Working principle and function of BMS system: It is a system used to monitor and control 48v lithium batteries. Effective management and maintenance are carried out for single battery to avoid overcharge and overdischarge of the battery, so as to improve the service life of the battery, and the operating condition of the battery is monitored. At the same time, adjust the collected data to maximize the performance of the 20kwh lithium battery.
Working principle of lithium battery protective cover:
The performance of 20kwh lithium battery depends on its own characteristics. Because of its own material, it cannot be overcharged, over discharged, over current, short circuit or over limit.
Because of charging and discharging, 48v lifepo4 powerwall lithium batteries always have a delicate protective plate and a current fuse. The lithium battery in the BMS system generally includes a protection circuit
The panel is composed of PTC, NTC and other components. The protection panel includes real-time monitoring of battery voltage and charging at - 40~+85 ℃.
Release the circuit current, and timely open and close the current circuit; PTC can effectively avoid serious damage to the battery at higher temperatures.
A simple conventional 18650 lithium battery pack protection board, generally including control IC, MOS switch, resistor, capacitor and auxiliary equipment FUSE, PTC, NTC, ID, memory, etc. Internal control
IC, under all working conditions, controls the MOS switch on to make the cell and the external circuit connected, and immediately controls when the cell voltage or loop current exceeds the predetermined value. The metal oxide switch is made to ensure the safety of the electric core.
If the protection board is normal, then Vdd is high, Vss, VM is low, DO and CO are high, and when any of Vdd, Vss, and VM changes, DO and CO are high. Or the level of CO end will change.
1. Overcharge detection voltage: under normal conditions, Vdd gradually increases to the voltage between high level and low voltage VDD-VSS at CO terminal.
2. Overcharge release voltage: during charging, Vdd decreases gradually, CO terminal changes from low to high, and the voltage between VDD-VSS changes.
3. Overdischarge detection voltage: under normal conditions, Vdd decreases gradually, and the voltage changes between VDD and VSS from high level to low level.
4. Overdischarge release voltage: Vdd increases gradually under the over discharge state, and the voltage between VDD-VSS changes from low to high at DO terminal.
5. Detection voltage of overcurrent 1: VM gradually rises to DO from high level to low level under normal conditions.
6. Detection voltage of overcurrent 2: under normal conditions, VM starts from OV, the rise rate of VM is greater than or equal to 1 ms or less than 4 ms, and the voltage between VM-VSS and DO terminal changes from high level to low level.
7. Load short-circuit detection voltage: under normal conditions, VM starts to rise at OV, its rate is greater than or equal to 1 μ S, less than or equal to 50 μ S, while the DO terminal changes from high level to low level, and the voltage between VM-VSS
8. Charger detection voltage: under the condition of over discharge, the voltage of VM decreases gradually, and the DO changes from low level to high level.
9. Current loss during normal operation: Generally, the current flowing at VDD terminal (IDD) is the loss during normal operation.
10. Overdischarge loss current: during discharge, the IDD through the VDD terminal is the overcurrent loss current