121 research outputs found
Heavy-duty hybrid transportation systems: Design, modeling, and energy management
No full textThis chapter is centered on the design, modeling and energy management of heavy-duty transportation systems. After showing general definitions and conventions, the problem of energy management is addressed with reference to heuristic approaches and global optimization control techniques. After presenting the problem in the most general formulation, a detailed case study is shown, related to the design of a working machine typically used in construction site. The main steps are modeling of the conventional hydraulic working machine, identification of an electrified hybrid architecture, selection of a heuristic energy management strategy to be implemented online, verification and comparison with respect to offline optimal control solution, in order to have a benchmark with the selected strategy
Integration of small-scale power systems
No full textElectrochemical storage systems are increasingly being considered today. This chapter focuses attention on the different lithium typologies available today, from the cell characteristics to the composition of the battery packs. As main characteristics, charging techniques and life issues have been addressed, also by defining indicators currently used. Lithium solutions have been presented also by distinguishing between energy-oriented and power-oriented typologies. Also, other kinds of power-oriented technologies have been presented, in particular, supercapacitors and flywheels. A significant part is dedicated to numerical modeling, in order to identify equivalent electrical networks for the electrochemical cell/battery. Finally, battery selection criteria are provided to the reader, in order to properly size the storage system for the considered application
Use of Modelica language to simulate electrified railway lines and trains
No full textSimulation of multi-engineering systems typically requires many issues to be solved, which are to be addressed by developing appropriate modeling and simulation programming techniques. In the last years, the authors have participated in several studies in which they analyzed in detail electrified railway systems and simulated them using Modelica language. After a few years of study, despite the huge complexity of these systems, it has appeared evident that Modelica language is very well suited and able to effectively solve the typical issues they present. While specific railway system simulations have already been discussed in specific papers, whose focus was on application and actual results, in this paper, the authors show how to use Modelica language to solve specific modeling issues through suitable programming techniques. Moreover, the issues to be solved and the conceived techniques may be interpreted in a general way and to be applied also in different engineering domains. Finally, this paper briefly recalls the principal results obtained in previous specific papers, in which these techniques were fully implemented
Cycle life evaluation of lithium cells subjected to micro-cycles
No full textThe typical operating condition of storage batteries requires to deliver and absorb small currents in large intervals of time, in order of minutes or hours. However, in the last years lithium batteries are more and more considered in “power oriented” applications in which they are required to manage large currents in short intervals of time, typically few seconds or tens of seconds. Unfortunately, very limited information on the cell life on this kind of usage are available in literature. Indeed, the paper is focused on the evaluation of the aging process for high power lithium batteries subjected to shallow-depth charge/discharge cycles. The aim is to evaluate if the battery life corresponding to such micro-cycles can reach several hundreds of thousands, allowing the hypothesis that battery performance is effectively much better than expected by the analysis of manufacturer data
High Power Lithium Batteries Usage in Hybrid Vehicles
No full textHybrid vehicles require an energy storage device capable
of delivering or absorbing high specific powers (powers per unit of the device size), and still, in some cases, adequate levels of
specific energy.
The paper shows that high power Lithium Batteries already on
the market are able to fulfil this task satisfactorily, by means of
experimental tests, whose results are shown and discussed.
The results show that very high power lithium batteries can be
used in hybrid vehicles as the sole energy storage device, thus avoiding the complexity of composite (e.g. battery plus supercapacitor)
storage systems
Renewable Electricity for Decarbonisation of Road Transport: Batteries or E-Fuels?
No full textRoad transport is one of the most energy-consuming and greenhouse gas (GHG) emitting sectors. Progressive decarbonisation of electricity generation could support the ambitious target of road vehicle climate neutrality in two different ways: direct electrification with onboard electrochemical storage or a change of energy vector with e-fuels. The most promising, state-of-the-art electrochemical storages for road transport have been analysed considering current and future technologies (the most promising ones) whose use is assumed to occur within the next 10–15 years. Different e-fuels (e-hydrogen, e-methanol, e-diesel, e-ammonia, E-DME, and e-methane) and their production pathways have been reviewed and compared in terms of energy density, synthesis efficiency, and technology readiness level. A final energetic comparison between electrochemical storages and e-fuels has been carried out considering different powertrain architectures, highlighting the huge difference in efficiency for these competing solutions. E-fuels require 3–5 times more input energy and cause 3–5 times higher equivalent vehicle CO2 emissions if the electricity is not entirely decarbonised
Modelling and simulation of EV high-power recharging pools with stationary storage
No full textHigh-power recharging pools are going to be widely deployed on the highways to guarantee a fast recharge for electric vehicles. These infrastructures may ask the grid for significant levels of power, which the grid may not be always capable to provide. In this context, stationary storage can provide peak power during the charging session, limiting the maximum power request to the grid and avoiding the need for an upgrade to the grid connection. This paper carries out the modelling and simulation of a high-power recharging pool connected to the LV distribution network and coupled with a stationary storage system. A technical-economic analysis is conducted for two different storage configurations: high-capacity storage and peak-shaving storage. Results show that the peak-shaving solution, at present, is the most convenient. In addition, it is observed that a reduced size could still support the EV recharge, with a reasonable additional waiting time, while improving the return of the investment
State-of-charge estimation based on model-adaptive Kalman filters
No full textThis article presents a set of algorithms for the estimation of state of charge, specifically deployed for lithium-ion batteries. These algorithms are based on appropriate battery models. These models can be developed having different levels of accuracy, also including the possibility to correctly represent the hysteresis voltage behaviour of the selected lithium cells. In addition, different identification methods of the battery model parameters may also be considered, considering tabulated parameters, calibrated in previous tests, or online parametrization tools. State of charge is then evaluated using non-linear Kalman filter techniques. Effectiveness of identification methods, also with the performance offered by Kalman filter itself, has been accurately evaluated through experimental tests. To verify the robustness of the proposed algorithms, some disturbances were introduced and evaluation was also conducted at different state of charge initial conditions and sampling times
Optimisation of hybrid vehicles operation with ON/OFF strategy
No full textIn the last years, many papers already addressed the analysis of techniques for optimizing energy management on-board hybrid vehicles. However, the large majority of them focused on detailed analyses for specific architectures, suggesting algorithms valid only for them. This paper, on the contrary, performs a basic analysis and tries to find general rules, adequate for a large variety of hybrid vehicles. In particular, strategies to minimize fuel consumption using ON/OFF technique to manage the ICE have been analysed, investigating whether these last are effectively useful, considering also the costs associated to each engine start-up. At the end, some practical case studies have been considered, to verify the validity of the general proposed approach
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