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Nowadays, the scale of power grid is remarkably increasing and there is a continuous reinforcement of AC–DC hybrid systems. Thus, the single-phase grounding fault currents on the AC grid-side of rectifier and inverter stations increase significantly, which may exceed the capacity limit of the circuit breakers. The large short-circuit currents would result in problems during equipment selection and threaten the safety of equipment and personnel. To solve such issue, the effect of the converter transformer on the single-phase grounding fault current on the grid-side is analyzed. The mechanism of high short-circuit current in DC near region is revealed. Also, the feasibility of neutral point earthing via small reactor at HVDC converter transformer to suppressing the single-phase grounding fault current is verified. In addition, the principle of selecting the suitable small reactor is summarized. The results show that the neutral point earthing via small reactor at converter transformer can effectively limit the single-phase grounding fault current on the AC-side. However, it would lead to an increase of overvoltage at the neutral point of HVDC transformer. Therefore, neutral grounding by small reactor might be implemented when the insulation level is satisfied.

The linear model of the three-phase voltage source rectifier (VSR) proposed before could not provide an accurate description for the stability and dynamics performance when the output power is high, the inductances are large or the boost ratio is high. Hence, an item of Right-Half Plane Zero (RHPZ), which contains the output power, the inductances and the boost ratio, is introduced into the linear model in this paper, where its derivation and physical interpretation are also provided. After the introduction, the quantitative analysis for the RHPZ effects, including the decrease of the stability, the deterioration of the dynamic performance and the overshoot of the DC-link voltage, are provided in this paper. According to the analysis, a novel control strategy is proposed to enhance the stability to improve the dynamic performance and to restrain the voltage overshoot. Finally, simulation and experimental results verify that this control strategy has a great validity to reduce the RHPZ effects.

The requirement of high power rated, efficient and high power density grid connected converters has increased due to their extended use in multiple applications such as battery chargers. The proliferation of electric vehicles (EVs) in the transportation market is essentially associated with the performance and reliability of battery chargers. An efficient, compact and fast battery charger is indispensable in order to provide a way to charge an EV in a short time. In view of this fact, this article proposes a soft-switching three-level T-type vienna rectifier, which can be used as a front-end power stage converter in an on-board EV battery charger. The proposed topology achieves high efficiency and high power density by employing soft-switching strategy, which is achieved by incorporating a simple auxiliary network in the proposed circuit. The reduced component stresses and simple control strategy make it an appealing candidate for EV industries to develop this front-end PFC rectifier as a fast battery charger. The high switching operation with reduced power losses, regulated DC at the output, low-harmonic grid current and power factor correction operation are achieved with the proposed topology. The construction, operating principle and simulation analysis of the proposed converter are discussed in detail. In order to show the stand-point of the proposed scheme, a fair comparison of the proposed soft-switched converter with an existing soft-switched 3-level neutral-point diode-clamped converter is carried out in terms of the number of components and complexity in the PWM signals generation. Additionally, an efficiency comparison of the suggested converter is carried out with some existing well-known rectifier topologies at different power loads. The practical implementation of the proposed power converter scheme is checked by building a laboratory-prototype to perform an experimental analysis.

This paper demonstrates the analysis of a long-distance high-power microwave wireless power transmission (MWPT) system based on asymmetrical resonant magnetron and cyclotron-wave rectifier. In the system, the novel magnetron with the asymmetrical resonant cavity, the straps, and the output loop coupling circuit can effectively promote the beam–wave interaction, suppress the mode competition, and enhance the output coupling, which results in a 400 kW output microwave power with a conversion efficiency of 45%. The transceiver Cassegrain antenna system with its simple structure, high conversion efficiency, and high power capacity can attain an integral power transmission efficiency of 2.6% at 10 km distance. The cyclotron-wave rectifier with high efficiency and single-tube high power capacity can achieve 85% microwave to DC conversion efficiency. Finally, the long-distance high-power MWPT system can achieve 8.5 kW DC power with about 1% DC–DC transmission efficiency at the operating 2.45 GHz frequency and for the 10 km distance. Such a system is likely a potential and attracting solution to remotely power the fuel-free aerial vehicle from the ground, can also provide electrical power to an isolated mountain top or an island, and even an alternative to transmit the power from space solar power satellite in geostationary orbit to the ground.

The flexible DC transmission system needs a DC circuit breaker to remove and isolate the bipolar short-circuit fault to prevent the excessive short-circuit current from damaging the DC transmission system. In this paper, a comprehensive model of DC circuit breaker and transmission system is established by using PSCAD based on capacitive buffered hybrid DC circuit breaker. The short-circuit current waveform and DC port voltage waveform of the three-terminal ± 350 kV flexible DC transmission system under the condition of double-pole short-circuit fault at the DC side of rectifier station are simulated and calculated. The simulation results show that the maximum current and voltage of the capacitor-buffering hybrid DC circuit breaker model is lower than that of the ideal DC circuit breaker model under the condition of bipolar short-circuit fault at the DC side of the rectifier station. The system fault waveform under different parameters of capacitor-buffered hybrid DC circuit breaker is compared and analyzed through simulation, so as to optimize the parameters of circuit breaker. It can be seen that the actual results more in line with the switching process can be obtained by using the capacitor buffer type hybrid DC circuit breaker.

Excessive reactive power generated by the filter and compensation devices of rectifier station will flow into the AC system when DC bipolar block occurs, which brings a high voltage threat to doubly-fed induction generator (DFIG)-based wind farms at the sending-end. This paper proposes a nonlinear robust tracking control (RTC) strategy to enhance the high-voltage ride through (HVRT) capability of DFIG-based wind farms. In the proposed strategy, the nonlinear characteristics of wind farms and the disturbance attenuation requirements during DC bipolar block is fully considered. The RTC problem is formulated with control objective of absorbing the reactive power injected into the AC system, and state-dependent Riccati equation (SDRE) technique is adopted to obtain an approximate solution. Case studies are performed on MATLAB/Simulink, the results illustrate the proposed HVRT control strategy has a better transient performance of suppressing overvoltage under Bipolar Blocking of HVDC System.

The present paper focuses on the use of the Multilevel Current Rectifier topology as an interconnection element between PV systems and the network or loads. In order to properly use the converter in connection with the PV system, several subjects such as the compatibility with the maximum power point tracking and the compatibility between the converter and the PV array must be taken into account. Compatibility between the converter and the PV array can be achieved by ensuring at least the maximum power point is a point that the converter can work with. In this sense, this work focuses on the operating conditions to guarantee the compatibility with the PV array. The main results are an analytical and experimental characterization of the operating range of the system using the Multilevel Current Rectifier. This operating range has a precision of 1 % . Leading to the conclution that not only the converter is a viable option, but also that the theory and methodology used can be extrapolated to another topologies.

The demand for green hydrogen is growing as the increasing production of pure hydrogen can no longer be based on fossil hydrocarbons. As water electrolysis would move from niche to a significant consumer of emission-free electricity, the efficiency of electrolytic gas production, lifetime of water electrolysis systems, and balance in the electricity grid become essential. The operational and investment costs of an industrial-scale alkaline water electrolyzer with four practical rectifier topologies are investigated. The results show thyristor-based rectifiers provide poor quality for the AC and DC sides, which leads to nonoptimal specific energy consumption (SEC) of the water electrolyzer and a notable reactive power component. Transistor-based topologies may offer up to 4.5% lower SEC of the electrolyzer than the conventional 6-pulse thyristor bridge. The reactive power results in additional costs in either investments in compensation equipment or regular allowance costs. An additional DC/DC converter can be installed to improve the power quality for the electrolyzer, but the second conversion stage adds to the system complexity and cost without eliminating reactive power. A modular single-stage rectifier based on insulated-gate bipolar transistor (IGBT) bridges is suggested as an alternative to provide improved power quality for both the electrolyzer and the electricity grid. Post-print / Final draft

The interest in reliable operation of electrical drives has increased in recent years. recently an AC electrical machine was typically a synchronous generator or a three-phase uncontrolled motor that would operate connected directly to the power grid, or if a DC machine, its speed would be controlled through a rectifier. Although these applications have been augmented by many others. Many developments have led to this explosion of applications. The ubiquitous use of power electronics and microcontrollers, DSPs, etc., have allowed control of speed, torque etc., and the introduction of new motor types: permanent magnet AC, switched and synchronous reluctance etc. with increased versatility, higher torque and power density. These new power electronics-controlled machines have been finding uses in applications in manufacturing, robotics, vehicle traction and operation, airplane propulsion, wind and wave generators, but also in medical, commercial and consumer electronics that are becoming vital in health and other necessary devices. Fault diagnosis in electrical drives covers the faults in the power electronics, the DC link capacitor, batteries if present, and electrical machines. In power electronics in particular, the faults can be open or short circuit of switches, and they can be identified from current and voltage measurements. In electrical machines the faults can be in the windings, with either incipient in precipitous degradation, and can be identified and their severity determined using either model- or signal-based techniques. Mechanical faults in bearings are usually detected through the measurement of vibrations, while eccentricity can be detected through the change of flux and inductances. Most of these faults can be identified accurately, and their development predicted. They can lead then to the estimation of the remaining useful life, and together with partial or full redundancies, can result in increased reliability on the drive.

With the widespread use of electric vehicles (EVs), the design of a highly quality and efficient battery charger has become an important research topic. In this study, an efficient AC-DC power factor corrected (PFC) boost converter with active snubber cell (ASC) is proposed for the battery charger. ASC integrated into the AC-DC PFC boost converter turns on the main switch with zero voltage transition (ZVT) and turns off with zero current transition (ZCT), which among soft switching techniques for eliminating the switching losses. In addition, it has been provided that other switching elements are operated with soft switching. Soft switching conditions and unity power factor (PF) are achieved from light load to full load conditions. Unlike the soft-switched PFC converter circuits in the current literature, no current and voltage stresses have been observed on any component in the main converter and ASC circuits. The paper also presents the steady-state operating principles and design guidelines of the proposed converter in detail. The efficiency improvement between the hard switched counterpart has been verified by making detailed loss analysis. The proposed converter has been constructed as 3.3 kW and tested according to European efficiency standards with various case studies. The total harmonic distortion (THD) of input current has been measured as less than 5% in compliance with EN 6100-3-2 Class D Limits (A) standards.

A thermal rectifier/diode is a nonreciprocal element or system that enables preferential heat transport in one direction. In this work we demonstrate a single-material thermal diode operating at high temperatures. The diode is made of nanostructured silicon membranes exhibiting spatially and temperature-dependent thermal conductivity and, therefore, falling into the category of spatially asymmetric, nonlinear nonreciprocal systems. We used an all-optical state-of-the-art experimental technique to prove rectification along rigorous criteria of the phenomenon. Using sub-milliwatt power we achieve rectification of about 14%. In addition, we demonstrate air-triggered thermal switching and passive cooling. Our findings provide a CMOS-compatible platform for heat rectification and applications in energy harvesting, thermal insulation and cooling, as well as sensing and potentially thermal logic., The work was supported by Polish National Science Centre (Sonata UMO-2018/31/D/ST3/03882 and Preludium UMO-2019/33/N/ST5/02902). B.G. acknowledge the support from the Foundation for Polish Science (POIR.04.04.00-00-5D1B/18). The ICN2 is funded by the CERCA programme/Generalitat de Catalunya. The ICN2 is supported by the Severo Ochoa Centres of Excellence programme, funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706). M.S., F.A. and C.M.S.T. acknowledge support from Spanish MICINN project SIP (PGC2018-101743-B-I00).

On August 17th, 2012, a diode rectifier at Nagano Traction Substation was broken. The broken rectifier was dismantled and investigated in detail and, as a result, it was estimated that the overvoltage caused by the lightning flash caused the dielectric breakdown in the rectifier. To confirm the assumption of the broken process, the field measurement at Nagano Traction Substation and FDTD (finite-difference time-domain) calculation analysis at Nagoya Institute of Technology were carried out. As a result, it was indicated that the direct lightning to the elevated bridge over the substation caused the transient overvoltage of the grounding system of the substation and resulted in the breakdown within the rectifier. Because the concrete bridge pier is located adjacent to the substation, the surge voltage from the elevated bridge is able to influence the potential of the substation mesh. In this paper, the investigation process to determine the cause of the trouble will be shown in detail.

This chapter first reviews two conventional stimulation strategies, constant-voltage and constant-current stimulation methods, and adiabatic stimulation, which can achieve high stimulation energy efficiency at the cost of design complexity. Then, it presents a fully-integrated RF-powered neural stimulator that achieves adiabatic energy-replenishing operation without any bulky external components. Adiabatic supply voltages, which can reach a differential range of up to 7.2 V, are directly generated from an on-chip 190-MHz resonant LC tank via a self-cascading/folding rectifier network, bypassing the losses that would otherwise be introduced by the 0.8 V system supply-generating rectifier and regulator. Using a charge replenishing scheme, the stimulator redirects the charges accumulated across the electrodes to the system power supplies for 63.1% of stimulation energy recycling. To benchmark the efficiency of stimulation, a figure of merit termed the Stimulator Efficiency Factor (SEF) is introduced.

[EN] In a previous paper the authors compared the AC-AC converters, useful for the frequency regulation in hydroelectric microplants varying the power dissipated in ballasts loads, with the new proposal consisting in a bridge three-phase rectifier using diodes with a serial switch with the load that is switched with symmetric angle. The paper showed that the aforementioned rectifier accomplishes to improve the power factor at the generator output, except for low power consumed by users, near to its minimal value. A way to solve this problem consists in to use three bridge single-phase rectifier using diodes with a serial switch with the load that is switched with symmetric angle. As a consequence, the objective of this article is to carry out a comparison between the aforementioned single-phase rectifier and the AC-AC converter, regarding the power factor at the output of the electric generator of hydroelectric micro-plants that regulate frequency by means of the ballast-load method., [ES] En un trabajo anterior se compararon los convertidores de corriente alterna/corriente alterna (AC-AC), típicamente utilizados para la regulación de frecuencia en microcentrales hidroeléctricas variando la potencia disipada en cargas lastres, con un rectificador trifásico a diodos tipo puente con un interruptor, en serie con la carga, conmutado con ángulo simétrico. En el mismo, se demostró que, con dicho rectificador, se logra mejorar el factor de potencia a la salida del generador eléctrico, excepto para potencias consumidas por los usuarios cercanas a su valor mínimo. Una vía para solucionar este problema consiste en emplear una terna de rectificadores monofásicos a diodos tipo puente con un interruptor, en serie con la carga, conmutado con ángulo simétrico. Así, el objetivo del presente artículo es comparar al rectificador monofásico mencionado y el convertidor de AC-AC, esquema empleado actualmente, respecto a parámetros de interés como es el factor de potencia a la salida del generador eléctrico de las microcentrales hidroeléctricas que regulan frecuencia por el método de carga lastre.

In this chapter, the various topologies of single-phase controlled rectifier are presented. In the first part of the chapter, topologies pertaining to low switching frequency such as half-wave, biphase, and full-wave rectifier with source inductance are presented. In the later parts, the various concepts and topologies pertaining to active rectification are presented. The performance issues pertaining to input currents, power factor, and commutation problems in control rectifier are addressed. The various topologies of unity-power-factor rectifiers, synchronous rectifiers, and rectifier using matrix converter are presented.

We study inductively loaded single-phase rectifiers, half-wave three-phase rectifiers and the three-phase bridge circuit. On the base of a numerical example we calculate the current flow in an R-L circuit connected to an AC-voltage source via a mechanical switch. From this calculation hence it follows the current equation in an inductively loaded single-phase rectifier. We calculate the time of maximum current strength, the average output voltage and the conduction angle. From the voltage waveform we can determine the “equal surface area criterion”. The study of the half-wave three-phase rectifier let us explain the “commutation”. For the three-phase bridge circuit we determine natural commutation points, the reference line voltages and the pulse number.

[EN] This paper introduces the use of a diode-based HVdc rectifier for the integration of a large off-shore wind power plant into an existing HVdc voltage source converter-based grid. The proposed control system allows for the wind power plant to energize the complete HVdc grid, in order to contribute to service restoration in the case of a black-out. The system exhibits good response to wind power plant black-start operation, rectifier breaker trip and reclosure, and short-circuit ride through at the on-shore ac-grid. The technical feasibility of the proposed topology has been validated by means of detailed PSCAD simulations using frequency dependent parameters for cable modeling. (C) 2017 International Association for Mathematics and Computers in Simulation (IMACS). Published by Elsevier B.V. All rights reserved., The authors would like to thank the support of the Spanish Ministry of Economy and European Union FEDER Funds under grant DPI2014-53245-R.

Power distortions such as power interruptions, voltage sags and swells, voltage spikes, and voltage harmonics can cause severe impacts on sensitive loads in the electric systems. Uninterruptible power supply (UPS) systems are used to provide uninterrupted, reliable, and high-quality power for these sensitive loads. Applications of UPS systems include medical facilities, life-supporting systems, data storage and computer systems, emergency equipment, telecommunications, industrial processing, and online management systems (Karve, 2000; Carle, 1995; Krishnan and Srinivasan, 1993). The UPS systems are especially required in places where power outages and fluctuations occur frequently. A UPS provides a backup power circuitry to supply vital systems when a power outage occurs. In situations where short-time power fluctuations or disturbed voltage occur, a UPS provides constant power to keep the important loads running. During extended power failures, a UPS provides backup power to keep the systems running long enough so that they can be gracefully powered down.

Rectifier circuits are commonly found in all types of electronic systems. The function of a rectifier circuit is to convert an ac voltage into a dc voltage as part of a power supply. Traditionally, the ac voltage is usually a single-phase or polyphase voltage at mains’ frequency. However in some modern applications, e.g., switching regulators, the ac voltage can also be a nonsinusoidal waveform at a frequency of more than 100 kHz.

Pulse width modulation or so-called switched mode rectifiers such as the boost rectifier and the regenerative rectifier and the multilevel regenerative rectifiers are presented and analyzed in this chapter. The state-of the-art control techniques used by these rectifiers such as maximum current control, hysteresis control, and sinusoidal pulse width modulation are presented as well. Solved problems and simulation results are included to help the reader understand the theory presented in this chapter.

Publisher Summary The power supply is a vital part of any electronic product. It is the interface between the noisy, variable, and ill-defined power source from the outside world, and the hopefully clear-cut requirements of the internal circuitry. A conceptual block diagram for the two common types of power supply is linear supply mode and switch mode. The component blocks of a linear supply are common to all variants, and are described as input circuit and transformers that isolate the output circuitry from the AC input, and step down (or up) the voltage to the required operating level. The advantage of the direct-off-line switch-mode supply is that it eliminates the 50-Hz mains transformer and replaces it with one operating at a much higher frequency, typically 30_300 kHz. This greatly reduces its weight and volume. The technical and commercial considerations that apply to a power supply can add up to a formidable list including input parameters, efficiency, output parameters, abnormal conditions, and cost and availability requirements.

This section provides for the complete field assembly and installation of major process equipment in an ethanol plant. The section includes the estimate man-hour tables, estimate sheets and installation man-hours for the pumps, filters, air compressors, receivers, buffers, chillers, beer and rectifier columns, vacuum system package and trays, conveyors, tanks, drums, pressure vessels, modules, condensers, generators, evaporators, process water package, and package boiler. The equipment craft man-hours were determined from time and methods for the measurement of construction labor for field erection of process equipment installed in an ethanol plant. The estimator estimates similarities and differences for proposed equipment and installation for previously installed equipment for which historical data are available. The purpose of this section is to provide a comprehensive and accurate method for compiling equipment direct craft man-hour estimates for the ethanol plant.

State-of-the-art diode rectifier topologies are presented and analyzed in this chapter. This chapter includes a number of useful tables related to the conduction states of various rectifier topologies, definitions of Fourier series analysis, general useful relations for power electronics analysis and current harmonic limits according to international standards. In this chapter, a method for power quality analysis that can be used to determine all necessary knowledge related to the power components of a rectifier at its input and output under different load conditions is introduced. The conduction overlap phenomenon between two diodes is also examined. Solved problems and simulation results are included to help the reader understand the theory presented in this chapter.

This paper presents a two-output indirect matrix converter feeding an open-ended winding induction machine. The modulation strategy for the converter input stage, which provides the DC voltage for the output stages, exploits the capability of the input rectifier to produce different DC voltage levels. Moreover, this paper includes a space vector modulation strategy for the converter output stages intended to eliminate the zero sequence load voltage. Furthermore, in order to decrease commutation losses, output stage commutation will take place at reduced voltage when load voltage requirements are low. Modulation strategies and overall system operation are verified via simulation in a PSim/Matlab platform with the machine operating under an open loop V/f control strategy. Experimental results are also presented to validate the control strategies. A topology for an open-end winding induction motor drive is presented.The topology is based on an Indirect Matrix Converter.Space Vector Modulation (SVM) strategies are presented for the converter.Occurrence of machine zero sequence voltage is eliminated by the SVM proposed.The system is modeled and simulated in Matlab/Psim platform.

[EN] We consider a nanopore network with simple connectivity, demonstrating a two-dimensional circuit (full-wave rectifier) with ensembles of conical pores acting as nanofluidic diodes. When the bridge nanopore network is fed with an input potential signal of fluctuating polarity, a fixed output polarity is obtained. The full-wave rectification characteristics are demonstrated with square, sinusoidal, and white noise input waveforms. The charging of a load capacitor located between the two legs of the bridge demonstrates that the nanofluidic network is effectively coupled to this electronic element. These results can be relevant for energy transduction and storage procedures with nanopores immersed in electrolyte solutions. Because the individual nanofluidic resistances can be modulated by chemical, electrical, and optical signals, the balanced bridge circuit can also be useful to miniaturize nanopore-based sensing devices. (c) 2015 Elsevier B.V. All rights reserved., We acknowledge the support from the Ministry of Economic Affairs and Competitiveness and FEDER (project MAT2015-65011-P) and the Generalitat Valenciana (project Prometeo/GV/0069 for Groups of Excellence). M.A., S.N. and W.E. acknowledge the funding from the Hessen State Ministry of Higher Education, Research and the Arts, Germany, under the frame of LOEWE project iNAPO.

The half-wave rectifier is a converter which carries out half-wave rectification. In a single-phase context, this is a converter including a diode which may be qualified as P1; in a three-phase context, we use P3, and in a generalized case with n phases, P n . A single-phase half-wave rectifier is shown. Note that the alternating current (AC) side is connected to an ideal voltage source V r , while the direct current (DC) side powers a resistance R . This configuration will also be used for other converters, but we will also study the case of a power supply to a current source I 0 presumed to be constant. Note that in the P 1 context, it is not possible to power a current source, as this would require permanent conduction through the only diode in the circuit.

This chapter outlines cathodic protection fundamentals, criteria, field data, and design aspects. A detailed description is given for monitoring methods such as potential survey, close interval potential survey, direct current voltage gradient, and corrosion rate measurement. Sacrificial protection system design illustrates total circuit resistance evaluation, anode output, number of anodes, and anode life. Impressed current systems (ICS) design is illustrated for a pipeline designed by the author and anode, rectifier, and ground bed selection is explained as well as rectifier output and service life. At the end of the chapter, a computer-aided cathodic protection design is addressed to illustrate troubleshooting existing structures, sacrificial and ICS design analysis, checking interference effects, attenuation, and system life prediction. Case studies and solved problems illustrate sacrificial and impressed current cathodic protection system design.

Multilevel and multicellular converters are currently the subject of extensive research activity, with a considerable number of publications in scientific journals and multiple conference papers on the subject. The primary objective of multilevel converters is to enable high voltages to be used with components with ratings which prevent the use of the converter topologies. The basic idea is the same as for the series association of rectifier assemblies, switches are used together in order to produce a high voltage on the load side. However, we do not simply synthesize high-voltage switches as substitutions for elementary switches; we also benefit from an increased number of degrees of freedom, provided by each elementary switch in the structure, to improve the performance of the converter. This notably allows us to increase the apparent switching frequency on the load side, in order to reduce harmonic distortion in the injected currents.

Mathematical models may be used for design or evaluation of cathodic protection (CP) systems. This chapter provides a historical perspective and a mathematical framework for the development of such models. The mathematical description accounts for calculation of both on- and off-potentials at arbitrarily located surfaces, thus making this approach attractive for simulation of external corrosion direct assessment (ECDA) methods. The approach also allows simulation of independent CP systems. Application of the model is presented for three cases: (a) enhancing interpretation of ECDA results in terms of the condition of the buried pipe; (b) simulating the detrimental influences of competing rectifier settings for crossing pipes protected by independent CP systems (e.g., rectifier wars); and (c) simulating the influence of coatings and coating holidays on the CP of above-ground tank bottoms.

In this paper an intelligent management of a grid-connected PV system is proposed. The MPPT is based on the online estimation of the solar irradiance by the Growing Neural Gas (GNG) network. The PV system is composed of a DC/DC boost converter performing the MPPT and a single phase active rectifier controlled by a VOC algorithm for the connection to the grid. Each part of the PV system is controlled in a coordinated way with respect to the others, according to a general intelligent management strategy. The whole PV system, including the adopted neural-based MPPT, has been experimentally tested on a suitably devised test rig. The PV source is obtained by a power emulator to properly test the system under all possible operating conditions, including partial shading. A comparison between the proposed approach and a classical P&O technique has been done on a real irradiance profile on a daily scale, showing an increase of the generated power of 13%. The main drawback of the GNG-based MPPT is the need for a preliminary knowledge of the set of PV characteristics based on either a mathematical model or measured data, for the off line training of the GNG. Furthermore, the proposed MPPT exhibits a higher robustness with respect to the P&O under partial shading.

Nowadays, the installation and operation of systems with minimum energy and material consumption is a main objective in the industrial ambit; this goal can be achieved through the implementation of recycle streams to recover raw materials and the use of energy integration techniques to minimize utilities requirements. However, when a process is highly integrated, e.g. processes with recycle streams and energy integration or thermal couplings, systems can present control problems. Several studies for Reactor-Separation-Recycle (RSR) systems using separation systems with conventional distillation columns have been reported, but few works have focused on energy-integrated columns or thermally coupled distillation sequences. This work presents a comparison between the dynamic behavior of a thermally coupled distillation column with side rectifier implemented within a RSR system and that obtained with a conventional distillation sequence.

Publisher Summary This chapter focuses on single-phase controlled rectifiers that are used in a wide range of applications. Line-commutated rectifiers with diodes, covered in a previous chapter of this handbook, do not allow the control of power being converted from ac to dc. The main disadvantages of the classical line-commutated rectifiers are that they produce a lagging displacement factor with respect to the voltage of the utility, and they generate an important amount of input current harmonics. The standard can be satisfied only by adding huge passive filters, which increases the size, weight, and cost of the rectifier. This standard has been the motivation for the development of active methods to improve the quality of the input current and, consequently, the power factor. An important issue in power electronics is the power losses in power semiconductors. The conduction losses are produced by the current through the semiconductor juncture, so these losses are unavoidable. The single-phase boost rectifier has become the most popular topology for power factor correction (PFC) in general purpose power supplies.

This paper presents a comparative study of several speed estimators to implement a sensorless speed control loop in Wind Energy Generation Systems driven by power factor correction three-phase boost rectifiers. This rectifier topology reduces the low frequency harmonics contents of the generator currents and, consequently, the generator power factor approaches unity whereas undesired vibrations of the mechanical system decrease. For implementation of the speed estimators, the compared techniques start from the measurement of electrical variables like currents and voltages, which contain low frequency harmonics of the fundamental frequency of the wind generator, as well as switching frequency components due to the boost rectifier. In this noisy environment it has been analyzed the performance of the following estimation techniques: Synchronous Reference Frame Phase Locked Loop, speed reconstruction by measuring the dc current and voltage of the rectifier and speed estimation by means of both an Extended Kalman Filter and a Linear Kalman Filter. © 2010 Elsevier Ltd., The first author thanks the support of the Instituto Politecnico Nacional (IPN) to finance his stay at the Universidad Politecnica de Valencia (UPV). This work was supported by the Spanish Ministry of Science and Innovation under Grant ENE2009-13998-C02-02.

Open and non-conventional closed batch column operation modes were compared by rigorous simulation. The configurations studied were the batch rectifier (“two vessel column”) and middle-vessel column (“three vessel column”). We simulated the separation of test mixtures (n-hexane-n-heptane and n-hexane-n-heptane-n-octane), and compared the recoveries of different methods under constant process duration. We proposed six different variants for the closed operation mode, which differ in the operation of the top (and in the case of middle-vessel column: bottom) vessel(s). The effects of the operational parameters were also studied. In case of negligible liquid hold-up, closed operation of batch rectifier provided better recoveries by 1.7–6%. However, the open operation mode of middle-vessel column proved to be better than the closed ones in every case.

The esterification of lauric acid and methanol is explored using a thermally coupled distillation sequence with a side rectifier and the Petlyuk distillation column. The study was conducted using as a design tool a multi objective genetic algorithm with restrictions. The product of the esterification can be used as biodiesel. It was found that the thermally coupled distillation sequence involving a side rectifier can produce biodiesel with a high purity (around 0.999) and also pure water, and the excess of methanol is recovered in a side rectifier. The results indicate that the energy consumption of the complex distillation sequence with a side rectifier can be reduced significantly by varying operational conditions. These reductions in energy consumption can be interpreted as reductions in carbon dioxide emissions.

Publisher Summary This chapter describes how different materials and component types can affect the performance of LED drivers. In an LED driver, the key function of a capacitor (symbol C) is energy storage. There are two types of storage, slow storage and fast storage. Slow storage is required across the DC terminals of a bridge rectifier, when the LED driver is powered from a low frequency AC supply. The purpose of this storage is to supply energy to the LED driver between the peaks of the AC voltage, which is twice every cycle. For slow storage, an aluminum electrolytic capacitor is often used because it has a high energy storage density (they take up less space for an equivalent amount of storage, compared to other dielectric types). These capacitors are made using aluminum foil with a wet dielectric material. Because of this construction, they cannot be used in a high temperature environment for long periods; the dielectric dries out and the capacitor eventually fails.

Publisher Summary This chapter describes the application and design of diode rectifier circuits. There are two types of single-phase diode rectifier that convert a single-phase ac supply into a dc voltage, namely, single-phase half-wave rectifiers and single-phase full-wave rectifiers. The transformer utilization factor (TUF), which is a measure of the merit of a rectifier circuit, is defined as the ratio of the dc output power to the transformer volt-ampere (VA) rating required by the secondary winding. Full-wave rectifier circuits with resistive load do not produce harmonic currents in their transformers. In half-wave rectifiers, harmonic currents are generated. The transformer core saturation problem in the three-phase star rectifier can be avoided by a special arrangement in its secondary windings, known as zig-zag connection. Three-phase bridge rectifiers are commonly used for high power applications because they have the highest possible transformer utilization factor for a three-phase system. The six-phase voltages on the secondary are obtained by means of a center-tapped arrangement on a star-connected three-phase winding. Therefore, it is sometimes referred to as a three-phase full-wave rectifier.

In this work we have extended the design and optimization methods for the separation of quaternary mixtures of hydrocarbons. Also, a controllability analysis using the singular value decomposition technique was performed in order to obtain the control properties of the distillation schemes. One conventional distillation sequence and three thermally coupled distillation sequences have been studied: one considering a side stripper and a side rectifier, one considering a side stripper and a side rectifier and heat integration between the side columns and a Petlyuk-type column. The design of a thermally coupled system starts from a conventional distillation sequence and then the recycle streams are varied until the minimum energy consumption is detected. The results show energy savings of around 30% of the thermally coupled distillation sequences in comparison to the conventional distillation sequence. Also, the system including both thermal and heat integration presented the lowest energy demand and the highest second law efficiency. When the integrated distillation sequences were subjected to a controllability analysis, the complex distillation sequence considering both thermal and heat integration presented the worst control properties in contrast to those of the complex schemes considering only thermal couplings.

A new silicon-controlled rectifier low voltage triggered (SCR-LVT), to be adopted as protection structure against electrostatic discharge (ESD) events, has been developed and characterized. A high holding voltage has been obtained thanks to the insertion of two parasitic bipolar transistors, achieved adding a n-buried region to a conventional SCR structure. These two parasitic transistors partially destroy the loop feedback gain of the two main npn and pnp BJTs, resulting in an increase of the sustaining (holding) voltage during the ESD event. A strong dependence of the holding voltage with the ESD pulse width has also been observed, caused by self-heating effects. 2D-device simulations (DESSIS Synopsys) have been performed obtaining results that perfectly fit the measurements over a wide temperature range (25 °C − 125 °C). Using device simulation results, the factors that influence the holding voltage, in terms of temperature dependence, but also in the behavior of the parasitic BJTs, are explained. A guideline to change the SCR holding voltage, related to the SCR design layout without any change to process parameters, is also proposed.

A power amplifier is the only place where one is likely to encounter a large number of components all in one big negative feedback loop. The failure of any components may simply jam the amplifier output hard against one of the rails, or cause simultaneous failure of all the output devices, possibly with a domino-theory trail of destruction winding through the small-signal section. A certain make of high-power amplifier in the mid-70s was a notorious example of the domino-effect, and it failed, which was often the case, the standard procedure was to replace all of the semiconductors, back to and including the bridge rectifier. By far, the most important step to successful operation is a careful visual inspection before switch-on. As in all power amplifier designs, a wrongly-installed component may easily cause the immediate failure of several others, making fault-finding difficult, and the whole experience generally less than satisfactory. Therefore, it is advisable to meticulously check that the supply and ground wiring is correct, all transistors are installed in the correct positions, the drivers and TO3 output devices are not shorted to their respective heatsinks through faulty insulating washers, and the circuitry around the bias generator TR13 in particular is correctly built.

Publisher Summary This chapter discusses various supporting circuits, including bipolar switch drivers, metal-oxide semiconductor field-effect transistor (MOSFET) drivers, dissipative snubbers, lossless snubbers, and feedback isolators. Bipolar devices are current-controlled devices. MOSFETs are voltage-controlled devices. Insofar as controlling the switch on/off state, the gate voltage control for MOSFET resembles the base current control for bipolar transistors. To achieve switch on/off for MOSFET at high speed, drivers with high forward and reverse current capability are often employed. The chapter describes the operating sequence of a RC-diode turn-off snubber circuit. It also describes single-phase full-wave rectifier with RC filter.

AC/DC rectifiers are the first group of the power switching circuits applied in industrial applications. In the 1940s, Mercury-arc rectifiers were very popular in DC power supply. In 1960s, semiconductor manufacture development brought power devices, such as power diode, thyristor—or silicon controlled rectifier, (SCR)—gate turn-off (GTO), Triac, bipolar transistor (BT), insulated gate bipolar transistors (IGBT), metal-oxide semiconductor field effected transistor (MOSFET), and so on into the DC power supply. The DC power supply equipment is totally changed. The corresponding control circuit has gradually changed from analog-to-digital control system since 1980s. The mathematical modeling for all AC/DC rectifiers is discussed widely worldwide. This chapter deals with different types of full-wave and half-wave AC/DC rectifiers and mathematical modeling for AC/DC rectifiers. It elaborates on the function of single-phase full-wave AC/DC rectifier, three-phase half-wave controlled AC/DC rectifier, three-phase full-wave controlled AC/DC rectifier, three-phase double-anti-star with interphase-transformer controlled AC/DC rectifier, six-phase half-wave controlled AC/DC rectifier, and six-phase full-wave controlled AC/DC rectifier.

Publisher Summary Rotating machines cover the whole spectrum of generators and motors of all types. They span the range from fractional horsepower motors to 1500-MVA generators with the family characteristic of a rotating shaft from which mechanical power is extracted or into which mechanical power is supplied. This chapter examines some of the common characteristics of both generators and motors as they concern power electronics. A commutator with brushes on the rotating windings maintains the torque in a constant direction with rotation. The torque produced is proportional to the flux, and the speed is inversely proportional to the flux. An inner current regulator loop is surrounded by a voltage or speed regulator loop. When a generator is short-circuited on the stator terminals, the current starts at a much higher value than the steady-state reactance would predict. A rectifier or converter operating from the terminals of a synchronous generator must transfer the load current from phase to phase in sequence.

This contribution focuses on the development of a dynamic conceptual model for a batch rectifier having an infinite number of stages without resorting to multistage calculations. For a given instantaneous still composition, the key feature of the method is the estimation of the instantaneous minimum reflux or the instantaneous distillate composition by using the Rectification Body Method. The usefulness of Bifurcation Analysis of pinch profiles is emphasized to model highly non-ideal behavior.

Separation of a maximum boiling azeotrope (chloroform / ethyl acetate) with intermediate boiling entrainer (2-chlorobutane) in batch rectifier is studied in this paper with a new configuration variant (IBED) of batch extractive distillation (BED). Feasibility study is performed, then the two configurations are compared on the basis of theoretical considerations, short-cut estimations, and rigorous simulations. More than 20 % of the applied entrainer can be saved if IBED is applied instead of BED for separating the studied system.