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With extensive access of distributed energy resources and DC loads, the traditional 10 kV AC distribution network has greatly increased the number of converters and reduced the reliability of power supply. A solid-state transformer (SST) containing AC and DC terminals to build AC/DC hybrid distribution networks has become the focus of the current research. This study presents an AC/DC hybrid distribution network structure with 10 kV AC, 10 kV DC, ±375 V DC, and 380 V AC four voltage levels. In this network, the load is data centre, which needs high security for power supply reliability. According to the characteristics of this network, this study takes the reliability evaluation by using the minimum path set method and the state enumeration method, and the reliability of this new structure with SST is calculated. Through the study of a numerical example, the results show that after adding the multi-terminal SST, the reliability of the AC/DC hybrid distribution network is suitable for data centre load, and the quantity of the converters can decrease. [ABSTRACT FROM AUTHOR]

In recent years, due to energy crisis, renewable energy distributed power generators, such as wind turbine, photovoltaic (PV) cell, fuel cell, and thermoelectric generation modules, are becoming more and more popular in industrial and residential applications. Many renewable energy such as PV cell, fuel cell and thermoelectric generation can only output dc voltage. So an inverter interface has to be utilized for grid-connected applications. So many inverter topologies have been proposed and reviewed recently like as Z-source proposed inverter. In this proposed semi-Z-source inverters for a single-phase photovoltaic (PV) system. With low cost and doubly grounded features. These semi-Z-source inverters only two active switches. To achieve the same output voltage as the traditional voltage-fed full-bridge z-source inverter. The input dc source and the output ac voltage of the semi-Z-source inverter share the same ground. Thus lead into less leakage ground current advantages over other non-doubly grounded inverters. [ABSTRACT FROM AUTHOR]

Series Z-Source network, Associate in Nursing enlargement of the favored conception of Z-source dc link, was initially projected for enhancing the output voltage of power electronic inverters. Throughout this paper, that concept is extended on a three-phase indirect matrix converter. The converter depends on the ultra-sparse matrix topology characterized by the minimum vary of semiconductor switches. The series Z-source network is placed between the three-switch input rectifier stage and additionally the six-switch output electrical converter stage, in either the positive or negative rail. A short shoot-through state produces the voltage boost. Associate in Nursing optimum pulse breadth modulation technique is developed for higher boosting capability of the converter and reduce of switch losses. A comparison is made between the matrix converters mistreatment series and customary cascade Z-source networks. The inpouring current and Z-source capacitor's voltage are reduced inside the series Z-source matrix converter. [ABSTRACT FROM AUTHOR]

Focuses on a study which analyzed data on alternating current (ac) and direct current (dc) field dependence of the conductivity of semi-insulating GaAs crystals. Background on filed conductivity dependence of thin films; Details on field dependence of ac and dc conductivity; Transient behavior; Conclusion.

This paper is aimed at the comparison of breakdown voltage (BDV) of oil mixtures consisting of Jatropha curcas methyl ester oil (JMEO) extracted from the fruit seeds of jatropha curcas plants, and mineral oil (MO) under AC and DC voltages. Two JMEO/MO oil mixtures were considered: (50% JMEO + 50% MO) and (80% JMEO + 20% MO). The goal was to predict the insulation behavior of power transformers when re-filling with JMEO after they were emptied of mineral oil. The statistical analyses of the experimental data shows that the BDV values conform to normal law. It is shown that the (80%JMEO+20%MO) oil mixture is the most interesting whether under DC or AC as it shows the highest breakdown voltage. The U1% of JMEO under AC voltage is higher than those of the other tested oils. And the U1% of oils mixture (50%JMEO+50%MO) is the lowest one. [ABSTRACT FROM AUTHOR]

In this work, we present novel general analytical solutions for the currents that are developed in the edges of network-like circuits when some nodes of the network act as sources/sinks of DC or AC current. We assume that Ohm's law is valid at every edge and that charge at every node is conserved (with the exception of the source/sink nodes). The resistive, capacitive, and/or inductive properties of the lines in the circuit define a complex network structure with given impedances for each edge. Our solution for the currents at each edge is derived in terms of the eigenvalues and eigenvectors of the Laplacian matrix of the network defined from the impedances. This derivation also allows us to compute the equivalent impedance between any two nodes of the circuit and relate it to currents in a closed circuit which has a single voltage generator instead of many input/output source/sink nodes. This simplifies the treatment that could be done via Thévenin's theorem. Contrary to solving Kirchhoff's equations, our derivation allows to easily calculate the redistribution of currents that occurs when the location of sources and sinks changes within the network. Finally, we show that our solutions are identical to the ones found from Circuit Theory nodal analysis. [ABSTRACT FROM AUTHOR]

Microgrid frequency and voltage regulation is a challenging task, as classical generators with rotational inertia are usually replaced by converter-interfaced systems that inherently do not provide any inertial response. The aim of this paper is to analyse and compare autonomous primary control techniques for alternating current (AC) and direct current (DC) microgrids that improve this transient behaviour. In this context, a virtual synchronous machine (VSM) technique is investigated for AC microgrids, and its behaviour for different values of emulated inertia and droop slopes is tested. Regarding DC microgrids, a virtual-impedance-based algorithm inspired by the operation concept of VSMs is proposed. The results demonstrate that the proposed strategy can be configured to have an analogous behaviour to VSM techniques by varying the control parameters of the integrated virtual-impedances. This means that the steady-state and transient behaviour of converters employing these strategies can be configured independently. As shown in the simulations, this is an interesting feature that could be, for instance, employed for the integration of different dynamic generation or storage systems, such as batteries or supercapacitors. [ABSTRACT FROM AUTHOR]

Most household electronic products and office equipment circuitry are operated internally at a low direct current (DC) voltage. However, they are designed to be plugged directly into wall outlets with alternating current (AC). AC to DC conversion is performed by devices called DC power supplies. Energy efficiency is a serious concern for most electrical and electronic appliances that require power supplies to operate. The majority of end users consume excess energy because of inefficient, bulky, and outdated power supply systems. A great gap exists in studies on energy saving in power supply design and selection. This article presents an overview of power supply energy consumption patterns and the effects of different operation modes on overall system power consumption. Recommendations for achieving an efficient energy system are presented. [ABSTRACT FROM AUTHOR]

This paper proposes a drive circuit for ac-direct LED lamps. The proposed circuit consists only of a line filter, an LED bridge, a load inductor, a bidirectional switch, and a switch-control circuit. The switch connects the LED bridge to the power line directly. Each leg of the LED bridge consists of LEDs and a protection diode, all connected in series. The load inductor limits the bridge current. The switch operates at a zero current switching condition, so the circuit has high power efficiency. The circuit can operate at a free-volt input condition ( $85 < V_{{\rm in,rms}} < 265\; {\bf V}$). For all input voltage conditions the circuit had PE > 89%, luminous efficiency ∼90 lm/W, power factor >0.9, and 120-Hz flicker index ∼0.3. The circuit satisfies the IEC 61000-3-2 Class C and the EN 55015 regulations. The proposed LED driver is well suited for use in household LED lamps. [ABSTRACT FROM AUTHOR]

The effects of DC and AC electric field at 50 Hz and 13.56 MHz and 41 MHz frequencies on the combustion characteristics of biomass pellets have been investigated using an experimental setup of average power 20-40 kW with continuous pellet feed into the setup at average rates 1.5-3 g/s by applying AC voltage to the flame base, where thermal decomposition of biomass pellets produces the axial flow of volatiles (CO, H2 ) determining the formation of the flame reaction zone. The AC and DC electric field effects on the flame composition and combustion efficiency are studied with account of field effects on thermal decomposition of biomass, ignition and combustion of volatiles. Main aspects of EM electric field-induced variations of the combustion characteristics and the formation of field-induced combustion instability are discussed and analyzed. [ABSTRACT FROM AUTHOR]

This paper proposes a new measurement-based approach that can solve synthesis problems in unknown linear circuits. The method makes use of a small number of measurements to determine the functional dependency of any circuit signal or variable on any set of design variables. Once the functional dependency is obtained, the design requirements can be applied to find the design parameter values. The results are described for linear direct current and alternating current circuits. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the dielectric and electrowetting properties of cyanoethyl pullulan (CEP) are studied as the insulator in electrowetting on dielectric (EWOD) device. The CEP film is formed by spin-coating and low-temperature annealing in atmosphere. The characterization results show that CEP can serve as the dielectric of EWOD with a high dielectric constant of 18 and a great electrowetting performance when annealed at 100°C in atmosphere. The reversibility, stability, polarity-dependence, and frequency-dependence of electrowetting on CEP are fully investigated. The spin-coated CEP exhibits little polarity-related electrowetting while having better driving performance under negative-potential. Frequency-related electrowetting is more sensitive at low-frequency alternating current (AC) potentials than at high-frequency ones. It also shows reversible and stable electrowetting with a small irreversibility of 2° after a 700-cycle test. Based on the above results, an EWOD device with 1μm thick CEP dielectric layer is fabricated. The EWOD device successfully manipulates water droplet at a low driving voltage of 20V and a large velocity under low voltage of DC or AC signals with different frequencies. The easy fabrication and excellent performance of CEP qualifies it as a superior dielectric material in the future EWOD devices and lab-on-a-chip system. [Copyright &y& Elsevier]

This paper unifies the underlying concepts of all basic single-switch, two-state, dc-to-dc voltage-sourced converters, by duality, as generic related current and voltage-sourced converters. By using ac and dc circuit theory, the three basic converters can be transformed to yield all known transfer functions and realizes a proliferation of 33 topologies, three being previously unidentified topologies with unique characteristics. The circuit based systematic unifying approach offers new insight and an alternative interpretation to the origin of the 33 topologies including the Zeta, Cuk, \pmLuo, CSC, Landsman, and Sepic converters. Converter time-domain simulations and corresponding practical results of the three new topologies extol and culminate the concepts and analysis presented. [ABSTRACT FROM PUBLISHER]

A distributed modeling approach has been developed to describe the dynamic behavior of ring resonators. The model includes the effect of large amplitudes around primary resonance frequencies, material and electrostatic nonlinearities. Through a combination of geometric and material nonlinearities, closed-form expression for third-order nonlinearity in mechanical stiffness of bulk-mode ring resonators is obtained. Moreover, to avoid dynamic pull-in instability, the choices of the quality factor, ac-drive and DC-bias voltages of the ring resonators, with a given geometry are limited by a resonant pull-in condition. Using the perturbation technique and the method of harmonic balance, the expressions for describing the effect of nonlinearities on the resonance frequency and displacement are derived. The results are discussed in detail, showing the effect of varying operating conditions and the quality factor on the harmonic distortions and third-order intermodulation distortion. The detailed nonlinear modeling and distortion analysis are applied as appropriate tools to design bulk-mode ring resonators with low motional resistance and high linearity. [ABSTRACT FROM AUTHOR]

It is shown that the excitation of charge carriers by ac electric field with zero average driving leads to a direct electric current in quantum well structures. The current emerges for both linear and circular polarization of the ac electric field and depends on the field polarization and frequency. We present a microscopic model and an analytical theory of such a nonlinear electron transport in quantum wells with structure inversion asymmetry. In such systems, the dc current is induced by ac electric field that has both the in-plane and out-of-plane components. The ac field polarized in the interface plane gives rise to a direct current if the quantum well is subjected to an in-plane static magnetic field. [ABSTRACT FROM AUTHOR]

A multiplier based on thermal converters was developed for use in broadband power measurements. The topology of the multiplier suppresses its static error by means of an improved summing circuit. It employs a fast synchronous ac-dc transfer technique to shorten the measurement time. The uncertainties evaluated at the nominal voltage of 3 V are on the order of a few parts in 10-6 for frequencies up to 30 kHz and a few parts in 10-5 for frequencies up to 100 kHz. [ABSTRACT FROM AUTHOR]

Presents a study that measured alternating current-direct current (ac-dc) difference from different type of ac-dc transfer standards placed under step humidity change conditions at 200 volts, 600 volts and 1kV in the frequency range from 40 herts to 100 kiHz. Measurement setup and procedure; Measurement results; Conclusion.

Describes the dependence of constriction resistance on signal frequency. Factors that contribute to constriction resistance in electrical interfaces; Differences between the direct current and alternating current (ac) constriction resistance; Functions of resistance in the electrical properties of the conductor; Numerical evaluation of ac constriction resistance.

Deals with a study which presented a primary-switched alternating current/direct current converter and its modulation. Circuit description; Voltage control strategy; Conclusions.

Presents a low-noise, low-power CMOS semiconductor on insulator (SOI) readout front-end aiming to dc coupling to silicon radiation detectors. Design of the charge sensitive preamplifier; Principle block diagram of semiconductor detector readout system with ac or dc coupling technique; Circuit diagram of the low-noise charge preamplifier.

Electrical transport behaviour of the valence compensated system Ca1− xLa xTi1− xCr xO 3( x≤ 0.50) has been investigated by studying the Seebeck co-efficient, DC and AC conductivity as a function of temperature. Seebeck co-efficient, DC conductivity of different compositions has been measured in the temperature range 300 K–1000 K. AC conductivity for different compositions were determined in the temperature range 100–550 K and frequency range 10 Hz–10 MHz. Positive values of Seebeck co-efficient show that holes are the majority charge carriers. Conduction seems to occur by correlated barrier hopping of holes among Cr3+and Cr4+ions or VO •and VO ••. Almost equal values of activation energies obtained for DC conductivity and dielectric relaxation process show that both the processes occur by the same mechanism. [ABSTRACT FROM AUTHOR]

The paper describes investigations of unsteady techniques for measuring leakage of buildings. The main investigation is theoretical. The theory used accounts for compressibility and inertia and is based on a quadratic flow equation. It is therefore an advance over what has been used in the few previous investigations. In particular, it allows uncertainties due to inertia to be assessed. The investigations cover three unsteady techniques i.e., the AC and the pulse techniques and a novel DC/AC technique. It is concluded that for most buildings, the conventional steady DC technique is preferable. However, for large buildings, the DC technique becomes increasingly inaccurate and an alternative technique is required. A novel form of pulse technique is proposed and theoretical and experimental investigations are presented which indicate that it has the potential to provide a simple and quick way of measuring the leakage of large buildings. [ABSTRACT FROM AUTHOR]

Presents a modulation strategy for a power factor corrected, isolated alternating current/direct current (ac/dc) converter derived from the integration of a nonisolated, two switch buck-boost ac/dc converter with an isolated dual active bridge dc/dc converter (2SBBDAB). Modulation strategy; Control circuit design; Prototype specification and parameters.

Discusses that the concepts of maximum power transfer of direct current (dc) systems and associated alternative current (ac) voltage variations have been extended to include various ac load models and an ac line in parallel with the dc line. Test system of the study; Significance of load models; Effect of load models with a higher Effective Short-Circuit Ratio (ESCR); Effect of a parallel ac line; Effect of tap changing; Conclusions.

Comprehensive energy and exergy analyses were performed to evaluate the thermodynamic performance of two ferroalloy pellet smelting systems named sintering-preheating-submerge arc furnace (SPSF) and rotary kiln-electric furnace (RKEF). The analyses considered the multi-energy supply and exergy destruction of the systems and identified the avoidable irreversibility of the processes. The energy efficiency of the SPSF and RKEF systems was 54.07% and 42.93%, respectively. The exergy efficiency of the two systems was found to be 28.37% and 30.71%, respectively. The largest exergy destruction of both systems was caused by the alternating current circuit which could be replaced by direct current circuit for better performance. The heat transfer between equipment was the major avoidable exergy destruction in systems. The integration of smelting equipment is a suitable method to reduce the avoidable exergy destruction. The environmental impact of the systems is also evaluated on the basis of resource utilization efficiency, system carbon dioxide emission rate and sustainability index. The SPSF is more environmental-friendly than the RKEF. The effective recycling of the exhaust gas in the preheating shaft kiln could pose significant energy saving. The present work could be employed for decision making on improving the existing smelting systems. • Energy and exergy analyses are developed to understand cleaner ferroalloy pellet smelting system. • Three indicators are used to evaluate environmental performance. • The multi-energy supply and exergy destruction are analyzed for thermodynamic performance. • The existing systems are compared to propose improvement ways. [ABSTRACT FROM AUTHOR]

A report is presented on the operation of an analogue programming circuit for accurately setting the state of a memristor. The circuit exploits the dynamic modulation of resistance under a constant DC bias while real-time measurements of the memristance are performed using an AC signal. The circuit employs feedback for converging the state of a device at any required level within a decade. This allows the memristor to act as an analogue potentiometer, with its resistance corresponding to an input analogue voltage. This implementation was tested with the HP memristor model revealing an accuracy of less than 0.4% (8 bit precision) in relation to the full dynamic range. [ABSTRACT FROM AUTHOR]

The impact of high-k gate dielectrics on device short-channel and circuit performance of fin field-effect transistors is studied over a wide range of dielectric permittivities κ. It is observed that there is a decrease in the parasitic outer fringe capacitance Cof in addition to an increase in the internal fringe capacitance Cif with high-κ dielectrics, which degrades the short-channel effects significantly. It is shown that fin width scaling is the most suitable approach to recover the degradation in the device performance due to high-κ integration. Furthermore, from the circuit perspective, for the 32-nm technology generation, the presence of an optimum κ for a given target subthreshold leakage current has been identified by various possible approaches such as fin width scaling, fin-doping adjustment, and gate work function engineering. [ABSTRACT FROM AUTHOR]

A novel rectifier based on a triple line-voltage cascaded VIENNA converter (LVC-VC) was proposed. Compared to the conventional cascaded H-bridge converters, the switch voltage stress is lower, and the numbers of switches and dc capacitors are fewer under similar operating conditions in the proposed new multilevel converter. The modeling and control for the LVC-VC ware presented. Based on the analysis of the operation principle of the new converter, the power factor correction of the proposed converter was realized by employing a traditional one-cycle control strategy. The minimum average value and maximum harmonic components of the dc-link voltages of the three VIENNA rectifier modules ware calculated. Three VIENNA dc-link voltages were unbalanced under the unbalanced load conditions, so the zero sequence current was injected to the three inner currents for balancing three VIENNA dc-link voltages. Simulation and the results of the experiment verified the availability of the new proposed multilevel converter and the effectiveness of the corresponding control strategy applied. [ABSTRACT FROM AUTHOR]

We present a fast Hall effect measurement system that can be used at high temperature. The use of a homogeneous high field permanent magnet in a Halbach configuration allows fast measurements in various DC and AC current fields with step and continuous measurement modes. The results are presented of measurements on platinum film at room temperature and Ge and BiCuSeO between 300 K and 650 K. [ABSTRACT FROM AUTHOR]