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This paper presents a high-power-density high-power-factor GaN-based two-stage electrolytic-free offline LED driver. The LED driver achieves high power density through the use of a hybrid film-ceramic stacked switched capacitor (SSC) energy buffer, and a comprehensive optimization methodology that evaluates various converter topologies and designs, and minimizes overall system volume while maintaining...
This paper introduces a new power factor correction scheme for a flyback converter with primary regulation technique, to ideally eliminate the distortion of the ac input current (practically a Total Harmonic Distortion (THD) lower than 5%). The effectiveness of the new control scheme is proved in a 35W driver with universal input range (90VAC∼277VAC). Application target is Solid State Lighting (LED...
For traditional AC/DC power factor correction (PFC) converters, the diode bridge rectifier is needed in the front-end. While a large current flowing through the bridge, the conduction voltage drop of diodes can result in large power loss. Bridgeless converter can be adopted to improve efficiency and bipolar gain property makes the function of PFC realizable. In this paper, an isolated PFC converter...
In this paper, an architecture of a single-stage power factor corrected AC-DC converter controlled by a high voltage resonant controller IC L6598 is proposed as LED street lighting driver. The converter is formed by the integration of two boundary conduction mode (BCM) boost circuits and a half-bridge LLC resonant circuit. The converter adapts dual half-wave rectifiers at the output side that supply...
In this paper; a single-stage three-loop power factor correction (PFC) technique is proposed for DC-DC converters used as driver for LED lights. The technique is demonstrated on a dc-dc Cuk converter which is used as driver for LED lamps wherein a two-zero; two pole digital compensator is used in the three-loop control structure for power factor correction. The converter is designed to operate in...
A Double integrated buck converter finds application in fields of solid state lighting. buck Converter is widely used for step down dc-dc conversion when there is no isolation requirement. The narrow duty cycle of the buck converter limits its application for high step down applications. The double integrated buck converter overcomes its limitaion. This converter also provides high power factor and...
Conventional AC/DC LED drivers require a large energy storage capacitor at the output to provide a constant current to the LEDs. In order to minimize the size and cost of the driver circuit, electrolytic capacitors are conventionally used due to its high energy density and low cost. However, electrolytic capacitors are sensitive to operating temperature and have much shorter lifetime than the LED...
LED lighting sources have been used in several applications than established lighting sources due to their high luminous efficiency, environmental friendly, long life, compact size, and not affected by cold temperature. This paper deals with the design of buck-boost LED driver for wide input voltage applications. The proposed LED driver is a combination of uncontrolled rectifier followed by buck-boost...
This paper presents a modified-Landsman converter fed power factor correction (PFC) based light emitting diode (LED) driver. The application is targeted for high brightness (HB) projection application with brightness control of high brightness red-green-blue (HB-RGB) LED. A pulse width modulation (PWM) technique is used for current control to achieve brightness control of LED driver without compromising...
This paper describes a novel control method for high-power-factor quasi-resonant (Hi-PF QR) flyback converters able to meet simultaneously three control objectives: a) performing constant-current control with primary sensing regulation (CC-PSR); b) achieving ideally no harmonic distortion of the ac input current; c) being fully compatible with real-world “phase-cut” wall dimmers. Simulation results...
In this paper a single stage offline LED driver that can drive N-color HB-LED strings is presented. The proposed converter provides multiple current outputs for N-Color HB-LED strings from an AC input. The current outputs are independently controllable to obtain the desired Correlated Color Temperature (CCT) and high Color Rendering Index (CRI) for dynamic lighting systems. Hybrid Average Current...
Traditional LED drivers generally use electrolytic capacitor as the storage element which will restrict the lifetime and power density of drivers. In this paper, an electrolytic capacitor-less LED driver which pluses an auxiliary winding in the transformer and an additional full-bridge circuit to Flyback converter is proposed. It not only eliminates the electrolytic capacitor to extend the lifetime,...
Light emitting diodes (LEDs) have great potential to replace existing light sources, like incandescent and fluorescent lamps due to their long life time and higher efficacy. Therefore, also the life time and efficiency of the LED-ballast are important factors in order to improve the overall system. In addition, size and costs are a relevant factor in the highly competitive LED market. With the benefits...
In recent years, high brightness light emitting diodes are widely used in many applications. This paper presents an integrated converter topology for driving HB LEDs. The integrated buck flyback converter is a single stage, low cost, high power factor AC-DC converter with fast output regulation. The converter is used to provide power factor correction in streetlight application. To obtain high power...
LED with constant output current and power factor correction are presented in this paper, the non-isolated Buck converters are used for the LED drivers, according to different operating mode of inductor current, power factor correction is realized with both of Voltage Follower Control under DCM and Nonlinear Carrier Control under CCM. NLC needn't the multiplier which is used in traditional power factor...
In high voltage AC input applications, buck PFC has the advantage of outputting a lower level voltage. This paper presents a variable on-time control buck PFC front-end for high-brightness light-emitting-diode (HB-LED) application, the function of the switch on-time in a half-line cycle is derived. Most high-order harmonics are lowered comparing to the constant on-time control in order to comply with...
White light emitting diode (LED) with high brightness has attracted a lot of attention from both industry and academia for its high efficiency, ease to drive, environmental friendliness, and long lifespan. They become possible applications to replace the incandescent bulbs and fluorescent lamps in residential, industrial and commercial lighting. The realization of this new lighting source requires...
With high input voltage or light load, the peak of AC line current for critical conduction mode (CRM) flyback power factor Correctors (PFCs) appears notably distorted. In this paper, the reasons of line current distortion are investigated. Moreover, the relationship between line current peak distortion and high input voltage or light load is presented. Based on theoretical analysis, a simple improved...
A constant current output Flyback converter with power factor correction used for LED driving is presented in this paper. The inductor voltage detection method is applied and acquired the inductor voltage to generate the control signal. Based on this design principle, the inner loop of input current shaping is eliminating, the input voltage sensing and multiplier are also not necessary. The simulation...
A buck-boost topology operating in discontinuous conduction mode (DCM) is used as an off line LED driver for lighting applications. Operating from a full wave rectified ac-voltage with minimum input capacitance, with a constant switching frequency and constant on-time, the utility current has near unity power factor. This LED driver is suitable for cost sensitive applications because this circuit...
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