**Introduction**
Environmental pollution and the increasing demand for energy have driven the development of new energy sources. To utilize these new energy sources efficiently, battery storage systems have become essential. A Battery Management System (BMS) plays a critical role in ensuring the safe and efficient operation of energy storage batteries. It monitors battery voltage, estimates the state of charge, and provides recommendations for battery runtime and usage.
In the early stages, BMS systems were primarily composed of distributed components with limited functionality. They mainly focused on monitoring the overall voltage and current of the battery pack, but lacked precision and scalability. These systems had poor fault detection capabilities and were not suitable for large-scale energy storage applications [1]. To address these limitations, this article presents a BMS design that uses the LTC6804 as its core component. The system includes features such as cell balancing, battery condition monitoring, and fault alarm functions, making it more reliable and adaptable for modern energy storage needs.
**1. Overview of LTC6804 Functionality**
The LTC6804 is the third-generation multi-cell battery monitoring IC from Linear Technology. It can monitor up to 12 series-connected battery cells simultaneously, and it can also handle configurations with fewer than 12 cells, provided the total series voltage exceeds 11V. Each individual cell can be monitored with a maximum voltage of 8V, and the total series voltage can go up to 75V. The device offers a high measurement accuracy of 1.5mV and can measure all cells in just 290 microseconds.
The LTC6804 supports an isoSPI communication interface, allowing multiple devices to be connected to a central control chip via serial communication. Each LTC6804 can be individually addressed, enabling parallel management of multiple units. With twisted pair cabling, the communication distance can extend up to 100 meters.
Additionally, the LTC6804 integrates an internal equalization circuit, which allows direct control of external switches to discharge individual cells when necessary. It also features five general-purpose digital I/O pins that can be used for sensor inputs or communication interfaces. The device consumes only 4µA in sleep mode, making it highly power-efficient.
The LTC6804 includes a 16-bit delta-sigma ADC with a programmable third-order noise filter, ensuring accurate voltage measurements. It also has an auxiliary ADC that can be configured using general-purpose I/O pins. This allows for temperature monitoring by connecting a thermistor to the ADC input, and current measurement can be achieved by connecting a Hall effect current sensor to the same port.
**2. Design of LTC6804 Peripheral Circuits**
The peripheral circuits for the LTC6804 include a power supply circuit, an ADC reference circuit, a communication interface, general-purpose I/O circuits, a watchdog circuit, and a voltage measurement circuit, among others. The hardware architecture is illustrated in Figure 1. The LTC6804 is powered directly from the battery pack, eliminating the need for a separate power supply unit.
This design ensures stability, reliability, and ease of integration into larger battery management systems. The use of the LTC6804 enhances the performance of the BMS by providing precise monitoring, efficient communication, and robust protection mechanisms.
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