DC link voltage swinging and load current unbalance in fault tolerant VSI. overview and compensation strategies

The topic of this paper is the discussion on the performance of a three-phase fault tolerant inverter with particular attention to the underrated aspect of current unbalances occurring due to the DC link voltage fluctuates after the inverter reconfiguration. Capacitor voltage unbalance affects not only the average output voltage of the inverter, but also its performance. In fact, the inverter performance depends on the fluctuating DC-link voltage components rather than on the average DC-link voltage. After a brief analysis of the voltage fluctuation phenomena resulting from fault tolerant configuration and their effect on load current unbalance, the Authors consider different compensating p…

Contract for the support of household appliances control and monitoring application interworking specification

Numerical Analysis of Medium Scale PV Plants and Their Power-Flow Control System With a Simple Three Phase Inverter

This paper presents a mathematical analysis of a medium scale Photovoltaic (PV) power generation system connected to the distribution network and of its control system, in which the conversion stage is unique thanks to the absence of a boost chopper. Boost choppers are usually used as actuator for maximum power point tracking (MPPT). The conducted analysis leads to the conclusion that the used inverter presents two degrees of freedom that can be easily exploited in a control system in which the inverter simultaneously realizes the interconnection to the grid and at the same time realizes the MPPT control. The structure of the control system is then presented, discussed and then validated by…

A novel correction method for a low cost sensorless control system of IPMSM electrical drives

In this paper a novel correction method for sensorless Field Oriented Control System of Brushless internal Permanent Magnet Electrical Drives is introduced discussed and experimentally validated. The novelty of this control system is the estimation of rotor speed and angular position is based on the back electromotive force space vector determination, without the aid of voltage probes. Actual voltage signals needed for estimation are replaced with the reference ones given by the current controller. This choice obviously introduces an error that have been vanished by means of a new compensating function or with the aid of data coming from experimental tests. Experimental verifications of the…

Current fault signatures of Voltage Source Inverters in different reference frames

This paper considers different current patterns used to identify the correct fault signatures in Voltage Source Inverters (VSI). At the beginning, the Authors consider the currents patterns from which a simple or a double fault can be encompassed both in the case of controllable device only or with its free wheeling companion diode. After the discussion of diagnosis algorithm suitable for electrical drives and principally based on a persistent near zero current condition current in the natural phase reference frame, the stationary reference frame is then considered as a tool to identify both the faulted phase as the device or various combination of faulted devices. On the contrary, the Auth…

A modular approach in teaching thyristor rectifiers with equation-oriented softwares

This article is devoted to some issues of teaching power electronics in university courses. In the modern education system the students are expected to be no longer subject of passive learning, but that, within a certain extent, they collaborate in their training interactively with the teacher to develop the applications and the topics of the studied framework. For this purpose, this article presents a modular approach for teaching module regarding three-phase thyristor rectifiers. A simulator based on the MATLAB equation solver has been developed by considering the detailed physical operation of such converters. In particular, the realized simulator takes various aspects into account, incl…

A photovoltaic charging system of an electrically assisted tricycle for touristic purposes

In this paper the design, realization and testing of a photovoltaic charging system suitable for the management of an electrically power assisted tricycle are described. This vehicle uses a photovoltaic module as a source of electric energy for the battery recharging. In this work, an overview on the needs of sustainable mobility and on the commercial electrically power assisted velocipedes is presented. The electrical rickshaw prototype, developed in the SDELab laboratory of the University of Palermo, is presented in detail, underlining the design, implementation and developing phases of the photovoltaic charging system assembled on the velocipede. Moreover, tests oriented on the setting u…

WITHDRAWN: Perspective on hydrogen energy carrier and its automotive applications

A review of multiple faults diagnosis methods in Voltage Source Inverters

This paper examines, as in short review, the methods of diagnosis of simple and multiple faults on Voltage Source Inverter (VSI). The methods examined here are essentially based on the inspection of the load currents. Some of these diagnosis methods are characterized by low computational effort, other for a better reliability avoiding faultless positive tests. Some solutions are characterized by a share of these benefits while others prefer an enforcement of trustworthiness, in spite of the lower calculation amount. The analysis of the technical literature, certainly, offers a glimpse about the creation of new algorithms and significant advances for the future.

Local DoS applications with micro wind generation systems

In this paper a wind electrical power generation system for Distributed on Site (DoS) applications is proposed. This system was developed and conceived in order to guarantee simple installation, use and service, obtaining a product that can be easily industrialized and put into the market with limited costs. The field of application of such an electrical generation system is addressed towards domestic or at the most toward condominium applications concerning moreover the opportunity of working in addition to combined photovoltaic and solar-thermal systems to enhance the renewable energy generation at house level (DoS). The proposed system has its hot spot in the blades shape, in the wind fl…

A DSP-Based Resolver-To-Digital Converter for High-Performance Electrical Drive Applications

This paper presents a low cost, simple, and highly accurate resolver-to-digital converter (RDC) for electrical drive applications based on an integrated software approach, thus allowing a significant reduction of hardware components count with significant improvements in terms of reliability, reduction of fault rate, and susceptibility to electromagnetic interference (EMI). Particular attention has been addressed to cost which is 25% off over conventional RDC. Simulations and experimental tests confirm the high quality of the proposed system.

Fast procedure for the calculation of maximum slot filling factors in electrical machines

This paper presents an algorithm for the calculation of maximum slot filling factor in electrical machines. The determination of whole wire cross section that occupy the area of a stator slot is very important in order to estimate the copper losses: The greater is the filling factor the lower are copper losses. The main goal of this paper is to define a simple algorithm for the determination of slot filling factors suitable for all type of slot profiles. The algorithm can be considered as an additional useful tool for the fast design of electrical machine windings.

Experimental investigation on high efficiency real-time control algorithms for IPMSMs

This paper describes an experimental investigation on the power losses variations occurring in an Interior Permanent Magnet Synchronous Motor (IPMSM) with respect to the direct axis current component. Such investigation can be useful to determine a mathematical model accounting for copper, iron and mechanical friction losses, and for the arrangement of a speed control drive system equipped with a real-time power losses minimization algorithm. In particular, a test bench has been set up in order to carry out all measurements and the final power loss identification. The test bed is composed by a IPMSM drive with a field oriented control (FOC) strategy, a power analyzer, a dynamometric brake a…

Il Laboratorio per lo Sviluppo Sostenibile e il Risparmio Energetico (SDESLab) nell’ambito industriale siciliano

L’articolo presenta le attività del Laboratorio per lo Sviluppo Sostenibile ed il Risparmio Energetico (SDESLAB) dell’Università degli Studi di Palermo nei confronti dell’ambito industriale, con particolare riguardo a quello siciliano. Vengono illustrati gli ambiti di intervento del Laboratorio: ricerca scientifica di base, consulenza alle industrie e alle imprese, formazione, informazione e divulgazione nei vari campi dello sviluppo sostenibile con particolare riguardo a energie rinnov- abili, azionamenti elettrici, automazione industriale e gestione automatizzata dell’energia. Vengono descritte le attrezzature di cui il Laboratorio si avvale per le proprie attività, i progetti di ricerca i…

Design issues for wind farms grid tied Inverter

In this paper the Authors give indications for the design of a grid tied Voltage Source Inverters (VSI) aimed to optimal use in energy conversion from wind source. In particular, the design of the inverter is more focused on the control system planning, with a particular glance on the grid synchronization problem. After the exposition of general issues concerning renewable energies and associated topics, the case of a grid tied inverter is considered and a methodology of design is sketched starting from the consideration of the DC side and also considering the power device losses, the protection issue against over voltages and over-currents, snubber circuits, heat sinks and, finally the con…

Perspective on hydrogen energy carrier and its automotive applications

The paper outlines the concept of energy carrier with a particular reference to hydrogen, in view of a more disseminated employment in the field of automotive applications. In particular hydrogen production is analyzed considering the actual state of the art and recent technologies applied in production from the primary sources (fossil fuels, renewable energies, and water electrolysis). Then the problem of hydrogen storage is considered both from technical and economical point of views. In particular, differences between physical and chemical storage are here considered with a particular glance to the most innovative technologies including carbon nanostructures. A review on the main problem…

A novel improved matlab-based software for the electric and magnetic analysis and design of rotating electrical machines

The aim of this paper is to present a software for the analysis and design of windings of rotating electrical machines, considering both the electric and the magnetic specifications on the machine. The considered machines are induction motors (IM) and PM synchronous motors (PMSM). The software accounts for the case of buried magnets (IPMSM), but with some limits, because the calculations require a much more detailed analysis regarding the magnetic circuit. However, this initial limitation of the software, that will be removed in a later version, does not constitute a major limitation as confirmed by the examples presented in this paper.

A General Mathematical Formulation for the Determination of Differential Leakage Factors in Electrical Machines with Symmetrical and Asymmetrical Full or Dead-Coil Multiphase Windings

This paper presents a simple and general mathematical formulation for the determination of the differential leakage factor for both symmetrical and asymmetrical full and dead-coil windings of electrical machines. The method can be applied to all multiphase windings and considers Gorges polygons in conjunction with masses geometry in order to find an easy and affordable way to compute the differential leakage factor, avoiding the adoption of traditional methods that refer to the Ossanna's infinite series, which has to be obviously truncated under the bound of a predetermined accuracy. Moreover, the method described in this paper allows the easy determination of both the minimum and maximum v…

Fault Tolerant Ancillary Function of Power Converters in Distributed Generation Power System within a Microgrid Structure

Distributed generation (DG) is deeply changing the existing distribution networks which become very sophisticated and complex incorporating both active and passive equipment. The simplification of their management can be obtained assuming a structure with small networks, namely, microgrids, reproducing, in a smaller scale, the structure of large networks including production, transmission, and distribution of the electrical energy. Power converters in distributed generation systems carry on some different ancillary functions as, for example, grid synchronization, islanding detection, fault ride through, and so on. In view of an optimal utilization of the generated electrical power, fault to…

Power Quality Savings with Controlled Fault-Tolerant Power Converters

Power quality is simply the interaction of electrical power with electrical equipments. If electrical equipments operate correctly and reliably without being damaged or stressed, a suitable level of power quality is assured. On the other hand, if the electrical equipment malfunctions, is unreliable, or is damaged during normal usage, power quality is poor and probably the economical loss could be preeminent over the technical one. In the scenario of the Distributed generation power quality issues will be more- over important because an higher dissemination of power conditioning equip- ment will be requested and this obviously will increase the sources of vulnera- bility for the electrical s…

A platform-independent software for the design and analysis of windings of rotating electrical machines

In this paper the Authors present a highly modular and platform-independent software, being based on the MATLAB® programming environment, which is proposed as a valuable aid in the design and analysis of the windings of rotating electrical machines. Unlike the major part of the commercial software, the cases of both symmetric and asymmetric (unbalanced) windings with any number of phases are here considered. The software can perform a considerable amount of calculations in order to determine automatically the optimal structure of the winding starting from its specifications. It is also able to draw the winding map and gives the results of calculation for the harmonic winding factors. The re…

A New Software Tool for Design, Optimization, and Complete Analysis of Rotating Electrical Machines Windings

In this paper, a new software tool developed by the authors for ac winding design, optimization, and complete analysis is presented. In particular, this software can be used as a valid aid in design and analysis for a wide variety of motor and generator windings with generic number of phases (including the case of those machines in which some slots are left empty), pole pairs, slot number, and so on. The calculation of winding factors and the evaluation of their harmonic distribution is also accomplished. The software is implemented in the MATLAB programming environment. By means of some examples, covering the most relevant winding types, the capabilities of this software will be shown. In …

Comprehensive Modeling and Experimental Testing of Fault Detection and Management of a Nonredundant Fault-Tolerant VSI

This paper presents an investigation and a comprehensive analysis on fault operations in a conventional three-phase voltage source inverter. After an introductory section dealing with power converter reliability and fault analysis issues in power electronics, a generalized switching function accounting for both healthy and faulty conditions and an easy and feasible method to embed fault diagnosis and reconfiguration within the control algorithm are introduced. The proposed system has simple and compact implementation. Experimental results operating both at open- and closed-loop current control, obtained using a test bench realized using a dSPACE system and the fault-tolerant inverter protot…

Energy Management via Connected Household Appliances

The study reported hereafter provides results based on a campaign of simulations conducted by University of Palermo on the basis of its knowledge in the field Energy Value Chain and in the field of Energy Management (EM) for household appliances. Inputs from CECED Convergence WG has been fundamental to base that study on realistic data and cases. Moreover, the so called EM study, offers also a clear picture about the opportunity to have energy management applications and services in house, being those opportunities strictly related to the cost of in- frastructure needed and to the benefits belonging to different actors in the energy value chain. Energy savings have been considered both in t…

An exact method for the determination of differential leakage factors in electrical machines with non-symmetrical windings

An exact and simple method for the determination of differential leakage factors in polyphase ac electrical machines with non-symmetrical windings is presented in this paper. The method relies on the properties of Gorges polygons that are used to transform an infinite series expressing the differential leakage factor into a finite sum in order to significantly simplify the calculations. Some examples are shown and discussed in order to practically demonstrate the effectiveness of the proposed method.

Comprehensive Analytical Investigation for PV Plants and Their Control System with Reduced Power Electronics Equipments

This paper presents a comprehensive analysis of a power generation system from PV source and it control system with a reduced power equipments connected with a power AC grid. The absence of the boost chopper as an actuator for Maximum Power Point Tracking concurs to make the system more reliable, affordable and moreover cheaper respect to a traditional one in which the boost chopper is used. The mathematical analysis exposed in the paper shows as a three phase inverter has two degrees of freedom allowing the simultaneous MPPT control and the synchronization with the power grid. The analysis also shows the way to determine the duty cycle of the inverter to deliver active power, and eventuall…

Implementation and experimental validation of a real-time PWM algorithm based on B-Spline carriers for three phase voltage source inverters

This paper presents the implementation and experimental results of an algebraic real-time sinusoidal pulse width modulation algorithm (SPWM) based on B-Spline carriers. B-spline functions are used as carrier signals with the aim to to reduce harmonic content of the three phase inverter output voltage. The presented algorithm eliminates the problem of B-spline recursive evaluation with convolution integrals or convolution sums in digital counterpart. The pulse pattern synthesis is made with the help pre-calculated duty cycle expressions. In this way there is no real need to synthesize the carrier signal so the hardware and the whole inverter control system becomes cheaper, more reliable and …

Analytical Investigation and Control System Set-up of Medium Scale PV Plants for Power Flow Management

In the field of photovoltaic (PV) plants and energy conversion from renewable sources, a large part of the technical literature is more devoted to practical aspects (new solar cells, electrically driven PV panels, safety, reduction of parasitic currents, etc.) than to theoretical investigations. Despite this tendency, this paper presents a mathematical analysis of a medium scale photovoltaic power generation system connected to the distribution network and of its control system. In such a system, the conversion stage is unique due to the absence of a boost chopper. The conducted analysis leads to the interesting conclusion that the inverter used in the plant presents two degrees of freedom,…

A software for the evaluation of winding factor harmonic distribution in high efficiency electrical motors and generators

In this paper a software developed for the determination of winding connections, the calculation of winding factors and the evaluation of their harmonic distribution of three and two phase windings is presented by using as input data simply the number of slots, pole pairs and phases. The software is implemented as a function in MATLAB environment. By means of some examples, covering the most relevant winding types, the capabilities of this software will be shown. Particularly, integer and fractional single and double layer winding can be treated. Some examples are presented and briefly discussed. The connections, the winding factor harmonic distribution, the electro-motive force (e.m.f) THD…

Self training and meta-cognition goals. New approaches, trends and tools in modern teaching of power electronics

Teaching a complex discipline like power electronics is an open question and the best educational approach or the objectives to be achieved at the end of a power electronic course are still in debate. This paper presents a visual didactic approach chosen by the Authors in the last years in their respective courses in power electronics. It also discuss the objectives and the skills required to the students at the end of the course: in particular, some meta-cognition objectives recently fully entered into the education world in general. Such meta-cognition goals are now discussed for the particular case of power electronics courses. The Switching Functions (SFs) generalized approach is then d…

Experimental characterization of a proton exchange membrane fuel-cell for hybrid electric pedal assisted cycles

This paper presents a feasibility study on the prototyping of a hybrid EPAC (Electric Pedal Assisted Cycle) through an FC-B-UC (Fuel Cell — Battery — Ultra-Capacitors) power system. Aim of this work is the characterization of a PEMFC (Proton Exchange Membrane Fuel Cell) in order to confirm its theoretical performances and to verify the possibility of its installation on an e-bike.

Algebraic real-time algorithm for B-Spline sinusoidal pulse width modulation in three phase voltage source inverters.

In this paper a novel algebraic real-time algorithm for implementation of sinusoidal pulse width modulation (SPWM) based on B-spline carriers is introduced and discussed. B-spline functions are used as carrier signals with the aim to to reduce harmonic content of the three phase inverter output voltage. This algorithm eliminates the problem of B-spline recursive evaluation with convolution integrals or convolution sums in digital counterpart. The pulse pattern synthesis is made with the help pre-calculated duty cycle expressions. In this way the carrier signals have not to be really synthesized, hence the hardware and the whole inverter control system becomes cheaper, more reliable and affo…

Computer Aided Optimization Via Simulation Tools of Energy Generation Systems With Universal Small Wind Turbines

This paper considers the general issues in the project and the optimization of energy generation systems using small universal wind turbines, suitable in Distributed Generation (DG) and computer aided optimization for a better exploitation of wind source. Optimization in this field reveal to be more and more important because the local generation and consumption of electrical power, even for grid connected generators can suffers for unevenness of wind source exploitation, also in terms of wrong directions and in not regular wind flows. Computer aided design and optimization of small plants may give significant improvements in the development of the wind source also in accordance with the pr…

Reducing DC Link Voltage Unbalance in a Fault-Tolerant Inverter

Today, continuous working of power inverter drives is mandatory for several applications. Damages to materials, machines or even risks to human life have to be absolutely avoided. In the literature, fault-tolerant algorithms and architectures to achieve a successful fault handling are investigated. Researchers aim at reducing the number and cost of additional components, improving at the same time the inverter performances under postfault conditions. Cost, post-fault power derating and increasing distortion are usually conflicting requirements. In this paper, a fault-tolerant three phase inverter is presented. A reconfigurable architecture and a novel fault-tolerant algorithm is designed to…

A Perspective on the Future of Distribution: Smart Grids, State of the Art, Benefits and Research Plans

Currently, the design and operation criteria for electrical distribution networks are fastly changing due to some factors; among these, the progressive penetration of Distributed Generation (DG) is destined to cause deep changes in the existing networks, no longer considered as passive terminations of the whole electrical system. Moreover, the increasing application of Information Communication Technologies (ICT) will allow the implementation of the so called “smart grids”, determining new interesting scenarios. In the paper the problems and the potential benefits of DG, the possible new electrical distribution system models and the major research projects on smart grids are faced and repor…

A General Mathematical Model for non-Redundant Fault-Tolerant Inverters

Industrial systems able to release trusted services is an integrated concept that resumes the attributes of availability, reliability, safety, integrity, and maintainability. In power electronics this can be aimed via the introduction of fault tolerant architectures. While In the past technical literature the mathematical modeling problem for non-redundant converters was fronted studying separately the cases of fault leg by leg, in this paper a general model able to include the three possible cases of leg faults with a unique set of equation is introduced and discussed. The same model allows to evaluate the DC Link transient and steady state evolution and also allows to develop with much ea…

Wireless Power Transmission for house appliances: A small-scale resonant coupling prototype

This paper presents a low cost prototype of wireless power transfer system based on resonant coupling. The system here proposed can be useful for house appliances battery charging systems: as a matter of fact, it consists mainly of two copper wire coils or windings, placed one in front of the other on the same axis. By exploiting the coils resonance coupling effect, electric energy can be transferred from the inductor coil to the receiver in order to charge the batteries. Low cost experimental tests demonstrated the effectiveness of the proposed wireless power transfer prototype, being it capable to reach an efficiency of about 80% and more along a distance of 30 cm.

Determination of differential leakage factors in electrical machines with non-symmetrical full and dead-coil windings

In this paper Gorges polygons are used in conjunction with masses geometry to find an easy and affordable way to compute the differential leakage factor of non symmetrical full and dead coil winding. By following the traditional way, the use of the Ossanna's infinite series which has to be obviously truncated under the bound of a predetermined accuracy is mandatory. In the presented method no infinite series is instead required. An example is then shown and discussed to demonstrate practically the effectiveness of the proposed method.

A New Digital Demodulator for Sensorless Control of Electrical Drives with Permanent Magnet Synchronous Motors

This paper deals a new digital demodulator algorithm for sensorless control of interior permanent magnet synchronous motors (IPMS) based on the estimation of speed and rotor angular position. To this aim a signal similar to that generated by a resolver connected to the shaft of the motor is obtained injecting high frequency stator currents. A new digital algorithm has been designed and set up to demodulate the above signal whose implementation can be carried out on the same DSP that processes the whole control algorithm. The proposed demodulator scheme is presented and justified on the theoretic point of view. Simulations results finally validate the effectiveness of the demodulator within …

Flexible power converters for the fault tolerant operation of Micro-Grids

The progressive penetration level of Distributed Generation (DG) is destined to cause deep changes in the existing distribution networks no longer considered as passive terminations of the whole electrical system. A possible solution is the realization of small networks, namely the Micro-Grids, reproducing in themselves the structure of the main production and distribution of the electrical energy system. In order to gain an adequate reliability level of the microgrids the individuation and the management of the faults with the goal of maintaining the micro-grid operation (fault tolerant operation) is quite important. In the present paper flexible power converters and a companion control al…

Digital demodulation for fast set-up of sensorless PMSM electrical drives based on magnetic anisotropy

This paper presents a demodulation algorithm applied to the sensorless control of permanent magnet synchronous motors (PMSM). The sensorless control technique reported in this paper is based on the injection of high frequency voltages to the stator so that the motor currents contain information on the rotor position. This information is then extracted by an appropriate demodulation technique. The presented demodulation algorithm is based on spectral analysis of the signal produced by the sensorless control technique because this is fully characterized and presents not ambiguous correlation between current harmonic content and rotor position. The most important feature of the demodulation al…

Main Fuel Cells mathematical models: Comparison and analysis in terms of free parameters

This paper resumes the main mathematical models of Fuel Cells (PEM models). In particular, a comparison study of the various models introduced in the technical literature is presented and the dependency of the various model parameters is analyzed in different operating conditions. As the manifold of the model parameter is very wide and their determination is difficult, it is mandatory to introduce approximations and simplifications on which each model is based. The novelty of this work is the organization of the existing models in three categories with regard to the number of free parameters and to the dependency of such parameters on the different running conditions and the usage of a refe…

A Small Power Transmission Prototype for Electric Vehicle Wireless Battery Charge Applications

In this paper a low cost prototype of wireless power transfer system based on air coupling is presented. The system here proposed can be useful for electric vehicle (EV) battery charging systems. It consists mainly of two copper wire coils, placed one in front of the other on the same axis. The inductor coil can easily be placed under the road surface (in a parking), while the other (the receiver coil) in the lower side of the vehicle. By exploiting the coils resonance coupling effect, electric energy can be transferred from the inductor coil to the receiver in order to charge the batteries. Low cost experimental tests carried out at DIEETCAM - University of Palermo, demonstrated the effect…

A General Mathematical Model for the Simulation of Common Faults in Three‐ phase Voltage Source Inverters

In the last years the fault problem in power electronics has been more and more investigated both from theoretical and practical point of view. This paper analyzes the problem of faults modeling in a three phase voltage source inverter(VSI) and presents a model of a VSI able to simulate both unfaulty and faulty conditions when one or more devices go broken. In the past the fault problem was faced step by step considering the fault on each single device building a model for each case. The model hereafter presented solves this drawback through the introduction of the concept of the Healthy Device Binary Variable (HDBV) and the more general Healthy Leg Binary Variable (HLBV) showing also as th…

Design of a grid connected inverter for sustainable small wind farms

The actual definition of sustainability is nowadays widely accepted. It provides a very general indication on what it is, but it reveals unable to assert how it should be reached. However, if one considers the multiplicity of human activities that have led to talk of real process of human settlement on the environment, it is then understood how it is close to the particular mankind activities. Then the task of providing a guidance on what to do within the sustainability concept is delegated case by case. In this paper, with reference to wind renewable source, The Authors give some indications in the design of a voltage source inverters aimed to optimal use of the wind source. In particular …

Approccio allo Sviluppo di Sistemi Diagnostici per il Funzionamento Fault Tolerant delle Micro-grid

Il progressivo aumento del livello di penetrazione della generazione distribuita(GD) è destinato a provocare un profondo mutamento nelle esistenti reti di distribuzione che non sono più considerate come terminazioni passive del sistema elettrico complessivo. Una soluzione possibile è quella relativa alla realizzazione di piccole reti, le micro-grid, che riproducono, al loro interno, la struttura del sistema di produzione e distribuzione dell’energia elettrica. Per ottenere una adeguata affidabilità della micro-grid risulta importante la individuazione e la gestione dei guasti ai fini del perseguimento dell’esercizio "fault tolerant" della micro-grid stessa. Nel presente lavoro, dopo aver in…

A Steady - State Model of a Photo Voltaic Array Directly Coupled to a Voltage Source Inverter and its Graphical Solution Method.

A suitable control technique for fault-tolerant converters in Distributed Generation

The penetration of Distributed Generation (DG) in power systems is deeply changing the existing distribution networks which is becoming a very sophisticated and complex systems incorporating both active (generators) and passive systems (distribution systems, converters and loads). The necessary simplification can be obtained dealing with small networks, namely Micro-Grids, reproducing, in a smaller scale, the structure and the problems of large networks including production, transmission and distribution of the electrical energy. In order to achieve an adequate level of reliability, fault-tolerant operations of micro-grids become very important. This result can be achieved only using power …

E-bike battery charging: Methods and circuits

Today, academic and industrial research is focused on innovative battery charging methods to ensure complete mobility of both handheld devices and electric vehicles. Wireless power transfer is actually the leading strategy even if efficiency related issues are to be solved for a successful marketing. In this paper, a wireless battery charging station is proposed for electric assisted pedal bikes. If compared with existing wireless solutions, the proposed system architecture improves power conversion efficiency of the charging equipment. The simulation model of the whole charging station is described in detail. The transmitter, receiver and inductive coupling circuits are described and desig…

MODELAMIENTO Y SISTEMA DE CONTROL DE UN INVERSOR DIRECTAMENTE ACOPLADO AD UN GENERADOR FOTOVOLTAICO PARA LA REGOLACIÒN DE LA POTENCIA ACTIVA Y REACTIVA ENTREGADA A LA RED.

A new modified Inc-Cond MPPT technique and its testing in a whole PV simulator under PSC

In this paper a new modified Inc-Cond MPPT technique able to lead PV plants to work in the real MPP (Maximum Power Point) under PSC (Partial Shading Condition) is proposed. The new Inc-Cond MPPT technique working principle is fully explained, discussed and then successfully tested in a whole and reliable PV simulator conceived and set-up by the Authors in order to test and compare several new MPPT algorithms. The simulation results show that the proposed Inc-Cond MPPT technique is able to successfully lead the PV plant to work in the real MPP both in the cases of instantaneous and gradual changing of shading and of temperature conditions.

A PV plant simulator for testing MPPT techniques

This paper introduces a versatile and reliable photovoltaic systems simulator. It includes the main components of a photovoltaic plant: a PV string and a PWM controlled boost chooper. The key feature of this simulator is the ability to consider different and non-uniform irradiation and temperature conditions (partial shading and partial heating of the strings). All the different I-V and P-V or P-I characteristics can then be determined in such non-uniform irradiation and temperature conditions, with the aim to try different MPPT algorithms. The simulator also allows to verify an enhanced version of the Incremental Conductance algorithm (IncCond) where, in order to reach the real absolute ma…

A Geometrical Simple Approach for Power Silicon Devices Fault Detection and Fault-Tolerant Operation of a Voltage Source Inverter

Fault-tolerant converters have been widely investigated for years and nowadays an extensive technical literature on this field exists. This paper presents a novel fault detection algorithm based on a simple geometrical approach. In the algorithm analysis both the case of faults in single device and the lose of an entire inverter leg have been considered. False positive detections are avoided by considering a proper number of current samples. The proposed fault detection algorithm is characterized by simplicity, low computational and implementation effort with a consequent enough fast execution, easy control integration with the possibility to use it both in hardware in the loop systems and …

Development of Diagnostic Systems for the Fault Tolerant Operation of Micro-Grids

The progressive penetration level of Distributed Generation (DG) is destined to cause deep changes in the existing distribution networks no longer considered as passive terminations of the whole electrical system. A possible solution is the realization of small networks, namely the Micro-Grids, reproducing in themselves the structure of the main production and distribution of the electrical energy system. In order to gain an adequate reliability level of the micro-grids the individuation and the management of the faults with the goal of maintaining the micro-grid operation (fault tolerant operation) is quite important. In the present paper after the introduction of the aims of several diagn…

Optimal Integration of Hybrid Supercapacitor and IPT System for a Free-Catenary Tramway

The aim of the paper is the study of an optimal integration of a supercapacitor-based storage system and inductive power transfer system for the free-catenary operation of a tramway. Starting from the definition of the topology of inductive power transfer system, we propose and analyze a design procedure for the pads of the inductive power system. In the second part of the paper, an optimal integration strategy for the correct size of on-board supercapacitors and the power of the inductive energy transfer are proposed. The results obtained by means of numerical simulations are discussed. © 2018 IEEE.

Back EMF Sensorless-Control Algorithm for High-Dynamic Performance PMSM

In this paper, a low-time-consuming and low-cost sensorless-control algorithm for high-dynamic performance permanent-magnet synchronous motors, both surface and internal permanent-magnet mounted for position and speed estimation, is introduced, discussed, and experimentally validated. This control algorithm is based on the estimation of rotor speed and angular position starting from the back electromotive force space-vector determination without voltage sensors by using the reference voltages given by the current controllers instead of the actual ones. This choice obviously introduces some errors that must be vanished by means of a compensating function. The novelties of the proposed estima…

A reexamination of voltage distortion for classical carrier-based vs B-Spline modulation of three-phase Voltage Sources Inverters

Voltage waveform improvement has been the object of several investigations for many years and a manifold of different solutions have been proposed to reduce the harmonic content in Voltage Source Inverters (VSI) power application. In many cases this improvements have been obtained by modifying the reference voltage modulating signal. The recent introduction of cardinal B-spline functions, used as carrier signals, has given rise to a new modulation technique whose main characteristic is a lower value of the Total Harmonic Distortion (THD). After the discussion on the B-Spline modulation principle and on its computational effort, a performance comparisons is carried out by means of Total Harm…

Assisted software design of a wide variety of windings in rotating electrical machinery

In this paper a software developed by the Authors for winding design is presented. In particular, this software can be used as a valid aid in design and analysis for a wide variety of windings with generic number of phases, pole pairs, slot number, etc.. The calculation of winding factors and the evaluation of their harmonic distribution is also accomplished. The software is implemented in MATLAB® environment. By means of some examples, covering the most relevant winding types, the capabilities of this software will be shown. Particularly, integer and fractional slot, single and double layer winding, concentrated windings, imbrication, belt widening and belt shifting techniques can be treat…

Experimental validation of a general model for three phase inverters operating in healthy and faulty modes

The paper presents the experimental verification of a general mathematical model of Voltage Source Inverters (VSI) able to simulate fault conditions and which is also useful for the simulation of fault-tolerant systems for different applications. In general, in the past, the problem of faulty inverters modeling has been addressed specifically by considering faults on the different phases as separate cases. Furthermore, traditional models include only the faulty mode and not the healthy mode, so resulting then not able to predict transient phenomena. The model hereafter presented overcomes this drawback. It was formulated by introducing the concept of “healthy leg binary variables”. Such var…

Reliability Analysis of Three Homogeneous Fault-tolerant Inverter Topologies

Abstract—In this article, non-redundant fault-tolerant inverter topologies are addressed. A novel fault-tolerant control strategy which enhances performances during post-fault operation is proposed. Benefits from the proposed strategy over conventional fault-tolerant topologies are investigated in terms of system reliability. Cost, post-fault performances, and system reliability of the proposed solution are compared with both a conventional triac-based fault-tolerant inverter and a T-type inverter. The reliability analysis of each selected configuration is carried out by means of Markov chains. The analysis is validated through a comparison of reliability and sensitivity curves. As shown by…

Speed Control of a two-Degrees of Freedom Induction Motor with Rotor Helical Motion for Industrial Applications

This paper describes the realization of a two-degrees of freedom induction motor prototype with rotor helical motion, suitable for several industrial applications as grinders, augers, drilling and milling spindles, robotic arms and drives for medical tools and prostheses. This prototype was realized by combining a three-phase tubular linear induction motor (TLIM) with the stator of a three-phase rotary induction motor, resulting in a THMIM (Tubular Helical Motion Induction Motor). Moreover, a possible simple electrical drive, capable to control the helical motion, is proposed, simulated and analyzed. In particular, the mathematical model of the THMIM has been initially developed and, then, …

Controlled Fault-Tolerant Power Converters for Power Quality Enhancement

Power quality depends generally on the interaction of electrical power with electrical equipments. If electrical equipments operate correctly and reliably without being damaged or stressed, a suitable level of power quality is assured. On the other hand, if the electrical equipment malfunctions, is unreliable, or is damaged during normal usage, power quality is poor and probably the economical loss could be important like the technical one. In the scenario of the Distributed Generation, power quality issues will be moreover important because an higher dissemination of power conditioning equipment will be requested and this obviously increases the sources of vulnerability of the electrical s…

Simulation of a single-phase five-level cascaded H-Bridge inverter with multicarrier SPWM B-Spline based modulation techniques

Multilevel Power Inverters are now often used to convert DC to AC voltage waveform. This kind of converter allows high power quality with low output harmonics and lower commutation losses with respect to the traditional ones in order to optimize this aspect. This paper presents a novel simulation analysis of the Multicarrier Sinusoidal Pulse Width Modulation (MC SPWM) techniques B-Spline functions based to control the switches of five-level single-phase cascaded H-bridge inverter. In order to verify the performance of the converter, the harmonic content of the voltage due to modulation techniques has been taken into account. Results highlight the comparison between different B-Spline functi…

Optimal Integration of Hybrid Supercapacitor and IPT system for a Free Catenary Tramway

The aim of the presented paper is the study of an optimal integration of Supercapacitor based storage system and Inductive Power Transfer system for the free-catenary operation of a tramway. The paper starts from the definition of the Inductive Power transfer pad system and proposed an optimal integration strategy for the correct size of on-board supercapacitors and the inductive energy transfer.

Experimental characterization of a wind generator prototype for sustainable small wind farms

This paper presents the experimental characterization of a wind turbine prototype used for micro wind farms. The proposed prototype, whose advantages can be summarized in versatility of application, low noise and compactness, can generate 1 kW of rated power for a wind speed equal to 4 m/s. The tests here reported and carried out by means of an experimental test bench confirm that the prototype is well designed and adequate for the purpose of its application.

Generalized PWM-VSI Control Algorithm Based on a Universal Duty-Cycle Expression: Theoretical Analysis, Simulation Results, and Experimental Validations

This paper presents a new approach in realizing various carrier-based pulsewidth-modulation techniques by a generalized control algorithm, which is referred to as the universal control algorithm and is obtained via unequal sharing of null states. The flexibility of such an approach allows one to easily and quickly control two-level inverters. Furthermore, this approach may be also extended with few changes to the control of multilevel inverters. The algorithm that is presented here for two-level voltage-source inverters (VSIs) also obtains efficient detection and management of both the linear and overmodulation ranges. In the overmodulation range, which is treated by using the alpha-beta co…

Controllo innovativo sensorless per motori sincroni a magneti permanenti