Optimization of hybrid energy storage system for electric vehicles

The paper deals with improvement of efficiency of energy storage devices for electric vehicles. The benefits and features of the hybrid energy storage system based on the batteries and ultracapacitors are described. The possible topologies and common schematics of bi-directional DC/DC converters for energy storage are analyzed in terms of efficiency, reliability and battery maintenance. An algorithm for optimization of its parameters is developed, analyzed, shown and explained in detail. The surfaces, which show the dependence between required battery and ultracapacitors’ capacities, energy storage cost and battery discharge ratio are obtained and analyzed. Conclusions are drawn concerning optimization strategy and results of optimization with possible further improvements.