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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.


Papers
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Journal ArticleDOI
TL;DR: A fundamentally different mechanism for photovoltaic charge separation is reported, which operates over a distance of 1-2 nm and produces voltages that are significantly higher than the bandgap.
Abstract: In conventional solid-state photovoltaics, electron-hole pairs are created by light absorption in a semiconductor and separated by the electric field spaning a micrometre-thick depletion region. The maximum voltage these devices can produce is equal to the semiconductor electronic bandgap. Here, we report the discovery of a fundamentally different mechanism for photovoltaic charge separation, which operates over a distance of 1-2 nm and produces voltages that are significantly higher than the bandgap. The separation happens at previously unobserved nanoscale steps of the electrostatic potential that naturally occur at ferroelectric domain walls in the complex oxide BiFeO(3). Electric-field control over domain structure allows the photovoltaic effect to be reversed in polarity or turned off. This new degree of control, and the high voltages produced, may find application in optoelectronic devices.

1,434 citations

Journal ArticleDOI
TL;DR: Simulation and experimental results show the superiority of the back-to-back diode-clamped converter over two-level pulsewidth-modulation-based drives.
Abstract: This paper presents transformerless multilevel power converters as an application for high-power and/or high-voltage electric motor drives. Multilevel converters: (1) can generate near-sinusoidal voltages with only fundamental frequency switching; (2) have almost no electromagnetic interference or common-mode voltage; and (3) are suitable for large voltampere-rated motor drives and high voltages. The cascade inverter is a natural fit for large automotive all-electric drives because it uses several levels of DC voltage sources, which would be available from batteries or fuel cells. The back-to-back diode-clamped converter is ideal where a source of AC voltage is available, such as in a hybrid electric vehicle. Simulation and experimental results show the superiority of these two converters over two-level pulsewidth-modulation-based drives.

1,398 citations

Journal ArticleDOI
TL;DR: The results show that the predictive method controls very effectively the load current and performs very well compared with the classical solutions.
Abstract: This paper presents a predictive current control method and its application to a voltage source inverter. The method uses a discrete-time model of the system to predict the future value of the load current for all possible voltage vectors generated by the inverter. The voltage vector which minimizes a quality function is selected. The quality function used in this work evaluates the current error at the next sampling time. The performance of the proposed predictive control method is compared with hysteresis and pulsewidth modulation control. The results show that the predictive method controls very effectively the load current and performs very well compared with the classical solutions

1,387 citations

Patent
08 May 2008
TL;DR: In this paper, the authors present a system and method for variable power transfer in an inductive charging or power system. In accordance with an embodiment, the system comprises a pad or similar base unit that contains a primary, which creates an alternating magnetic field, and a receiver comprises a means for receiving the energy from the magnetic field from the pad and transferring it to a mobile device, battery, or other device.
Abstract: A system and method for variable power transfer in an inductive charging or power system. In accordance with an embodiment the system comprises a pad or similar base unit that contains a primary, which creates an alternating magnetic field. A receiver comprises a means for receiving the energy from the alternating magnetic field from the pad and transferring it to a mobile device, battery, or other device. In accordance with various embodiments, additional features can be incorporated into the system to provide greater power transfer efficiency, and to allow the system to be easily modified for applications that have different power requirements. These include variations in the material used to manufacture the primary and/or the receiver coils; modified circuit designs to be used on the primary and/or receiver side; and additional circuits and components that perform specialized tasks, such as mobile device or battery identification, and automatic voltage or power-setting for different devices or batteries.

1,317 citations

Journal ArticleDOI
TL;DR: In this paper, the authors presented a small (component volume 1 cm3, practical volume 1 5 cm3) electromagnetic generator utilizing discrete components and optimized for a low ambient vibration level based upon real application data.
Abstract: Vibration energy harvesting is receiving a considerable amount of interest as a means for powering wireless sensor nodes This paper presents a small (component volume 01 cm3, practical volume 015 cm3) electromagnetic generator utilizing discrete components and optimized for a low ambient vibration level based upon real application data The generator uses four magnets arranged on an etched cantilever with a wound coil located within the moving magnetic field Magnet size and coil properties were optimized, with the final device producing 46 µW in a resistive load of 4 k? from just 059 m s-2 acceleration levels at its resonant frequency of 52 Hz A voltage of 428 mVrms was obtained from the generator with a 2300 turn coil which has proved sufficient for subsequent rectification and voltage step-up circuitry The generator delivers 30% of the power supplied from the environment to useful electrical power in the load This generator compares very favourably with other demonstrated examples in the literature, both in terms of normalized power density and efficiency

1,313 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
20235,895
202212,948
20215,020
202011,354
201914,763