Charger with Two Balanced Outputs for Li-Ion Battery Packs

Inhalt:
The design and modeling of a balanced two-output battery charger capable to charge two high-power LiFePO4 battery packs is presented. The proposal is based on a two-phase resonant converter which is designed as a voltage-controlled current-source working at constant switching frequency. The output stage consists of two independent current-doubler rectifiers. The structure of the output stage naturally imposes the self-balance-of-charge of both battery packs provided that both current-doubler rectifier stages have a negligible winding coupling mismatch. The analysis and design of the proposed charger is fully explained. In order to study the charge equalization of the both batteries, the long-term simulation of the charging process is carried out using the electrical model of the batteries. The results are obtained considering two 48NPFC50 battery packs with 48 V rated voltage and 50 Ah current capacity.