10 vital Battery Management System（BMS）functions

Battery Management System (BMS) is commonly known as battery nanny or battery housekeeper, mainly for intelligent management and maintenance of each battery unit, to prevent the battery from charging and discharge, prolong the service life of the battery, monitor the state of the battery.

The BMS Battery 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 meet the relevant standards and specifications, the BMS battery management system shall have the following functions.

10 Battery Management System functions

Battery Parameter Detection

Including total voltage, total current, single battery voltage detection (to prevent overcharging,over-discharge and even reverse pole phenomenon), temperature detection (best each string of battery, key cable joints all have temperature sensors), smoke detection (monitoring electrolyte leakage, etc.), insulation detection.

Battery Status Estimation

Including the state of charge (SOC) or discharge of depth (DOD), state of health(SOH), state of function (SOF), state of energy (SOE), state of safety(SOS), etc.

Online Troubleshooting

Including fault detection, fault type judgment, fault positioning, fault information output, etc. Fault detection refers to the diagnostic algorithm and early warning. Battery failure refers to the sensor failure, actuator failure (such as contactor, fan, pump, heater, etc.) of the battery pack, high voltage circuit, thermal management subsystem, network failure, various controller hardware and software failure, etc.

The fault of the battery pack itself refers to the over-voltage (overcharge), under-voltage (over-discharge), over-current, ultra-high temperature, internal short circuit fault, loose joint, electrolyte leakage, insulation reduction, etc.

Battery Safety Control and Alarm

Including thermal system control, high-voltage electric safety control. After BMS Battery Management System diagnose the fault, notify the vehicle controller through the network, and require the vehicle controller to be effectively processed (BMS Battery Management System can also cut off the main circuit power after a certain threshold), to prevent high temperature, low temperature, overcharge, over-discharge, over-current, leakage and other damage to the battery and personal.

Charge Control

Battery Management System BMS has a charging management module, which can control the charger to charge the LiFePO4 battery safely according to the battery characteristics, the temperature level, and the power level of the charger.

Battery Equilibrium

The presence of the inconsistency makes the capacity of the battery pack smaller than the capacity of the smallest monomer in the group. Battery equalization is based on the single battery information, using active or passive, dissipated or dissipative or non-dissipative equilibrium methods, so as to make the battery pack capacity close to the minimum single capacity as far as possible.

Heat Management

According to the temperature distribution information in the battery pack and the charge and discharge requirements, the strength of active heating / heat dissipation is determined, so that the battery works at the most suitable temperature as far as possible, and gives full play to the performance of the battery.

Internetwork Communication

Battery Management System BMS needs to communicate with network nodes such as the vehicle controller; meanwhile, BMS is inconvenient to dismantle on the vehicle, including online calibration, monitoring, automatic code generation and online program download (updated without removing the product). The general vehicle network adopts CAN bus technology.

Storing of Information

To store key data, such as SOC, SOH, SOF, SOE, cumulative charge and discharge Ah number, fault codes, and consistency, etc. Real BMS in a vehicle may have only part of the hardware and software mentioned above. Each battery cell shall have at least one battery voltage sensor and one temperature sensor. For battery systems with dozens of batteries, there may be only one BMS controller, or even integrating the BMS functionality into the vehicle’s main controller.For battery systems with hundreds of battery cells, there may be a master controller and several subordinate controllers that manage only one battery module. For each battery module with dozens of battery cells, there may be some module circuit contactors and balance modules, and manage the battery module from the controller as if measuring voltage and current, control the contactors, balance the battery cell, and communicate with the main controller. Based on the reported data, the master controller will perform battery status estimation, fault diagnosis, thermal management, etc.

Electromagnetic Compatibility

Due to the harsh use environment of electric vehicles, BMS is required to have good anti-electromagnetic interference ability, while BMS is required to have small external radiation.

BMS management system as a new energy vehicle power battery pack monitoring management center, must be the battery temperature, voltage and charge and discharge current and other related parameters for real-time dynamic monitoring, when necessary, can take emergency measures to protect the monomer battery, avoid battery pack overcharged, excessive, high temperature and short circuit safety problems.

In addition, Battery Management System (BMS) must accurately estimate the SOC of the battery pack, and timely feedback to the driver about the remaining power, driving range and abnormal fault in an appropriate manner. At the same time, the data exchange function between the system and the vehicle ECU or host computer is completed in an appropriate way.