Taguchi-based PSO for searching an optimal four-stage charge pattern of Li-ion batteries

Abstract

Abstract This study utilizes a Taguchi-based particle swarm optimization algorithm to search an optimal four-stage constant current charge pattern for delivering the maximum capacity to provide long runtimes within the shortest charging time. The goal is to maximize the cost function for the applied charge pattern based on the charging time and discharge capacity ratio that both share the same weight. The discharge capacity ratio is defined as the total capacity of a cell discharged at a constant current of 0.3 C using the four-stage constant current charging strategy until reaching the preset voltage of 3.0 V to the one employs the constant current constant voltage charging method. The charging time is the overall charging duration of the 4SCC charging process. Sanyo UR14500P batteries in the cylindrical shape with a nominal voltage of 3.7 V and a rated capacity of 840 mAh are tested. In the tests, the optimal 4SCC sequence of 1.262 C, 1.082 C, 0.662 C and 0.258 C is allowed to charge the battery up to 94.7% of the nominal capacity for 67 min, and the constant current constant voltage charging arrangement of 0.7 C to 4.2 V and the cut-off of 0.05 C are used to charge the battery up to 99.5% of the nominal capacity in 119 min.