Maintaining Stability During a Conducted-Ripple EMC Test

An improved technique, and electronic circuitry to implement the technique, have been developed for a military-standard electromagnetic-compatibility (EMC) test in which one analyzes susceptibility to low-frequency ripple conducted into the equipment under test via a DC power line. In the traditional technique for performing the particular test, the ripple is coupled onto the DC power line via a transformer. Depending upon some design details of the equipment under test, the inductance of the transformer can contribute a degree of instability that results in an oscillation of amplitude large enough to destroy the equipment. It is usually possible to suppress the oscillation by connecting a damping resistor to the primary terminals of the ripple-injection transformer. However, it is important to emphasize the usually in the preceding sentence: sometimes, the resistive damping becomes insufficient to suppress destructive oscillation. In addition, undesirably, the resistor contributes to power dissipation and power demand, and thereby also necessitates the use of a larger ripple voltage amplifier. Yet another disadvantage of the transformer-coupling technique is that the transformer introduces low-frequency distortion of the injected ripple voltage. The improved technique makes it possible to inject ripple with very low distortion at low frequency, without inducing oscillation. In this technique, a transformer is not used: Instead, power is fed to the equipment under test via series power field-effect transistors (FETs) controlled by a summing operational amplifier. One of the inputs to the amplifier controls the DC component of the power-line voltage; the other input, generated by an external oscillator, controls the ripple component. The circuitry for implementing this technique includes panel displays, an internal power supply for the operational amplifier and panel displays, and amplitude controls for the DC and ripple powerline voltage components

Unified Heat Kernel Regression for Diffusion, Kernel Smoothing and Wavelets on Manifolds and Its Application to Mandible Growth Modeling in CT Images

We present a novel kernel regression framework for smoothing scalar surface data using the Laplace-Beltrami eigenfunctions. Starting with the heat kernel constructed from the eigenfunctions, we formulate a new bivariate kernel regression framework as a weighted eigenfunction expansion with the heat kernel as the weights. The new kernel regression is mathematically equivalent to isotropic heat diffusion, kernel smoothing and recently popular diffusion wavelets. Unlike many previous partial differential equation based approaches involving diffusion, our approach represents the solution of diffusion analytically, reducing numerical inaccuracy and slow convergence. The numerical implementation is validated on a unit sphere using spherical harmonics. As an illustration, we have applied the method in characterizing the localized growth pattern of mandible surfaces obtained in CT images from subjects between ages 0 and 20 years by regressing the length of displacement vectors with respect to the template surface.Comment: Accepted in Medical Image Analysi

Effect of formant frequency spacing on perceived gender in pre-pubertal children's voices

<div><p>Background</p><p>It is usually possible to identify the sex of a pre-pubertal child from their voice, despite the absence of sex differences in fundamental frequency at these ages. While it has been suggested that the overall spacing between formants (formant frequency spacing - ΔF) is a key component of the expression and perception of sex in children's voices, the effect of its continuous variation on sex and gender attribution has not yet been investigated.</p><p>Methodology/Principal findings</p><p>In the present study we manipulated voice ΔF of eight year olds (two boys and two girls) along continua covering the observed variation of this parameter in pre-pubertal voices, and assessed the effect of this variation on adult ratings of speakers' sex and gender in two separate experiments. In the first experiment (sex identification) adults were asked to categorise the voice as either male or female. The resulting identification function exhibited a gradual slope from male to female voice categories. In the second experiment (gender rating), adults rated the voices on a continuum from “masculine boy” to “feminine girl”, gradually decreasing their masculinity ratings as ΔF increased.</p><p>Conclusions/Significance</p><p>These results indicate that the role of ΔF in voice gender perception, which has been reported in adult voices, extends to pre-pubertal children's voices: variation in ΔF not only affects the perceived sex, but also the perceived masculinity or femininity of the speaker. We discuss the implications of these observations for the expression and perception of gender in children's voices given the absence of anatomical dimorphism in overall vocal tract length before puberty.</p></div

Torsade de Pointes with an antihistamine metabolite: Potassium channel blockade with desmethylastemizole

AbstractObjectives. Proarrhythmic effects have been observed with the selective histamine1 (H1) receptor antagonist drug astemizole, a widely prescribed antihistamine. The metabolites of astemizole and those of other antihistamine compounds have not been implicated as causative agents of cardiac arrhythmias. The purpose of this study was to examine whether desmethylastemizole, the principal metabolite of astemizole, blocks delayed rectifier potassium (K+) channels.Background. QT interval prolongation and torsade de pointes are associated with astemizole intake and have been ascribed to block the repolarizing K+ currents, specifically the rapidly activating component of the delayed rectifier iKr. Astemizole undergoes extensive first-pass metabolism, and its dominant metabolite, desmethylastemizole, has a markedly prolonged elimination time. We report the clinical observation of QT prolongation and torsade de pointes in a patient with undetectable serum concentrations of astemizole (<0.5 ng/ml) and “therapeutic” concentrations of desmethylastemizole (up to 7.7 ng/ml or 17.3 nmol/liter).Methods. The perforated patch clamp recording technique was used to study the effects of desmethylastemizole (20 nmol/liter) on action potentials and iKr in isolated rabbit ventricular myocytes.Results. Desmethylastemizole produced action potential prolongation and the induction of plateau early afterdepolarizations. Under voltage clamp conditions, desmethylastemizole suppressed iKr amplitude by ≈65%. The drug E-4031 (100 nmol/liter), which selectively blocks iKr, had a similar effect on current amplitude.Conclusions. Desmethylastemizole, the major astemizole metabolite, blocks the repolarizing K+ current iKr with high affinity. The clinical observation of QT prolongation and torsade de pointes found with astemizole intake may principally be caused by the proarrhythmic effects of its metabolite desmethylastemizole

Solution of triple problems in transformer windings for current resonant converter with high power density and wide input voltage range

The realization of wide input voltage and high power density on the conventional current resonant converter such as LLC converter remarkably increases transformer winding loss and its design difficulty. Therefore, it is difficult for the conventional LLC converter to satisfy both requirements. In order to apply the LLC converter with both conditions, this paper investigates the mechanism of the transformer winding loss occurrence in the conventional LLC converter. Moreover, the solution for mentioned above problems is proposed which can removes the transformer design difficulty as well by only changing the resonant operation mode.Power Electronics and Applications (EPE\u2717 ECCE Europe), 2017 19th European Conference on, 11-14 Sept. 2017, Warsaw, Polan

Low power wind energy conversion system based on variable speed permanent magnet synchronous generators

This paper presents a low power wind energy conversion system (WECS) based on a permanent magnet synchronous generator and a high power factor (PF) rectifier. To achieve a high PF at the generator side, a power processing scheme based on a diode rectifier and a boost DC-DC converter working in discontinuous conduction mode is proposed. The proposed generator control structure is based on three cascaded control loops that regulate the generator current, the turbine speed and the amount of power that is extracted from the wind, respectively, following the turbine aerodynamics and the actual wind speed. The analysis and design of both the current and the speed loops have been carried out taking into consideration the electrical and mechanical characteristics of the WECS, as well as the turbine aerodynamics. The power loop is not a linear one, but a maximum power point tracking algorithm, based on the Perturb and Observe technique, from which is obtained the reference signal for the speed loop. Finally, to avoid the need of mechanical sensors, a linear Kalman Filter has been chosen to estimate the generator speed. Simulation and experimental results on a 2-kW prototype are shown to validate the concept. © 2013 John Wiley & Sons, Ltd.Carranza Castillo, O.; Garcerá Sanfeliú, G.; Figueres Amorós, E.; González Morales, LG. (2014). Low power wind energy conversion system based on variable speed permanent magnet synchronous generators. Wind Energy. 17(6):811-827. doi:10.1002/we.1598S811827176Ackermann, T. (Ed.). (2005). Wind Power in Power Systems. doi:10.1002/0470012684Muyeen, S. M., Shishido, S., Ali, M. H., Takahashi, R., Murata, T., & Tamura, J. (2008). Application of energy capacitor system to wind power generation. Wind Energy, 11(4), 335-350. doi:10.1002/we.265Ladenburg, J. (2009). Stated public preferences for on-land and offshore wind power generation-a review. Wind Energy, 12(2), 171-181. doi:10.1002/we.308Maeda, T., & Kamada, Y. (2009). A review of wind energy activities in Japan. Wind Energy, 12(7), 621-639. doi:10.1002/we.313Baroudi, J. A., Dinavahi, V., & Knight, A. M. (2007). A review of power converter topologies for wind generators. Renewable Energy, 32(14), 2369-2385. doi:10.1016/j.renene.2006.12.002Di Gerlando, A., Foglia, G., Iacchetti, M. F., & Perini, R. (2012). Analysis and Test of Diode Rectifier Solutions in Grid-Connected Wind Energy Conversion Systems Employing Modular Permanent-Magnet Synchronous Generators. IEEE Transactions on Industrial Electronics, 59(5), 2135-2146. doi:10.1109/tie.2011.2157295Yungtaek Jang, & Jovanovic, M. M. (2000). A new input-voltage feedforward harmonic-injection technique with nonlinear gain control for single-switch, three-phase, DCM boost rectifiers. IEEE Transactions on Power Electronics, 15(2), 268-277. doi:10.1109/63.838099Athab, H. S., Lu, D. D.-C., & Ramar, K. (2012). A Single-Switch AC/DC Flyback Converter Using a CCM/DCM Quasi-Active Power Factor Correction Front-End. IEEE Transactions on Industrial Electronics, 59(3), 1517-1526. doi:10.1109/tie.2011.2158771Barbosa, P., Canales, F., Crebier, J.-C., & Lee, F. C. (2001). Interleaved three-phase boost rectifiers operated in the discontinuous conduction mode: analysis, design considerations and experimentation. IEEE Transactions on Power Electronics, 16(5), 724-734. doi:10.1109/63.949505Yao, K., Ruan, X., Mao, X., & Ye, Z. (2011). Variable-Duty-Cycle Control to Achieve High Input Power Factor for DCM Boost PFC Converter. IEEE Transactions on Industrial Electronics, 58(5), 1856-1865. doi:10.1109/tie.2010.2052538Andriollo, M., De Bortoli, M., Martinelli, G., Morini, A., & Tortella, A. (2009). Control strategy of a wind turbine drive by an integrated model. Wind Energy, 12(1), 33-49. doi:10.1002/we.281Hansen, A. D., & Michalke, G. (2008). Modelling and control of variable-speed multi-pole permanent magnet synchronous generator wind turbine. Wind Energy, 11(5), 537-554. doi:10.1002/we.278Salvatore, N., Caponio, A., Neri, F., Stasi, S., & Cascella, G. L. (2010). Optimization of Delayed-State Kalman-Filter-Based Algorithm via Differential Evolution for Sensorless Control of Induction Motors. IEEE Transactions on Industrial Electronics, 57(1), 385-394. doi:10.1109/tie.2009.2033489Kazmi, S. M. R., Goto, H., Guo, H.-J., & Ichinokura, O. (2011). A Novel Algorithm for Fast and Efficient Speed-Sensorless Maximum Power Point Tracking in Wind Energy Conversion Systems. IEEE Transactions on Industrial Electronics, 58(1), 29-36. doi:10.1109/tie.2010.2044732Pucci, M., & Cirrincione, M. (2011). Neural MPPT Control of Wind Generators With Induction Machines Without Speed Sensors. IEEE Transactions on Industrial Electronics, 58(1), 37-47. doi:10.1109/tie.2010.2043043Ming Y Li G Ming Z Chengyong Z Modeling of the wind turbine with a permanent magnet synchronous generator for integration IEEE Power Engineering Society General Meeting, 2007 2007 1 6Carranza O Figueres E Garcera G Gonzalez LG Gonzalez-Espin F Peak current mode control of a boost rectifier with low distortion of the input current for wind power systems based on permanent magnet synchronous generators 13th European Conference on Power Electronics and Applications, EPE ’09 2009 1 10Eltamaly, A. M. (2007). Harmonics reduction of three-phase boost rectifier by modulating duty ratio. Electric Power Systems Research, 77(10), 1425-1431. doi:10.1016/j.epsr.2006.10.012Vorperian, V. (1990). Simplified analysis of PWM converters using model of PWM switch. Continuous conduction mode. IEEE Transactions on Aerospace and Electronic Systems, 26(3), 490-496. doi:10.1109/7.106126Ridley, R. B. (1991). A new, continuous-time model for current-mode control (power convertors). IEEE Transactions on Power Electronics, 6(2), 271-280. doi:10.1109/63.76813Carranza O Figueres E Garcera G Trujillo CL Velasco D Comparison of speed estimators applied to wind generation systems with noisy measurement signals ISIE 2010 IEEE International Symposium on Industrial 2010 3317 3322Yaoqin J Zhongqing Y Binggang C A new maximum power point tracking control scheme for wind generation International Conference on Power System Technology, PowerCon 2002 IEEE-PES/CSEE 2002 144 148PSIM 7.0 User's Guide (2006), Powersim Inc. 2006Carranza, O., Garcerá, G., Figueres, E., & González, L. G. (2010). Peak current mode control of three-phase boost rectifiers in discontinuous conduction mode for small wind power generators. Applied Energy, 87(8), 2728-2736. doi:10.1016/j.apenergy.2010.02.01

A low-cost photovoltaic emulator for static and dynamic evaluation of photovoltaic power converters and facilities

In testing maximum power point tracking (MPPT) algorithms running on electronic power converters for photovoltaic (PV) applications, either a PV energy source (PV module or PV array) or a PV emulator is required. With a PV emulator, it is possible to control the testing conditions with accuracy so that it is the preferred option. The PV source is modeled as a current source; thus, the emulator has to work as a current source dependent on its output voltage. The proposed emulator is a buck converter with an average current mode control loop, which allows testing the static and dynamic performance of PV facilities up to 3 kW. To validate the concept, the emulator is used to evaluate the MPPT algorithm of a 230-W experimental microinverter working from a single PV module.This work is supported by the Spanish Ministry of Science and Innovation under grant ENE2009-13998-C02-02.González Medina, R.; Patrao Herrero, I.; Garcerá Sanfeliú, G.; Figueres Amorós, E. (2014). A low-cost photovoltaic emulator for static and dynamic evaluation of photovoltaic power converters and facilities. Progress in Photovoltaics. 22(2):227-241. https://doi.org/10.1002/pip.2243S227241222Prapanavarat, C., Barnes, M., & Jenkins, N. (2002). Investigation of the performance of a photovoltaic AC module. IEE Proceedings - Generation, Transmission and Distribution, 149(4), 472. doi:10.1049/ip-gtd:20020141Durán, E., Andújar, J. M., Galán, J., & Sidrach-de-Cardona, M. (2009). Methodology and experimental system for measuring and displayingIâ Vcharacteristic curves of PV facilities. Progress in Photovoltaics: Research and Applications, 17(8), 574-586. doi:10.1002/pip.909Piliougine, M., Carretero, J., Mora-López, L., & Sidrach-de-Cardona, M. (2011). Experimental system for current-voltage curve measurement of photovoltaic modules under outdoor conditions. Progress in Photovoltaics: Research and Applications, 19(5), 591-602. doi:10.1002/pip.1073Sanchis, P., López, J., Ursúa, A., Gubía, E., & Marroyo, L. (2007). On the testing, characterization, and evaluation of PV inverters and dynamic MPPT performance under real varying operating conditions. Progress in Photovoltaics: Research and Applications, 15(6), 541-556. doi:10.1002/pip.763Kjaer, S. B., Pedersen, J. K., & Blaabjerg, F. (2005). A Review of Single-Phase Grid-Connected Inverters for Photovoltaic Modules. IEEE Transactions on Industry Applications, 41(5), 1292-1306. doi:10.1109/tia.2005.853371Kondrath, N., & Kazimierczuk, M. K. (2012). Comparison of Wide- and High-Frequency Duty-Ratio-to-Inductor-Current Transfer Functions of DC–DC PWM Buck Converter in CCM. IEEE Transactions on Industrial Electronics, 59(1), 641-643. doi:10.1109/tie.2011.2134053Tan, Y. T., Kirschen, D. S., & Jenkins, N. (2004). A Model of PV Generation Suitable for Stability Analysis. IEEE Transactions on Energy Conversion, 19(4), 748-755. doi:10.1109/tec.2004.827707Villalva, M. G., Gazoli, J. R., & Filho, E. R. (2009). Comprehensive Approach to Modeling and Simulation of Photovoltaic Arrays. IEEE Transactions on Power Electronics, 24(5), 1198-1208. doi:10.1109/tpel.2009.2013862Shengyi Liu, & Dougal, R. A. (2002). Dynamic multiphysics model for solar array. IEEE Transactions on Energy Conversion, 17(2), 285-294. doi:10.1109/tec.2002.1009482Mekki, H., Mellit, A., Kalogirou, S. A., Messai, A., & Furlan, G. (2010). FPGA-based implementation of a real time photovoltaic module simulator. Progress in Photovoltaics: Research and Applications, 18(2), 115-127. doi:10.1002/pip.950Mohan N Undeland T Robbins W Power electronics: converters, applications and design (3rd edn) 2003Garcera, G., Figueres, E., Pascual, M., & Benavent, J. M. (2004). Robust model following control of parallel buck converters. IEEE Transactions on Aerospace and Electronic Systems, 40(3), 983-997. doi:10.1109/taes.2004.1337469Vorperian, V. (1990). Simplified analysis of PWM converters using model of PWM switch. Continuous conduction mode. IEEE Transactions on Aerospace and Electronic Systems, 26(3), 490-496. doi:10.1109/7.106126Packiam, P., Jain, N. K., & Singh, I. P. (2011). Microcontroller-based simple maximum power point tracking controller for single-stage solar stand-alone water pumping system. Progress in Photovoltaics: Research and Applications, n/a-n/a. doi:10.1002/pip.1207Chuanzong F Shiping S Simulation studying of MPPT control by a new method for photovoltaic power system Electrical and Control Engineering (ICECE), 2011 International Conference on 2011 10.1109/ICECENG.2011.605791