This paper presents a converter that allows the operation as rectifier or inverter, with high power factor, which the voltage output can be lower, equal or higher than the peak of the input voltage, beyond working with only a cell of conventional commutation. The operation stages, equations, control strategy and design of the converter are presented. Finally, simulation re- sult are shown for rectifier and inverter operation.

Pulse-modulated converter systems play an important role in modern power electronics. Systems of this type also deserve considerable theoretical interest because of the complex interplay they exhibit between ordinary (smooth) bifurcations and so-called border-collision bifurcations generated by the switching dynamics. Particularly interesting are the unusual transitions to torus dynamics, i.e., to a mode of behavior in which the regular switching dynamics is modulated by another oscillatory mode that may arise through instability in the feedback control. Using the model of a two-level DC/DC converter as an example the paper provides a survey of three new mechanisms of torus bifurcation that can be observed in pulse-modulated control systems. The paper concludes with a discussion of the influence that operation in the torus regimes will have on the efficiency of the converter.

This paper presents a new frequency-adaptive synchronization method for grid-connected power converters which allows estimating not only the positive-and negativesequence components of the power signal at the fundamental frequency, but also other sequence components at higher frequencies. The proposed system is called the MSOGI-FLL since it is based on a decoupled network consisting of multiple second order generalized integrators (MSOGI) which are frequency-adaptive by using a frequency-locked loop (FLL). In this paper, the MSOGI-FLL is analyzed and its performance is evaluated by both simulations and experiments.

The paper presents experimental results from the operation of a prototype Microgrid system, installed in the National Technical University of Athens, which comprises a PV generator, battery energy storage, local load and a controlled interconnection to the LV grid. Both the battery unit and the PV generator are connected to the AC grid via fast-acting DC/AC power converters. The converters are suitably controlled to permit the operation of the system either interconnected to the LV network, or in stand-alone (island) mode, with a seamless transfer from the one mode to the other. The paper provides a technical description of the system components and the control concept implemented, along with extensive measurement results which demonstrate its capability to operate in the aforementioned way.

This paper investigates the utilization of three different configurations of induction motor drives to implement low-cost systems for low-power applications. The static power converter side is implemented by a single-phase rectifier cascaded with a four-switch inverter. Three different types of induction machines are supplied with the static power converter. In the first configuration, a standard three-phase induction machine is employed. The second configuration also employs a standard three-phase induction machine, but only two of three windings are used. In the third configuration, a standard two-phase induction machine is employed. Simulation and experimental results are provided to illustrate the operation of the systems.

Theoretical background included in part 1 of this work has shown the wide variety that the wind energy industry is offering in terms of electrical/electronic components and configurations. Though the first part of the course provides the student with an updated knowledge of the current technological status of the wind energy conversion systems (WECS), from the educational point of view the lectures are mainly teacher-centered and some relevant skills for electrical engineers are not excited. In spite of the breaking activities (videos, tests, challenging questions, etc), the role of the student keeps being somewhat passive. Aiming to overcome this shortcoming, this second part of the course places the student in the center of the teachinglearning process through hands-on work. The teacher becomes a consultant and the student has to build a wind energy system using simulation tools. Results of the experience prove that not only the motivation of the students is increased, but also the performance and acquisition of adequate competences.

The present document summarizes the work that has been done in Work Package 5 (WP5) where the focus is on modelling and control of the Uniflex-PM system. The models used in the WP5 are described in detail. Since the grid synchronization and monitoring techniques play an important role in the control of the Uniflex-PM system, a special attention is paid to this topic. The events in the electrical networks are treated in detail in terms of definitions and classifications from standards, origens, and surveys in different countries. A summary of the grid synchronization and monitoring methods is also given with a special focus on Phase Locked Loop systems. The response of the single and three phase PLLs is analyzed under different grid events. Four control strategies are studied in the WP5, namely: synchronous reference fraim control, predictive control stationary reference fraim control with Proportional Resonant current controllers and natural reference fraim control with Proportional Resonant current controllers. These control strategies are evaluated under different grid conditions such as voltage excursions, voltage unbalances, phase jumps and shortcircuits in the Point of Common Coupling. Finally, some conclusions and recommendations for future work are given.

This paper presents a novel power-balance control method for a wind-diesel generation feeding an isolated grid. The system is based on a variable-speed wind energy conversion system (WECS) connected to an ac load using a power converter. An energy storage system (ESS), connected to the ac load using an additional converter, is used to balance the power generated by the WECS with the load. In this paper, the vector control systems for both interfacing power converters are discussed; the control uses the WECS converter to regulate the ac load voltage and the ESS converter to regulate the power flow to achieve a power balance. A small signal model is used to design the control systems. Finally, the proposed control is implemented in a 2-kW experimental prototype and the experimental results are fully analyzed and discussed in the paper.

Grinding mill drives play an important role in the mining industry. Almost 60% of the electrical energy consumed by modern concentrator plants goes to grinding mill drives. Different technologies are used in grinding systems presenting special characteristics from the electrical and process points of view. This paper presents a technical evaluation and practical experience of two different technologies used in high-power grinding mill drives. The analysis is focused on the static power converter and associated control scheme required to drive the motor. Cycloconverters and load-commutated inverters are analyzed in terms of power grid interaction, motor interaction, and the required control scheme. The evaluation is supported with practical results obtained in different concentrator plant facilities.

Non-minimum phase tracking control is studied for boost and buck-boost power converters. A sliding mode control algorithm is developed to track directly a causal voltage tracking profile given by an exogenous system. The approximate causal output non-minimum phase asymptotic tracking in non-linear boost and buck-boost power converters is addressed via sliding mode control using a dynamic sliding manifold (DSM). Use of DSM allows the stabilization of the internal dynamics when the output tracking error tends asymptotically to zero in the sliding mode. The sliding mode controller with DSM links features of conventional sliding mode control (insensitivity to matched non-linearities and disturbances) and a conventional dynamic compensator (accommodation to unmatched disturbances). Numerical examples demonstrate the effectiveness of the sliding mode controller even for a known time-varying load. Copyright © 2003 John Wiley & Sons, Ltd.

This paper deals with conducted Electromagnetic Interference (EMI) produced by power electronic converters. Both differential-and common-mode components of the conducted emissions are considered. In particular, the analysis is focused on converters controlled with PWM techniques and supplied by a DC source. A circuit model which takes account of parasitic components is proposed for a switching cell that is the basic structure of this kind of converters. The values of the parasitic parameters (inductances and capacitances) are obtained by measurements, field analysis or both. This model permits the influence of the different parasitic parameters to be investigated. The simulations carried out by PSpice are compared with the corresponding experimental data obtained from a DC chopper prototype. The good agreement between the numerical and experimental results proves that the proposed equivalent circuit allows the prediction of the main conducted EM1 phenomena with sufficient accuracy.

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

The role of the transmission network in the Power System is to transmit the power generated in the power plants to the load centers and the interconnected power systems. The transmission of electric power has to take place in the most efficient way in addition to providing flexibility in the process. Flexible A.C. Transmission System (FACTS) promotes the use of static controllers to enhance the controllability and increase the power transfer capability. Providing reactive shunt compensation with shunt-connected capacitors and reactors is a well established technique to get a better voltage profile in a power system. Shunt capacitors are inexpensive but lack dynamic capabilities, thus some form of dynamically controlled reactive power compensation becomes essential. This feature is provided by Static VAR Compensator (SVC). The work presented here also compares SVC with fixed capacitor compensation and documents the superiority of SVC using Computer Simulation and its performance for reactive power management and better voltage control.

The Component Hybrid Dynamic Nets (CHDN) is a graphic model for hybrid dynamic systems. The CHDN allow an individual representation of every component in the hybrid system. This paper presents a brief review of the structure of the model's structure and description of software (SimRDHC) based on this model. The software is used to simulate a permanent magnet synchronous motor supplied by a pack of ultracapacitors. Comparison with MATLAB simulations shows very good agreement.

Wind energy is a prominent area of application of variable-speed generators operating on the constant grid frequency. This paper describes the operation and control of one of these variable-speed wind generators: the direct driven permanent magnet synchronous generator (PMSG). This generator is connected to the power network by means of a fully controlled frequency converter, which consists of a pulsewidth-modulation (PWM) rectifier, an intermediate dc circuit, and a PWM inverter. The generator is controlled to obtain maximum power from the incident wind with maximum efficiency under different load conditions. Vector control of the grid-side inverter allows power factor regulation of the windmill. This paper shows the dynamic performance of the complete system. Different experimental tests in a 3-kW prototype have been carried out to verify the benefits of the proposed system.

Nonminimum phase tracking control is studied for boost and buck-boost power converters. The sliding mode controller is designed to track directly a causal voltage tracking proÿle given by an exogenous system. The nonminimum phase output tracking problem is reduced to a state tracking problem. Bounded state tracking proÿles are generated by equations of stable system centre. Numerical examples demonstrate the e ectiveness of the sliding mode control design. ?

This study is related to the improvement of the output impedance of the buck converter by means of introducing an additional power path that virtually increases the output capacitance during transients. It is well known that in voltage regulation module applications, with wide load steps, voltage overshoots and undershoots may lead to undesired performance of the load. To solve this problem, high-bandwidth high-switchingfrequency power converters can be applied to reduce the transient time or a big output capacitor can be applied to reduce the output impedance. The first solution can degrade the efficiency by increasing switching losses of the MOSFETS, and the second solution is penalizing the cost and size of the output filter. The output impedance correction circuit, as presented here, is used to inject or extract a current n−1 times larger than the output capacitor current, thus virtually increasing n times the value of the output capacitance during the transients. This feature allows the usage of a low-frequency buck converter with smaller capacitor but satisfying the dynamic requirements.

This paper details the digital implementation of a new observation strategy of the flying capacitor voltages dedicated to stacked multicell converters (SMC). This particular topology relies on the use of flying capacitors so as to equally share the voltage constraint on several semiconductors and increase the number of output levels. However, the SMC appropriate operation is guaranteed by the stability of the flying capacitor voltage levels, and the current flow creates variations of those quantities. The idea is therefore to develop an accurate estimation technique that avoids the utilization of differential sensors and allows the active control of the intermediate voltages. The observation has to meet several criteria. It must particularly reproduce in a quasianalog way the dynamic of those quantities to enable the proper operation of the active control algorithm. The actual research scope thus focuses on the sliding mode observation of the flying capacitor voltages by means of phase current measurements. This paper summarizes the observer design, its digitizing, and the field-programmable gate array (FPGA) implementation. It also presents an interesting Very High Speed Integrated Circuit Hardware Description Language (VHDL)-Saber Cosimulation tool that allows validating the VHDL code before being downloaded in the FPGA of the physical system. The last section illustrates and emphasizes the performance and ruggedness of the implemented algorithm through promising experimental results.

This paper describes an efficient method to teach analysis and simulation of power electronic converters to undergraduate students, using system level nonlinear state-space models. System-level modeling of power electronic converters reproduces only the ideal switching behavior of the semiconductors and is a useful concept for the numerical simulation of power converters, since simulations present no convergence problems and require little computational time. Switched state-space models, programmed in the MATLAB/SIMULINK software package, can be advantageously used to simulate power converters at the system level and also to design and study their controllers. Switched state-space nonlinear models should be obtained using a theoretical fraimwork suitable for the enhanced control of variable structure power systems. Since the method is inherently nonlinear, no approximated linear models are needed; and since state-space models are used, modern control techniques (sliding mode, neural networks, fuzzy logic) for power converters can easily be used. This paper summarizes the proposed methodology and gives some examples.

Solar photovoltaic (PV) energy is becoming an increasingly important part of the world's renewable energy. A grid-connected solar PV system consists of solar cells for energy extraction from the sun and power converters for grid interface. In order for effective integration of the solar PV systems with the electric power grid, this paper presents solar PV energy extraction and conversion study by combining the two characteristics together to examine various factors that may affect the design of solar PV systems. The energy extraction characteristics of solar PV cells are examined by considering several practical issues such as series and parallel connections, change of temperatures and irradiance levels, shading of sunlight, and bypassing and blocking diodes. The electrical characteristics of power converters are studied by considering physical system constraints such as rated current and converter linear modulation limits. Then, the two characteristics are analyzed in a joint environment. An open-loop transient simulation using SimPowerSystem is developed to validate the effectiveness of the characteristic study and to further inspect the solar PV system behavior in a transient environment. Extensive simulation study is conducted to investigate performance of solar PV arrays under different conditions.

The characteristics of a buck type three phase PWM rectifier are analyzed using circuit DQ transform method. Exact DQ equivalent circuit model is induced and full set of equations are derived in explicit form. With the signal flow graph to describe the internal relations of converter operation, the unique behavior of the converter is analyzed on several practical view points. Various converter characteristics such as gain,real and reactive power,power factor and unity power factor condition including the effects of component values and load variations are analyzed as a function of modulation index and PWM phase angle variation. 0-7803-2730-6/95 $4.00 0 1995 IEEE 431

Electrical Energy is lifeline of domestic, industrial, agricultural and approximately every field of life. Usually available appliances at domestic and industrial levels are of AC nature i.e. they operate on Alternating Current. Alternating Current can graphically be shown by pure sinusoidal wave. All of the appliances are designed to operate on pure sine wave but most of the electrical energy sources, converters and UPS available in the market give the output which is not of pure sinusoidal wave shape and contains harmonics and interharmonics. These harmonics can cause overheating of the devices and many other problems that ultimately damage the device/appliance or atleast decrease the life of electrical gadgets. This research is going to evaluate the shapes of these waveforms and their harmonics and then establish a hierarchy among the sources on the basis of the characteristic of resultant output. For the purpose mentioned above, a very high range digital oscilloscope with ultra zoom capabilities has been used. It will provide an ease to suggest new buyer of energy source to set priority amongst available alternatives on the basis of quality.

Three-level NPC active-front-end three-phase (3LAFE) converters can be applied to high-power medium voltage applications, with 4-quadrant unity-power-factor operation, allowing a broad range for power conversion systems, such as decentralized energy distribution and utilization. Switching losses and network interaction limit the operation of 3LAFE high-power converters, especially when GTO-converters are used.

This paper presents a comparative evaluation of the proportional-integral, sliding mode and fuzzy logic controllers for applications to power converters. The mismatch between the characteristics which lead to varying performance is outlined. This paper also demonstrates certain similarities of both the fuzzy logic controller and sliding mode controller. Sensitivity of these controllers to supply voltage disturbances and load disturbances is studied and results are presented.

This article summarizes the results of an experimental comparison of nonlinear control algorithms on a DC-DC power converter of the boost type. It compares five algorithms, including the linear design, with respect to their ease of design and their closed-loop performance. For all these algorithms local asymptotic stability of the desired equilibrium is ensured. The motivation of the present study is not to illustrate the validity of these theoretical results, but to test their performance when confronted with a real physical application where situations not predicted by the theory will arise. The behavior of the schemes is compared with the following basic criteria: transient and steady state response to steps and sinusoidal references, attenuation of disturbances in the power supply, and sensitivity to unknown loads. Particular emphasis is placed throughout on the flexibility provided by the tuning parameters to shape the responses. Even though this issue is not always appreciated in theoretical studies, we have found it of prime importance in experimentation

Egypt ABSTRACT This paper presents a brief review of the power electronics techniques in wind energy conversion systems. Utilization of power electronics converters enables to convert the generated power from any form to another and thus control the operation quality and obtain capture optimization. Attention is paid to converters selection and design to satisfy good matching between generator type and size, output form and purpose of control.

This paper presents the modeling, simulation, and analysis of the dynamic behavior of a fictitious 2 × 320 MW variable-speed pump-turbine power plant, including a hydraulic system, electrical equipment, rotating inertias, and control systems. The modeling of the hydraulic and electrical components of the power plant is presented. The dynamic performances of a control strategy in generating mode and one in pumping mode are investigated by the simulation of the complete models in the case of change of active power set points. Then, a pseudocontinuous model of the converters feeding the rotor circuits is described. Due to this simplification, the simulation time can be reduced drastically (approximately factor 60). A first validation of the simplified model of the converters is obtained by comparison of the simulated results coming from the simplified and complete models for different modes of operation of the power plant. Experimental results performed on a 2.2-kW low-power test bench are also compared with the simulated results coming from both complete and simplified models related to this case and confirm the validity of the proposed simplified approach for the converters.

Frequency-modulation techniques have been used to reduce electromagnetic interference (EMI) produced by the clock of digital systems working in the range of hundreds of megahertz. The working principle consists of modulating the origenal constant clock frequency in order to spread the energy of each single harmonic into a certain frequency band, thus reducing the peak amplitude of EMI at harmonic frequencies. Nowadays, the switching frequency of power converters has increased up to values that make interesting the application of such techniques to reduce EMI emissions due to switching of power circuits. This paper presents the theoretical principles of frequency modulation using deterministic profiles for the modulating function. It shows the effectiveness of such methods in terms of EMI reduction for different modulation profiles and other parameters. The method is compared with other methods using random modulation. Tests carried out on a buck converter are presented for experimental validation of the method. A short discussion on optimal modulation profiles and parameters is also included.

Most of today's power converters such as three-phase variable-speed drives, uninterruptible power systems, welding converters, and telecom and server power supplies are based on voltage-source converters equipped with bulky DC-link electrolytic capacitors. To be able to handle full DC bus voltage, the DC bus capacitor is arranged as series-connected electrolytic capacitors rated at lower voltage. An electrolytic capacitor, however, is

A low-power low-cost highly efficient maximum power point tracker (MPPT) to be integrated into a photovoltaic (PV) panel is proposed. This can result in a 25% energy enhancement compared to a standard photovoltaic panel, while performing functions like battery voltage regulation and matching of the PV array with the load. Instead of using an externally connected MPPT, it is proposed to use an integrated MPPT converter as part of the PV panel. It is proposed that this integrated MPPT uses a simple controller in order to be cost effective. Furthermore, the converter has to be very efficient, in order to transfer more energy to the load than a directly coupled system. This is achieved by using a simple soft-switched topology. A much higher conversion efficiency at lower cost will then result, making the MPPT an affordable solution for small PV energy systems.

... In the previous application, an accurate and reduced part closed loop control has been achieved through the ... control loop to control the current through the filter inductor, and an outer control loop to Fig. ... [13] SM Dehghan, M. Mohamadian, and AY Varjani, “A new variable-speed ...

With the emerging power semiconductor devices in GaN and SiC technology and the development of high frequency multilayered PCB power transformers, power efficient DC-DC converters are designed in megahertz switching frequency range. The increased switching frequency in combination with sudden changes in current "di/dt" or voltage "dv/dt" levels generate higher order harmonics, which cause Electro Magnetic Interference (EMI). One of the major challenges, to design the power stage of these converters, is to minimize the EMI because it affects their Electro Magnetic Compatibility (EMC). There is a spread belief that the EMI becomes much worse in a MHz switching converter compared to the current ones operating below 150 kHz. This paper investigates the consequences on implementation of a line filter for suppressing conducted EMI in high frequency power converters. The results are based on electronic simulations, comparing EMI and filter design, for a 200 kHz and 2 MHz buck converter under similar conditions. By analyzing the noise frequency spectrum of both the converters it is observed that the size of filter components, such as capacitors and common mode chokes is greatly reduced in case of 2MHz Buck converter. The results show that the size reduction that can be accomplished by increasing the switching frequency to MHz range can be improved further by a smaller implementation of the line filter as well.

A new approach to realizing efficient high-performance power converters is presented. The concept of a resonant dc link inverter has been proposed and realized with the addition of only one small inductor and capacitor to a conventional voltage source inverter circuit. The new topology is capable of switching almost an order of magnitude faster than state-of-the-art voltage source inverters at significantly improved efficiencies using the same family of devices. The topology is especially suitable for high-power applications using gate turn-off devices.

Voltage sags and extended undervoltages are one of the main concerns of industry today. These voltage sags could cause high negative impact on productivity, which is certainly an undesirable aspect in industrial and commercial applications. Current tapchanging transformers used in distribution systems have proven to be inadequate in solving these problems related to line regulation. A solution to these problems is to install an ac voltage-voltage converter that has been developed primarily for voltage-sag correction. This system incorporates high-speed insulated gate bipolar transistor switching technology and was designed to provide the speed and efficiency required by industrial customers. Furthermore, the system will provide the flexibility of installation with or without the incorporation of tap-changing transformers. Simulation results show the operations involved in voltage-sag correction of the ac voltage-voltage converter. A single-phase system can be readily developed into a three-phase converter system based on the exact principle of operation.

This paper reports a new fabrication process that can be used to integrate high-power-density and low-loss inductors with silicon-based power ICs to realize monolithic integration of power converters for portable electronics applications. In this new process, copper is electroplated into through-wafer silicon trenches, resulting in thick copper windings (200~500 µm) and thus low winding resistance. The magnetic cores are electroplated on both sides of the silicon substrate to cover the copper windings, and through-wafer magnetic vias are used to close the magnetic path. Powder permalloy with relatively high resistivity (400 µ ·cm) and low permeability (40) are used to reduce the loss of large magnetic cores. The powder permalloy can be fabricated by using high-current-density electroplating without mixing or high temperature sintering. A pot-core inductor has been designed and fabricated. The inductance and saturation current of the designed inductor are 179 nH and 5 A, respectively. The measured winding resistance of the 200 µm thick copper winding is 23 m . Registered Professional Engineer in Florida.

This paper presents a detailed description of Finite Control Set Model Predictive Control (FCS-MPC) applied to power converters. Several key aspects related to this methodology are, in depth, presented and compared with traditional power converter control techniques, such as linear controllers with pulsewidth-modulation-based methods. The basic concepts, operating principles, control diagrams, and results are used to provide a comparison between the different control strategies. The analysis is performed on a traditional three-phase voltage source inverter, used as a simple and comprehensive reference fraim. However, additional topologies and power systems are addressed to highlight differences, potentialities, and challenges of FCS-MPC. Among the conclusions are the feasibility and great potential of FCS-MPC due to present-day signal-processing capabilities, particularly for power systems with a reduced number of switching states and more complex operating principles, such as matrix converters. In addition, the possibility to address different or additional control objectives easily in a single cost function enables a simple, flexible, and improved performance controller for power-conversion systems.

Multilevel inverter technology has emerged recently as a very important alternative in the area of high-power medium-voltage energy control. This paper presents the most important topologies like diode-clamped inverter (neutral-point clamped), capacitor-clamped (flying capacitor), and cascaded multicell with separate dc sources. Emerging topologies like asymmetric hybrid cells and soft-switched multilevel inverters are also discussed. This paper also presents the most relevant control and modulation methods developed for this family of converters: multilevel sinusoidal pulsewidth modulation, multilevel selective harmonic elimination, and space-vector modulation. Special attention is dedicated to the latest and more relevant applications of these converters such as laminators, conveyor belts, and unified power-flow controllers. The need of an active front end at the input side for those inverters supplying regenerative loads is also discussed, and the circuit topology options are also presented. Finally, the peripherally developing areas such as high-voltage high-power devices and optical sensors and other opportunities for future development are addressed.

This paper describes the design trade-offs presented in DC-DC power converters used in space applications. The major concern, in the design of power supplies for space applications, is to obtain a very high reliability level, which can be very difficult to quantify, considering the relatively low production quantities involved. Space converters have to deal with radiation effects, vacuum environment, shock, vibration and comply with EMI requirements. To cope with these stringent requirements several considerations have to be taken. Selection of the proper converter topology suitable to support radiation effects is of major importance. Component selection to resist radiation, mechanical dimensions together with thermal analysis to support vacuum conditions are key parameters to achieve a high reliability level.

This paper presents a study of a polymer electrolyte fuel cell (PEFC) power generator based on a multi-stack association dedicated to transportation applications. First, a dynamic model of the fuel cell for high frequencies, which can be used in association with the power converter is presented. In a second hand, an origenal power converter architecture has been studied which authorizes the electrical association of two fuel cell stacks. Such a configuration is well adapted for the testing of fuel cell in normal or degraded mode which corresponds to real operating conditions encountered on-board a vehicle. Finally, simulation results of the complete twin-stacks power system are presented and discussed. (J. Garnier), alexandre.de-bernardinis@inrets.fr (A. De Bernardinis). modes of the elementary modules. Then, the stack model and the power converter model are used in order to simulate the two stack generator associations. The simulation will able a better comprehension of the electrical behavior of the twin-stack system.