Riassunto analitico
The current thesis work has been realized at Automobili Lamborghini S.p.A., where also the 6-months internship activity has been carried out.
The EU Regulation 2023/1542 of the European Parliament and of the Council of 12 July 2023 concerning batteries and waste batteries lays down new constraints on batteries production, management and traceability, bringing forwards Europe ambitions for the realization of circular economy, with focus on the batteries’ sustainability throughout their lifetime. In the attempt of standardizing the batteries market, the Regulation provides the realization of a battery passport for each single battery, containing information about performance parameters such as rated capacity, internal resistance, power, energy round trip efficiency and their degradation once battery reaches its end-of-life state. In addition, runtime indication of the State of Health of the battery, intended as State of Certified Energy by the law, and the declaration of the Carbon Footprint covering the complete lifetime of the battery from the preliminary processes of raw materials extraction, the production of cell components, the assembly of the whole battery pack, up to the dismantling and recycling are demanded. The fact of accessing the battery passport digitally by means of a QR code reported on the battery label, fully tracing the history of that specific battery, gives the possibility of a battery second life reuse.
As already mentioned, many articles constrain electric and/ or hybrid vehicles OEMs to the declaration of battery parameters which are derived from software algorithms based upon experimental tests data. This represented the main driver for the realization of a complete battery pack software model, which can be employed in an embedded real time environment. In fact, some battery functional parameters, such as the State of Charge (SOC), need to be calculated runtime during the vehicle usage.
The model algorithms were built in MATLAB Simulink, while analysis and postprocessing of the battery experimental tests were carried out by means of MATLAB and Python scripts.
The core of the functional part of the battery software is the battery cell model: in accordance with the Equivalent Electric Circuit method for the modelling of the main electrochemical phenomena affecting cell behaviour in terms of voltage response profile, a procedure was developed for the derivation of these cell parameters, by using experimental data from testbeds, whose profiles in terms of applied current are thought for the obtainment of specific cell parameters. In this way, the estimation of the battery pack voltage runtime in the vehicle is met, thus permitting the derivation of all the other main battery parameters, such as the SOC and the ones varying with the ageing state of the battery, such as the internal resistance and the capacity.
Consequently, the estimation of the battery State of Health is achieved; the algorithms just discussed are compliant with what required by articles 10 and 14 of the EU Battery Regulation.
Moreover, algorithms for the management of the battery contactors and the current limits were developed.
To validate the results obtained from the software, real vehicle logs are considered: for instance, the comparison between the voltage curve whose values are measured by sensor and the voltage profile derived from the software algorithm succeeds the project target error in the voltage estimation of being below 1% at pack level.
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