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- 2019
- LED AC direct driver IC
- THD adjustment
- different situation
- external resistor
- current
- Optoelectronic Information Science and Engineering
- Zhejiang University
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[IEEE 2019 IEEE 62nd International Midwest Symposium on Circuits and Systems (MWSCAS) - Dallas, TX, USA (2019.8.4-2019.8.7)] 2019 IEEE 62nd International Midwest Symposium on Circuits and Systems (MWSCAS) - Multi-Channel LED Driver with Accurate Current Matching for Portable Applications
摘要： In this paper, we present a multi-string LED driver based on a current-limiting hysteretic boost converter, which is capable of driving ten LEDs in five parallel strings. An accurate current matching circuit with low voltage headroom requirement is implemented to match currents in all LED strings. Dynamic compensation of the LED forward voltage mismatch between the strings is achieved with the introduction of a minimum voltage selector block. A PFM dimming circuit is designed to operate with a 200 kHz clock and has 11 programmable dimming ratios, ranging from 2:1 to 2048:1. This LED driver is implemented in 0.6-μm CMOS process and operates from a Li-ion battery with a voltage range 3 – 4.2 V. It is suitable for backlight LED displays in mobile devices.
关键词： dimming,hysteretic controller,DCM,current matching,LED driver,forward voltage mismatch
更新于2025-09-12 10:27:22
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Investigations on Driver and Layout for Paralleled GaN HEMTs in Low Voltage Application
摘要： Gallium nitride is becoming more popular in low-voltage applications. Gallium nitride (GaN) high electron mobility transistors (HEMTs) has positive temperature feature. It makes parallel application feasible for GaN HEMTs. Meanwhile, paralleled GaN HEMTs will increase the power handling capability and the efficiency of the converter. The parasitic parameters of both driving and power loop layout are critical which need to be equalized and minimized in GaN HEMT parallel operation. The parameters mismatch of the parallel branch will lead to significant effect on the dynamic characteristics and bring thermal problem of the GaN HEMTs. This paper focuses on the design of paralleled low-voltage enhancement GaN HEMT, and evaluates the effect of the parasitic inductances in both driver and power loops. The LT-spice and ANASYS Q3D Extractor simulation are carried out to analysis the effect of the unbalance parameters. The design guidelines for driver and PCB design are summarized as well. Finally, a 300W isolated DC-DC converter is built to verify the analysis and simulation on parallel operation.
关键词： Solar Energy,DC-DC Converter,Driver Design,Paralleling,Enhancement,Low-Voltage GaN HEMT,Parasitic Parameters
更新于2025-09-12 10:27:22
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Output current ripple reduction of LED driver using ceramic‐capacitor‐input circuit and buck‐boost converter
摘要： This article proposes an LED driver that consists of a ceramic-capacitor-input rectifier and a buck-boost converter. The LED driver has an advantage of long life because it does not contain any electrolytic capacitors. However, the issue with electrolytic capacitor-less LED driver is that the ripple of the smoothed voltage becomes large due to insufficient capacitance of the smoothing capacitor. The proposed method, which uses the discontinuous current mode of a buck-boost converter, reduces the output current ripple under such conditions. Experimental results using a 5.7 W LED driver prototype demonstrate that the proposed method reduces the output current ripple and that the percent flicker becomes 4.4%, which is smaller than the recommended upper limit of 8%.
关键词： ceramic capacitor,LED driver,buck-boost converter,electrolytic capacitor-less,discontinuous current mode
更新于2025-09-12 10:27:22
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Attosecond pulse generation by relativistic flying mirrors in laser-plasma interaction: Effect of plasma density and driver amplitude on the generated pulse
摘要： The generation of high-intensity attosecond pulses by the interaction of two counterpropagating short laser pulses with underdense plasma is investigated. By using parallel fully kinetic particles in cell simulation, which shows the formation of relativistic ?ying mirrors in the wake wave of the intense driver laser pulse and the focusing re?ection of the weak source pulse, it is demonstrated that intense attosecond pulses can be produced under the optimized conditions of plasma density and driver laser amplitude according to the relativistic similarity theory. In addition, it is shown that the frequency of the source pulse is upshifted by a factor from 10 to 80 corresponding to a re?ected radiation wavelength from 20 to 164 nm which lies in the extreme ultraviolet region, while most of the energy lies around a frequency upshift of 20, in agreement with the measured Lorentz factor. The intensity of the main attosecond pulse is two orders higher than the source pulse intensity.
关键词： plasma density,driver amplitude,attosecond pulse generation,relativistic flying mirrors,laser-plasma interaction
更新于2025-09-12 10:27:22
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Efficiency Improvement of Multi-Channel LED Driver with Selective Dimming
摘要： There is a widespread application of selective dimming of multi-channel LED drivers. In this paper, two new selective dimming methods to improve efficiency of multi-channel LED drivers are proposed. The proposed methods are based on a two-stage multi-channel LED driver that consists of an ac-dc boost power factor correction converter at its front-end and a dc-dc non- resonant converter at its second stage. Primary side digital peak current control method is applied to the dc-dc converter to control the LED peak currents during selective dimming operation. The auxiliary back-to-back switches are connected across each transformer winding either at the primary side or secondary side to perform selective dimming. The duty ratios of these auxiliary back-to-back switches are varied at lower than switching frequency of dc-dc converter to control the brightness of LED loads. The proposed topologies offer high efficiencies in both full load and during selective dimming operations, and meet the IEEE 1789 recommendation with 3 kHz dimming frequency. The design of proposed dc-dc converters, modes of operation as well as detailed theoretical analysis are presented in this paper. A 150W prototype of the proposed LED driver with a non-DSP micro- controller, is implemented to verify the feasibility of such LED drivers. Comparisons between the proposed methods and the converters reported previously are presented in the paper.
关键词： selective dimming,Multi-channel LED driver,shorting transformer windings,primary side peak current control
更新于2025-09-12 10:27:22
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Analysis and implementation of soft‐switched bidirectional buck‐boost DC‐DC converter for solar PV‐fed LED street lighting systems
摘要： This paper presents a single-stage solar photovoltaic (SPV) fed light-emitting diode (LED) street lighting system (LED-SLS) using a novel soft-switched buck-boost bidirectional DC-DC converter (BDC). A coupled inductor (CI) based auxiliary circuit is used in the proposed BDC to achieve soft switching, which leads to improved efficiency with reduced ripple. As SPV power is available during day time alone, a battery storage system (BSS) is used. The BSS is charged from SPV during day time through the proposed CI-BDC. The BSS powers the LED-SLS during night time through the same CI-BDC. The proposed CI-BDC provides various advantages like buck/boost operation in either direction of power flow, zero voltage switching (ZVS) soft-switching, use of single magnetic core, high efficiency, reduced ripple in output current, and simple control. Also, it provides an illumination control of the LED-SLS using pulse-width modulation (PWM) dimming. To maintain high efficiency even at light loads, the proposed CI-BDC works as conventional BDC by turning OFF the auxiliary circuit. Thus, avoiding the high conduction losses in it at light loads. The detailed working principle and design analysis are presented along with simulation results. A prototype of 40 W LED lighting system has been developed, and experimental validation is presented.
关键词： buck-boost,bidirectional,soft switching,coupled inductor,LED driver
更新于2025-09-12 10:27:22
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A Single-Stage High-Power-Factor Light-Emitting Diode (LED) Driver with Coupled Inductors for Streetlight Applications
摘要： This paper presents and implements a single-stage high-power-factor light-emitting diode (LED) driver with coupled inductors, suitable for streetlight applications. The presented LED driver integrates an interleaved buck-boost power factor correction (PFC) converter with coupled inductors and a half-bridge-type series-resonant converter cascaded with a full-bridge rectifier into a single-stage power conversion circuit. Coupled inductors inside the interleaved buck-boost PFC converter sub-circuit are designed to operate in discontinuous conduction mode (DCM) for achieving input-current shaping, and the half-bridge-type series resonant converter cascaded with a full-bridge rectifier is designed for obtaining zero-voltage switching (ZVS) on two power switches to reduce their switching losses. Analysis of operational modes and design equations for the presented LED driver are described and included. In addition, the presented driver features a high power factor, low total harmonic distortion (THD) of input current, and soft switching. Finally, a prototype driver is developed and implemented to supply a 165-W-rated LED streetlight module with utility-line input voltages ranging from 210 to 230 V. Experimental results demonstrate that high power factor (>0.99), low utility-line current THD (<7%), low-output voltage ripples (<1%), low-output current ripples (<10%), and high circuit efficiency (>90%) are obtained in the presented single-stage driver for LED streetlight applications.
关键词： converter,streetlight,light-emitting diode (LED),driver
更新于2025-09-12 10:27:22
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[IEEE 2019 International Russian Automation Conference - Sochi, Russia (2019.9.8-2019.9.14)] 2019 International Russian Automation Conference (RusAutoCon) - Precision Medium-Power Laser Diode Drivers: Design Principles and Functional Features
摘要： Laser diodes are semiconductor emitting crystal enclosed in a single package, as well as a number of additional optical and electronic components. Such diodes are widely used in high-tech systems and equipment and are among the most important elements of the entire class of modern optoelectronic devices. To control the operation of laser diodes, specialized devices are used - laser diode drivers, which structure and operation principles can be fundamentally different. The paper considers the typical structures of medium power laser diodes in butterfly and 14pin-DIL package-types, and their application areas. Basic approaches to current driver circuitry and thermal stabilization process are described. An example of a digital driver with a microprocessor-based control system is shown.
关键词： source controller,medium power diodes laser diode,driver,microprocessor control,TEC controller
更新于2025-09-11 14:15:04
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New electrolytic capacitor-less LED driver based on model predictive control
摘要： The lifetime of light-emitting diode (LED) drivers is mainly affected by electrolytic capacitors. Therefore, it is necessary to eliminate electrolytic capacitors from LED drivers. Firstly, basic concept of LED driver without electrolytic capacitors is addressed in this paper. Then, a new electrolytic capacitor-less LED driver is proposed and its operation principles are analyzed in detail. In order to achieve better control effect, model predictive control (MPC) strategy is introduced in this topology. Following that, the mathematical model of the circuit which adopts MPC is derived. Finally, simulations and experiments on a 24 V, 3A laboratory prototype are carried out to verify the feasibility of the proposed topology and control strategy.
关键词： Flyback,Model predictive control,LED driver,Bidirectional cuk,Electrolytic capacitor-less
更新于2025-09-11 14:15:04
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Single Stage High Brightness LED Driver with Improved Power Quality
摘要： A single switch single stage 24watt power supply is presented to run a light emitting diode (LED) load. In this power supply, the Zeta converter is used to operate in continuous conduction mode (CCM) for maintaining desired output voltage. A proportional integral (PI) controller is also proposed in the feedback to make system stable. The need of proposed controller is justified from stability analysis of the system with the help of small signal average modeling. A simulation model of the proposed LED driver is also carried out in MATLAB/SIMLINK using sim-power toolbox environment for a universal ac input mains. The results confirm a constant current of 0.4amp at output with improved power quality parameters such as total harmonic distortion (THD) and power factor (PF). All outcomes lie under the limit of IEC 61000-3-2 standards that verifies the theoretical analysis.
关键词： Small Signal Average (SSA) Modeling,Continuous Conduction Mode (CCM),THD,LED Driver,Power Factor (PF),Stability,Zeta dc-dc Converter
更新于2025-09-11 14:15:04