Control Strategy for Battery-Ultracapacitor Hybrid Energy Storage System

Hybrid energy storage systems have been investigated with the objective of improving the storage of electrical energy. In these systems, two (or more) energy sources work together to create a superior device in comparison with a single source. In particular, batteries and ultracapacitors have complementary characteristics that make them attractive for a hybrid energy storage system. But the result of this combination is fundamentally related to how the sources are interconnect and controlled. The present work reviews the advantages of battery-ultracapacitor hybridization, some existing solutions to coordinate the power flow, and proposes a new control strategy, designed for the improvement of performance and energy efficiency, while also extending the battery life. The control strategy uses classical controllers and provides good results with low computational cost. Experimental results are presented.