1,720,970 research outputs found
Analysis of the lithium-ion batteries resistance hysteresis phenomenon
No full textIn recent years, lithium-ion batteries are broadly employed in a lot of different applications. In both high-power and high-energy applications, the onboard estimation of the internal parameters, such as capacity and internal resistance, is of paramount importance. In particular, the battery internal resistance limits the power that the battery can deliver affecting, also, the overall efficiency. The battery resistance changes under different conditions such as temperature, state of charge, and aging. In the literature, these dependencies have widely been analyzed and it has also been studied that the battery shows a different resistance during charge and discharge phases. Nevertheless, there is no evidence in the technical literature of the analysis of a hysteresis phenomenon interesting the battery resistance. The experimental campaign performed by the authors and reported in this paper shows, for the first time, that the lithium-ion battery resistance is affected by a hysteresis phenomenon as it happens to the open circuit voltage. Moreover, in this paper, the effect of the temperature on the battery resistance hysteresis is analyzed too
Sizing and Energy Management Strategy of a Hybrid Energy Storage System for EVs
No full textNowadays, hybrid and full-electric vehicles are promising solutions to reduce carbon emissions related to mobility. In this scenario, hybrid energy storage systems are under analysis, and continuous efforts are being made to cope with sizing and managing different sources to improve efficiency and increase sources lifetime. In the context of the IEEE VTS Challenge 2022, this paper proposes the storage system sizing and the energy management strategy for a vehicle powered by batteries and supercapacitors
Energy management strategy for a fuel cell/lead acid battery/ ultracapacitor hybrid electric vehicle
No full textHybrid electric vehicles are considered to be the future of the mobility, in particular fuel cell hybrid electric vehicles are believed to be a promising solution. As for every hybrid system, a good energy management strategy is fundamental to improve the efficiency and preserve the sources. This paper presents a new, simple energy management strategy, developed for the IEEE VTS Motor Challenge 2020, an international contest focused on the energy management of a fuel cell/ lead acid battery/ ultracapacitor electric vehicle
Aging effect on lithium-ion battery resistance hysteresis
Full text linkIn recent years, lithium-ion batteries have been broadly employed in many different applications that require high energy and power density. In both static and mobile applications, the onboard estimation of internal parameters such as the capacity and internal resistance is of paramount importance. In particular, the internal resistance of a battery limits the power it can deliver and affects the overall efficiency. The battery resistance changes under different conditions, such as temperature, state of charge, and aging. In addition, a hysteresis resistance phenomenon was discovered and analyzed for different temperatures in a previous work. Indeed, the internal resistance of a battery changes based on the charging or discharging phase for a fixed state of charge and temperature. In the present work, the hysteresis phenomenon was deeply analyzed, even considering the cycle aging of the battery. To do this, several tests were performed using the electrochemical impedance spectroscopy method. Finally, a mathematical model capable of predicting how the hysteresis changes as a function of aging, for a fixed state of charge and temperature, was proposed
Automated test equipment for battery characterization: a proposal
No full textThe fast pace of innovation in the field of lithium-ion batteries and changing battery chemistry has resulted in significant scientific research in the development of battery models. Considerable emphasis is placed on battery state of health estimation and rest of useful life predictions. Tackling these challenges requires large datasets of aged batteries currently obtained using very expensive test setups. Furthermore, as the number of manufacturers increases, such setups are necessary for the validation and comparison of competing cells. This paper presents an economical, automated battery testing system, capable of aging batteries of different sizes. Moreover, it enables users to programmatically define various testing cycles. Its capabilities and performances are proven by aging 8 Li-ion cells under different state of charge and voltage limits
MMC-PV System with dc-link integrated battery energy storage system
No full textRenewable energy sources, such as photovoltaic (PV) panels, are spreading day by day. Nevertheless, their intermittent and uncertain generation can be an issue for the connection in the electrical grid or for self-consumption. In order to face these problems, battery energy storage systems (BESSs) are used to store the energy in excess and deliver it when required. With and without the integration of BESSs, many solutions to interface PV panels to the grid are analyzed and proposed in the literature. Focusing on the PV power extraction, several maximum power point trackers have been analyzed, also facing the issue related to the partial shading conditions. In fact, the latter can cause inefficiency in maximizing the power extraction when many PV panels are subjected to different irradiations. Modular multilevel converters (MMCs) are recently used even in low voltage systems for their intrinsic advantages. In particular, PV panels and BESSs can be integrated into the MMC at either the submodule level or the dc-link of the MMC itself. Taking the advantages of both kinds of connection, in the present paper, a three-phase MMC with PV panels integrated into its submodules and a battery pack connected to its dc-link is proposed and analyzed
Cost and efficiency analysis of different powertrain architectures for fuel cell electric vehicles
No full textFuel Cell Electric Vehicles are becoming more and more important for the future of mobility, in particular for long trips. The efficiency and the performances of the vehicles are fundamental for the development of this technology. In this paper, three fuel cell vehicles electrical architectures are compared in terms of efficiency, performances and costs. The three analysed architectures differ for the number and position of dc/dc converters used to connect battery and fuel cell to the dc bus. To perform the comparison, powertrain components of the three vehicles have been properly sized, a model has been built in Simulink and the worldwide harmonized light vehicle test procedure cycle has been used as a reference cycle for the simulations. The developed model is then used to compare the same architecture for three different dc bus voltages
Cycle Aging Effect on the Open Circuit Voltage of Lithium-Ion Battery
No full textNowadays, the issues concerning green mobility and energy production are leading researchers to study novel energy storage systems. Among them, lithiumion batteries are currently one of the most popular technologies under study. Battery modeling and parameter estimation are important challenges to build reliable battery management systems able to allow the battery to work in proper conditions. State of charge (SOC) estimation is one of the most important for predicting the current battery available energy. Many methods to estimate the SOC need knowledge of the open circuit voltage (OCV) curve. In the literature, it is possible to find a lot of OCV models as a function of SOC. Another important aspect is how these curves change as a function of battery degradation. Some studies deal with the correction of the OCV-SOC curve considering the aging, but the dependency of the OCV curve as a function of the exchanged absolute charge on aging seems to be lacking. In the present work, a simple model of the OCV-charge curve that considers the cycle aging is proposed and analyzed. An experimental campaign was carried out to validate the proposed model
Influence of Battery Aging on Converter Switching Device Degradation
No full textIn this work, a methodology to examine the influence of battery degradation on the converter semiconductor switching devices is presented. A PV-battery case study is used to demonstrate the methodology and show possible results. Initially, the results indicate a very limited influence of the battery on converter lifetime of 1 %. This is due to counteracting effects during battery degradation, which both decreases the power flow through the converter but increases the losses. A second simulation with constant power flow, isolating the effect of the reduced energy flow, showed an 9 % converter lifetime decrease using a degrading battery, demonstrating the underlying effect. The paper shows the battery model, converter model and case study results including battery degradation profiles, converter losses and reliability distributions
Integrated Electro-Thermal Model for Li-Ion Battery Packs
Full text linkLithium-ion battery is considered one of the most attractive energy storage systems for electric vehicles. However, one of its main drawbacks is the sensitivity to temperature. In a battery pack composed of lithium-ion batteries, during the charge/discharge operations, the temperature gradually increases, especially in the batteries positioned in the central part of the battery pack. This leads the central batteries to age faster and exposes them to the risk of a thermal runaway. In order to mitigate these problems, thermal management systems are needed. However, for the implementation of the control, it is important to know the temperature distribution inside the whole pack. In this paper, an integrated electro-thermal model capable of estimating the thermal behavior of each battery cell, composing the battery pack, only knowing the total current and ambient temperature, is proposed and analyzed. The proposed model was tuned and validated by means of experimental results. The circuital approach used in this model gives good results with a low degree of complexity
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