What is battery module?
Battery module are intermediate products between battery cells and battery packs. We can understand a battery module when multiple battery cells are package together in the same housing frame. And connected to the outside through a uniform boundary.
Cells, batteries modules and battery pack are different forms of batteries at different application stages. The smallest of these units is a battery cell, several cells can form a module. And several battery modules can form a battery pack by adding a battery management system ( BMS ).
Why use battery modules instead of directly using cells?
●Usually, the voltage of the battery pack of an electric vehicle is very high, which requires more batteries. So the battery modules are usually composed of battery cells in series and parallel. If there is a problem with one battery, it will render the whole battery unusable. And it is very troublesome to replace the battery in this case. Therefore,the design in the form of a battery modules to effectively avoid the situation where one cell broken and the entire battery pack cannot used.
●Designing the form of the battery pack can modularize and standardize the entire battery. It can effectively improve the overall structural strength, improve the heat dissipation efficiency, and reduce the risk of thermal runaway.
●Standardized modules, which can facilitate the advantages of standardized production and installation and fixation. Modular production, easy to weld, module transportation, improve production efficiency. And improve the structural strength between cells, and have good vibration resistance.
What role does the battery modules play in the power system?
As has been noted, the battery modules is the intermediate state of the lithium battery pack. Several modules plus a protective plate can form a battery. The battery modules has the function of supporting, fixing and protecting the cells. But the modular design is convenient for transportation. Facilitates battery cooling. Improve production efficiency and improve the structural strength between cells.
Products and reference designs of Multimodule battery with CAN
Insulation resistance detection
This subsystem contains MCU, ADC, solid-state relay and isolated CAN interface. The MCU switches on/off the solid-state relays to calculate the insulation resistance of the rack or container to detect insulation failure. Insulation resistance detection includes Arm Cortex-M0+ MCUs、Digital isolators、Transformer drivers、Isolated amplifiers、CAN transceivers、Precision ADCs、General-purpose op amps、Solid-state relays, the corresponding products are MSPM0G3507、ISO7721、SN6501-Q1、AMC3330、TCAN1057A-Q1、ADS1115、TPSI2140-Q1
Communication
This subsystem includes several isolated communication interfaces and ESDs. The most popular communication includes CAN, RS-485 and Ethernet. Communication interfaces between on-board MCU and system. Communication includes Isolated CAN transceivers、Digital isolators、Isolated RS-485 transceivers、CAN transceivers、ESD protection diodes, the corresponding products are ISO1042、ISO6521、ISO1410、TCAN1057A-Q1、TPD4E001-Q1
High voltage monitoring unit
This subsystem includes current sensing, ADC and amplifier to monitor rack current and bus voltage information that can be replaced with UIR to allow for a more compact and easier system. Solid-state relays are used to monitor the insulation resistance at battery side. High voltage monitoring unit High voltage monitoring unit Battery monitors & balancers、Digital power monitors、Analog current-sense amplifiers、Precision ADCs, the corresponding products are BQ79718-Q1、INA229、INA240-Q1、ADS1118
Auxiliary power supply
This subsystem includes DC/DC buck converter, isolated DC/DC converters and LDOs. It supports stable power supply for MCU, communication interface, measurements and other bias supply needed devices. Auxiliary power supply includes Linear & low-dropout (LDO) regulators、Isolated DC/DC converters & modules、Transformer drivers, the corresponding products are TPS7A24、UCC12050、SN6505B
Battery control unit
This subsystem includes MCU and related devices to secure MCU runing as expected. It also has isolated CAN to talk with BMUs and isolators/bridge interfaces to talk with RMU. It reads battery infomation and calculates the SOX information. The MCU also handles the whole system control, including cell-balancing and charge/discharge control. Battery control unit includes Battery monitors & balancers、Supervisor & reset ICs、High-side switches、Digital isolators、Isolated CAN transceivers、CAN transceivers、Real-time clocks (RTCs) & timers, the corresponding products are BQ79616、TPS3823、TPS4H160-Q1、ISO7721、ISO1042、TCAN1057A-Q1、BQ32000
Battery data monitoring
This subsystem includes AFE, protector, temperature and humidity senser and TMUX. It is responsible for monitoring the voltage and temperature of each single cell including the humidity and temp of the pack. It also alerts the system if any faults are detected. Battery data monitoring includes Battery monitors & balancers、Load switches、Thermistors, the corresponding products are BQ79616、TPS22810、TMP61
Battery data communication
This subsystem includes isolated CAN interfaces, MCU, isolators or bridge interfaces for the communication transfer from daisy-chain/SPI to isolated CAN. It sometimes integrates isolated power to avoid too much power pulled from each pack. Battery data communication includes Arm Cortex-M0+ MCUs、Battery monitors & balancers、Linear & low-dropout (LDO) regulators、Digital isolators、Transformer drivers、CAN transceivers, the corresponding products are MSPM0G3507、BQ76972、TPS7A24、ISO7721、SN6501-Q1、TCAN1042HGV-Q1
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