Modelling and Application of Battery Energy Storage Systems in Electric Vehicle Charge

The present PhD dissertation deals with the dynamic modelling and implementation of a molten salt battery storage system of the SMHB (Sodium Metal Halide) topology. Chapter 1 focuses on the state of the art of Battery Energy Storage System (BESS) technologies, highlighting the most widespread technologies and their relative advantages and disadvantages. In addition, different modelling techniques are presented for the description of the storage system behaviour. Next, the main fields of application for BESS are presented. Chapter 2 introduces the Sodium Metal Halide Battery. Its chemical characteristics have been deeply investigated. In particular, an equivalent circuit model of Thevenin is presented for the description of the dynamic behaviour of the battery. A comparison between two different models of iron (present in SMHB) has been investigated, showing the improvements through experimental tests. Chapter 3 concerns the development of a Dual Active Bridge (DAB) DC/DC converter to be interfaced with the SMHB battery. The converter has been developed in two configurations: the standard and the partial. The two configurations have been compared considering the efficiency of the battery-converter system. A round trip efficiency analysis has been performed, the results of which show higher efficiencies for the partial configuration. In Chapter 4, the main applications of second-life batteries (SLBs) are presented. In particular, the DCFC application has been analysed and compared with other power profiles. The application of Li-ion SLB battery packs has been considered for the DCFC application, developing different power profiles and studying the impact of degradation and replacement rate for a specific system design. Correlations between the characteristics of SLBs and the replacement rate are presented. Finally, a comparison between the lithium-ion SLB technologies and the SMHB for the application of DCFC is presented. The aging effects of SMHB highlight how this technology is a good candidate for the application of DCFC in support of SLBs.