Electronics for Battery-Management-Systems
The image above shows the simplified schematic/block diagram of a battery-management-system with its main electronic components for cell balancing. The battery is implemented as a set of energy cells connected in series. For charge balancing every cell has a current bypass made of a resistor and a transistor. During charging the BMS- or balancing-IC controls these transistors in a way that cells with a fuller charge are temporarily bypassed and discharged and the rest of the cells can catch up. This is called passive balancing. The BMS-ICs and a microcontroller are part of a daisy-chain loop for communication. Since the electric potential of each BMS-IC is different in the chain of energy cells they have to be galvanically isolated from each other. Electronic components like capacitors, transformers, opto-couplers or RF-devices perform galvanic isolation. Current sensing is in the upper left corner. Fuses protect the battery against overcurrents, see upper right corner.
Energy Cells
Rutronik is an officially franchised sales partner of Samsung SDI, the market leader in Li-Ion cells. Please find EDLCs from various manufacturers in our webshop Rutronik24.
BMS or Balancing-IC
Rutronik carries BMS-ICs from Infineon and STMicroelectronics. ROHM’s BMS-IC balances batteries made of Electric Double Layer Capacitors (EDLC).
- Infineon, TLE9012
- STMicroelctronics, L9963, automotive qualified, for up to 14 Li-Ion cells, up to 7 NTC temperature sensors, ISO 26262 compliant, ASIL-D ready
- ROHM, BD14000, automotive qualified, for up to 6 EDLC
Fuses
For safety reasons the string of energy-cells is protected against overcurrents and short circuits. Protection devices can be semiconductor fuses i. e. lead fuses for the protection of semiconductors, pyro fuses or electronic fuses with power semiconductors as switches.
Current Sensing
- Precision power chip resistors or Power Metal Strip® shunt resistors from Vishay
- Magnetic current sensors from Micronas (TDK) and Melexis
- Current sense amplifiers from STMicroelectronics
Microcontrollers
CAN-Transceivers
| Supplier | Type | Features |
| Infineon | TLE925x | CAN-FD up to 5 Mbit/s |
| Infineon | TLE725x | CAN-FD up to 2 Mbit/s |
| Infineon | TLE625x | CAN up to 1 Mbit/s |
| BOSCH | CF1xx | CAN up to 1Mbit/s |
Galvanic isolation
- Automotive opto-couplers from Toshiba and Vishay
