Overcurrent protection scheme of BMS for Li-Ion battery used in electric bicycles

Li-Ion batteries are widely used as the power source supplying the electric drive of electric bicycles. They are sensitive to the operation outside their recommended operating area, which could lead to shortened life-time, damage and explosion risk. A battery management system (BMS) is applied in order to monitor and to protect the battery from the abnormal conditions. In general, the commercial BMSs for Li-Ion batteries in electric bicycles typically focus on only the protection of the battery without consideration of other devices in the system, especially, the switching MOSFETs inside the converter. This paper presents the development of an overcurrent protection scheme for BMS which is capable of not only protecting the battery but also protecting other system components from damages. In addition, it can discriminate temporary fault currents so that unnecessary interrupted operations can be avoided. The developed scheme is designed based on the SOA of MOSFETs and the current-time characteristic of fuses. The proposed scheme was validated by experimental results.