What functions does the lithium-ion battery BMS battery management system have?

BMS battery management system is commonly known as battery nanny or battery housekeeper, mainly for the intelligent management and maintenance of each battery unit, preventing the battery from overcharging and overdischarging, prolonging the service life of the battery, and monitoring the status of the battery.

 BMS management system is mainly composed of various sensors, actuators, controllers and signal lines. In order to enable new energy vehicles to drive safely on the road and comply with relevant standards and regulations, the BMS management system should have the following functions:

Battery parameter detection

 Including total voltage, total current, single battery voltage detection (to prevent overcharge, overdischarge and even reverse polarity), temperature detection (preferably each string of batteries, key cable joints, etc. have temperature sensors), smoke detection (monitoring electrolysis Liquid leakage, etc.), insulation detection (monitoring leakage), collision detection, etc.

Battery state estimation

 "Includes state of charge (SOC) or depth of discharge (DOD), state of health (SOH), state of function (SOF), state of energy (SOE), state of failure and safety (SOS), etc.

Online fault diagnosis

 includes fault detection, fault type judgment, fault location, fault information output, etc. Fault detection refers to the use of diagnostic algorithms to diagnose fault types through the collected sensor signals, and early warning. Battery failures refer to sensor failures, actuator failures (such as contactors, fans, pumps, heaters, etc.) of various subsystems such as battery packs, high-voltage electrical circuits, and thermal management, as well as network failures, and various controller software and hardware failures. Wait. The failure of the battery pack itself refers to overvoltage (overcharge), undervoltage (overdischarge), overcurrent, ultra-high temperature, internal short-circuit failure, loose joints, electrolyte leakage, reduced insulation, etc.

Battery safety control and alarm

  includes thermal system control, high-voltage electric safety control. After BMS diagnoses the fault, it informs the vehicle controller through the network and requires the vehicle controller to perform effective processing (the BMS can also cut off the main circuit power supply when a certain threshold is exceeded) to prevent high temperature, low temperature, overcharge, overdischarge, and over discharge. Current, leakage, etc. damage the battery and human body.

charge control

BMS has a charge management module, which can control the charger to safely charge the battery according to the characteristics of the battery, the temperature level and the power level of the charger.

Battery balance

 "The existence of inconsistency makes the capacity of the battery pack smaller than the capacity of the smallest cell in the pack. Battery balancing is based on the information of single cells, using active or passive, dissipative or non-dissipative balancing methods to make the capacity of the battery pack as close as possible to the capacity of the smallest single cell.

 Thermal Management

 According to the temperature distribution information in the battery pack and the charging and discharging requirements, determine the intensity of active heating/dissipation, so that the battery can work at the most suitable temperature as much as possible, and give full play to the performance of the battery.

 Telecommunication

 The BMS needs to communicate with network nodes such as the vehicle controller; at the same time, the BMS is inconvenient to disassemble on the vehicle. It needs to be online calibration, monitoring, automatic code generation and online program download without disassembling the shell (program update without disassembling the product) ), etc., the general in-vehicle network adopts CAN bus technology.

Information storage

 is used to store key data, such as SOC, SOH, SOF, SOE, accumulated charge and discharge Ah number, fault code and consistency, etc. The real BMS in the vehicle may only have some of the hardware and software mentioned above. Each battery unit should have at least one battery voltage sensor and one temperature sensor. For a battery system with dozens of batteries, there may be only one BMS controller, or even integrate the BMS function into the main controller of the vehicle. For a battery system with hundreds of battery cells, there may be a master controller and multiple slave controllers that manage only one battery module. For each battery module with dozens of battery cells, there may be some module circuit contactors and balancing modules, and the slave controller manages the battery modules like measuring voltage and current, controls the contactors, balances the battery cells and communicates with the master controller Communication. Based on the reported data, the main controller will perform battery state estimation, fault diagnosis, thermal management, etc.

 Electromagnetic Compatibility

Due to the harsh environment for electric vehicles, BMS is required to have good anti-electromagnetic interference capability, and at the same time, BMS is required to have low external radiation.

 As the monitoring and management center of the power battery pack of new energy vehicles, the BMS management system must dynamically monitor the temperature, voltage, charge and discharge current and other related parameters of the battery pack in real time, and take emergency measures to protect each cell when necessary. Avoid safety issues such as overcharging, overdischarging, overheating, and short-circuiting of the battery pack.

 In addition, the BMS management system must accurately estimate the battery's SOC during the entire life cycle of the battery pack, and feed back key information such as remaining power, driving range, and abnormal faults to the driver in a suitable manner. A suitable way to complete the data exchange function between the system and the vehicle ECU or host computer.