Development of Lithium-ion battery pack balanced controller based on fuzzy control

For the characteristics of time variation, nonlinearity and uncertainty which exist in balancing process of Lithium-ion battery pack, and for strong coupling between internal error voltage and external load current, this paper proposes a fuzzy control balancing algorithm based on closed-loop energy model. In this paper, the maximum degree of non-equilibrium and external load current is regarded as the inputs, and the duty cycle of drive signal of power switch as the output in single cells. This algorithm solves such a bottleneck that conventional PID control cannot further improve the equalization performance. Simulation experiments about static equilibrium without load and about dynamic equilibrium with load were carried out. Results show that the proposed balancing algorithm has good control accuracy and it can improve the equalization performance of lithium-ion batteries.