Modeling and analysis of hybrid energy storage systems used in Electric vehicles

This paper deals with the design and modelling aspects of hybrid energy storage system (HESS) used in Electric vehicles. Modelling of HESS includes modelling of battery, Ultra-capacitor and the vehicle load modelling for Light electric vehicle used in the work. A detailed analysis for vehicle load is carried out to find out capacity of motor, battery and ultra-capacitor in both acceleration and in regenerative braking. This paper also discusses different types of converters used in HESS for electric vehicle application along with its suitability to the light electric vehicles. The HESS in this work uses a bidirectional dc/dc converter along with battery and ultra-capacitor. A simple power sharing algorithm based on heuristic approach is presented to ensure the different modes of operation of electric vehicles. From the performance analysis at different speeds and at different gradients it is concluded that HESS reduces the size of the battery, weight of the system. Due to this the range of the vehicle can be improved in a single charge.