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[IEEE 2018 25th International Conference "Mixed Design of Integrated Circuits and System" (MIXDES) - Gdynia, Poland (2018.6.21-2018.6.23)] 2018 25th International Conference "Mixed Design of Integrated Circuits and System" (MIXDES) - Optimization of Class-D Amplifier Output Stage for Piezoelectric Actuator Control
摘要： Design of a piezoelectric driver for a microelectromechanical actuator in a small form factor for laser telecommunications is introduced. The driver introduces a number of challenges due to its size and power limitations as a Microelectromechanical Systems (MEMS) actuator. Because of the small form factor, the driver must be integrated into the actuator itself, which limits its size and power. The efficiency of a linear amplifier becomes a major drawback due to the dissipated heat of only 20 W for the Laser Telecommunications Module (LTM), low efficiency of a linear amplifier becomes a major drawback due to the dissipated heat. Switching Class-E amplifiers provide exceptional efficiency compared to non-switching solutions at a price of high frequency harmonics, which allows for higher output power without additional heat dissipation. The efficiency, however, comes at a price of high frequency harmonics, which must be reduced by implementing a High-Energy-Efficiency Interference (HEEI) and Total Harmonic Distortion (THD). Driving a capacitive load, such as a piezoelectric actuator, at a high frequency with a Class-E amplifier requires a matching network to achieve the desired output power. The measurements were performed on a custom-made driver model for piezoelectric stack actuators with 270 V peak-to-peak voltage, 500 kHz switching frequency and a range of capacitive load from 2.1 nF to 20 nF.
关键词： Actuator,Driver,Amplifier,Distortion,LTM.2,Output Stage,SMPS,Class-E,Total,LTM,THD,MEMS,Harmonic,Transmission,Telecommunications,Laser,Module,High-Energy-Efficiency,HEEI,Interference,Piezoelectric,Microelectromechanical
更新于2025-09-23 15:22:29
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Efficient and stable emission of warm-white light from lead-free halide double perovskites
摘要： Lighting accounts for one-fifth of global electricity consumption1. Single materials with efficient and stable white-light emission are ideal for lighting applications, but photon emission covering the entire visible spectrum is difficult to achieve using a single material. Metal halide perovskites have outstanding emission properties2,3; however, the best-performing materials of this type contain lead and have unsatisfactory stability. Here we report a lead-free double perovskite that exhibits efficient and stable white-light emission via self-trapped excitons that originate from the Jahn–Teller distortion of the AgCl6 octahedron in the excited state. By alloying sodium cations into Cs2AgInCl6, we break the dark transition (the inversion-symmetry-induced parity-forbidden transition) by manipulating the parity of the wavefunction of the self-trapped exciton and reduce the electronic dimensionality of the semiconductor4. This leads to an increase in photoluminescence efficiency by three orders of magnitude compared to pure Cs2AgInCl6. The optimally alloyed Cs2(Ag0.60Na0.40)InCl6 with 0.04 per cent bismuth doping emits warm-white light with 86 ± 5 per cent quantum efficiency and works for over 1,000 hours. We anticipate that these results will stimulate research on single-emitter-based white-light-emitting phosphors and diodes for next-generation lighting and display technologies.
关键词： lead-free halide double perovskites,self-trapped excitons,white-light emission,photoluminescence efficiency,Jahn–Teller distortion
更新于2025-09-23 15:21:21
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Building Deformation Assessment by Means of Persistent Scatterer Interferometry Analysis on a Landslide-Affected Area: The Volterra (Italy) Case Study
摘要： In recent years, space-borne InSAR (interferometric synthetic aperture radar) techniques have shown their capabilities to provide precise measurements of Earth surface displacements for monitoring natural processes. Landslides threaten human lives and structures, especially in urbanized areas, where the density of elements at risk sensitive to ground movements is high. The methodology described in this paper aims at detecting terrain motions and building deformations at the local scale, by means of satellite radar data combined with in situ validation campaigns. The proposed approach consists of deriving maximum settlement directions of the investigated buildings from displacement data revealed by radar measurements and then in the cross-comparison of these values with background geological data, constructive features and on-field evidence. This validation permits better understanding whether or not the detected movements correspond to visible and effective damages to buildings. The method has been applied to the southwestern sector of Volterra (Tuscany region, Italy), which is a landslide-affected and partially urbanized area, through the use of COSMO-SkyMed satellite images as input data. Moreover, we discuss issues and possible misinterpretations when dealing with PSI (Persistent Scatterer Interferometry) data referring to single manufactures and the consequent difficulty of attributing the motion rate to ground displacements, rather than to structural failures.
关键词： Volterra,Persistent Scatterer Interferometry,angular distortion,building damages,landslide
更新于2025-09-23 15:21:21
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[IEEE 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Trebic, Czech Republic (2018.9.18-2018.9.20)] 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Electrical Parameters of Dimmable Luminaire
摘要： Lighting systems are currently one of the main uses of electricity. The most popular option for reducing of electricity consumption is the use of dimming. Dimming is a type of regulation in which we can regulate luminous flux of a lamps and luminaires. This system of regulation is used in the road lighting industry, but also in households. Dimming allows adaptation of the lighting system according to specific requirements and various ambient conditions such as traffic density, daylight, etc. The regulation of the luminous flux depending on the dimming system can affect the electrical parameters of the luminaires such as the power factor. The article deals with the electrical parameters of luminaires with various lamps at different types of dimming.
关键词： LED,total harmonic distortion,Power factor
更新于2025-09-23 15:21:21
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[IEEE 2019 IEEE Workshop on Power Electronics and Power Quality Applications (PEPQA) - Manizales, Colombia (2019.5.30-2019.5.31)] 2019 IEEE Workshop on Power Electronics and Power Quality Applications (PEPQA) - Determination and Performance Analysis of the Norton Equivalent Models for Fluorescents and LED Recessed Lightings
摘要： For long-wavelength space-based radars, such as the P-band radar on the recently selected European Space Agency BIOMASS mission, system distortions (crosstalk and channel imbalance), Faraday rotation, and system noise all combine to degrade the measurements. A first-order analysis of these effects on the measurements of the polarimetric scattering matrix is used to derive differentiable expressions for the errors in the polarimetric backscattering coefficients in the presence of Faraday rotation. Both the amplitudes and phases of the distortion terms are shown to be important in determining the errors and their maximum values. Exact simulations confirm the accuracy and predictions of the first-order analysis. Under an assumed power-law relation between σhv and the biomass, the system distortions and noise are converted into biomass estimation errors, and it is shown that the magnitude of the deviation of the channel imbalance from unity must be 4–5 dB less than the crosstalk, or it will dominate the error in the biomass. For uncalibrated data and midrange values of biomass, the crosstalk must be less than ?24 dB if the maximum possible error in the biomass is to be within 20% of its true value. A less stringent condition applies if the amplitudes and phases of the distortion terms are considered random since errors near the maximum possible are very unlikely. For lower values of the biomass, the noise becomes increasingly important because the σhv signal-to-noise ratio is smaller.
关键词： Biomass,Faraday rotation,polarimetric measurements,system distortion,calibration,long-wavelength radar
更新于2025-09-23 15:21:01
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Phase-locked Strategy of Photovoltaic Connected to Distribution Network with High Proportion Electric Arc Furnace
摘要： With the rapid development of industrialization, the proportion of electric arc furnaces (EAF) in distribution networks is getting higher and higher. Aiming at the problem that grid voltage is distorted by a large number of arc furnace nonlinear loads accessing to distribution networks, it is crucial to make dynamic analysis of distribution network voltage and adopt a control strategy of grid-connected converter based on the new phase-locked loop (PLL) technology. As a result, the harmonic distortion rate is reduced and the quality of grid-connected current and voltage is improved. In this paper, photovoltaic (PV) system model and the typical dynamic model of the EAF are established. By analyzing the influence of the EAF model on the PV grid-connected converter with the traditional phase-locked loop while connected to distribution network, a control strategy of the PV grid-connected converter with the self-adjusting double SOGI (MAF-SASOGI) phase-locked loop with the ideal low-pass filter is proposed. Through the simulation analysis, it is verified that precise phase locked can be realized and harmonic content of the system can be reduced by the PLL strategy proposed in this paper. Therefore, the quality of PV grid-connected voltage and current is improved.
关键词： Electric arc furnaces (EAF),Photovoltaic(PV) grid-connected,Voltage distortion,Distribution network,Phase-locked strategy
更新于2025-09-23 15:21:01
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[IEEE 2019 7th International Renewable and Sustainable Energy Conference (IRSEC) - Agadir, Morocco (2019.11.27-2019.11.30)] 2019 7th International Renewable and Sustainable Energy Conference (IRSEC) - Power Quality Improvement of A Photovoltaic Active Power Filter using A Fuzzy Hysteresis Band Current Controller
摘要： This paper investigates a Fuzzy Hysteresis Band Current Control technique (Fuzzy-HBCC) for a Photovoltaic active power ?lter connected at PCC to the AC grid and a non-linear load. This connection offers good bene?ts of producing PV power as well as ensuring the power quality enhancement. In order to demonstrate the ef?ciency of the proposed system command using Fuzzy-HBCC, Fuzzy Vdc controller and Fuzzy-MPPT controller; several simulation cases have been carried out under an online solar variation, and a variable/?xed ignition angle of the nonlinear load. The proposed Fuzzy band current control technique (Fuzzy-HBCC) is developed and compared by simulation, in a Matlab/Simulink environment, with an adaptive Hysteresis controller (adaptive-HBCC) and a ?xed Hysteresis controller (?xed-HBCC) which require mathematical model determination. The results show the robustness of the proposed Photovotaic active power ?lter system with a better dynamic response and signi?cant reduction in Total harmonic distortion levels even under a sudden variation of the nonlinear load and of solar irradiance.
关键词： photovotaic active power ?lter,fuzzy band current control technique,dynamic response,total harmonic distortion
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 2nd International Conference on Automation, Electronics and Electrical Engineering (AUTEEE) - Shenyang, China (2019.11.22-2019.11.24)] 2019 IEEE 2nd International Conference on Automation, Electronics and Electrical Engineering (AUTEEE) - Influence of Grid-connected Photovoltaic Systems on Power Quality
摘要： This paper reviews the power quality indicators and evaluation methods specified in the IEEE. Based on the experiments, the power quality problems caused by the switching of small-scale single-phase photovoltaic (PV) systems and large-scale three-phase PV power plants are analyzed. Meanwhile, under the state of PV systems input and cut-out, the influence of load switching of different properties on power quality is analyzed. Experiments show that the switching of PV systems will lead to voltage sags and impulsive transients, as well as current waveform distortion. However, the input of PV systems has a good restraint effect on voltage sags and impulsive transients caused by loads switching.
关键词： impulsive transients,voltage sags,photovoltaic systems,unbalanced,harmonic distortion,power quality
更新于2025-09-23 15:21:01
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[IEEE 2019 International Conference on Intelligent Computing and Control Systems (ICCS) - Madurai, India (2019.5.15-2019.5.17)] 2019 International Conference on Intelligent Computing and Control Systems (ICCS) - Controlled PV Systems Power Quality Retention and Output Power Escalation
摘要： Due to the burden on fossil fuels the trend of generating power through renewable energy resources is gaining more importance day by day. In such systems there are issues related to efficiency and reliability. The paper focuses mainly on developing a model using MATLAB / SIMULINK software to overcome the above mentioned obstacles to the PV system and improve its overall performance by introducing appropriate control schemes. The aim of the PV system design is to escalate the output power under varying environmental conditions and also to retain the power quality of the PV system during faulty conditions. MPPT is applied to optimize through Incremental conductance thus ensuring the system is running at its maximum power point irrespective of the partial shading effect and temperature variations in the environment. With the employment of power quality compensation scheme that in turn uses a DVR, the system is capable of restoring the power quality thereby commuting the power quality issues. Significant fall in the THD levels is attained by usage of DVR control scheme along with a CHB multilevel DC/AC converter. The significance of developing MPPT algorithm is illustrated by examining the impact of partial shading condition and the temperature variations on its productivity. The demonstration of the power quality compensation capability of the PV system is achieved by the power quality compensation control scheme under faulty conditions.
关键词： Cascaded H-Bridge Multilevel Inverter (CHB),Incremental Conductance (IncCond),Total Harmonic Distortion (THD),Dynamic Voltage Restorer (DVR),Maximum Power Point Tracking (MPPT)
更新于2025-09-23 15:21:01
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Effect of non-metallic X(X=F, N, S) and Cr co-doping on properties of BiFeO3: A first-principles study
摘要： In this study, the structural, magnetic, electric and optical properties in X (X=F, N, S) and Cr co-doped BiFeO3 (BFO) are calculated using the density functional theory. For Cr–X co-doping case, the structure of BFO undergo a phase transition from monoclinic to triclinic structure accompanying net magnetic moments of 5.92 μB, 6.04 μB and 7.80 μB, for Cr–F co-doping, Cr–N co-doping and Cr–S co-doping, respectively. The underlying physical mechanisms are the lattice distortions tunned by doping. The decreased Fe–O–Fe bond angles and Fe–O bond lengths will bring weak antiferromagnetism superexchange interaction. In addition, the band gaps of Cr–X co-doping cases are decreased from 2.20 eV (BFO bulk) to 1.31 eV and 1.80 eV for Cr–F co-doping and Cr–S co-doping, respectively, which are well for photovoltaic applications according to the well-known Shockley-Queisser criterion, suggesting a possible great improvement optical properties in Cr–X co-doped samples.
关键词： Lattice distortion,Optical properties,Non-metal and transition-metal co-doped BiFeO3,Magnetic moments
更新于2025-09-23 15:21:01