Balanced Control Strategies for Interconnected Heterogeneous Battery Systems

This paper develops new balanced charge/discharge strategies that distribute charge or discharge currents properly so that during operation, battery systems maintain uniform state-of-charge (SOC) all the time. The proposed balanced charge/discharge control strategies are useful for interconnected heterogeneous battery systems that can be built from battery modules with different types, ages, and power/capacity ratings. Both voltage-based and SOC-based balanced charge/discharge strategies are developed. Their convergence properties are rigorously established, and illustrative examples using production batteries demonstrate their convergence behavior under different charging current profiles. The approach will be especially useful for battery storage systems to support power grids with renewable energy sources where the battery systems are required to operate continuously.