1,720,993 research outputs found
Smart LiFePO4 battery modules in a fast charge application for local public transportation
No full textThis paper describes the research effort jointly carried out by the University of Pisa and ENEA on electrochemical energy storage systems based on Lithium-ion batteries, particularly the Lithium-Iron-Phosphate cells. In more detail, the paper first illustrates the design and experimental characterization of a family of 12 V modules, each of them provided with an electronic management system, to be used for electric traction. Then, the sizing of the energy storage system for an electric bus providing a service with 'fast and frequent' charge phases is described. © 2014 AEIT
Implementation of the fast charging concept for electric local public transport: The case-study of a minibus
No full textThis paper shows an effective implementation of the fast charging concept in the electric local public transport context. An electric minibus powered with a lead-acid battery is considered as a case-study. Its traction battery is redesigned using 12 V standard lithium-iron-phosphate modules to benefit from the higher performance of the lithium battery technology compared to the lead-acid one. The minibus can achieve a continuous operation characterised by 20 min of traveling alternated with 10 min of standstill for fast recharging of the battery. Experiments performed on a single module of the battery show that the load profile is sustained without appreciable issues both in temperature and life degradation of the lithium cells. © 2015 IEEE
Design and prototyping of a rapid-charge electric bus for urban passenger transportation
No full textCollective transport means must obviously be designed and used to minimize their environmental impact. The way to reach this aim, however, is certainly not obvious, since it must consider a number of aspects connected both with the fulfilment of users' expectations in terms of number and frequency of vehicle stops, and with the energetic and economic balances of the service offered. Taking the lead from these consideration, one of the authors previously developed a easy-to-use tool for the energetic assessment of alternative transport means to be used on a given route. Here, this tool is put in use by the authors for the design and prototyping of a rapid-charge electric bus for urban passenger transportation, within a close cooperation with an Italian Transportation Authority
Design of the battery management system of LiFePO4 batteries for electric off-road vehicles
No full textThis paper describes the design of a modular battery management system for electric off-road vehicles, where lithiumion batteries are expected to be widely used. A massive electrification of off-road vehicles can be enabled by the availability of a standard battery module, provided with an effective management unit. The design and some preliminary experimental results of the module management unit are discussed in this paper. The unit contains a high current active equalizer that enables the dynamic charge equalization among cells and maximizes the usable capacity of the battery. © 2013 IEEE
Electrification of off-road vehicles: Examining the feasibility for the Italian market
No full textThe study, made by ENEA in cooperation with the University of Pisa as part of the activities supported by the Italian Ministry of Economic Development in the framework of the Program Agreement for the Research on the Electric System, is related to the situation of Italian market and demonstrates the feasibility of the electrification for off-road vehicles and the possibility to realize it by the means of standard modules. The preliminary dimensioning of the standard modules is also reported, defining the main electric characteristics (voltage and capacity) and the type of chemistry: LiFePO4 is proved to be a very effective solution for this kind of application. The activity goes on towards the final design and the realization of demonstrator units. © 2012 WEVA
Fast charge life cycle test on a lithium-ion battery module
No full textThe paper analyzes the effects of fast charge on a lithium-ion battery module made by 4 lithium-iron-phosphate cells series connected, submitted to a test profile which includes a fast charge step at current rate 3C. This test profile simulates the real working profile requested to the batteries of a electric bus to perform a particular service of local public transportation with recharge of the batteries at the end of line. More than 3,000 shallow cycles were performed: the battery module did not show a significant reduction of performances in terms of capacity and energy, but, on the other side, a relevant increase of the inner resistance was observed. As an effect of this, the autonomy of the electric bus is reduced correspondingly. Fixing a minimum value for the autonomy, a life estimate of the battery module was made. Finally, on the base of this result, a cost estimate and comparison between slow and fast charge was made, under the same service conditions and all through the vehicle life, for a real case of a minibus equipped with a battery system sized for fast charge at the end of line and a larger battery system sized for slow charge at the end of a working day. This comparison proved that, in the case study considered, the solution with fast charge is cheaper and the fast charge can be a valid instrument to solve the problem of short autonomy of electric vehicles. © 2017 MOBI -Mobility, Logistics and Automotive Technology Research Centre
Life cycles test on a lithium battery system
No full textThe topic of the paper is the life cycles test on a lithium battery system 288 V-40 Ah, 11,5 kWh. The test procedure tries to simulate the typical utilization of an electric vehicle: the batteries are discharged by means of a typical profile in urban and suburban context and charged by means of traditional charges and fast charges alternatively. In this way it is possible to simulate the utilization of a driver who uses the electric vehicle and charges the batteries at home (traditional charge) or at a public charging point (quick charge). These tests permit to identify and understand possible problems of the storage system under quick charge and discharge cycles, as well as to define how the performances decrease during the operation. The paper shows the details of the battery system under test, the complete test procedure and the results in terms of reduction of the global performances (life determination as number of cycles) and behavior of the single cells (unbalancing). © 2014 IEEE
Experimental performances and life cycle estimation of hybrid electric storage systems
No full textThe reliability of electrical energy storage systems, related to the various mobile applications, needs to be carefully measured. The Italian research centre ENEA's "Low Environmental Impact Vehicles" Laboratory has started experimental testing activities on storage systems, as illustrated here with reference to acid batteries reliability performances. In this paper, starting from the results of the campaign of laboratory tests, a probabilistic method for describing the distributions of battery lifetime is presented. The approach is based upon the Rakhmatov and Virudhula battery model. In the final part of the paper, numerical tests show that the battery expected lifetime can be well described by models, such as the Inverse Weibull or the Lognormal, with decreasing hazard rate for large mission times, a fact which has been sometimes observed in literature as a paradox. Some considerations with respect to parameter estimation of the reliability models close the paper. © 2013 IEEE
Experimental analysis of an electric minibus with small battery and fast charge policy
No full textThe lead-acid battery of an electric minibus has been replaced with a smaller size lithium-ion battery system consisting of standard 12 V modules and a hierarchical battery management system. The minibus has experimentally been tested to show that the reduced battery capacity, which also cuts costs, does not affect the daily operational mission. This is assuming that the driving phases are alternated with fast charging periods. Experiments show that fast charging of 8 min guarantees up to 1 h of operation. © 2016 IEEE
A flexible Customer Power Device for energy management in a real Smart Micro-Grid
No full textIn the present paper an overview on Customer Power Devices (CPDs) for application in Smart Micro-Grid (MG) is reported. A particular attention is given to a real CPD equipped with an Energy Storage System, consisting in Lithium batteries, able to perform also functions of Distribution Static Compensators (D-STATCOM). Its typical layout, its main components and its possible functions are reported. A special focus is on its control modes and strategies for the energy management in a Smart MG and on its Battery Management System (BMS). The main figures of a real Smart MG, where the CDP is located, for active and reactive power service, are finally reported. © 2013 IEEE
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