Introduction of a Lithium Battery Active Balance System in American Company

The National Semiconductor Corporation of the United States was affiliated with Texas Instruments Corporation since its acquisition in April 2011. The National Semiconductor Corporation established in 1959 was soon incorporated into Texas Instruments. An active balanced battery management system is developed to maintain the balance of internal modules and small batteries when charging, discharging and idle.

In the previous active battery balance system, the balance between the modules was to connect all the small cells of each module with one of the small cells in the adjacent module in order to establish a path between the two to transmit charge. Because the charge must be transmitted to a small battery first and then distributed to other small batteries; For further modules, the charge needs to be transmitted several times separately, which greatly reduces the efficiency of the internal operation and causes more current to be consumed in the form of heat. The National Semiconductor's active balanced battery management system starts from the improvement of old problems and provides a comprehensive system solution for large lithium-ion batteries. This is a printed circuit board equipped with a number of special application integrated circuits that can provide active battery balance, high-precision data acquisition, battery protection and management.

1. Active battery balance: The system adopts an isolated inductor topology, which can provide high current and high efficiency battery balancing function. The charge can be transmitted bidirectionally between any small battery and different modules in the module. Small batteries and modules can be balanced at the same time. . At the same time, each battery module manages 14 small batteries, and each module's battery management system (board) can be stacked together to manage high-voltage lithium battery packs. The amount of balancing current depends on the components (engineers can choose differently targeted components between performance and cost).

2.Data acquisition: The battery management system is responsible for fully monitoring the operation of the battery pack and ensuring that the system accurately measures the voltage of each small cell. The analog front-end circuit responsible for this work can not only balance the charge, but also ensure that the battery charge and health status estimates are accurate.

3, battery protection and management: The system has a multi-layer diagnosis and fault detection circuit. If a fault such as undervoltage, overpressure, and overheat of the battery is found, the small battery or module will actively signal to the main controller. The parameters are compared with the programmable thresholds stored in the firmware and then protected by the switch program. The circuit board that controls each module is equipped with a multi-contact insulation bus interface that allows the circuit board to adjust communication with other modules and the main controller. At the same time, using the bus to perform diagnosis, programming and configuration management functions.

This battery management system has advanced functions. It can quickly respond to the internal balance of charging, discharging, and idling of power lithium batteries. It accurately controls the charging, storage, and discharge of small cells, improving safety, and facilitating the extension of service life. The system is expected to be used in the management of large lithium batteries for power station energy storage facilities.

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