Electric Vehicle Battery Pack - Flexible Module Design

Electric Vehicle Battery Pack - Flexible Module Design In the pursuit of cleaner and more sustainable transportation, the electrification of existing vehicles has emerged as a compelling solution. Retrofitting conventional vehicles with electric drive-trains is a promising step forward. However, one of the challenges in this attempt is the development of adaptable battery packs that can conform to the available space within different vehicle models. This thesis embarks on a journey to create the "Electric Vehicle Battery Pack - Flexible Module Design" a cutting-edge solution tailored to the specific needs of electric vehicle retrofits. A Battery Module is essentially a combination of battery cells. These cells are connected in parallel and series configurations and are equipped with essential voltage and temperature sensors, alongside equalizing electronics. A Battery Pack, in turn, assembles multiple Battery Modules, typically in series, and encloses them in a housing equipped with vital electrical components. The Battery Pack designed for this thesis uses prismatic battery (BYD_96V) cells. It comprises two modules, each containing 20 cells, and an additional module with 16 cells. The unique configuration of this battery pack involves 2P28S which means 2 cells connected in parallel assembly and 28 parallel assemblies connected in series, totalling 56 cells. Significantly, each parallel assembly is equipped with its electronic module for monitoring temperature and voltage, as well as for ensuring charge equalization. This modular approach empowers the assembly of Flexible Battery Modules, customized to meet the distinct spatial constraints and energy requirements of various retrofitting projects. The primary aim of this research is twofold. First, it focuses on the mechanical design aspects of the Battery Pack. SolidWorks software is employed to meticulously design and validate the mechanical structure of both the overall battery pack and individual modules. Rigorous R_100 testing is conducted to assess the safety performance under inertial loads that may occur during vehicle crashes. Ultimately, the expected results of the R100 tests will serve as a crucial validation of the mechanical design, ensuring that the Battery Pack's safety measures align with the demanding standards of electric vehicle technology, thereby enhancing its reliability and suitability for retrofitting existing vehicles. Second, this work includes the electrical and thermal properties of the Battery Pack Flexible Module. The MATLAB/Simulink environment, complemented by the Battery Builder App, is utilized for constructing and verifying the electrical and thermal characteristics. A simplified equivalent electrical circuit model is developed, accounting for open-circuit voltage and internal resistance dependencies on temperature and state of charge. Although various equivalent circuit models can be explored, the selected Rint model captures the general behaviour of the BYD cell, considering its sensitivity to temperature and state of charge. In conclusion, this thesis marks a significant step towards greener and more sustainable transportation solutions. By addressing the challenges of retrofitting existing vehicles with adaptable and safe battery packs, this research not only contributes to reducing emissions but also paves the way for a future where electric mobility is more accessible and environmentally responsible.