A novel charging and active balancing system based on wireless power transfer for Lithium-ion battery pack

Lithium-ion batteries are widely used in applications that require tightness, such as underwater unmanned vehicles and mine-searching robots. The traditional wired charging and balancing for battery pack is not suitable for the required tightness and safety of battery pack. Therefore, this paper proposes a novel charging and active balancing system based on wireless power transfer (WPT) for lithium-ion battery packs. This system only uses a set of energy-transmitting and energy-receiving coils, to wirelessly transfer the energy required for both battery pack charging and single battery balancing. The charging and balancing power is adjusted according to the voltage level of the primary side of the DC/DC converter. The switching matrix functions acts as a switch to connect either the battery pack or any single battery in the pack to be balanced. In addition, a multiobjective optimal balancing strategy based on a genetic algorithm (GA) is proposed to optimize the pack available capacity and the balancing time of the pack. The experimental results show that the proposed system achieves the dual functions of wireless pack charging and wireless battery balancing. In addition, compared with the traditional state of charge (SOC) consistency balancing strategy, the proposed balancing strategy simultaneously increases the pack available capacity by 7.9 %, and the pack maximum difference in SOC is only 2.19 %.