work takes advantage of the Tunable White technology for the realization of an efficient method for LED light source characterization. In order to evaluate how the light changes as a function of the electric power supplied by the LED drivers, an experimental setup to characterize LED light sources has been designed. Starting from the data acquired from the experimental setup, a model for dimming the LED driver and obtaining the desired values of quality of light has been developed. The proposed model is based on the least squares method and its accuracy is evaluated by comparing the obtained values of illuminance and Correlated Color Temperature with those measured by an illuminance spectrophotometer. Results achieved an error of 0.3% for Correlated Color Temperature and 1.5% for illuminance using the proposed approximation functions. Full article

(This article belongs to the Special Issue Latest Developments in LED Drivers)

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21 pages, 4277 KiB

Open AccessArticle

A Single-Stage LED Streetlight Driver with Soft-Switching and Interleaved PFC Features

by Chun-An Cheng, Chien-Hsuan Chang, Hung-Liang Cheng, En-Chih Chang, Tsung-Yuan Chung and Man-Tang Chang

Electronics 2019, 8(8), 911; https://doi.org/10.3390/electronics8080911 - 18 Aug 2019

Cited by 14 | Viewed by 4946

Abstract

This paper presents a single-stage driver with soft-switching and interleaved power-factor correction (PFC) features suitable for light-emitting diode (LED) energy-saving streetlight applications. The proposed LED streetlight driver integrates an interleaved buck-boost PFC converter with coupled inductors and a half-bridge LLC resonant converter into [...] Read more.

This paper presents a single-stage driver with soft-switching and interleaved power-factor correction (PFC) features suitable for light-emitting diode (LED) energy-saving streetlight applications. The proposed LED streetlight driver integrates an interleaved buck-boost PFC converter with coupled inductors and a half-bridge LLC resonant converter into a single-stage power-conversion circuit with reduced voltage stress on the DC-linked capacitor and power switches, and it is suitable for operating at high utility-line voltages. Furthermore, coupled inductors in the interleaved buck-boost PFC converter are operated in discontinuous-conduction mode (DCM) for accomplishing PFC, and the half-bridge LLC resonant converter features zero-voltage switching (ZVS) to reduce switching losses of power switches, and zero-current switching (ZCS) to decrease conduction losses of power diodes. Operational modes and design considerations for the proposed LED streetlight driver are introduced. Finally, a 144 W (36V/4A)-rated LED prototype driver is successfully developed and implemented for supplying a streetlight module and operating with a utility-line input voltage of 220 V. High power factor, low output-voltage ripple factor, low output-current ripple factor, and high efficiency are achieved in the proposed LED streetlight driver. Full article

(This article belongs to the Special Issue Latest Developments in LED Drivers)

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17 pages, 7370 KiB

Open AccessArticle

Single-Switch LED Post-Regulator Based on a Modified Class-E Resonant Converter with Voltage Clamp

by Javier Ribas, Pablo J. Quintana, Jesus Cardesin, Antonio J. Calleja and Emilio Lopez-Corominas

Electronics 2019, 8(7), 798; https://doi.org/10.3390/electronics8070798 - 16 Jul 2019

Cited by 4 | Viewed by 3295

Abstract

The strict restrictions imposed both by mandatory regulations and by the recommendations contained in current standards have led to the fact that most commercially available LED ballasts nowadays use two-stage topologies. The first stage is intended to comply with the harmonics standards and [...] Read more.

The strict restrictions imposed both by mandatory regulations and by the recommendations contained in current standards have led to the fact that most commercially available LED ballasts nowadays use two-stage topologies. The first stage is intended to comply with the harmonics standards and the second stage is used to control the LED current and reduce the low frequency ripple. In this work, a new DC–DC resonant converter topology is presented. This topology is derived from a modified Class-E resonant inverter by adding a clamping diode. This diode achieves a double goal: it limits the maximum switch voltage and works as a power recirculating path. This way, the proposed topology behaves as a loss-less impedance placed in series with the LED thus allowing to control the output power. This converter maintains the extremely small switching losses inherent to the Class-E inverter while reducing the voltage stress across the switch. This work presents a simplified design methodology based on the fundamental approach. This methodology was used to design and build a DC–DC post-regulator for a 40 W LED lamp. The results obtained with the laboratory prototype show that this circuit can be used to stabilize and dim the LED current while maintaining very small losses. The measured efficiency was 95.7% at nominal power and above 90% when dimmed down to 25%. Full article

(This article belongs to the Special Issue Latest Developments in LED Drivers)

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18 pages, 3744 KiB

Open AccessArticle

Optimization of a Series Converter for Low-Frequency Ripple Cancellation of an LED Driver

by Jorge Garcia, Sarah Saeed, Pablo Quintana, Jesus Cardesin, Ramy Georgious, Marco A. Dalla Costa and Douglas Camponogara

Electronics 2019, 8(6), 664; https://doi.org/10.3390/electronics8060664 - 12 Jun 2019

Cited by 5 | Viewed by 2930

Abstract

In this paper, the optimization of the power and control stages of a previously proposed topology for an off-line LED electronic driver is presented. The full system avoids the use of electrolytic capacitors at the

D C

link, therefore increasing the lifespan and [...] Read more.

In this paper, the optimization of the power and control stages of a previously proposed topology for an off-line LED electronic driver is presented. The full system avoids the use of electrolytic capacitors at the

D C

link, therefore increasing the lifespan and reliability of the driver. As a consequence of having a relatively small capacitance, the

D C

link operates with a large Low-Frequency (

L F

) voltage ripple. This work presents a design optimization for the power and control stages of a current-fed bidirectional buck converter, operating as the LED current control stage. As this block processes only the

A C

power arising from the

L F

voltage ripple, it can increase the system efficiency against the typical two-stage solution. In the original proposal, the main drawback was the high inductor losses due to the resulting large inductor currents and large inductance value. The proposed optimization ensures an enhanced design of the inductor while keeping a constant current through the LEDs. A new optimization methodology is proposed and the theoretical results have been validated in a built prototype for a 40 W LED lamp. Full article

(This article belongs to the Special Issue Latest Developments in LED Drivers)

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17 pages, 5926 KiB

Open AccessArticle

Heterogeneous Integration of GaN and BCD Technologies

by Mei Yu Soh, T. Hui Teo, S. Lawrence Selvaraj, Lulu Peng, Don Disney and Kiat Seng Yeo

Electronics 2019, 8(3), 351; https://doi.org/10.3390/electronics8030351 - 22 Mar 2019

Cited by 8 | Viewed by 5755

Abstract

Light-emitting diodes (LEDs) are solid-state devices that are highly energy efficient, fast switching, have a small form factor, and can emit a specific wavelength of light. The ability to precisely control the wavelength of light emitted with the fabrication process enables LEDs to [...] Read more.

Light-emitting diodes (LEDs) are solid-state devices that are highly energy efficient, fast switching, have a small form factor, and can emit a specific wavelength of light. The ability to precisely control the wavelength of light emitted with the fabrication process enables LEDs to not only provide illumination, but also find applications in biology and life science research. To enable the new generation of LED devices, methods to improve the energy efficiency for possible battery operation and integration level for miniaturized lighting devices should be explored. This paper presents the first case of the heterogeneous integration of gallium nitride (GaN) power devices, both GaN LED and GaN transistor, with bipolar CMOS DMOS (BCD) circuits that can achieve this. To validate this concept, an LED driver was designed, implemented and verified experimentally. It features an output electrical power of 1.36 W and compact size of 2.4 × 4.4 mm². The designed fully integrated LED lighting device emits visible light at a wavelength of approximately 454 nm and can therefore be adopted for biology research and life science applications. Full article

(This article belongs to the Special Issue Latest Developments in LED Drivers)

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9 pages, 2528 KiB

Open AccessArticle

Improvement of the Approximation Accuracy of LED Radiation Patterns

by Ivan Rachev, Todor Djamiykov, Marin Marinov and Nikolay Hinov

Electronics 2019, 8(3), 337; https://doi.org/10.3390/electronics8030337 - 20 Mar 2019

Cited by 13 | Viewed by 3793

Abstract

For the great variety of light-emitting diodes (LEDs), there exists a wide range of LED radiation patterns. An approach for constructing patterns of higher accuracy is here considered. The latter is required when the design of optoelectronic systems or their optimization is carried [...] Read more.

For the great variety of light-emitting diodes (LEDs), there exists a wide range of LED radiation patterns. An approach for constructing patterns of higher accuracy is here considered. The latter is required when the design of optoelectronic systems or their optimization is carried out analytically. A weighting function is introduced that allows increasing the gradient of the diagram of different widths. It has been selected through mathematical analysis of the emission diagrams of different LEDs used in optoelectronic systems. Based on the least squares method an algorithm is created, and programs are developed in MATLAB environment to estimate the parameters of the approximation function. Its accuracy is evaluated by comparison with the approximation with Lambert source of order n. The results show higher accuracy of the proposed approximation function compared to those obtained by conventional methods. Recommendations on the application of the proposed approach are given. Full article

(This article belongs to the Special Issue Latest Developments in LED Drivers)

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