A Battery Management System (BMS) is a system that monitors and manages a battery. It collects and calculates parameters such as voltage, current, temperature, and state of charge (SOC) to control the battery's charging and discharging process, thereby protecting the battery and improving its overall performance. It is a crucial link between the vehicle's power battery and the electric vehicle. The hardware architecture of a battery management system includes the following four aspects:
1. Mainboard: Collects sampling information from various slave boards, communicates with the vehicle via a low-voltage electrical interface, controls the relay operation within the BDU, monitors various battery statuses, and ensures safe battery use during charging and discharging.
2. Slave Board: Monitors information such as individual cell voltage and temperature of the module, transmits the information to the main board, and has battery balancing function. The communication method between the slave board and the main board is usually CAN communication or daisy-chain communication (a communication method that goes from the center to the periphery like a daisy).
3. BDU: Connects to the vehicle's high-voltage load and fast charging harness via a high-voltage electrical interface, including the pre-charging circuit, main positive relay, main negative relay, fast charging relay, etc., and is controlled by the mainboard;
4. High-voltage control board: It can be integrated into the motherboard or separated out. It monitors the voltage and current of the battery pack in real time, and also includes pre-charge detection and insulation detection functions.
The main chips used in a Battery Management System (BMS) include Analog Front-End (AFE), Microcontroller Unit (MCU), Analog ADC (Analog Converter), and Digital Isolator. The AFE (Analog Front-End) chip (specifically referring to the battery sampling chip in a BMS) is used to collect information such as cell voltage and temperature, and also supports battery balancing; typically, this chip integrates passive balancing functionality. The MCU chip in the BMS processes the information collected by the AFE chip and calculates the State of Charge (SOC). SOC is a crucial parameter in the battery management system; all other parameters are calculated based on SOC. Therefore, the battery management system places high performance requirements on the MCU chip.
Currently, automotive-grade BMS chips have high technological barriers, and suppliers are mainly foreign companies. The rapid development of the new energy vehicle industry has driven the continuous expansion of the overall BMS market, highlighting the increasing importance of BMS chips. However, the technological barriers for BMS chips are relatively high. For example, BMS MCU chips require extensive know-how experience, and many mature solutions are currently controlled by manufacturers such as NXP; the main suppliers of BMS AFEs are overseas companies such as Analog Devices and Texas Instruments. Without long-term R&D accumulation and a large amount of data, companies find it difficult to develop BMS chips that truly meet the needs of downstream applications.
Automotive-grade BMS chip certification requirements are stringent and time-consuming. With the continued advancement of the national "carbon neutrality" strategy, China's new energy vehicle industry is poised for a golden five years, providing a vast market for BMS chip applications. Before entering the supply chain of OEMs, automotive-grade semiconductor companies typically need to pass certifications such as the IATF 16949 quality management system and the AEC-Q series reliability standards. After completing the certification and audit of relevant automotive-grade standards and specifications, they must undergo rigorous application testing and verification, as well as lengthy on-vehicle verification, before entering the automotive OEM supply chain. We recommend paying attention to the following related stocks:
1) BMS chips: BYD Semiconductor (pending IPO), Chipown Microelectronics;
2) MCU Chips: Chipown Microelectronics, GigaDevice, Beijing Junzheng, Chipsea Technologies, National Technology, Unigroup Guoxin Microelectronics, Ninestar, Espressif Systems, Broadcom Integrated Circuits, Fudan Microelectronics, Shanghai Belling, Chipone Technology;
3) ADC chips: Shanghai Belling, Silergy, SG Micro, Chipsea Technologies;
4) Power management chips: Chipown Microelectronics, SG Micro, Yachuang Electronics, Silan Microelectronics, Chipone Technology, Sipu Technology, Shanghai Belling, Awinic Electronics, Mingwei Electronics, Fuman Electronics, Lixin Microelectronics, and Xidi Microelectronics.
