A Microcontroller-Based Fast Charger with State-Of-Charge Estimation for LiCoO2 Battery

In this paper, a microcontroller-based charger of the LiCoO2 battery module is realized. The main structure of the proposed system is the power factor corrector with a full-bridge phase-shift converter, the charging strategy is varied according to the battery module's state of charge (SOC). Furthermore, we directly capture the related data of the battery cells from the battery management system via the (IC)-C-2 interface, and then through the open-circuit voltage method integrating the coulomb integral method to find the lowest state of charge of the battery cell as a benchmark charge to adjust charging strategy. The pre-charge current is used when the SOC of the battery is lower than 15%. And then we employ the constant current charging if the SOC is from 15% to 75%. Finally, the charging strategy of the last phase will change to constant voltage charging to avoid the over-charging phenomenon.