Battery Management System and its Applications

13 Communication Interface for BMS

BMS performs internal communication between its master and slave modules and external communication with other system devices like the charge controller, power controller, energy management system, etc. Both communications, internal and external, require a high speed and robust data transfer. Interfaces and protocols should be compatible to accommodate multidevice communications. In addition, interfaces should have bidirectional capabilities and buffer capacity.

An overview of the BMS system in Figure 13.1 describes a master–slave BMS configuration. The master is a central control of BMS that communicates internally with cell/pack level hardware and externally with high level hardware like a laptop or other controllers. Each slave is attached to a battery pack and transfers the essential pack information to the master. The pack essential information consists of the pack and cell voltages, temperatures, pack current, SoC, SoH, and other information related to safety and control. The master BMS is responsible for processing the received information and then communicates with external devices for charge and safety controls [1]. In Figure 13.1, slaves talk to the master with a serial protocol RS-485 (Modbus) and the master connects with other external devices through protocols RS-485 and CAN. A few common protocols used for data exchange between the BMS master and slave are the Controller Area Network (CAN)/FlexRay, Modbus, etc.

Figure 13.1 BMS ...