Battery Management System and its Applications

8 Battery Monitoring

8.1 Discussion on Real Time and Synchronization

During battery state monitoring, the state information acquisition, the information transmission, and the information process are more or less lagging, while the “real-time” is relative. According to the factors that may cause delay in the battery management system, this section intends to analyze the reasons for non-real-time and non-synchronous conditions in the state monitoring process and describe their negative impacts in order to propose some solutions to solve the problems.

8.1.1 Factors Causing Delay

During power battery state monitoring, the state information delay may be caused by the information acquisition of the battery monitoring circuit (BMC), the information transmission of the communication network, and the battery control unit (BCU) responsible for whole decision-making.

1. Delay caused by BMC

BMC consists of a chip closest to the acquired physical quantities and its auxiliary circuits. According to different applications, the front-end chip comprises a single-chip microcomputer, an analog–digital converter and some chips specially designed for the battery management system, which are responsible for converting analog signals, such as battery voltage, into digital information. The delay is mainly caused by the analog/digital conversion time. Generally, it takes about 100 μs to complete an 8-bit analog/digital conversion of a signal. The time delay of the voltage acquisition increases with ...