New energy vehicle high-voltage battery system composition and structure

Infineon / Mitsubishi / Fuji / Semikron / Eupec / IXYS

New energy vehicle high-voltage battery system composition and structure

Posted Date: 2024-01-15

High voltage battery system composition and structure

The high-voltage battery module is placed in a sealed and shielded high-voltage battery box. The high-voltage battery system uses reliable high- and low-voltage connectors to connect to the vehicle. The installation position of the high-voltage battery module is shown in the figure below.

▲ Installation location of high-voltage battery module

The BMS in the high-voltage battery system collects data such as the voltage value of each battery cell, the temperature value of each temperature sensor, the total voltage value and total current value of the battery system, and the insulation resistance value of the battery system in real time, and based on the settings set in the BMS The threshold determines whether the battery system is working normally and monitors faults in real time. The high-voltage battery system uses CAN to communicate with the VCU or charger through the BMS, and performs comprehensive management of charging and discharging of the high-voltage battery system.

The high-voltage battery system also receives and stores high-voltage DC power provided by on-board chargers, generators, brake energy recovery devices and external charging devices, and provides high-voltage components such as drive motor controllers, DC/DC, electric air conditioners, and PTCs. DC.

The high-voltage battery system mainly consists of four parts: high-voltage battery module, battery management system, high-voltage battery box and auxiliary components, as shown in the figure below.

▲ High-voltage battery system composition (BAIC E150EV)

The battery cell is the smallest unit that constitutes a high-voltage battery module. It is generally composed of a positive electrode, a negative electrode, an electrolyte and a casing, etc., and can realize direct conversion between electrical energy and chemical energy; a battery module is a combination of a group of parallel battery cells. The rated voltage of the combination is equal to the rated voltage of the battery cells. It is the smallest grouping of battery cells connected in physical structure and circuit and can be replaced as a unit; the module is composed of multiple battery modules or battery cells connected in series. A combination, as shown in the figure below.

▲ High-voltage battery module structure (JAC new energy models)

The high-voltage battery box is a component that supports, fixes, and surrounds the battery system. It mainly includes an upper cover and a lower tray, as well as auxiliary components, such as transition pieces, guard plates, bolts, etc. The high-voltage battery box carries and protects the high-voltage battery pack and electrical The role of the component.

The battery box is connected under the vehicle floor with bolts. Its protection level is IP67, and the bolt tightening torque is 80~100N·m. During vehicle maintenance, it is necessary to observe whether the bolts of the battery box are loose, whether the battery box is damaged or severely deformed, and whether the sealing flange is intact to ensure that the high-voltage battery can operate normally; in appearance, the outer surface color of the battery box is required to be silver gray Or black, matte, as shown in the picture below; the surface of the battery box must not have scratches, sharp corners, burrs, residual oil stains and other appearance defects, and the welding joints must be polished and smooth.

The auxiliary components of the battery module mainly include the electrical components inside the high-voltage battery system, such as fuses, relays, shunts, connectors, maintenance switches, smoke sensors, etc., as well as sealing strips, insulating materials, etc.

▲ Internal auxiliary components of high-voltage battery module

High voltage battery management system

The full English name of the battery management system is BatteryManagementSystem, abbreviated as BMS. The BMS module entity is shown in the figure below.

▲ BMS module entity (BAIC E150EV)

① BMS function:The core component of battery protection and management. In high-voltage battery systems, its role is equivalent to the human brain. It not only ensures the safe and reliable use of the battery, but also fully utilizes the battery's capabilities and extends its service life. As a battery and The vehicle controller (VCU) is the bridge between the driver and the driver. It controls the charge and discharge of the high-voltage battery pack by controlling the contactor, and reports the basic parameters and fault information of the high-voltage battery system to the VCU.

② BMS functions:Through functions such as voltage, current and temperature detection, the overvoltage, undervoltage, overcurrent, overtemperature and undertemperature protection, relay control, SOC estimation, charge and discharge management, balance control, fault alarm and processing of the high-voltage battery system are realized, and Other controller communication and other functions; in addition, the battery management system also has a high-voltage loop insulation detection function and a heating function for the high-voltage battery system.

③BMS composition:It can be divided into hardware and software according to its nature, and it can be divided into data acquisition unit and control unit according to its function.

④ BMS hardware:The main board, slave board and high-voltage box also include electronic devices that collect voltage, current, temperature and other data.

⑤ BMS software:Monitor the voltage, current, SOC value, insulation resistance value, and temperature value of the battery, and control the charge and discharge of the high-voltage battery system through communication with the VCU and charger.

Review Editor: Huang Fei

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