Enhanced SOH Balancing Method of MMC Battery Energy Storage System with Cell Equalization Capability

摘要

Using retired electric vehicle batteries in battery energy storage system (BESS) saves the cost but the state-of-health (SOH) of each battery is hard to be equal, which could significantly worsen the life time of whole battery system. When using the modular multilevel converter (MMC) to integrate the battery packs, it can achieve the SOH balancing among sub-modules (SMs). This paper further proposes an enhanced SOH balancing for MMC-BESS with cell equalization capability including traditional state-of-charge (SOC) equalization and SOH equalization to deal with the cell imbalance issue inside SM. Simulation and experimental results are presented to verify the performance of the proposed method.