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Smart grids aim to dramatically change residential area energy systems by creating active grid interaction. Specifically, renewable energies will play a key role when it comes to handling energy storage systems (ESS) at houses within a Smart Community. This paper presents a novel global control strategy for distributed micro-storage energy system. Each home receives the active and reactive power set- points from the Smart Community Energy Management System (SCEMS), providing energy resources to the community in function of the expected demand and production. Once SCEMS requirements are fulfilled, harmonic current components demanded by the household circuitry are injected according to the ESS available capacity. The proposed approach not only causes a local improvement in the power quality of the demanded current, but also contributes to the global power quality consumption of the community. Experimental tests are conducted using a prototype of the proposed ESS charger, validating the control strategies. [ABSTRACT FROM PUBLISHER]

Predictive current control (PCC) has been recently proposed like an alternative to conventional PI-PWM current control techniques. Implemented solutions are based on inaccurate estimation of the rotor electrical variables to reduce the computational cost of the method. In this study, the utility and computational cost of PCC with different methods for the online estimation of the rotor variables are studied. Experimental results are provided to characterize the obtained benefits and drawbacks, using a five-phase induction machine as a case example. [ABSTRACT FROM PUBLISHER]

Although the concept of a multiphase drive system dates back to the middle of the 20th century, the initial pace of development was rather slow, as witnessed by the first two surveys of the area published in the beginning of this century. However, considerably new developments have resulted in the last decade of the 20th century and the beginning of this century, leading to an authoritative survey of the asymmetrical six-phase drive control and subsequently of the review of the complete area. This also initiated the organization and subsequent publication of the first IEEE Transactions on Industrial Electronics "Special Section on Multiphase Machines and Drives" in May 2008, which commenced with another survey paper, and that contained 12 original research papers. Since the publication of this Special Section in May 2008, the level of interest and pace of developments in the area have further accelerated and substantial new knowledge has been generatedwith an ever-increasing number of published research papers and reported new industrial applications. Such a trend has been emphasized in a recent paper. It therefore seemed appropriate to revisit the area and organize this Special Section as a sequel to the first one. The call for the Special Section papers resulted in 51 submissions, almost twice as many as the total back in 2008, thus confirming a substantial growth of the area. Indeed, the amount of new knowledge acquired since the publication of the first Special Section in 2008 has meant that it was not possible to provide a complete and thorough survey of the field in a single review paper. [ABSTRACT FROM AUTHOR]

Multiphase machines are well recognized as an attractive alternative to conventional three-phase machines in a number of applications where high overall system reliability and reduction in total power per phase are required. The pace of developments in the field has accelerated in the last few years, and substantial knowledge has been recently generated. The main objective of the two-part survey named ‘Recent Advances in the Design, Modeling, and Control of Multiphase Machines’ is to present relevant contributions to encourage and guide new advances and developments in the field. More specifically, part 1 of the work analyzes the recent progress in the design, modeling, and control, including healthy operation, of multiphase motor drives, and discusses open challenges and future research directions in the area. [ABSTRACT FROM AUTHOR]

The main objective of this two-part state-of-the-art paper called “Recent Advances in the Design, Modeling, and Control of Multiphase Machines” is to present latest contributions in the multiphase machines' field. The first part of this paper focuses on the recent progress in the design, modeling, and control, whereas the drive is in healthy operation. This second part presents relevant contributions in two not analyzed fields. The first is in relation with the use of the additional degrees of freedom of multiphase machines and the exploitation of their fault-tolerant capabilities without adding extra hardware. The second one analyzes multiphase generation, particularly in grid-connected wind energy conversion systems and stand-alone applications. Recent progresses are shown and open challenges and future research directions are discussed. [ABSTRACT FROM AUTHOR]

Multiphase machine drives are gaining importance in high-reliability applications due to their fault-tolerance capability and their ability to cope with the postfault operation without any extra electronic components. Predictive current controllers have been recently proposed for managing postfault operation of these drives when an open-phase fault is considered. However, the faulty situation assumes zero stator current while freewheeling diodes can continue conducting in a noncontrolled mode. This work analyzes the postfault operation of the five-phase drive when the freewheeling diodes of the faulty phase are still conducting. Experimental results are provided using a conventional insulated-gate bipolar transistor (IGBT)-based multiphase power converter to quantify the effect of the freewheeling diodes, when an IGBT-gating fault occurs, on the model-based predictive current-controlled drive. [ABSTRACT FROM PUBLISHER]

Space vector modulation (SVM) technique has become a standard method for the impression of voltage references in conventional three-phase voltage source inverters. The method is nowadays used in multiphase (more than three) drives, where linear and overmodulation regions are covered only for the five-phase case. This work proposes a general SVM procedure for linear and overmodulation regions in n -phase drives (being n any odd number, n > 3) and simplifies the extension of SVM to the multiphase case. The proposed method achieves the reference voltage at the fundamental frequency while reducing introduced harmonic components in the overmodulation region compared to previous proposals. [ABSTRACT FROM PUBLISHER]

Power electronics interfaces play an increasingly important role in the future clean vehicle technologies. This paper proposes a novel integrated power electronics interface (IPEI) for battery electric vehicles (BEVs) in order to optimize the performance of the powertrain. The proposed IPEI is responsible for the power-flow management for each operating mode. In this paper, an IPEI is proposed and designed to realize the integration of the dc/dc converter, on-board battery charger, and dc/ac inverter together in the BEV powertrain with high performance. The proposed concept can improve the system efficiency and reliability, can reduce the current and voltage ripples, and can reduce the size of the passive and active components in the BEV drivetrains compared to other topologies. In addition, low electromagnetic interference and low stress in the power switching devices are expected. The proposed topology and its control strategy are designed and analyzed by using MATLAB/Simulink. The simulation results related to this research are presented and discussed. Finally, the proposed topology is experimentally validated with results obtained from the prototypes that have been built and integrated in our laboratory based on TMS320F2808 DSP. [ABSTRACT FROM AUTHOR]

Multiphase electric drives have been recently proposed for applications where the highest overall system reliability and a reduction in the total power per phase are required. Strategies derived from the conventional field-oriented control have been traditionally used in high-performance speed-control applications of multiphase drives. The well-known direct torque control (DTC) technique has been also applied in the multiphase case, but the achieved performance with a hysteresis-control-based approach is far from that obtainable with the three-phase drive, although the control structure is actually more complex. In this paper, a predictive-torque-control method is introduced as an alternative to the DTC technique for the high-performance variable-speed operation of multiphase drives. Simulation and experimental results are provided to illustrate the properties of the developed method. [ABSTRACT FROM PUBLISHER]

Wind energy conversion systems (WECS) nowadays offer an extremely wide range of topologies, including various different types of electrical generators and power converters. Wind energy is also an application of great interest to students and with a huge potential for engineering employment. Making WECS the main center of interest when teaching power electronics and electrical machines can therefore be highly advantageous. This paper describes a novel teaching experience using wind energy as the starting point for understanding power electronics and electrical machines. The results point out the wide variety of concepts involved in the course, the numerous competences that it can enhance, and its positive reception by learners. [ABSTRACT FROM AUTHOR]

The interest in predictive control approach and multiphase drives has been steadily growing during the last decade. Predictive control techniques have been recently introduced as a viable alternative to conventional PI controllers with carrier-based or space vector PWM techniques in the current regulation of multiphase power converters and drives. The developed schemes have demonstrated a good performance at the expense of a high computational cost, an unknown switching frequency, and the appearance of large undesirable stator current harmonic components. In this paper, an enhanced predictive current control technique with fixed switching frequency is introduced for an asymmetrical dual three-phase ac drive. Fast torque and current responses are achieved while favoring stator current harmonic suppression. The experimental results are provided to verify the benefits of the proposed control method when compared to the other existing predictive control methods. [ABSTRACT FROM PUBLISHER]

Multiphase (more than three phases) drives exhibit interesting advantages over conventional three-phase drives. Over the last years, topics related to the extension of control schemes to these specific drives have been covered in depth in the literature. Direct torque control and predictive current control are normally used in conventional ac drives when fast electrical dynamic performance is required. In this paper, a one-step modulation predictive current control technique is proposed for asymmetrical dual threephase ac drives. Based on the use of a predictive model including the motor and the inverter, the control algorithm determines the switching state which minimizes errors between predicted and reference state variables. The period of application of the selected switching state is then obtained, resulting in a sub-modulation method. The proposed predictive current control algorithm uses a prediction horizon of one sampling period; however, two switching states are applied during the sampling period. The switching states are the selected optimum active vector and a null voltage combination. Simulation and experimental results are provided to examine the features of the control method. Performances, advantages, and limitations are also discussed. [ABSTRACT FROM AUTHOR]

Multiphase (more than three phases) drives possess interesting advantages over conventional three-phase drives. Over the last years, various topics related to the extension of the classical control schemes to these specifics drives have been covered in depth in literature, such as vector control of a six-phase induction machine with two sets of three-phase stator windings spatially shifted by 30 electrical degrees (also called asymmetrical dual three-phase ac machine). In this paper, a model-based predictive control (MBPC) for the current regulation of asymmetrical dual three-phase ac machines is analyzed. MBPC overcomes the difficulties of multiphase current control, avoiding complex controllers and modulation techniques, but at the expense of an increased computational cost. Simulation results are provided to examine the potential of the control method. The influence of the number of voltage vectors considered to evaluate the predictive model is studied, and different cost functions are analyzed. The computation time needed for the implementation of the control method is discussed to prove its real-time feasibility. Finally, experimental results are given to illustrate the capability of the control method. [ABSTRACT FROM AUTHOR]

The prevailing tendency in modern university reforms is towards "how people learn," following a learner-centered approach in which the learner is the main actor of the teaching-learning process. As a consequence, one of the key indicators of the teaching-learning process is the measurement of learner satisfaction within the classroom. Learner satisfaction has traditionally been measured using survey responses to a standard learning survey. However, more scientific analysis should be performed to assess adequately not only learner satisfaction but also the main dimensions that have a positive impact on learner satisfaction. The purpose of this paper is to define a structural and measurement model in which causal relationships among these different dimensions are adequately established. The methodology is based on a multivariate regression model (Structural Equation Models) to establish scientifically a structural model for learner satisfaction within a classroom, measuring its validity and reliability. The proposed approach has been applied to model learner satisfaction in an electronic instrumentation course at the University of Seville, Spain. The results and implications of this study will contribute to improve student satisfaction with respect to the dimensions considered. [ABSTRACT FROM AUTHOR]

This paper presents an exploratory study about the improvement and validation of a Web-based educational tool. The tool, designed with Shockwave and Macromedia Director, is used as a teaching methodology in an undergraduate course using modern microprocessors, architectures, and applications. An information system theory, called the Technological Acceptance Model (TAM), has been applied to detect both the use of the tool and the external variables that have a significant influence over it. The obtained results illustrate the strengths and weaknesses to be reinforced and have been taken into account to implement the final version of the tool. The proposed method may be extended to similar tools and experiments to fill the lack of scientific studies in the validation and acceptance of computer-based educational tools. [ABSTRACT FROM AUTHOR]

The main goal of this study is to develop a scientific method for designing a teaching methodology used in a basic digital signal processing (DSP) course. The proposed method is based on concept-mapping techniques, which applies multivariate statistic analysis to summarize the experience and knowledge of teachers involved in basic DSP teaching. As a result, a set of teaching methodologies is obtained. This result, as well as other information obtained related to the relative importance of the concepts to be covered, has been used to program the course. Moreover, different teaching tools have been developed to implement the proposed teaching methodology. Finally, the reliability of the method has been compared with similar studies to validate the proposed methodology. [ABSTRACT FROM AUTHOR]

This paper describes an improved universal active power line conditioner designed to attenuate every disturbance in the electric power system and critical loads, except frequency variations. The circuit has a series voltage filter and a parallel current filter interconnected through a shared dc bus. In case of a supply interruption, the current filter reconfigures to UPS and feeds a preselected 20% of load during 500 ms at the expenses of the dc bus. Over previous reconfigurable solutions, the input and output series static switches have been eliminated improving the reliability, efficiency and cost. Optional parallel LC tuned current filters have also been proved to be control compatible. The search has been guided by an iterative analysis+synthesis cost comparative method, initiated in previous works, showing the cost of the components involved in each explored topology. Experimental results on three laboratory models and a 400 kVA industrial prototype validate the topology and suggest improvement of some control loops. [ABSTRACT FROM AUTHOR]

Presents a critical analysis of various topologies for power circuits used in power line conditioners designed to attenuate or remove disturbances in the electric power system. Description of the basic lines for designing practical equipment; Results of a novel topology which reconfigurates to uninterruptible power supply in the case of a power line failure.

Presents a counterpart to the Cardan-Viete formulas that expresses the polynomial coefficients or the regression vector of an autoregressive filter. Information on the Levinson recursion; Close expression of the coefficients as functions of the reflection coefficients; Link between two representations.

Finite control set predictive controllers perform a direct digital control of power converters without a modulation stage such as pulsewidth modulation. Opposed to the inherent positive traits such as high flexibility and enhanced bandwidth, an increase in harmonic content is usually reported. The concept of variable sampling time (VST) has been recently introduced as a means to alleviate the harmonic content. The nonuniform sampling approach can be seen as an extra degree of freedom that is conferred to the controller, keeping its model-based feature. This paper goes beyond the state-of-the-art of VST controllers, introducing a new scheme for the computation of the sampling time. The resulting VST controller is experimentally assessed for a two-level five-phase induction motor drive, where steady-state and dynamic performance tests confirm the interest of the proposal. [ABSTRACT FROM AUTHOR]

Discrete-time control of power converters without modulation blocks have been considered in recent times in modern high-performance electromechanical drives, particularly with the appearance of model predictive control in its finite set version. The shortcomings produced by the fixed discretization of time used in this kind of control systems has been analyzed, and several methods have been put forward to deal with them. Most of the alternatives increase the complexity of the controller introducing different analytical modulation methods. However, a variable sampling time can be a simpler and more natural solution, at the expense of using a less-known paradigm for implementation. This paper introduces a new control approach based on a model of the system as in predictive controllers but using variable sampling time. It can be applied to modern power converters and drives, including conventional three-phase or advanced multiphase ones. Experimental results are provided to test the ability of the controller using a five-phase induction motor drive as a case example. [ABSTRACT FROM AUTHOR]

Direct torque control (DTC) has been recently used for the development of high-performance five-phase induction motor (IM) drives, where normal operation of the system has been usually considered and the ability of DTC to manage the situation has been analyzed in comparison with different rotor-field-oriented control (RFOC) strategies. The exploitation of fault-tolerant capabilities is also an interesting issue in multiphase machines, where the utility of RFOC controllers has been stated when the open-phase fault operation is considered. In this paper, the performance of DTC and RFOC controllers based on proportional resonant regulators and predictive control techniques is compared when an open-phase fault appears in a five-phase IM drive. Experimental tests are provided to compare the performance of the system using these control alternatives. [ABSTRACT FROM PUBLISHER]

Induction motor drives supplied from diode front-end rectifiers are commonly used in industrial applications due to their low cost and reliability. However, the two-quadrant operation of such a topology makes the regenerative braking impossible. Braking resistors can be used to dissipate the braking power and provide enhanced braking capability, but additional hardware is then necessary. Alternatively, the braking power can be dissipated within the inverter/motor by control software reconfiguration. In this scenario, the additional degrees of freedom of multiphase drives can be used to increase the system losses without disturbing the flux and torque production. Experimental results confirm the possibility to enhance the braking capability of six-phase drives with only few changes in the control scheme. [ABSTRACT FROM AUTHOR]

Direct torque control (DTC) has been widely used as an alternative to traditional field-oriented control (FOC) methods for three-phase drives. The conventional DTC scheme has been successfully extended to multiphase drives in recent times, using hysteresis regulators to independently track the desired torque and flux in symmetrical five-phase induction machines (IMs). The fault-tolerant capability of multiphase drives is an interesting intrinsic advantage for safety-critical applications, where recent research has demonstrated the effectiveness of FOC schemes to perform ripple-free postfault operation. In spite of the utility of DTC methods in normal operation of the multiphase machine, no extension to manage the postfault operation of the drive is found in the literature. In this paper, a novel fault-tolerant DTC scheme is presented. The performance of the proposed method is experimentally validated in a five-phase IM drive considering an open-phase fault condition. Provided tests analyze steady and transient states, including the transition from pre- to postfault operation. Obtained results prove the interest of the proposal, which ensures the open-phase fault-tolerant capability of DTC-controlled five-phase IM drives. [ABSTRACT FROM AUTHOR]

The redundancy of multiphase drives provides an inherent fault-tolerant capability that is appreciated in applications with a complicated corrective maintenance or safety-critical requirements. Fault restrictions, however, force the system to be reconfigured to operate in a smooth and efficient manner. Previous works have been focused on the optimization of current waveforms to generate an undisturbed operation but still maintaining the prefault rated flux settings. This study shows that efficient controllers can improve the postfault performance in six-phase induction machines supplied by parallel-connected converters if offline optimization is used to obtain a variable reference flux. Theoretical and experimental results confirm that the proposed flux adaptation method provides higher torque/power capability, lower degree of imbalance in the current sharing between windings and efficiency improvement. [ABSTRACT FROM AUTHOR]

A response to a letter to the editor about the article "Implementation of a Web-Based Educational Tool for Digital Signal Processing Teaching Using the Technological Acceptance Model" is presented.

Model predictive control (MPC) has recently been applied to induction motor (IM) drives in a configuration known as finite control set MPC (FCS-MPC). Its implementation must solve the problem of estimating rotor quantities, a task that is usually done using a simple backtracking procedure. On the other hand, observers have been used with field-oriented control (FOC), sensorless drives, and for fault detection but they have not been used yet for finite control set predictive current control of drives. This paper shows the benefits of incorporating a rotor current observer in a finite control set model predictive controller for the stator current of a five-phase drive. The observer design methodology employed in this work uses pole placement based on Butterworth filter design. The new estimation scheme is compared with the standard one in which nonmeasurable state components and other variables are lumped into one term that is updated. The differences between both approaches are experimentally analyzed and verified. [ABSTRACT FROM PUBLISHER]

One of the most attractive features of multiphase machines is the fault-tolerant capability due to the higher number of phases. Different postfault control strategies based on hysteresis, proportional integral (PI)-resonant, and predictive techniques have been recently proposed. They all proved their capabilities to withstand fault situations and to preserve the fundamental component of the air-gap field, while achieving minimum losses, maximum torque per ampere, and reducing torque vibrations. Nonetheless, due to their recent introduction, no thorough study has yet appeared comparing the performance of these controllers. In this paper, two open-phase fault-tolerant control schemes are experimentally compared in a real five-phase induction machine. The controllers being compared are based on PI-resonant and predictive control techniques, respectively. The experiments include pre- and postfault situations. Obtained results show that both control methods offer nearly the same performance. When compared, predictive control provides faster control response and superior performance at low-speed operation but is found to be less resilient to fault detection delays and to have higher current ripple. Regarding the controller implementation, it is shown that the transition from prefault to postfault operation involves modeling the nonlinear effects observed when an open-phase fault occurs for the predictive controller and proper retuning of the PI trackers for the PI-resonant controller, to ensure postfault operation. [ABSTRACT FROM AUTHOR]

Fault tolerance is one of the most interesting features in stand-alone electric propulsion systems. Multiphase induction motor drives are presented like a better alternative to their three-phase counterparts because of their capability to withstand faulty situations, ensuring the postfault operation of the drive. Finite-control set model-based predictive control (FCS-MPC) has been introduced in the last decade like an interesting alternative to conventional controllers for the electrical torque and current regulation of multiphase drives. However, FCS-MPC strategies for multiphase drives with the ability to manage pre- and postfault operations have not been addressed at all. This paper proposes a fault-tolerant speed control for five-phase induction motor drives with the ability to run the system before and after an open-phase fault condition using an FCS-MPC strategy. Experimental results are provided in order to validate the functionality of the proposed control method, maintaining rated currents and ensuring fast and ripple-free torque response. [ABSTRACT FROM PUBLISHER]

The growing interest in multiphase electrical drives has required the extension of control schemes and modulation techniques already well known for three-phase drives. Specifically, different and more complex space-vector pulse width modulation (SVPWM) methods have been developed for multiphase machines taking into account the increased number of switching possibilities and the new components resulting from generalized Clarke's transformation. In spite of the intensive work undertaken in the last decade, no SVPWM techniques with common-mode voltage (CMV) reduction have been developed for five-phase drives. This work proposes two SVPWM methods that are capable of reducing the peak-to-peak CMV by 40% and 80% compared to standard five-phase modulation strategies. Reduction of the CMV is done at the expense of higher phase voltage and current distortion. Simulation and experimental results confirm the CMV reduction and quantify the performance penalties of the proposed methods. [ABSTRACT FROM PUBLISHER]

This study presents a space vector pulsewidth modulation algorithm for five-phase converters operating in the overmodulation region that forbids the use of zero vectors, covering the whole overmodulation range and providing minimum x\--y voltages. Avoiding zero vectors reduces the content of low-order current harmonics and, at the same time, reduces the common-mode voltage (CMV) by 40%. The method is first implemented using medium and large voltage space vectors, showing good performance in terms of current harmonic content. Then, the algorithm is applied to the case when four large vectors are used, further reducing the peak-to-peak CMV by 80% and still demonstrating a satisfactory performance. Both methods are experimentally compared to existing overmodulation algorithms obtaining better current quality and lower peak-to-peak CMV. [ABSTRACT FROM AUTHOR]

Multiphase drives are advantageous when high overall system reliability and the reduction in the total power per phase are required. The control strategies for these applications require a good knowledge of the machine parameters to ensure a high quality of the dynamic and steady-state drive performance. Multiphase machines are still not common in industry and it appears that very little work has been done so far in relation to parameter identification techniques. This paper presents and implements a procedure to estimate the parameters of a five-phase induction machine, which can be also extended to other multiphase machines with higher phase numbers. The method is based on standstill time-domain tests and recursive least-squares algorithms. Experimental results are provided to illustrate the developed identification method using tests on two different five-phase induction machines. Correlation with corresponding parameters obtained in Part 1 of this paper is established, where electrical parameters of the same two five-phase inverter-fed induction motor drives were identified using various procedures, based on sinusoidal excitation of the machine. [ABSTRACT FROM AUTHOR]

The common-mode voltage (CMV) is known to be a source of electromagnetic interference, and it is potentially dangerous for the machine windings' insulation and bearings. CMV has been analyzed for three-phase machines supplied by voltage-source inverters, showing that modified pulsewidth modulation and model predictive control (MPC) techniques can significantly reduce the CMV at the expense of increased current distortion. This paper analyzes the CMV for five-phase drives and proposes a modified MPC strategy that accounts for the CMV reduction. The MPC can adjust the weights of the cost function to find a good balance between CMV reduction and low current distortion. The MPC strategy is experimentally tested showing how the CMV can be effectively reduced, thus improving the multiphase drive performance. [ABSTRACT FROM AUTHOR]

This paper reports on flux harmonic distortion factor and current ripple analysis for various discontinuous pulse-width-modulation (PWM) techniques, which are applicable in conjunction with five-phase two-level inverter-fed induction motors. The analysis is based on the application of the complex space vector approach. The results are compared throughout with the corresponding continuous PWM techniques. Different space vector PWM and carrier-based PWM methods are encompassed by the analysis. This paper is supported by extensive simulation results. Verification of theoretical findings is provided through experimental measurements on a five-phase induction motor. [ABSTRACT FROM AUTHOR]

Predictive control techniques have recently been applied with success to conventional and multiphase electrical drives. The additional degrees of freedom in multiphase drives make the real-time implementation of optimal solutions difficult due to the increased number of iterations. This paper proposes a predictive control technique that reduces the available voltage source inverter switching states according to predefined constraints. The introduced method, called as restrained search predictive control, favors on-line implementation and improves the current tracking performance. Simulation and experimental results are provided to test the viability of the presented technique. [ABSTRACT FROM PUBLISHER]

A novel multiconverter conditioner topology and its control stage are proposed in this paper. It is formed by an active conditioner in parallel with a hybrid conditioner composed of an active filter in series with one or more passive filters. This topology allows the reduction of the inverter ratings, constituting an effective solution at high-power levels. Collaborative control strategies are developed for the new topology, which share the compensation objectives between the two converters. These control strategies and the tracking techniques are based on estimating the load current, achieving new algorithms with a reduction in the number of meters in the control stage. The conditioner operates properly in three-phase four-wire systems reducing the harmonic distortion and/or imbalance and attaining the unity displacement power factor. Experimental results are included for the testing of the topology and its control. [ABSTRACT FROM AUTHOR]

The article discusses embedded multimedia processors to be used for road-traffic parameter estimation. These multimedia processors will provide the basis for future intelligent transportation electronic installations as directed by the U.S. Department of Transportation. Multimedia processors also provide special support for video applications.

Strategies for extracting the three-phase reference currents for shunt active power filters are compared, evaluating their performance under different source and load conditions with the new IEEE Standard 1459 power definitions. The study was applied to a three-phase four-wire system in order to include imbalance. Under balanced and sinusoidal voltages, harmonic cancellation and reactive power compensation can be attained in all the methods. However, when the voltages are distorted and/or unbalanced, the compensation capabilities are not equivalent, with some strategies unable to yield an adequate solution when the mains voltages are not ideal. Simulation and experimental results are included. [ABSTRACT FROM AUTHOR]

A variation of the pulse width modulation (PWM) operating technique, which we call "adjustable carrier PWM," is analyzed. The technique is applied to an active filter in order to compensate the low harmonics present in a load current. The aim is to prove that the proposed technique performs better at minimizing the root mean square (RMS) tracking error between the reference and the real currents than the usual PWM techniques in active filtering. Four generating techniques were simulated and compared in terms of the total and individual harmonic distortion (THD and IHD) in the supply current. The proposed technique was tested against experiments. [ABSTRACT FROM AUTHOR]

Integration of renewable energy sources, active role of consumers, and energy management systems is currently among research priorities in energy systems. This paper proposes an innovative coordinated energy scheduling for a microgrid of neighbor prosumers with different consumption patterns. All prosumers have photovoltaic generation systems, Li-ion batteries as energy storage systems, and regular household loads. A genetic algorithm is used to schedule each prosumer's battery charge/discharge, with the aim of reducing energy exchange losses by minimizing the power in the point of interconnection of the microgrid with the main grid, with several advantages compared to classical optimization objectives, and without worsening battery lifespan degradation. Individual and coordinated strategies are compared, and self-consumption and self-sufficiency of the prosumers’ set are evaluated with the aim of showing the advantage of coordination. The paper concludes that coordinated operation can contribute to improve the exploitation of energy resources in the prosumer microgrid, reducing the amount of energy interchanged with the distribution grid by approximately 13%, and, at the same time, avoiding increasing the battery cycling and consequent degradation. [ABSTRACT FROM AUTHOR]

Achieving a self-reconfigurable fault-tolerant control in multiphase machines requires a fast fault detection and localization. Most fault detection techniques inherit the three-phase approach by defining fault indices in a per-phase basis. A recent approach suggests an alternative fault detection mechanism based on vector space decomposition (VSD) variables, but the study is limited to open-phase faults (OPFs) for a six-phase drive that is regulated under field-oriented control. It is known, however, that 1) the open-switch faults (OSFs) in the converter are more likely than the OPF in the machine and 2) the drive performance in the event of an open-circuit fault is more critical when model predictive control (MPC) is used. This work extends the study of the VSD fault detection method to multiphase machines with different number of phases (five), control strategy (MPC), and type of faults (OPF and OSF). Although experimental results show that MPC misbehaves after the fault occurrence, the fast detection provided by the VSD approach allows a satisfactory transition to postfault mode of operation. [ABSTRACT FROM AUTHOR]

The most serious and recent competitor to the standard field oriented control for induction motors (IM) is the finite control set model predictive control (FCS-MPC). Nevertheless, the extension to multiphase drives faces the impossibility to simultaneously regulate the flux/torque and the secondary current components (typically termed $x - y$ in the literature). The application of a single switching state during the whole sampling period inevitably implies the appearance of $x - y$ voltage/currents that increase the system losses and deteriorate the power quality. These circulating currents become intolerably high as per the unit $x - y$ impedance and the switching frequency diminish. Aiming to overcome this limitation, this work suggests the integration of virtual voltage vectors (VVs) into the FCS-MPC structure. The VVs ensure null $x - y$ voltages on average during the sampling period and the MPC approach selects the most suitable VV to fulfill the flux/torque requirements. The experimental results for a six-phase case study compare the standard FCS-MPC with the suggested method, confirming that the VV-based MPC maintains the flux/torque regulation and successfully improves the power quality and efficiency. [ABSTRACT FROM PUBLISHER]

Fault tolerance is much appreciated at industry in applications with high-reliability requirements. Due to their inherent fault-tolerant capability against open-phase faults (OPFs), drives with multiple three-phase windings are ideal candidates in such applications and for this reason many efforts have been devoted to the development of different fault-tolerant control strategies. Fault detection is, however, a previous and mandatory stage in the creation of fault-tolerant drives, and the study of specific OPF detection methods for six-phase drives is still scarce. Taking advantage of the secondary currents (so called x-y currents) that are unique in multiphase machines, this study proposes new fault indices that detect and locate the OPFs without additional hardware. The method proves to be simple and independent of the operating point, control technique, and drive parameters. Comparative experimental results confirm the capability of the proposed method to achieve fast detection times with good robustness. [ABSTRACT FROM PUBLISHER]

Multiphase energy conversion systems have been recently proposed for motoring and generating applications where bidirectional power flow is required. When such multiphase systems are connected to the grid (e.g., in multimegawatt wind energy systems), efficiency is maximized by operating the system in a balanced manner with an equal distribution of the power among phases. However, the situation differs when the multiphase system is connected to different microgrids with individual active and reactive power requirements. In this scenario, an unequal power sharing between the different phases of the multiphase machine becomes mandatory. This story explores the control strategy to operate in speed mode with an independent regulation of the power contribution to the microgrids. Experimental results confirm the capability of the system to satisfactorily operate in unbalanced mode both in steady-state and transient conditions, thus providing the flexibility to divert the power from one three-phase winding to the other with no impact on the system dynamics. [ABSTRACT FROM AUTHOR]

The fault tolerance provided by multiphase machines is one of the most attractive features for industry applications where a high degree of reliability is required. Aiming to take advantage of such postfault operating capability, some newly designed full-power energy conversion systems are selecting machines with more than three phases. Although the use of parallel converters is usual in high-power three-phase electrical drives, the fault tolerance of multiphase machines has been mainly considered with single supply from a multiphase converter. This study addresses the fault-tolerant capability of six-phase energy conversion systems supplied with parallel converters, deriving the current references and control strategy that need to be utilized to maximize torque/power production. Experimental results show that it is possible to increase the postfault rating of the system if some degree of imbalance in the current sharing between the two sets of three-phase windings is permitted. [ABSTRACT FROM PUBLISHER]

Multiphase drives and parallel converters have been recently proposed in low-voltage high-power applications. The fault-tolerant capability provided by multiphase drives is then extended with parallel converters, increasing their suitability for safety-critical and renewable uses. This advantageous feature, compared with standard three-phase drives, has been analyzed in the event of open-phase faults. However, when using parallel converters, a converter fault does not necessarily imply an open-phase condition, but usually just a limited phase current capability. This paper analyzes the fault-tolerant capability of six-phase drives with parallel converter supply. Different scenarios considering up to three faults for single and two neutral configurations are examined, optimizing offline the postfault currents and modifying accordingly the control strategies. Experimental results confirm the smooth transition from prefault to postfault situation and the enhanced postfault torque capability. [ABSTRACT FROM AUTHOR]

Multiphase induction machines (IMs) are gaining increasing interest in industry due to their numerous advantages over the conventional three-phase ones. A lot of different parameter estimation methods have been developed for three-phase IMs, but the existing literature regarding specific identification techniques for multiphase IMs is almost nonexistent at this point. This paper proposes simple offline methods to estimate the stator resistance and stator leakage inductance of multiphase IMs with distributed windings, under different conditions, utilizing the machine’s degrees of freedom associated with the nonflux/torque producing current components. Once these parameters are identified, the rotor ones can be easily calculated by combination with the total values obtained from locked-rotor tests. The procedure enables segregation of the stator and rotor parameters in a simple manner, something that is very difficult to achieve in three-phase IMs where, usually, equality of leakage inductances and a constant stator resistance are assumed. In this manner, the magnetizing inductance can be then also more accurately assessed from no-load tests, because the error in its estimation that would be caused by assuming both leakage inductances to be equal is avoided. The proposed methods are experimentally tested on two different five-phase IMs. [ABSTRACT FROM AUTHOR]

A cross-analysis of EU masters' programs and professional profiles in information and communication technology reveals deficiencies in many areas. Reform initiatives are already addressing some of these deficiencies, but work remains. [ABSTRACT FROM PUBLISHER]

Multiphase variable-speed drives supplied from two-level voltage source inverters (VSIs) are, at present, contenders for numerous industrial applications. Various pulsewidth modulation (PWM) methods for multiphase VSIs, aimed at sinusoidal output voltage generation, have been developed using both carrier-based and space-vector approaches. An increased number of voltage space vectors, available for the synthesis of the output voltage, offer greater flexibility for the PWM scheme development, compared to the three-phase case. This paper presents comprehensive analytical analysis and comparison of switching ripple characteristics of two continuous space vector PWM (SVPWM) methods for a five-phase two-level VSI. Considered SVPWM schemes select a different set of four active space vectors per switching period in order to generate sinusoidal output voltages. This paper also presents the evaluation of the flux harmonic distortion factors of the SVPWM techniques. Correlation with corresponding current ripple and total harmonic distortion is established in Part 2 of this paper, where theoretical considerations are verified by simulations and through experimental investigation on a five-phase VSI-fed induction motor drive. [ABSTRACT FROM AUTHOR]