Electrothermal Modeling and Optimization of a Supercapacitor‐Based Braking Energy Recovery System to Enhance Efficiency and Thermal Stability in Electric Vehicles

ABSTRACT A major challenge in electric public transport is the loss of kinetic energy during dynamic braking, which reduces overall energy efficiency and increases operational costs. This study addresses the challenge of dynamic braking energy losses by employing a Supercapacitor Energy Storage System (SESS) capable of recovering and reusing braking energy. Supercapacitors (SCs) are employed to significantly enhance the power performance of Electric Vehicles (EVs), including trolleybuses and tramways. This study investigates the modeling, optimization, and thermal analysis of SESS. A detailed dynamic model of the trolleybus traction system is developed using the PSIM (Power Simulation) environment. The model emphasizes key components such as Induction Motors (IMs), power converters, controllers, and supercapacitors to accurately represent both electrical and thermal behavior. Various control strategies ranging from scalar constant Voltage‐to‐Frequency (V/f) to variable frequency approaches are explored to optimize the capture and utilization of braking energy. The sizing of the SESS is optimized by considering the vehicle's kinetic energy and the operational parameters of the supercapacitors. The supercapacitor's nonlinear electrical behavior and temperature sensitivity are characterized experimentally, providing critical data to establish the electrothermal model. The evaluation of the system, including its power electronics, demonstrates that it operates within safe thermal limits without the need for auxiliary cooling mechanisms. The integration of supercapacitors not only improves energy efficiency and extends vehicle range but also ensures the thermal stability of the storage system, as confirmed by simulation results. This study highlights the importance of accurate electrothermal modeling for reliable system operation and provides essential design insights for electric vehicle braking systems. Ultimately, the work contributes to enhancing energy recovery and management in trolleybuses, supporting the development of more sustainable public transportation systems.