Digital Control of a Bidirectional Converter for an Energy Storage System with a Second Life Battery

Battery energy storage systems play a crucial role in renewable energy systems and smart grids, and second life batteries offer a cheaper and interesting technical solution for storage as well as for voltage and frequency regulation services, despite the challenges that still exist. The power management in an energy storage system is usually done using one or more DC/DC converter. This paper provides a detailed design of a bidirectional DC/DC converter to manage the power flow between a DC source, a battery and a load. A solar panel is considered as the DC source and a power management strategy is proposed, based on the power provided by the solar panel and the battery’s state of charge. Then, the bidirectional DC/DC converter’s control approach is first validated using PLECS simulator. The battery modelling is presented and validated by manufacturer data. Simulation results verify the desired battery charge and discharge profile, particularly, the constant current constant voltage charging methodology. Finally, the experimental results verify the effectiveness of the proposed control method.