18650 battery 1800 mah

　　Research and implementation of 18650 battery 1800 mah management system - research purpose and significance

　　1. Overview of 18650 battery 1800 mah management system

　　Since the 1990s, the research and production of lithium batteries have made significant progress, and their applications in various fields have become more and more widespread. Because lithium batteries have the advantages of stable discharge voltage, wide operating temperature range, low self-discharge rate, long storage life, no memory effect, small size, light weight and no pollution, they have gradually replaced lead-acid batteries and nickel-cadmium batteries and become the most popular battery. The mainstream of power batteries. In recent years, lithium batteries have also been used by researchers as power sources for underwater robots and electric vehicles. The management and application of lithium batteries have become one of the key technologies for the development of underwater robots and electric vehicles. The battery management system directly detects and manages 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.:

　　(1) Battery charging and discharging process management: that is, real-time monitoring of temperature, voltage, current and other parameters during battery charging and discharging, and when abnormal conditions are found, promptly disconnect the charging circuit, send out alarm messages and other corresponding processing. (2) Battery temperature detection: that is, the temperature of a single cell of the electric vehicle battery is detected, and the safe temperature parameter range of the battery is set according to the battery type. When the temperature is found to be outside the safe range, corresponding processing is performed, and an alarm message is issued to indicate the problem battery. s position. (3) Battery voltage and current detection: that is, detecting the voltage and current of each battery group, using an algorithm to determine the quality of the battery based on the detection parameters, and estimating the remaining power. (4) Power estimation: that is, the measurement of the remaining power of the battery, and accurate estimation of the state of charge (State of Charge, or SOC) of the power battery pack based on the measured parameters. (5) Balance between single cells: that is, balanced charging of single cells so that each battery in the battery pack reaches a balanced and consistent state. (6) Battery fault diagnosis: Diagnosis is made based on the measured temperature, voltage and other parameters of a single battery compared with its normal parameter range. At present, the difficulty and key of battery management are:

　　(1) How to establish a more accurate mathematical model to determine the remaining energy of each battery based on the collected historical data of voltage, temperature and charge and discharge current of each battery, that is, the SOC state measurement technology of energy storage batteries. (2) Fast charging technology and balanced charging technology for energy storage batteries. This technology is another key technology of battery energy management system that the world is currently researching and developing.

　　2. Current research status of 18650 battery 1800 mah management system

　　Research status of foreign battery management systems

　　As the research and use of electric vehicles has continued to heat up in the past decade, some large foreign automobile manufacturers and battery suppliers have conducted a lot of research and experiments on various batteries, summarized mathematical models of batteries, and successfully developed many battery management systems. The system is installed in the car for trial use. The more representative ones include: the BADICHEQ system and the BADICOaCH system designed by Germany's Mentzer Electronic GmbH and Werner Retzlaff; the BATTMAN system designed by B. Hauck of Germany; the battery management system on the electric vehicle EV1 produced by General Motors of the United States; and the battery management system developed by the American Aerovironment Company. SmartGuard system (Long-LifeBatteryUsingIntelligentModularControlSystem); a high-performance battery management system called BatOpt developed by the American ACpropulsion company. 1. BADICHEQ system and BADICOaCH system The BADICHEQ system was designed in 1991, led by Mentzer Electronic GmbH and Werner Retzlaff, and was first installed in a vehicle for testing in December 1991. After continuous experiments and modifications, it achieved the following functions in April 1992:

　　●Can measure the voltage of 20 battery units at the same time;

　　●Can measure current and temperature;

　　●Can control the charging current of the main charger according to the battery unit;

　　●Can use a small charger to balance charge a single battery;

　　●Can store historical data and communicate with PC;. The remaining power of the worst battery unit, battery current, actual battery power and various abnormal alarms are displayed on the instrument panel. BADICOaCH is an improvement of the BADICHEQ system. It has the following features:

　　●One of its most important features is to add a non-linear circuit (WLC) to each battery cell to measure the voltage, and transmit the voltage of the eight cells of a battery pack to the BADICOaCH system through a signal line, where it decoding;

　　●Equipped with two pWM signal output lines to control the charging current and voltage;

　　●The remaining power of the worst battery unit is displayed;

　　●Provide over-discharge protection for the worst battery unit and give a signal to stop using it;

　　●Storage detailed data of the last 24 charge and discharge cycles and allows quick search of basic battery information and incorrect usage when judging the quality of the battery;

　　●Data transmission with PC machine adopts RS232 standard.

　　2. BATTMAN system The BATTMAN battery management system designed by B.Hauck of Germany emphasizes the management of all different models of power battery packs into one system. By changing the hardware jumpers and adding selection parameters to the software, Realize the management of different types of battery packs. The reason for this is that the management of different models of battery packs can be divided into common parts and special parts. And the common parts account for a large proportion. He believes that these common parts are:

　　●Determine the current energy that the battery can store;

　　●Determine the remaining power of the weakest battery unit;

　　●Can affect battery operation and data recording;

　　●Measurement of temperature.

　　3. EV1 battery management system The EVl electric vehicle launched by General Motors is powered by 26 lead-acid batteries, with a discharge depth of 80%. The battery life is 450 deep discharge cycles and an urban driving range of 113 kilometers (U.S. Environmental Protection Agency indicator, USAEpASchedule ), 145 kilometers of highway mileage (U.S. Environmental Protection Agency indicator, USAEpASchedule). The concept definition of EV1’s battery management system includes four components:

　　●Battery modules (for car drives and other power systems);

　　●Software BpM (BatterypackModule);

　　●Battery pack thermal system;

　　●Battery pack high voltage power outage protection device (HighVoltageDisconnect). It can be seen that the core of EVl's battery management system is BpM. BpM has the following functions:

　　●Single battery voltage monitoring;

　　●Battery pack current shunt sampling;

　　●Battery pack high voltage protection (fuse);

　　●Six thermistors for temperature sampling;

　　●Control charging based on the average characteristics of the battery pack;

　　●Over-discharge alarm and reduce the driving performance of electric vehicles;

　　●Battery or mileage calculation;

　　●High voltage return relay (HighVoltageBusRelays).

　　Generally speaking, EVl's battery management system is different from battery management systems in the general sense. It focuses the system on the reliability of the battery pack (SafetyFeatures).

　　The reliability measures of EVl battery management system are:

　　●Battery pack high voltage power outage protection device;

　　●Manual power off switch;

　　●Ground insulation failure detection;

　　●Automatic switch and manual switch are interlocked. 4. SmartGuard system The main feature of this system is that a distributed management device (using a special IC) is installed on the battery to measure the voltage and temperature of the battery. It can also activate the current bypass circuit when a signal comes from the main control component. The main functions of SmartGuard are:

　　●Overcharge detection and prevention of overcharge;

　　●Provide discharge polarity reverse alarm;

　　●Battery history and archiving;

　　●Provide the remaining power information of the worst battery unit. 5. BatOpt system This system consists of a monitoring module on each battery and a central control unit to form a distributed system. Through the two_wire bus, the monitoring module reports battery voltage, temperature and other information to the main control unit. After collecting the single battery information, the main control unit provides manual and automatic charging strategies. It has the following characteristics:

　　●Each module provides 5 amps of equalizing current;

　　●The module has temperature monitoring;

　　●two_wire bus interface. 6. Battery management system in the deep sea field. With the widespread application of lithium batteries in deep sea fields such as submarines and underwater robots, some scientific research institutions and battery suppliers have successfully developed battery management systems suitable for application in the deep sea field. For example, the 18650 battery 1800 mah management system developed by Bruce M. Howe and others for the MARS ocean observation system. The system's monitoring unit reports the battery's state of charge to the upper-level control unit. When the battery needs to be replaced, it notifies the upper-level control unit to return to the dock to replace the battery. The monitoring unit manages the voltage, current, temperature and other information of the battery. Through these data, the following functions can be achieved:

　　●Temperature protection function, charging can only be carried out between 0~45ooCC;

　　●Over-current protection function, the charging current is lower than 0.7C (C is the battery capacity);

　　●Short circuit protection function;. Battery pack high voltage protection (fuse);

　　●Overcharge protection function, stops charging when the single battery voltage exceeds 4.3V;

　　●Over-discharge protection function, stops discharging when the single battery voltage is lower than 3.2V;

　　The 18650 battery 1800 mah management system developed by phoenix for the Navy's unmanned underwater robot adopts a three-level distributed design and is managed at three levels: single battery, battery module and battery pack. Each single battery has the lowest level control unit to protect the single battery from charge and discharge. Battery modules can be connected in series or parallel to form a battery pack according to voltage or current requirements. The three levels read the working data of each battery in real time through network connection, and control the work of each battery and battery pack in real time. This battery management system enables the following functions:

　　●Short circuit and overload protection function;

　　●Overcharge and over-discharge protection function;

　　●Automatically restart within 1 second after failure;

　　●Single battery shutdown function, after shutting down the faulty battery, the remaining batteries in the system can still work normally;

　　●Real-time reporting function of voltage, current and temperature;

　　●Over-temperature protection function, a single battery will automatically shut down when it exceeds 135℃;

　　The battery management system is shown in the figure below:

　　Current research status of domestic battery management systems

　　Domestic battery management systems for electric vehicles are still in their infancy. At present, it is mainly some universities that rely on their own scientific and technological advantages to jointly carry out research with some large automobile manufacturers and battery suppliers, such as Tsinghua University, Beijing Institute of Technology, Tongji University, Beijing University of Aeronautics and Astronautics, etc., and have achieved fruitful results. Results: Tsinghua University developed a battery management system for the EV-6580 light electric bus. During driving, the battery's charging and discharging current, voltage and other parameters can be measured and monitored in real time to prevent overcharging and over-discharging, improving battery life and efficiency. At the same time, a charging system has been developed to match this system.

　　The main functions of the lithium-ion battery management system of Tongji University and Beijing Xingheng Battery Co., Ltd. are:

　　Collection of current, voltage and battery module temperature, SOC estimation, automatic balancing, accident handling and recording, etc.

　　The main functions of the nickel-metal hydride battery management system developed by Beijing Special Aeronautical University are:

　　Collection of current, voltage and battery box temperature, SOC estimation, operating status judgment and protection functions, etc.

　　The main functions of Chunlan Research Institute’s HEV-BMS are:

　　Collection of current, voltage and battery box temperature, SOC estimation, automatic balancing, battery fault diagnosis and safety protection.

　　The battery management system developed by Wang Jianqun of Beijing Institute of Technology and others for pure electric vehicles uses a single-chip microcomputer as the core and adopts a distributed network control system structure, which can detect various operating parameters of the power battery in real time:

　　Battery SOC, total voltage, total current, single module voltage, and characteristic temperature inside the battery pack;

　　It can perform fault diagnosis and alarm based on battery status, and also has thermal management functions;

　　The system parameters are calibrated through PC and communicate with other systems of the vehicle through CAN bus to achieve information sharing.

　　The system has been installed on the BK6121EV pure electric bus. It can effectively manage the limited energy of electric vehicles, maximize the efficiency of electric vehicles, estimate the remaining power of the battery pack and the vehicle's driving range, detect single cells and battery packs, and control the temperature of the battery pack, energy consumption of motors and air conditioners. The power distribution of components, etc.; and solves problems such as fault diagnosis, high-voltage safety, charging communication interface, extending battery life, and improving the reliability of electric vehicles during the operation of electric vehicles. The battery management system developed by Jiang Lijun of Northern Jiaotong University and others is the research result of a major special sub-project of electric vehicles under the National 863 Program. The system uses a microcontroller to collect battery charging and discharging information. The collected information includes real-time charging and discharging current, voltage, and temperature. All the information of the total and single battery packs are analyzed and summarized by the management software of the microcontroller to find the charging and discharging modes required for faulty batteries and battery packs in the most reasonable and optimized way, thereby deciding which method to use for charging and discharging. The execution of the decision is automatically completed by a set of power four-quadrant inverters. The four-quadrant inverter can charge forward or reversely to invert the power in the battery and feed it to the grid. In this way, the battery can often discharge the charge, erase the memory, and "exercise" the capacity to achieve the effect of extending the battery life. The high-power and high-capacity lithium power batteries developed and produced by Shenzhen Leitian Company are widely used in the deep sea field. They are used by researchers as the battery pack power source for the main thrusters of special tourist and conventional submarines. The supporting battery management system developed by Leitian Company for lithium power batteries has the following characteristics:

　　●The battery management system consists of a management host (CpU), voltage and temperature acquisition module, current acquisition module and communication interface module.

　　●Can detect and display the total voltage, total current, and reserve capacity of the battery pack; the voltage of any single cell and the temperature of the battery box; the highest and lowest single cell voltage and battery number, the highest and lowest temperature, and the charging status of the battery pack. Discharge amount.

　　●The host also provides alarm and control output interfaces to provide alarm and control output for overvoltage, undervoltage, high temperature, low temperature, overcurrent, short circuit and other extreme conditions.

　　●Provides RS232 and CAN bus interfaces, which can directly read all information on the battery management system on the computer. As a powerful guarantee for the safe use of batteries, this battery management system enables the battery to be in a safe and controllable charging and discharging process at all times, greatly improving the cycle life of the battery in actual use. The battery management system is shown in the figure below:

　　3. Research content of this article

　　BookThis article proposes a design method for a 18650 battery 1800 mah management system for the 18650 battery 1800 mah pack, the power source of underwater robots. The 18650 battery 1800 mah 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, battery estimation, balance between single cells, battery fault diagnosis, etc. aspect. The main content of this article includes the following parts:

　　The first chapter analyzes the working principle, working characteristics and issues that should be paid attention to during the charging and discharging process of lithium batteries. Chapter 2 analyzes the factors that affect the remaining capacity of the battery. Based on the analysis and comparison of several estimation methods currently mainly used at home and abroad, the SOC estimation method used in this system is further studied, that is, the combination of open circuit voltage and power accumulation. Methods. Chapter 3 analyzes the hardware implementation of the 18650 battery 1800 mah management system, and analyzes the working principles and circuit implementation of the processor, data acquisition module, charging control module, balancing module, data display and serial communication in detail by functional modules. Chapter 4 analyzes the software implementation of the battery management system through the software block diagram, and conducts a detailed analysis of each software implementation unit. Chapter 5: System debugging and running results of the battery management system. Chapter 6 summarizes the work and gives an outlook on the next key research content.

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