Modelling and Comparative Analysis of Switchable Battery Configurations for Dual Voltage Charging in Electric Vehicles

Abstract

Abstract This thesis explores and evaluates two electric vehicle (EV) battery architectures: an existing 800V single battery system using inverter-based 400V charging referred to as the DC boost system, and a proposed dual 400V battery system that allows seriesparallel switching for direct 400V charging, referred to as the Greenfield system. The main aim is to identify energy losses in these systems and investigate architectural and material solutions to enhance efficiency, thermal performance, reliability, and cost-effectiveness. A MATLAB Simulink model was created to simulate energy flows, battery behaviour, and thermal dynamics under a variety of charging conditions, spanning from realistic to sensitivity-driven scenarios. Battery balancing mechanisms were incorporated to evaluate system performance when SOC mismatches occur. Although both systems achieve comparable efficiencies during 400V charging, the proposed architecture shows lower energy losses, improved thermal performance and longer component lifespan due to decreased current stress and the removal of voltage boosting with the inverter. Furthermore, the possibility of replacing aluminium with copper busbars was studied, revealing lower thermal peaks while retaining electrical performance. Overall, the findings indicate that even though the energy efficiency differences between the two systems are slight, the Greenfield system provides significant benefits in thermal stability and component durability, particularly during high-current operation. These results highlight the trade-offs involved in system complexity, material choice, and long-term performance in the design of EV battery systems.