Search results for "Capacitance"
showing 10 items of 112 documents
A Methodology for the Design of MOS Current-Mode Logic Circuits
2010
In this paper, a design methodology for the minimization of various performance metrics of MOS Current-Mode Logic (MCML) circuits is described. In particular, it allows to minimize the delay under a given power consumption, the power consumption under a given delay and the power-delay product. Design solutions can be evaluated graphically or by simple and effective automatic procedures implemented within the MATLAB environment. The methodology exploits the novel concepts of crossing-point current and crossing-point capacitance. A useful feature of it is that it provides the designer with useful insights into the dependence of the performance metrics on design variables and fan-out capacitan…
Wind Turbine Generation System With Optimized DC-Link Design and Control
2013
This paper presents an optimized capacitance design for the dc link of a back-to-back converter for wind turbine power generation. The design method combines switching ripple and dynamic specifications to give the smallest possible dc-link capacitance and the required proportional-integral compensator for the voltage regulation. Furthermore, a novel concept to globally manage the on/off switching of back-to-back power subconverters, based on a finite-state machine, is presented. The proposed management system keeps control of the dc-link voltage for proper operation of both subconverters regardless of wind or grid conditions.
Charge measurement using an array of Faraday’s Cups on a printed circuit board
2014
Abstract An absolute method of measuring charge is to use a Faraday Cup (FC) principle. This study relates to a novel method of measuring charge on a flat substrate, which is coated with charged powder particles. The substrate consists of an array of FC with different dimensions. The sensor is manufactured using flame-retardant printed circuit board (PCB) technology. The objective of this work is to reduce the charge sharing by developing a grounded shield cup around each conductive cup in the array and accordingly increase cup-to-ground capacitance. The results have confirmed that the improved well shielding would provide a more accurate quantitative charge measurement.
Development of a Coupling System for Medium Voltage Power Line Communication in the CENELEC A Frequency Band
2016
In this paper the performances of a new power line communication (PLC) coupling system for medium voltage (MV) smart grids are investigated in the CENELEC A frequency band (i.e. 3 - 95 kHz). The new coupling solution is based on the use of the capacitive divider of the voltage detecting system (VDS) as PLC coupler to the MV network. According to IEC 61243-5, VDS are worldwide used to reveal the presence of the mains voltage to ensure the safety of the operators. A proper interface circuit has been invented and patented to couple the PLC signal through the VDS. In this way no dedicated MV PLC coupler is required, thus avoiding the related costs of the coupler, of its installation, and those …
Electronic Design for a Bleeding Detector to be Used in Intraoperative Radiotherapy Applications
2021
An electronic design for a bleeding detector used with mobile linac during intraoperative radiotherapy (IORT) is presented. It consists on a readout circuit based on a De Sauty Bridge and a wireless power supply using a supercapacitor. The goal is the measurement of the height of fluid present in the applicator in order to avoid a misadministration dose during the irradiation process. A minimum measurement height of 5 mm is required by clinic to be confident with the selected radiation dose. The measurement circuit uses a capacitive sensor which detects variations lower than 0.1 pF. The readout circuit converts dynamic capacitance variation from the bleeding detector into an analog voltage …
Photonic nanopatterns of gold nanostructures indicate the excitation of surface plasmon modes of a wavelength of 50-100 nm by scanning near-field opt…
2003
Scanning near-field optical microscopy images of metal nanostructures taken with the tetrahedral tip (T-tip) show a distribution of dark and bright spots at distances in the order of 25-50 nm. The images are interpreted as photonic nanopatterns defined as calculated scanning near-field optical microscopy images using a dipole serving as a light-emitting scanning near-field optical microscopy probe. Changing from a positive to a negative value of the dielectric function of a sample leads to the partition of one spot into several spots in the photonic nanopatterns, indicating the excitation of surface plasmons of a wavelength in the order of 50-100 nm in metal nanostructures.
Scanning probe microscopies applied to the study of the domain wall in a ferroelectric crystal.
2007
Summary Scanning near-field optical microscopy is capable of measuring the topography and optical signals at the same time. This fact makes this technique a valuable tool in the study of materials at nanometric scale and, in particular, of ferroelectric materials, as it permits the study of their domains structure without the need of chemical etching and, therefore, not damaging the surface (as will be demonstrated later). We have measured the scanning near-field optical microscopy transmission, as well as the topography, of an RbTiOPO4 single crystalline slab, which exhibits two different of macroscopic ferroelectric domains. A chemical selective etching has been performed to distinguish b…
Impedance and admittance characteristics of Bi2S3 nanowire arrays
2013
Current studies of the electrical impedance and admittance characteristics of the anodised aluminum oxide (AAO) nanoporous arrays and bismuth sulphide (Bi2S3) nanowire within AAO membranes are presented. The influence of potential and frequency scan rate effect produced on the real, imaginary and complex electrochemical impedance and double layer capacitance of the AAO nanopore and the Bi2S3 nanowire arrays were studied.
Oxygen-deficient Co3O4 submicron porous sphere films as highly active supsercapacitor electrodes
2021
Abstract Herein, we report Co3O4 films with different content of oxygen vacancies and shapes of particles for supercapacitor electrodes. Under the similar area ratio of OII peak in the XPS spectrum of oxygen elements, the specific capacitance of electrode films with hollow spongy-like particles (963 F/g under a scan rate of 5 mV/s) is 1.6 times higher than that of the electrodes with solid irregular particles (596 F/g), indicating the effect of particle shapes on electrochemical properties. The films composed of submicron porous spheres and containing highest content of oxygen vacancies exhibited the specific capacitances as high as 1700 F/g under the scan rate of 5 mV/s. By contrast, after…
High-Frequency Experimental Characterization and Modeling of Six Pack IGBTs Power Modules
2016
In this paper, a method to characterize the high-frequency (HF) behavior of six pack insulated gate bipolar transistors (IGBTs) power module (PM) is presented. The method is based on experimental measurements at the external pins of the device and it allows one to extract internal inductive and capacitive parasitic coupling without the knowledge of structural and physical parameters of the PM. The HF model of a six pack IGBTs PM has been developed, in the frequency range of 150 kHz-30 MHz, and it has been implemented in MATLAB environment. The method has been experimentally validated by comparing the frequency behavior of the PM with the simulated response. Moreover, the HF conducted distur…