A Preventive Approach for Solving Battery Imbalance Issue by Using a Bidirectional Multiple-Input Cuk Converter Working in DCVM

State of charge (SoC) imbalance among batteries in a battery energy storage system (BESS) degrades the system performance and may lead to safety issue. A bidirectional multiple-input Cuk converter for the BESS is proposed to prevent batteries from SoC imbalance issue. Compared to the traditional BESS, the battery balancing and voltage/current regulation subsystems are combined into one. As a result, the overall system complexity is significantly reduced. Moreover, the current flow of each battery is self-adjusted according to its terminal voltage. Therefore, the system does not require sophisticated control algorithm for battery balancing. Moreover, the proposed system has no energy dumping and energy transferring between batteries, which avoids unnecessary energy lose. Due to the nature of multiple-input converter structure, the proposed system can handle certain component failure. The proposed approach of designing the BESS has been investigated through simulation and validated experimentally.