Fuzzy-PI control battery equalization for series connected lithium-ion battery strings

A novel battery equalization scheme is presented to balance series-connected lithium-ion battery string. The proposed balancing circuit has simple structure which is easily used to design the bidirectional nondissipative equalizer for batter management system. A fuzzy-PI controller is design to control the balancing process of batteries, which improves the balancing speed and accuracy within a safe balancing range. Simulation and experiment results show the advantages of the proposed balancing circuit and control algorithm.