Date of this Version
2012 Twenty-Seventh Annual IEEE Applied Power Electronics Conference and Exposition (APEC) Digital Object Identifier: 10.1109/APEC.2012.6166137
Bidirectional DC/DC converters are commonly used for charging and discharging multicell batteries under various modes, such as Pulsed Current (PC), Constant Current (CC), and Constant Current Constant Voltage (CCCV). The charge and discharge are usually terminated by the converters when battery voltages reach some threshold values. However, cell state imbalance is commonly present in traditional multicell batteries, which reduces the available capacities of the batteries in certain charge/discharge cycles and shortens the life cycles of the batteries. To solve this problem, this paper proposes a series-connected, self-reconfigurable, multicell battery with a bidirectional DC/DC converter capable of safe and effective charging, discharging, and balancing operations. The DC/DC converter uses a unified Constant Current Adaptive Voltage (CCAV) control scheme, which can fully charge each cell of the battery without damage as well as discharge the battery safely. Moreover, with the proposed design, balancing and self-healing can be achieved during operation. This enhances the reliability and energy conversion efficiency of the battery. The proposed design is validated by simulation studies for a six-cell, series connected, lithium-ion battery pack. The proposed design is universal and can be applied to any types of batteries.