Control of LEDs

Ackermann, B.; Schulz, Volkmar; Martiny, C.; Hilgers, A.; Zhu, Xiaoyan

doi:10.1109/ias.2006.256907

Cited by 47 publications

(21 citation statements)

References 6 publications

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“…The efficiency of conventional LED drivers involving resistorbased current limiters, linear regulators, and charge pumps is very low [7], [8]. Switching power supplies can achieve a high efficiency, high power density, and high control accuracy, which make them ideal candidates as high-power LED drivers [9].…”

mentioning

confidence: 99%

A Flicker-Free Electrolytic Capacitor-Less AC–DC LED Driver

Wang

Ruan

Yao

et al. 2012

IEEE Trans. Power Electron.

343

108

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The electrolytic capacitor is the key component that limits the operating lifetime of LED drivers. If an ac-dc LED driver with power factor correction (PFC) control is allowed to output a pulsating current for driving the LEDs, the electrolytic capacitor will no longer be required. However, this pulsating current will introduce light flicker that varies at twice the power line frequency. In this paper, a configuration of flicker-free electrolytic capacitor-less single-phase ac-dc driver for LED lighting is proposed. The configuration comprises an electrolytic capacitor-less PFC converter and a bidirectional converter, which serves to absorb the ac component of the pulsating current of the PFC converter, leaving only a dc component to drive the LEDs. The output filter capacitor of the bidirectional converter is intentionally designed to have a large voltage ripple, thus its capacitance can be greatly reduced. Consequently, film capacitors can be used instead of electrolytic capacitors, leading to the realization of a flicker-free ac-dc LED driver that has a long lifetime. The proposed solution is generally applicable to all single-phase PFC converters. A prototype with 48-V, 0.7-A output is constructed and tested. Experimental results are presented to verify the effectiveness of the flick-free electrolytic capacitor-less ac-dc LED driver.

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mentioning

confidence: 99%

A Flicker-Free Electrolytic Capacitor-Less AC–DC LED Driver

Wang

Ruan

Yao

et al. 2012

IEEE Trans. Power Electron.

343

108

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“…These critical issues have been the focal point in [1]- [6]. Despite the claims of high efficacy, such high-efficacy figures are only true at low junction temperature and not sustainable at high temperature, which is the normal operating condition for LED applications unless expensive heat sinks and/or forced cooling can be used to keep the junction temperature to low level.…”

Section: Introductionmentioning

confidence: 97%

A Simple Method for Comparative Study on the Thermal Performance of LEDs and Fluorescent Lamps

Qin

Lin

Hui

2009

IEEE Trans. Power Electron.

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A simple method is proposed to measure the heat dissipation of LEDs and fluorescent lamps in an open system that allows light energy to escape. Based on this method, a comparative study on the thermal and luminous performance of high-brightness LEDs and fluorescent lamps is presented. At rated power, T5 and T8 fluorescent lamps generate about 73%-77% of their total power as heat, while three types of high-brightness LEDs dissipate about 87%-90% of input power as heat. Heat dissipation is an important factor particularly for air-conditioned buildings when overall energy efficiency is considered. T5 fluorescent lamps perform better than some existing LEDs in terms of luminous efficacy and heat generation in this study.

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“…15 Subsequent research evaluated the use of neural networks to maintain accurate chromaticity 16 and explored optical feedback using three or more unique LED wavelengths. 15,17 This is achieved by fixing the ratio of intensity at one wavelength to another at the cost of saturated colors and a decreased color gamut. This does not guarantee the best color rendering index for a given white point.…”

Section: 14mentioning

confidence: 99%

“…17 For example, if we add an amber color, we make amber a fixed ratio, α, of the red setpoint. In this example, the solution is…”

Section: Exact and Minimum Square Error Solutionsmentioning

confidence: 99%

Energy efficient control of polychromatic solid state lighting using a sensor network

2010

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Motivated by opportunities in smart lighting, energy efficiency, and ubiquitous sensing, we present the design of polychromatic solid-state lighting controlled using a sensor network. We developed both a spectrally tunable light source and an interactive lighting testbed to study the effects of systems that adjust in response to changing environmental lighting conditions and users' requirements of color and intensity. Using both linear and nonlinear optimization, the setpoints of overdetermined systems (greater than three wavelengths) and the energy consumption of the network are adjusted according to the room's lighting conditions (e.g., lux and color temperature of multiple fixtures). Using these techniques, it is possible to maximize luminous efficacy or the color rendering index for a given intensity and color temperature. We detail the system modeling, design, optical calibration, and control theory required to modulate the luminous output and minimize wasted energy.

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Control of LEDs

Cited by 47 publications

References 6 publications

A Flicker-Free Electrolytic Capacitor-Less AC–DC LED Driver

A Flicker-Free Electrolytic Capacitor-Less AC–DC LED Driver

A Simple Method for Comparative Study on the Thermal Performance of LEDs and Fluorescent Lamps

Energy efficient control of polychromatic solid state lighting using a sensor network

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