Lithium battery protection board, introduction to the balancing principle of lithium battery protection board. What is the principle of lithium battery protection board? The lithium battery protection board is to protect the charge and discharge of the series-connected lithium battery pack. The principle of the lithium battery protection board is to prevent overcharge and over-discharge (limit the current), and play a protective and safe role in the battery. Ordinary lithium battery protection boards usually include control IC, MOS switches, resistors, capacitors and auxiliary devices FUSE, PTC, NTC, ID, memory, etc. In this article, the editor will introduce the balancing principle of lithium battery protection board. I hope it will be helpful to you.

　　The composition of lithium battery:

　　Lithium batteries are mainly composed of two large parts, the battery core and the protective plate PCM. The battery core is equivalent to the heart of the lithium battery, and the BMS management system is equivalent to the brain of the lithium battery. The battery core is mainly composed of positive electrode material, negative electrode material, electrolyte, diaphragm and casing, while the protective board is mainly composed of protection chip (or management chip), MOS tube, resistor, capacitor and PCB board.

　　What is a lithium battery protection board?

　　The lithium battery protection board is to protect the charge and discharge of the series-connected lithium battery pack; when fully charged, it can ensure that the voltage difference between each single cell is less than the set value, achieving even charging of each single cell of the lithium battery pack, effectively improving It improves the charging effect in series charging mode; simultaneously detects the overvoltage, undervoltage, overcurrent, short circuit, and overtemperature status of each single cell in the battery pack to protect and extend the service life of the battery; undervoltage protection ensures that each single battery Avoid battery damage due to over-discharge during discharge use.

　　Lithium battery protection board, as the name suggests, is used to protect lithium batteries. The function of the lithium battery protection board is to protect the battery from discharge, charge, and current, as well as output short-circuit protection.

　　Lithium battery protection function:

　　Ordinary lithium battery protection boards usually include control IC, MOS switches, resistors, capacitors and auxiliary devices FUSE, PTC, NTC, ID, memory, etc. The protection function of lithium batteries is usually completed by a protection circuit board and current devices such as PTC. The protection board is composed of electronic circuits and can accurately monitor the voltage and charge return circuit of the battery core at all times in an environment of -40°C to +85°C. Current, timely control the on and off of the current loop; PTC prevents severe damage to the battery in high temperature environments.

　　Detailed analysis of the principle of lithium battery protection board:

　　All lithium batteries require a protection circuit to effectively monitor the charging and discharging status of the battery, and to shut down the charging and discharging circuit under certain conditions to prevent damage to the battery. When the protective board is normal, Vdd is high level, Vss and VM are low level, DO and CO are high level. When any parameter of Vdd, Vss and VM changes, the level of DO or CO terminal will change. The principle is as follows:

　　1. Overcharge detection voltage: Under normal conditions, Vdd gradually increases to the voltage between VDD and VSS when the CO terminal changes from high level to low level.

　　2. Overcharge release voltage: In the charging state, Vdd gradually decreases to the voltage between VDD and VSS when the CO terminal changes from low level to high level.

　　3. Over-discharge detection voltage: Under normal conditions, Vdd gradually decreases to the voltage between VDD-VSS when the DO terminal changes from high level to low level.

　　4. Over-discharge release voltage: In the over-discharge state, Vdd gradually rises to the voltage between VDD-VSS when the DO terminal changes from low level to high level.

　　5. Overcurrent 1 detection voltage: Under normal conditions, VM gradually rises to the voltage between VM and VSS when DO changes from high level to low level.

　　6. Overcurrent 2 detection voltage: Under normal conditions, VM rises from OV at a speed of more than 1ms and less than 4ms to the voltage between VM and VSS when the DO terminal changes from high level to low level.

　　7. Load short circuit detection voltage: Under normal conditions, VM starts from OV and rises to the voltage between VM and VSS when the DO terminal changes from high level to low level at a speed of more than 1μS and less than 50μS.

　　8. Charger detection voltage: In the over-discharge state, VM gradually drops from OV to the voltage between VM and VSS when DO changes from low level to high level.

　　9. Current consumption during normal operation: Under normal conditions, the current flowing to the VDD terminal (IDD) is the current consumption during normal operation.

　　10. Over-discharge current consumption: In the discharge state, the current (IDD) flowing through the VDD terminal is the over-discharge current consumption.

　　Introduction to the balancing principle of lithium battery protection board:

　　Lithium battery protection board balancing principle Commonly used balancing charging technologies include constant shunt resistance balancing charging, on-off shunt resistor balancing charging, average battery voltage balancing charging, switched capacitor balancing charging, buck converter balancing charging, inductor balancing charging, etc. When charging a group of lithium batteries in series, each battery should be charged evenly, otherwise the performance and life of the entire battery group will be affected during use. However, the existing single-cell lithium battery protection chips do not contain the balanced charge control function. The balanced charge control function of the multi-cell lithium battery protection chip requires an external CPU; it is realized through serial communication with the protection chip (such as I2C bus), which increases the This increases the complexity and design difficulty of the protection circuit, reduces the efficiency and reliability of the system, and increases power consumption.

　　According to the needs of the application, the balancing principle of lithium battery protection board can realize protection and equal charging of power lithium battery packs of any structure and voltage level after changing the protection chip model and series number, and the power level of switching devices and energy consumption components in the circuit. .

　　As a kind of battery with relatively large power reserve, lithium batteries are used in various computer rooms, communication base stations, data centers and other fields. The lithium battery protection board has the function of protecting the battery and preventing the battery from overcharging. The above is the editor’s brief introduction to the functions of the lithium battery protection board. I hope that everyone must pay attention to whether the quality of the lithium battery protection board is intact when using or purchasing lithium batteries.

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