Cooperative Charging of Supercapacitor Trams With Current Overshoot Suppression

Current overshoot in the charging is an undesired behavior that accelerates the aging of both chargers and batteries. This phenomenon is even more severe in parallel-connected multicharger systems of supercapacitor trams, as the overshooting of each charger is stacked up in the charging current. To address this issue, in this article, we propose a current-overshoot-suppression charging method for supercapacitor trams. First, the system modeling of the charging system is developed and the motivation of this article is highlighted. Then, a cooperative charging protocol is designed to achieve the current balancing of chargers, and a set point modulation method is presented to adjust the set-point of chargers smoothly with the aim of suppressing the current overshoot. The implementation of the proposed method is illustrated with a physical case study. A laboratory testbed has been built to verify the effectiveness of the design. Experiment results show that the proposed method can suppress the current overshoot without prolonging the settling time.