Pulsed Current Operation and Adaptive State-of-Charge Balancing for Smart Battery Energy Storage Systems

This paper advances the development of next-generation energy storage systems based on smart batteries. The investigated approach integrates a half-bridge converter into each battery, enabling pulsed current operation. Two State-of-Charge (SOC) balancing strategies are investigated. The first, inspired by existing literature, employs a proportional controller. The second is based on an adaptive controller that dynamically adjusts its gain based on real-time SOC deviation. As a second contribution, this work explores the interactions between the smart battery pack and the power conversion system (PCS) in a grid-connected application. The proposed balancing strategies are analytically modeled and validated through simulations in PLECS and Control Hardware-in-the-Loop (C-HIL) experiments. Additionally, the study examines the impact of battery bypass on the dc bus voltage and power processing in the two-stage PCS. Results indicate that the adaptive balancing scheme reduces balancing time by approximately four times compared to the proportional controller-based approach. Moreover, the interaction between the smart battery pack and the PCS enables stable regulation of the dc bus voltage, minimizing fluctuations caused by battery switching and ensuring stability in active power delivery, reinforcing its viability for grid-connected applications.