Series-connected reconfigurable multicell battery: A novel design towards smart batteries

The traditional multicell battery design usually employs a fixed configuration to connect multiple cells in series during operation in order to achieve the required voltage. This design has low reliability and can only utilize a part of the total battery capacity if cell state variations are present. Recently, several reconfigurable multicell battery topologies have been proposed. However, these topologies are too complex and unrealistic for the battery systems with large numbers of cells. This paper proposes a novel series-connected, reconfigurable, multicell battery design. A new switching circuit topology is proposed where each cell in the battery only uses two switches to fully control its operation independently. The cell switching circuit and the control circuit for each cell are designed and implemented by using high-efficiency semiconductor devices. The proposed design can maximally utilize the battery's capacity and is tolerant to failures of single or multiple cells. These prolong the operating time and lifespan and enhance the reliability of the battery system. By using the proposed design, additional monitoring, control, protection, and optimization functions can be readily added to each cell and the battery system to produce a smart battery. The proposed design is validated by simulation and experimental studies for a six-cell polymer lithium-ion battery pack. The proposed design is universal and can be applied to any type and size of battery cells.