The reason why Tesla electric vehicles have become the leader in the industry is partly due to its powerful battery management system. Only by effectively controlling and managing complex and numerous battery packs can we break through the bottleneck in the promotion and popularization of electric vehicles. Let’s take a look at how the battery management system works.

Figure 1 Schematic diagram of the safe working area of lithium-ion batteries

1Battery Management System (BMS) Definition

The safe working area of lithium-ion batteries is shown in Figure 1. The main task of BMS is to ensure the design performance of the battery system: 1) safety; 2) durability; 3) power.

The basic framework of BMS software and hardware is shown in Figure 2. It should have the following functions: 1) Battery parameter detection. 2)Battery status estimation. 3) Online fault diagnosis. 4) Battery safety control and alarm. 5)Charging control. 6) Battery balancing. 7) Thermal management. 8) Network communication. 9) Information storage. 10) Electromagnetic compatibility.

Figure 2 Basic framework of automotive BMS software and hardware

2 Key technologies of battery management system

2.1 Requirements of battery management system for sensor signals

2.1.1 Single-chip voltage collection accuracy

Generally, for safety monitoring, the voltage of each battery string in the battery pack needs to be collected. Different systems have different requirements for accuracy.

Figure 3 Single cell OCV curve and voltage acquisition accuracy requirements

For LMO/LTO batteries, the cell voltage collection accuracy only needs to reach 10mV. For LiFePO4/C batteries, the cell voltage collection accuracy needs to be about 1mV. However, most current voltage collection accuracy of single cells can only reach 5mV.

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