Sneak Circuit Theory Based Approach to Avoiding Short-Circuit Paths in Reconfigurable Battery Systems

The efficiency and safety issues caused by cell differences are the key factor to hinder the use of retired batteries. The reconfigurable battery technique is an effective method to break through the bottleneck. However, the potential short-circuit paths increase exponentially with the number of cells, which makes manual analysis unapplicable and brings serious risks in large scale reconfigurable battery systems. Existing researches are about topology and energy efficiency optimization, but the problem of short circuit is ignored. In this article, a systematic approach based on the sneak circuit theory is proposed to fundamentally avoid the short-circuit problem of reconfigurable battery systems. A novel sneak circuit theory based approach is creating a short circuit path table, which will be indexed to avoid connecting the anode and cathode of a battery cell/string. In addition, all the paths are further studied and analyzed, and the simplest path table can be obtained to improve the energy efficiency. To validate the theoretical foundation and feasibility of proposed approach, a reconfigurable battery system containing two kinds of batteries is developed. All experimental results well verify the effectiveness and feasibility of proposed approach. This work provides theoretical foundation for avoiding short-circuit paths in reconfigurable battery systems, which will break through the bottleneck in scale application.