Voltage

About: Voltage is a research topic. Over the lifetime, 296395 publications have been published within this topic receiving 1755443 citations. The topic is also known as: electromotive force & U.

Performance characterization of a high-power dual active bridge DC-to-DC converter

Abstract: The performance of a high-power, high-power-density DC-to-DC converter based on the single-phase dual active bridge (DAB) topology is described. The dual active bridge converter has been shown to have very attractive features in terms of low device and component stresses, small filter components, low switching losses, high power density and high efficiency, bidirectional power flow, buck-boost operation, and low sensitivity to system parasitics. For high output voltages, on the order of kilovolts, a cascaded output structure is considered. The effects of snubber capacitance and magnetizing inductance on the soft switching region of control are discussed. Various control schemes are outlined. Coaxial transformer design techniques have been utilized to carefully control leakage inductance. The layout and experimental performance of a prototype 50 kW 50 kHz unit operating with an input voltage of 200 V DC and an output voltage of 1600 V DC are presented. >

Understanding the rate-dependent J–V hysteresis, slow time component, and aging in CH3NH3PbI3 perovskite solar cells: the role of a compensated electric field

Abstract: In this work we show that the rate-dependent hysteresis seen in current–voltage scans of CH3NH3PbI3 perovskite solar cells is related to a slow field-induced process that tends to cancel the electric field in the device at each applied bias voltage. It is attributed to the build-up of space charge close to the contacts, independent of illumination and most likely due to ionic displacement, which is enhanced when the device undergoes aging. This process can also lead to a reduction of the open-circuit voltage or the steady-state photocurrent and does not directly correlate with the development of the hysteresis if it is measured at a fixed voltage sweep rate.

A self-consistent iterative scheme for one-dimensional steady state transistor calculations

Abstract: A self-consistent iterative scheme for the numerical calculation of dc potentials and currents in a one-dimensional transistor model is presented. Boundary conditions are applied only at points representing contacts. Input data are: doping profile, parameters governing excess carrier recombination, parameters describing the dependence of mobility on doping and on electric field, applied emitter and collector voltages, and a trial solution for the electrostatic potential. The major limitation of the present approach results from use of Boltzmann rather than Fermi statistics. Convergence of the iteration scheme is good for low and moderate injection levels.

Voltage-Sourced Converters in Power Systems : Modeling, Control, and Applications

Abstract: Presents Fundamentals of Modeling, Analysis, and Control of Electric Power Converters for Power System ApplicationsElectronic (static) power conversion has gained widespread acceptance in power systems applications; electronic power converters are increasingly employed for power conversion and conditioning, compensation, and active filtering. This book presents the fundamentals for analysis and control of a specific class of high-power electronic converters—the three-phase voltage-sourced converter (VSC). Voltage-Sourced Converters in Power Systems provides a necessary and unprecedented link between the principles of operation and the applications of voltage-sourced converters. The book:Describes various functions that the VSC can perform in electric power systemsCovers a wide range of applications of the VSC in electric power systems—including wind power conversion systemsAdopts a systematic approach to the modeling and control design problemsIllustrates the control design procedures and expected performance based on a comprehensive set of examples and digital computer time-domain simulation studiesThis comprehensive text presents effective techniques for mathematical modeling and control design, and helps readers understand the procedures and analysis steps. Detailed simulation case studies are included to highlight the salient points and verify the designs.VoltageSourced Converters in Power Systems is an ideal reference for senior undergraduate and graduate students in power engineering programs, practicing engineers who deal with grid integration and operation of distributed energy resource units, design engineers, and researchers in the area of electric power generation, transmission, distribution, and utilization.

Estimating the Voltage Stability of a Power System

Abstract: A method for the online testing a power system is proposed which is aimed at the detection of voltage instabilities. Thereby an indicator L is defined which varies in the range between 0 (noload of system) and 1 (voltage collapse). Based on the basic concept of such an indicator various models are derived which allow to predict a voltage instability or the proximity of a collapse. The indicator uses information of a normal load flow. The advantage of the method lies in the simplicity of the numerical calculation and the expressiveness of the result.