BATTERY STATE ESTIMATION METHODS FOR ELECTRIC VEHICLES UNDER REAL TEMPERATURE CONDITIONS

Lithium batteries are increasingly becoming the preferred energy storage technology for many applications. The interest for its use in applications that require a large storage capacity, such as the automotive industry or renewable energies, demands better control and health monitoring procedures in order to prevent unforeseen failures because of the significant cost involved. The state of charge (SOC) and state of health (SOH) are two crucial indicators needed for a proper and safe operation of the battery. These indicators cannot be measured directly, so they must be estimated from parameters such as the voltage or current flowing through the battery. Depending on the method applied, certain factors such as temperature or discharge rate can affect the precision of the estimation. For this reason, it is necessary to investigate the influence that these factors have in order to ensure an accurate estimation in the entire operating range of the battery.

Among the purposes of this PhD Project there is the analysis of the degradation of batteries in real life situations. This applies especially to the case of electric vehicles, in which demanding discharge cycles are alternated with long periods of rest as well as large temperature variations in the process. Different estimation mechanisms will also be studied under variable load and temperature conditions. Finally, the feasibility of different methods to evaluate the SOH through the charger of an electric vehicle will be studied.

Funding: eVolution2G-V2G, WABAT projects