18650 battery 10000mah

　　Research and implementation of 18650 battery 10000mah management system - Software implementation of 18650 battery 10000mah management system

　　4.1 Software block diagram of 18650 battery 10000mah management system 4.2 Software implementation of 18650 battery 10000mah management system

　　After the hardware circuit is determined, the main functions of the control system will depend on the implementation of the system software. Whether the control system can work normally and reliably is inseparable from the reasonable design of the hardware and the design of the software with complete functions. When designing software, we must first analyze the tasks to be achieved by the software according to the requirements of the control system, and then carry out the overall design of the software, including the overall structure design of the program and the modular design of the program. Divide it into multiple different modules according to the overall function, design, program, and debug separately, and then combine and debug each module to realize all functions of the software.

　　This system software is implemented based on the C language of ATMEGA8L. Among them: the voltage measurement module controls the analog switch by the microcontroller and measures the voltage value of a single battery through the 10-bit A/D module of the microcontroller. In order to improve the accuracy of measurement, the software adopts the software wave filtering method of "sieve average". When measuring the analog quantity of each battery, measure multiple times continuously, then filter out the highest and lowest values, and then average the remaining measurement values to obtain the best measurement results. Then according to the voltage calculation method, the voltage of the battery is obtained. After the voltage measurement is completed, the "bubble sort" program must be run to sort all battery voltages and mark the lowest and highest batteries to serve the balancing module. The charging management module determines the charging stage of the battery through the detected single-cell battery voltage, and uses the pulse width modulation output (pWM) of the microcontroller to control the MOSFET to achieve small current charging in the precharge stage and pulse charging in the sustain charging stage. When it is detected that the battery is fully charged, the charging circuit is automatically disconnected and the charging completed indicator light is illuminated. The charging management module determines whether the battery is working in a normal state through the detected voltage, current, and temperature values. If overvoltage, overcurrent, overtemperature, etc. occur, it will immediately close the charge and discharge circuit through the MOSFET and light up the fault indicator light. The remaining capacity estimation includes detecting the open-circuit voltage and calculating it through the corresponding relationship between the open-circuit voltage and the battery capacity. In addition, it mainly relies on the ampere-hour integration method to integrate the current value detected in real time during charging and discharging, which is generated by the timer of the microcontroller. accomplish. Serial communication uses the USART serial port of the microcontroller to communicate with the RS232 of the PC. In the host PC, the main tasks are to select and control the serial port settings, read and display the collected data, and store the collected data. We chose VC++6.0 to complete the interface design, communication serial port settings and data storage. There are two main methods for developing serial communication programs in VC++6.0:

　　1. Use the MSComm control provided by VC++6.0;

　　2. Use the API functions provided by the specialized Windows SDK.

　　This article uses the MSComm control. The MSComm control is very convenient for serial port programming. Programmers do not have to spend time to understand more complex API functions, they only need to configure the serial port in the properties of the serial port communication resource. The baud rate, data bits, stop bits, parity check, send buffer size, receive buffer size, and timeout settings for serial communication are all configured at this time. After completing the serial port configuration, you can open the serial port and read and write data. It has only one event, the OnComm event. Through event driving, the occurrence of time is tracked and processed, thereby detecting and processing communication errors and processing and displaying data.

　　5. System debugging. The on-site debugging of the system is carried out in the laboratory. The picture below shows the on-site operation experiment of the 18650 battery 10000mah management system. It proves that the system can perform more accurate data sampling. The voltage measurement accuracy can reach 0.05V, which can realize staged charging of lithium batteries. control, SOC estimation is basically reliable. The picture below shows the data display of the circuit board and host computer:

　　6Summary and Outlook

　　This article proposes a design method for a battery management system for the lithium-ion battery pack, the power source of underwater robots. The battery management system can directly detect and manage the entire process of energy storage battery work, including battery charge and discharge process management, battery temperature detection, battery voltage and current detection, power estimation, balance between single cells, battery fault diagnosis, etc. . It meets the requirements in terms of single cell voltage measurement, total voltage, total current, temperature measurement, SOC estimation and other functions. The system inevitably has some shortcomings, and the prospects for further research work are as follows:

　　(1) Add CAN communication module. The CAN (Control Area Network) bus is a serial data communication protocol developed by the German BOSCH company in the early 1980s to solve the data exchange between numerous control and test instruments in modern automobiles. It has real-time It has the characteristics of strong resistance, strong anti-interference ability, simple structure, convenient application and low price, and has certain advantages in fieldbus. A distributed 18650 battery 10000mah management system with a two-level control structure that can manage multiple 18650 battery 10000mah packs simultaneously is formed through the CAN bus. The system uses 1 CECU (central electric control unit) and 5 LECU (local electrical control unit). The schematic diagram is shown in Figure 6-1. 8 lithium batteries are a battery pack, and each battery pack is managed by 1 LECU. This article designs The 18650 battery 10000mah management system only manages one battery pack as one LECU. CECU receives data from each LECU and processes the data. (2) The research on the SOC estimation scheme has not yet reached an ideal state, and needs to be further in-depth and introduce some unconsidered factors that have an impact on SOC into the algorithm, such as: changes in battery capacity caused by battery aging. , the impact of single cells on the battery pack, the impact of temperature and battery capacity on self-discharge, etc.

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