A Power Conversion System and Its Control Strategy Design for Parallel-Connected Battery Packs

Due to the effects of inconsistencies between the individual cells, the life of the series battery pack is limited. The parallel connection method can avoid the damage of the entire battery pack by bypassing the faulty battery, but the disadvantage of the parallel battery pack is that the voltage level is too low. Based on this, this paper proposes a two-stage power conversion system for parallel battery packs, with an interleaved Boost converter in the front stage and a quadruple active bridge (QAB) converter in the rear stage. The pre-stage converter can effectively reduce the current stress of the switch tube while achieving voltage boost, and the post-stage achieves high voltage gain through the high-frequency transformer and the output port in series, thus making the system practical. Finally, the control strategy of the system is designed, and the effectiveness of the proposed scheme is verified by simulation.