What is a battery management system?
Battery Management System
From Wikipedia’s definition:
A Battery Management System (BMS) is any electronic device thatmanages A rechargeable Battery (cell or Battery pack), suchas by
Monitoring its state, evaluating secondary data, reporting that data, caring it, controlling its environment, and 1 or balancing it.
The battery management system is an electronic device capable of monitoring and managing the battery. By collecting and calculating the parameters such as voltage, current, temperature and S0C, the charging and discharging process of the battery is controlled, so as to protect the battery and improve the comprehensive performance of the battery.
Why do Wisdom Power lithium batteries need BMS?
Safety requirements:
The downside of Wisdom Power lithium batteries is that they are “delicate” and can be permanently damaged by a single discharge.
In extreme cases, a lithium-ion battery can overheat or overcharge, causing the heat to go out of control, rupture or even explode.
BMS is needed to strictly control the charging and discharging process to avoid over-charge, over-discharge and overheating.
Functional requirements:
During the use of lithium battery, it is necessary to know the S0C parameters of the battery and predict the battery’s remaining power through SOC.
BMS can calculate the S0C of lithium battery in real time to meet customer application needs.
Large capacity potassium battery has obvious inconsistency, which will affect the charging and discharging capacity and cycle life of the battery.
BMS can improve the inconsistency and improve the overall performance of lithium battery through balance.
The battery will have different performance at different temperatures, and the best working temperature of lithium ion battery is
25 ~ 40 ° C.
The change of temperature will change the battery’s SOC, open circuit voltage, internal resistance and available power, and even affect the battery’s service life.
BMS can control the ambient temperature of the battery and improve the battery performance.
The nature of overfilling and overfilling
Wisdom Power lithium batteries charging and discharging process
★ During charging, the lithium ions are removed from the positive plate and embedded into the negative plate by electrolyte.
★ During discharge, the lithium ions are removed from the negative plate and embedded into the positive plate by electrolyte.
★ The charging and discharging process of li-ion battery is the process of li-ion embedding and debonding on the plate.
★ During charging, the volume of the positive electrode material will shrink with the slipping of lithium ions.
★ When discharge occurs, a certain amount of expansion of the positive electrode material will occur with the insertion of lithium ions.
★ When overcharged, the anode lattice collapses, and lithium ions in the cathode form dendrites that puncture the diaphragm, causing battery damage.
★ When overdischarge, the positive electrode material becomes less active, preventing lithium ions from embedding, and the battery capacity drops sharply.
★ If the positive electrode material expands excessively, it will also damage the physical structure of the battery and cause damage to the battery.
Wisdom Power lithium batteries Basic functions of BMS？
★ Single battery voltage acquisition;
★ Temperature collection of single battery;
★ Battery current detection;
★ Calculation of cell/battery S0C;
★ Evaluation of battery SOH;
★ Charge-discharge equalization function;
★ Insulation detection and leakage protection;
★ Thermal management control (heat dissipation and heating);
★ Key data recording (circular data, alarm data);
★ Battery fault analysis and on-line alarm;
Communication function (able to communicate with charging machine, motor controller, etc.)
Wisdom Power lithium batteries BMS Schematic composition
★ As shown in the figure, it adopts Master Slave structure and contains a Master controlMultiple slave controls, each slave control D0 0 CAN manage more than 60 batteries.
★ The master control communicates with the charger and the vehicle controller through the external CAN bus, and the master control communicates with the handheld device through RS232, the master slaveThrough the internal CAN bus I 011 0002…IOIIN cascade.
★ Voltage collection, temperature collection and thermal management can be realized from controlFunctions such as testing and communication with other equipment
Wisdom Power lithium batteries BMS topology—Distributed
★ Definition: the functions of voltage, temperature collection and equalization are distributed to each battery and communicate with the main control through the bus.Slav
★ Definition: the functions of voltage, temperature collection and equalization are distributed to each battery and communicate with the main control through the bus.Slav
★ Cons: every battery needs a bugBlock control board, easy installation and high cost
Wisdom Power lithium batteries BMS topology centralized
★ Definition: all functions such as voltage, temperature collection and equalization are completed by the master control (uncontrollable). The master control and the battery have no bus communication and direct lead
★ Pros: simple design and construction
★ Disadvantages: long connection, many connection,Low reliability, not too much battery management.
★ Definition: one main and multiple slave structure, voltage, temperature acquisition and equalization functions
★ Pros: no need to install control board on each battery, flexible connection;From control close to the battery, avoid too long connection;To facilitate
★ Disadvantages: communication isolation between master and slave should be considered. Communication is diversified and control is complex
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