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[IEEE 2019 Electric Power Quality and Supply Reliability Conference (PQ) & 2019 Symposium on Electrical Engineering and Mechatronics (SEEM) - K?rdla, Estonia (2019.6.12-2019.6.15)] 2019 Electric Power Quality and Supply Reliability Conference (PQ) & 2019 Symposium on Electrical Engineering and Mechatronics (SEEM) - Power Quality Assessment of Indoor LED Luminaires
摘要： Due to the fact that it is a semiconductor based lighting equipment, the LEDs have important effects on the power quality. In the ever-expanding lighting industry, the use of LED equipment is increasing day by day. Therefore, it is very important to analyze and interpret the effects of LEDs on the grid. In this study, power quality measurements of 4 different commercial LED luminaires have been realized and the results obtained have been interpreted. According to the measurements, it is found that the power factor values are acceptable for the luminaries when they are completely on. However, when the luminaries are dimmed, it has been observed that the power factor decreased and the current harmonics exceeded the limit values determined by the related standards. On the other hand, it is seen that all the luminaires provide flicker boundaries. As a result of the study, it has been concluded that the effects of dimmable equipment on power quality should be analyzed in more detail.
关键词： LED lamps,harmonics,flicker,power quality,power factor
更新于2025-09-16 10:30:52
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Impact of optimum power factor of PV-controlled inverter on the aging and cost-effectiveness of oil-filled transformer considering long-term characteristics
摘要： The photovoltaic (PV) system is one of the most widespread of the renewable energy generation systems that are being used to meet the continuously increasing energy demand. A proposed analytical method is used to find the optimum power factor of PV inverter (PVI) that leads to minimum aging, reduced energy losses cost of the transformer, lower payback period of PV system, and lower green houses gases (GHG) emissions due to the transformer energy losses. In this study, the thermal performance of a 630?kVA mineral oil-filled transformer is simulated in MATLAB programming language. For an association, it is mandatory to connect a PV system to the grid to minimise the transformer loading. The PV output power is used to study the long-term impact of the solar irradiance on the transformer thermal performance. Also, the long-term climatic characteristics are considered. The ambient temperature surrounding the transformer is considered all day long. The load current profile was measured all day long. The results show the aging and cost-effectiveness of the transformer and the payback period of PV system and GHG emissions are a function of PVI power factor.
关键词： transformer aging,PV inverter,photovoltaic system,power factor,cost-effectiveness,GHG emissions
更新于2025-09-16 10:30:52
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Inductive decoupling-based multi-channel LED driver without electrolytic capacitors
摘要： Light-emitting diode (LED) drivers in outdoor street lighting applications suffer from short-lifetime because of the prolonged exposure to harsh environmental conditions such as high operating temperature, high humidity etc. A long-lifetime multi-channel LED driver consisting of front-end AC–DC boost power factor correction (PFC) converter followed by a DC–DC power conversion stage with dimming capability for LED-based street light is proposed in this study. This LED driver uses an inductor-based auxiliary decoupling circuit at the output of the AC–DC converter for mitigating the double-line-frequency power ripple present in the DC bus. The inductive ripple power storage circuit has a longer lifetime than a conventional capacitive storage circuit which is usually implemented by electrolytic capacitors. A digital control method is proposed to realise the decoupling control along with PFC control by a single non-digital signal processor micro-controller ST STM32F103RBT6. The proposed LED driver for street lighting is analysed and validated on a 150?W test setup. A comparison of active decoupling AC–DC converters for eliminating secondary-harmonic power ripple is displayed.
关键词： inductive decoupling,electrolytic capacitors,street lighting,LED driver,power factor correction
更新于2025-09-16 10:30:52
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Analysis and Modeling of Conducted EMI From an AC–DC Power Supply in LED TV up to 1 MHz
摘要： Critical conduction mode (CRM) boost power factor correction (PFC) converter is widely used in ac–dc power supplies to achieve high power factor. The switching frequency varies in a half-line cycle. In this article, both the differential-mode (DM) and common-mode (CM) electromagnetic interference (EMI) noises below 1 MHz from the ac–dc power supply in a LED TV are analyzed and modeled. The power supply consists of two parts: CRM boost PFC converter and LLC resonant converter. The conducted EMI noise and noise source voltages are measured in the time domain and then converted to the frequency domain via short-time fast Fourier transform (STFFT). Through the joint time-frequency analysis using STFFT, the drain-to-source voltage of the power MOSFET in the PFC converter is identified as the dominant noise source of both CM and DM EMI below 1 MHz from the power supply. The EMI current path changes during different periods of a cycle of the line voltage. During most time of a cycle, two diodes of the bridge rectifier are forward biased, and the bridge rectifier can be treated as short circuit. The current paths of DM and CM EMI are explained and modeled by a linear equivalent circuit model. Three parasitic capacitances need to be considered to model the CM EMI noise in this device under test. From the circuit model, transfer functions relating DM and CM EMI spectra to noise source voltage spectrum are obtained. The conducted EMI spectra is predicted by multiplying the spectrum of noise source voltage by the transfer functions. The prediction matches with measurement. The effects of parasitic capacitances on CM EMI noise are analyzed by simulation and then validated by measurement. The analysis can help with EMI design to reduce the CM EMI.
关键词： conducted emissions (CE),differential mode (DM),Common mode (CM),electromagnetic interference (EMI),switched-mode power supply (SMPS),critical conduction mode (CRM),power factor correction (PFC)
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE Energy Conversion Congress and Exposition (ECCE) - Baltimore, MD, USA (2019.9.29-2019.10.3)] 2019 IEEE Energy Conversion Congress and Exposition (ECCE) - A Multiplexing Off-Line LED Driver Achieves High Power Factor and Flicker-Free Operation
摘要： Although a single-stage off-line LED driver can achieve low cost and high efficiency, the notorious double-line-frequency flicker issue with a single-stage LED driver limits its usage in high-quality lighting applications. To solve lighting flicker, multiplexing operation is proposed in this paper. One switching cycle is further divided into two portions, namely phase one and phase two, which produces a main output voltage and an opposite ripple voltage. The main and the opposite ripple voltage are connected in series to form the LED voltage, which is a DC because of ripple cancellation. Therefore, a DC LED current can be produced and achieves flicker-free LED driving performance. A 7.5W experimental prototype had been built and tested to verify the design concept.
关键词： power factor correction,ripple cancellation,multiplexing operation,flicker-free,LED driver
更新于2025-09-12 10:27:22
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Grid Integration Scheme for a Three Phase Single Stage Photovoltaic system employing EKF
摘要： In this work, a nonlinear Kalman filer based synchronization strategy is proposed for a single stage three phase grid tied PV system. We employed Extended Kalman Filter (EKF) to estimate the fundamental voltage components of the voltage at Point of common coupling (PCC) and the fundamental components of the load current. A Proportional-Integral (PI) controller is designed to control the DC bus capacitor voltage. Simulation and experimental studies of the proposed EKF based control scheme show that the proposed control scheme provides maximum PV power extraction and mitigates load current harmonics while reducing the Total Harmonic Distortion (THD) of the grid current and PCC voltage to a lower value these are well within the prescribed limits of IEEE 519 standards even for distorted grid voltage condition.
关键词： Extended Kalman Filter,Unity Power Factor,Photovoltaic,Grid Synchronization
更新于2025-09-12 10:27:22
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[IEEE 2018 International Power Electronics Conference (IPEC-Niigata 2018-ECCE Asia) - Niigata (2018.5.20-2018.5.24)] 2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia) - Optimized Variable On-Time Control for LED Lighting Driver
摘要： This paper focus on how to implement variable on-time control to predictive boundary conduction mode boost PFC converter for driving LED lighting applications. Normally, the constant on-time control is implemented in predictive PFC converter, which leads to high THD of input line current. Varies of variable on-time control methods have been proposed to improve the THD of input line current. However, most of the proposed variable on-time calculation methods are too complex to be implemented in predictive control. In order to implement the variable on-time control to predictive control, a simple but very accurate variable on-time calculation method is applied. The optimized variable on-time control takes very short calculation time in DSP controller, hence it can be implemented in predictive control. The effectiveness of the proposed method which can reduce THD of line current is demonstrated on a 100 V input and 400 V/30 W output PFC prototype.
关键词： Predictive control,power factor correction,boundary conduction mode,zero-crossing point,total harmonic distortion.,power factor
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
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Buck-Boost-Buck Type Single-Switch Multi-String Resonant LED Driver with High Power Factor and Passive Current Balancing
摘要： An integrated buck-boost-buck type single-switch multi-string resonant LED driver is proposed and analyzed. It combines buck-boost and buck converters to achieve passive current balancing and power factor correction (PFC). With this circuit configuration, the proposed LED driver employs only one low-side connection active switch, resulting in a very simple control requirement involving one closed-loop controller for regulating one output current. Other output currents can be balanced automatically by resonant capacitor and storage capacitors, making the control strategy economical. In addition, high efficiency is achieved due to single-stage power conversion. Taking three-string LED driver as an example, the proposed buck-boost-buck type single-switch LED driver is studied in terms of operating principle, current balancing principle, power factor (PF) analysis, voltage gain and key circuit parameter design. Finally, an 84W high PF three-string LED driver prototype with 94.3% peak efficiency is built to verify the analytical results.
关键词： passive current balancing,multi-string,single switch,power factor correction (PFC),Buck-boost-buck,LED driver
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE International Conference on System, Computation, Automation and Networking (ICSCAN) - Pondicherry, India (2018.7.6-2018.7.7)] 2018 IEEE International Conference on System, Computation, Automation and Networking (ICSCA) - Power Factor Correction in Z-Source Resonant Converter for Wireless Power Transfer Applications
摘要： In this paper the Z-source converter is introduced to power factor correction (PFC) applications. The concept is demonstrated through a wireless power transfer (WPT) system for electric vehicle battery charging, namely Z-source resonant converter (ZSRC). Due to the Z-source network (ZSN), the ZSRC inherently performs PFC and regulate the system output voltage simultaneously, without adding extra semiconductor devices and control circuitry to the conventional WPT system such as conventional PFC converters do. In other words, the ZSN can be categorized as a family of the single stage PFC converters. In addition, the ZSN is suitable for high power applications since it is immune to shoot-through states, which increases reliability and adds a boost feature to the system. The ZSRC-based WPT system operating principle is described and analyzed in this paper. Simulations, and experimental results based on a 1-kW prototype with 20-cm air gap between the system primary and secondary side are presented to validate the analysis, and demonstrate the effectiveness of the ZSN in the PFC of the WPT system.
关键词： Power factor correction (PFC),Wireless Power Transfer (WPT),Total Harmonic Distortion (THD),Z-source resonant converter (ZSRC),Series resonant converter (SRC)
更新于2025-09-10 09:29:36