Internal Communication of a Three-Layer Energy Storage BMS Architecture

The three-layer architecture of a BMS system consists of the Battery Module Management Unit (BMU), the Battery Cluster Management Unit (BCMU), and the Battery Stack Management Unit (BAMS). The Battery Stack Management Unit is also referred to as the PCS (Battery Unit Management System).

The Battery Module Management Unit (BMU) has one CAN 2.0 bus. It comprises the Battery Acquisition Unit (BCU) and the Battery Balancing Unit (BEU). It collects various individual cell information (voltage, temperature), calculates and analyzes the SOC and SOH of the cells, performs active balancing of individual cells, and uploads abnormal cell information to the Battery Stack Unit (BCMU). External communication is via CAN 2.0 bus.

The Battery Cluster Management Unit (BCMU) has three CAN 2.0 buses and two RS485 buses (backup). It is responsible for collecting various individual cell information uploaded by the BMU, collecting various information about the battery pack (pack voltage, pack temperature), charging and discharging current, etc., calculating and analyzing the SOC and SOH of the battery pack, and uploading all information to the Battery Stack Unit (BAMS). Communication is also via CAN 2.0 bus.

The battery stack management layer, called BAMS, has one Ethernet port, two CAN 2.0 buses, and one RS485 (backup) bus. It is responsible for collecting various battery information uploaded by the BCMU and uploading all information to the energy storage monitoring EMS system via RJ45 interface; it also communicates with the PCS, sending relevant battery anomaly information to the PCS (CAN or RS485 interface), and is equipped with a hardware dry contact for the PCS.

To ensure the safe, reliable, and stable operation of the energy storage system, electrostatic discharge (ESD) protection must be installed on each communication port to protect related equipment from ESD, EFT, and lightning surge damage.