An active balancing circuit for lithium battery management system with optoelectronic switches

The traditional active balancing circuit has problems on the hardware cost, control complexity, balance speed, etc. This paper proposes a lithium battery management system (BMS) for the active battery pack balancing, and the BMS has the advantages of low hardware cost, good flexibility and better balancing performance. The fly back converter is used to implement the parallel balancing scheme. The optoelectronic switches are used as the control components for better safeties. Only one MOSFET is required for the low cost application. The circuit performance is calculated and simulated. A hardware BMS system based on the proposed circuit topology is also developed. The error between the sampling voltage and the measured voltage is less than 0.1%. The experiment results show the voltage difference changes from 535.2mV to 9mV in only 30 minutes.