Design and implementation of hess for small vehicle applications

Abstract

This thesis investigates the integration and optimization of hybrid energy storage systems (HESS) for small electric vehicles, focusing on the combined use of batteries and Super Ca- pacitors (SCs). The primary objective is to enhance the overall performance and longevity of the storage system by leveraging the complementary characteristics of batteries and SCs. This research encompasses the modeling, simulation, and control of HESS, utilizing control strategies to manage the distribution and separation of energy between the two sources, en- suring the safety of the energy sources. Initially, the thesis delves into the state of the art of HESS, detailing the different plant and control configurations, including passive and active topologies. The dynamic models of batteries and SCs are developed using equivalent circuits, emphasizing the balance between model fidelity and control complexity. Additionally, the study explores various driving cycles, such as UDDS, EUDC, and Artemis Road, to assess the performance of HESS under different driving conditions. The core of the research is the implementation of a battery protection system. The State of Power (SOP ) algorithm is employed to dynamically adjust power limits based on real bat- tery conditions, thereby enhancing safety and performance. Furthermore, a global controller, specifically a Rule Base (RB) algorithm, is integrated to manage the State of Charge (SOC) of the SC. This ensures proper power distribution, reduces battery stress, and extends the lifes- pan of the storage components. Simulation results, conducted using MATLAB and SIMULINK, are presented to demonstrate the effectiveness of the proposed HESS configuration and control strategies. The simulations include the conversion of speed profiles into power demands and the allocation of power to the battery and SC using a low pass filter (LPF ). The results highlight the differences between ideal and actual power allocation, showcasing the effectiveness of the SOP and RB algo- rithms in managing energy allocation. The converter controllers maintain the desired voltage levels in the DC bus. The findings underscore the importance of integrating batteries and SCs in a HESS for small electric vehicles, offering performance improvements. The research also identifies areas for future work, including the need for more accurate models and real-world testing to validate the simulation results.