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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.

Lithium-ion batteries are often operated to reach excellence in technical and economical performance, but they rapidly degrade as a consequence of charge/discharge profiles. Maintaining the knowledge of the actual capacity of the battery is mandatory to pursue the objectives without incurring into unexpected constraints. This paper addresses battery prognostic from the viewpoint of probabilistic prediction of the State of Health (SoH) and of the Remaining Useful Life (RUL) of the batteries. Two probabilistic models based on time series and quantile regression, each developed in a different framework, are developed and compared for this purpose. They are specifically suited up to exploit data coming from Accelerated Degradation Tests (ADTs). Moreover, a dedicated procedure to extract a single, point value from the probabilistic predictions is presented to let the models work also in deterministic scenarios. Numerical experiments conducted on actual public data confirm the validity of the proposal, within a rigorous comparison with relevant benchmarks taken from the literature on the topic.

The transport system, a primary factor in the human activity, plays a major role in the context of the use of electricity, on environmental impact and on the social health. The Electric Mobility, in compliance with the EU Mandate, can bring a contribution to the transport system with user friendly means and solutions, reducing the negative effects in these areas. Considering that the use of electric energy has a beneficial effect in the transfer chain Well To Wheel, it appears worthy to consider means and ways to increase as much as possible the operation capability of the electric vehicles by getting involved a reduced electricity quantity. This objective requires the study of the system vehicle - power supply for identifying the ways and tools to transfer power grid to vehicle with simple and effective user friendly operation. The key points to be considered are the strategic positioning of the charging points, the appropriate coordination and govern of the mobility, the communication with the user and the technology for connection to the grid. An ultimate effect of structuring this system can be the possibility of rivisitation of the battery design, which could be reduced, with consequent benefits in weight, volume, cost, energy use and pollution during manufacturing and recycling. Various EU Projects deal with this matter, among which the Project FABRIC considers the feasibility for transferring power by magnetic field from electric infrastructure to the vehicle in motion, including the possible application, in interoperable way. with static, quasi dynamic and dynamic mode. The implementation and the effective operation of the system requires the Information and Communication Technology support for the interaction E-Mobility Center - User and the standardization at the international level of the requirements for the definition, production and application of the different elements and actors. The system Electric Vehicle - Grid infrastructure- Use definition and management is the object of a harmonized bulk of Standards, IEC, ISO, SAE, UL, to assure an effective utilization of the system for the benefit of the User and for the rational utilization of the energy.

In this study, the design optimisation of a synchronous reluctance machine for light electric vehicles is proposed, to increase efficiency and reduce torque ripples. The existing machine was structurally optimised, using dedicated genetic algorithms, replacing only the rotor and keeping the stator and it's winding untouched. Starting from the original design of the rotor implemented in Flux2D, a finite element analysis software, and the genetic algorithm optimisation implemented in Matlab, a complex co-simulation was accomplished to obtain a rotor architecture that increases the machine's performances and decreases the torque ripples. By this, performing rotor skewing is not needed any more, hence the torque loss due to it was cancelled. The optimised rotor design increases the machine performances by higher mean torque, no skewing

The aim of this study is to present a new, accurate, and user-friendly software procedure for the analysis and rapid design of rotating induction machine windings, considering both the electric and the magnetic specifications of the machine itself. This procedure is a valid aid for quick first stage design without the necessity of using finite element method (FEM)-based design procedures. FEM can be used in a second design phase in order to refine the first stage results. The design procedure is hereafter outlined and some examples show its capability.

Historically, asymmetrical windings in electrical machines have been rarely used and only for specified needs, because the adoption of symmetrical configurations has always been considered the only solution during the design stage of electrical machines. The aim of this work is to demonstrate with several examples that the use of slightly asymmetrical windings can be a reasonable choice and, in certain cases, a favorable option during the machine design stage, allowing the possibility of selecting a wider range of slot/pole number combinations, without affecting the performances of the machines. More in detail, an interior permanent magnet synchronous machine equipped with a symmetrical 3-phase winding has been considered as a reference structure. Then, this geometry has been adequately modified in other 3 models to equip asymmetrical windings on each of the modified structures. Afterwards, the performances have been compared in generated torque, magnetic forces, magnetomotive force harmonic content, cogging torque, and iron core losses. This comparison has led to promising results, obtaining in some cases even a reduction of power losses, cogging torque, and harmonic content.

The growing interest in the use of energy storage systems to improve the performance of tramways has prompted the development of control techniques and optimal storage devices, displacement, and sizing to obtain the maximum profit and reduce the total installation cost. Recently, the rapid diffusion of renewable energy generation from photovoltaic panels has also created a large interest in coupling renewable energy and storage units. This study analyzed the integration of a photovoltaic power plant, supercapacitor energy storage system, and railway power system. Random optimization was used to verify the feasibility of this integration in a real tramway electric system operating in the city of Naples, and the benefits and total cost of this integration were evaluated.

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.

Recently, there has been a growing interest in reducing the number or replacing the hydraulic/pneumatic actuators utilised on aircraft with electric actuators coupled to mechanical gears, which would improve the reliability and performance. This is involved in the concept of more electric aircraft. The electrification of actuators would affect the primary and secondary flight controls, as well as the movement of flight surfaces, retraction of the landing gear, and steering of the nose landing gear, which is also considered in this study. This study considers the design of a multiphase permanent-magnet (PM) motor to be utilised for the electric steering of a commercial aircraft nose landing gear. This multiphase motor would make it possible to achieve a highly reliable actuator and, coupled with a harmonic drive, avoid the use of a multi-motor configuration. Moreover, a multiphase motor would increase the power density and efficiency of the actuator, through improving the torque ripple. The performance variation due to temperature swings is considered, and a design procedure for the PM motor is described using the worse operation case for the electric actuator. The adequate performance of the designed motor and actuator is demonstrated by means of a finite element analysis.

This paper presents a DC side oriented diagnostic method for photovoltaic fields which operates on string currents previously supplied by an appropriate monitoring system. The relevance of the work relies on the definition of an effective and reliable day-by-day target for the power that every string of the field should have produced. The procedure is carried out by comparing the instantaneous power produced by all solar strings having the same orientation and by attributing, as producible power for all of them, the maximum value. As figure of merit, the difference between the maximum allowed energy production (evaluated as the integral of the power during a defined time interval) and the energy actually produced by the strings is defined. Such a definition accounts for both weather and irradiance conditions, without needing additional sensors. The reliability of the approach was experimentally verified by analyzing the performance of two medium size solar fields that were monitored over a period of four years. Results allowed quantifying energy losses attributable to underperforming solar strings and precisely locating their position in the field.

The ability to forecast the production of power by photovoltaic(PV) systems accurately and reliably is of major importance for the appropriate management of future electrical distribution systems. Several forecasting methods have been proposed in the relevant literature, and many indices have been used to quantify the quality of the forecasts. The methods can provide either deterministic or probabilistic forecasts; the latter seem to be the most appropriate to take into account the unavoidable uncertainties of PV power production. Similarly, indices were used to quantify the quality of both deterministic and probabilistic forecasting methods, but they usually do not account for the economic consequences of forecasting errors. In this paper, two advanced probabilistic forecasting approaches based on the Bayesian inference method are applied to the short-term forecasting of PV power production. Moreover, new probabilistic indices were proposed with the aim of comparing the probabilistic forecasting methods in such way that the value of the forecast is not included only by the users in their decision-making process; instead, it is partially anticipated by the forecasters in their quality-assessment process. Numerical applications also are presented to provide evidence of the performances of the Bayesian-based approaches and the probabilistic indices that were considered.

The paper deals with problems in distributed generation using synchronous machines equipped with squirrel cage for line starting. These machines need suitable control systems necessary to avoid damages during transients occurring when a network fault happens. The main characteristics of the behavior of controlled synchronous machines during synchronizing phenomena are analyzed and compared with those of asynchronous machines. Analytical models of the two generation systems based on the two machines have been carried out and results of numerical simulation are reported.

The paper deals with anisotropic PM brushless motors used in railways traction drives. A control algorithm is presented for optimizing performances in a wide speed range. Starting from the assigned torque-speed traction characteristic and taking into account the limit values of armature current and voltage and of air-gap flux magnitude, the expressions of reference values for the current control are found in the different operating regions. Particular attention is devoted to the flux weakening region and to conditions to avoid saturated operations. In order to show the validity of the proposed control algorithm numerical investigation are carried out with reference to some significant operations of a real light-rail traction drive.

Squirrel cage induction machines represent a common solution widely adopted in wind generation. The induction machine is simple, reliable, cheap and requires very little maintenance. Some problems are, however, connected with the use of induction machines in wind power generation systems. In particular two effects have to be taken into account: the torque fluctuations at the generator shaft and the critical clearing time (CCT). Both problems represent a serious limitation for weak networks in which the first effect can cause flicker effect while the CCT is very short. In the paper a full modelling of a wind energy plant constituted by n machines is presented. Using the set-up model the behaviour of the plant for a different number of connected machines is analysed. In particular, the system stability connected with voltage sags and network faults is studied.

The paper presents a direct torque control DTC for induction motor drive using a 3-level NPC inverter. The control is optimized for torque oscillation reduction. The control is described evidencing the good performance validated by means of simulation. The results are reported and discussed in the paper.

Traditionally two different algorithms are used for the estimation of angular velocity with an incremental encoder. At steady state, both of them ensure good performances only in a restricted range of velocity. In the paper an innovative hybrid algorithm specifically conceived for digital control system is proposed. The algorithm is quite easy to implement and guarantees a reduced relative error in a wide range of velocity variation. The algorithm is analyzed with an analytical approach and the results are confirmed by numerical simulations. Since in dynamic conditions the error in the measurement of the angular velocity with an encoder is strictly connected with the observation time, a correct method for the dimensioning of the observation time is discussed. The method can be combined with the preceding algorithm to obtain adaptive capabilities.

The paper deals with the problem of velocity estimation of rotating machines with the use of an incremental encoder. Working conditions both at steady state or in dynamic operations have been studied. An innovative algorithm for the measurement of velocity has been proposed and compared with classical algorithms. Implementations of the estimation method proposed by authors have been made by means of numerical simulations either at steady state or in dynamic operations. The results achieved in terms of measure precision and dynamic response are very satisfactory, as shown in the paper.

The problem of the estimation of rotating speed is a very important problem, especially for systems that works with high dynamics. Actually the most common way to measure velocity is to use an incremental encoder. However the precision of the velocity estimation is yet a not completely solved problem. Typically, it is possible to increase the accuracy of the measure increasing the observation time, but during dynamic phenomena this could be dangerous for the efficiency and the stability of the control of the system. In the paper authors have proposed an innovative algorithm for the estimation of velocity starting from the output signal of an incremental encoder. The algorithm proposed can be used either at steady state or in dynamic conditions because it has a self-adjustable observation time in function of velocity and acceleration of the system. The algorithm has been tested in laboratory and experimental results have been reported in the paper.

Nowadays there is an increasing interest in road vehicles with no emissions, with special application to urban transport systems, either public or private. In this scenario, electric vehicles equipped with fuel cell systems are being more developed. Despite this, the state of the art in fuel cells manufacturing presents some operative problems not solved in using fuel cells. Because of these problems there is the necessity to use either an electronic device at the output of the fuel cells or an auxiliary power device. A power plant for electric road vehicles, equipped with fuel cells, is considered. The optimal configuration of the system, by using batteries as auxiliary energy source, has been analyzed. The whole system has been dimensioned for a particular application and has been modeled for the implementation of numerical simulation. An integrated control strategy is proposed to manage all the components of the system to obtain a voltage control and the regulation of the load network. The proposed control strategy is implemented in simulation and the results are discussed considering the system response to power load request. Moreover, by using components of industrial production, an easy and cheap solution of the problem of voltage drop on the AC network is defined.

A three level NPC-rectifier versus three level NPC-inverter with direct torque controlled asynchronous motor is examined. Three level inverters have the problem of the DC-link voltage balance, especially if DTC control is considered. To reduce the problem both DC voltage and the potential of its middle point are controlled through a three level V.S.R. An appropriate feedback control is proposed to make the V.S.R. able to impose in the network nearly sinusoidal currents with unity power factor. The proposed control scheme is verified by means of simulations under significant conditions; the results are presented and discussed.

The skidding phenomenon in railway traction is analysed, a procedure for indirect identification of friction force is proposed and the results obtained from the procedure are experimentally validated. Validation is achieved through testing of a scale model of a E402 locomotive. The scale model is presented. The derivative of friction force with respect to time can be assumed as a parameter to deduce skidding, but is insufficient to realise anti-skidding control. The purpose of the control is both to keep the force between wheel and rail near the maximum of adhesion and to prevent slip-stick oscillation. To optimise a classical scalar or vector control algorithm for drive traction system, it is necessary to study the nature of the load. In this paper the load is investigated through the interaction between torsional oscillation of all components of motion, mechanical transmission and the friction force during the skidding phenomena. Technical improvements on the model are proposed to reproduce the same natural oscillation frequencies of different shafts of a real drive traction system in order to get results useable in control optimisation.