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BMSSPV - Battery Management System for Solar Powered Vehicles applied to Técnico Solar Boat prototype

Sebastião Maria Antelo de Holbeche Beirão
Supervisors: Rui Manuel Rodrigues Rocha, Carlos Manuel Ribeiro Almeida
University: Instituto Superior Técnico
Keywords: BMS, Battery Management System, Solar Powered Boat, Electrical Vehicle, Lithium-Ion Polymer Battery 1. Introduction In the past few years, not only due to environ- mental concerns, but also due to the instability in fuelprices,wehavewitnessedanincreasingdemand for Electric powered Vehicles (EVs). This demand is not only seen in terrestrial applications, such as cars, buses and even trucks, but also in the mar- itime and, more recently, aviation industries [1]. Regardlessofthetypeofvehicleused, allofthem sharethesametypicalarchitecturecomposedbyan energystoringunit,atleastoneelectricmotoranda power converter. This work will be focused mainly on the first one, the energy-storing unit, and more specifically on its BMS. BMSs are real-time systems that control many functionsvitaltothesafetyandreliabilityoperation of energy storing units in EVs. This includes tasks such as: monitoring temperature, individual cell voltage,current,batteryhealthandStateofCharge (SoC) and handling the communication with other systemcomponents. Thissystemshouldbecapable of identifying any potentially dangerous situation, such as over-voltage, and work in order to stop this faulty condition. Given that the competition’s regulations limit both the battery capacity and the area of the solar panels,thebatteryanditsBMShavetobedesigned in such a way that all the energy available is used but, at the same time, the boat is able to finish the races. This is especially important during the en- durance race, where we need to use all the available energy while making sure that the battery remains within its Safe Operating Area (SOA) 1 . For such a race, it is crucial to have an accurate estimate of how much energy there is left on the battery, .e. the battery SoC. 1.1. Motivation and objectives When TSB started, in 2015, we tried to develop ourownBMS. However, problemswithitsdevelop- ment, some lack of knowledge and the limited time until our first competition forced us to search for a commercial alternative that would meet, at least partially, our needs. Althoughthissolutionwasusedforcompetingfor two years, it was far from perfect and required ad- ditional hardware to make it comply with the com- petition’s regulations. To account for the missing 1 TheSOAisdefinedasthetemperature, voltageandcur- rentconditionsoverwhichthecellorbatterycanbeexpected to operate without self-damage or degradation. 1
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