BMS Master Controller (BCU) Reference Design
An illustrative battery cluster control unit (BCU) reference design for the ESS side: it collects voltage / temperature measurements from each BMU over the isoSPI daisy chain, calculates SOC / SOH and controls the main positive / main negative contactors, exchanges charge / discharge limits with the PCS and communicates with in-cluster devices over isolated CAN; the high-voltage-side total voltage and insulation detection have their own isolated supply. Each position is marked with the VOOHU parts available, recommended part numbers and package pinouts.
Illustrative PCB ⇄ Schematic
Illustrative top-side view arranged by functional zone (not the actual layout). Red numbered dots mark positions VOOHU can supply. Click a component on the board, an entry in the index below or a part in the schematic to see recommended parts and package pinouts on the right.
Illustrative isoSPI daisy-chain topology: MCU SPI is converted to differential pulses by isoSPI bridge IC U2; after termination, IP / IM pass the VOOHU BMS isolation transformer T1 (WHS12503A0, dual channel, built-in common-mode choke) to daisy-chain connector J1 and down to the first BMU; the second channel is used for loop-back redundancy. Termination resistor values per the IC manual.
Board bill of materials
Summarized by position; click any row to locate it on the board above.
| No. | Zone | Position | Ref. | VOOHU category | Recommended part | Availability |
|---|---|---|---|---|---|---|
| 01 | A isoSPI daisy chain | isoSPI daisy-chain connector | J1 | — | — | Non-VOOHU |
| 02 | A isoSPI daisy chain | BMS isolation transformer (isoSPI) | T1 | BMS Isolation Transformers | WHS12503A0 | VOOHU |
| 03 | A isoSPI daisy chain | isoSPI bridge IC | U2 | — | — | Non-VOOHU |
| 04 | B CAN (isolated) | CAN connectors ×2 (PCS / in-cluster) | J2 | — | — | Non-VOOHU |
| 05 | B CAN (isolated) | CAN CMC ×2 | L1 | Signal Line Common Mode Chokes | WHAC-3225B-510U0 | VOOHU |
| 06 | B CAN (isolated) | CAN ESD / TVS ×2 | D1 | TVS ESD | WHALD30E2B | VOOHU |
| 07 | B CAN (isolated) | Isolated CAN transceivers ×2 | U3 | — | — | Non-VOOHU |
| 08 | B CAN (isolated) | Push-pull driver + rectifier / LDO | U4 | — | — | Non-VOOHU |
| 09 | B CAN (isolated) | Push-pull isolation transformer | T2 | Push-Pull Transformers | WHST06K02A0 | VOOHU |
| 10 | C High-voltage sensing | Total voltage / insulation detection ADC (high-voltage side) | U6 | — | — | Non-VOOHU |
| 11 | C High-voltage sensing | Digital isolator | U7 | — | — | Non-VOOHU |
| 12 | C High-voltage sensing | Push-pull driver + rectifier / LDO | U5 | — | — | Non-VOOHU |
| 13 | C High-voltage sensing | Push-pull isolation transformer (high-voltage side) | T3 | Push-Pull Transformers | WHST06K02A0 | VOOHU |
| 14 | D Control core | MCU (SOC / balancing strategy / contactor control) | U1 | — | — | Non-VOOHU |
| 15 | E 24 V power | 24 V power connector | J3 | — | — | Non-VOOHU |
| 16 | E 24 V power | Bidirectional input TVS | D2 | TVS ESD | WHTB058VA | VOOHU |
| 17 | E 24 V power | Input power-line common-mode choke | L2 | Power Line Common Mode Chokes | WHAL-7060A-102T0 | VOOHU |
| 18 | E 24 V power | Buck converter (24 V → 5 V) | U8 | — | — | Non-VOOHU |
| 19 | E 24 V power | Buck converter (5 V → 3.3 V / core) | U9 | — | — | Non-VOOHU |
| 20 | E 24 V power | Molded inductors ×2 (DC-DC) | L3 L4 | Molded Inductors | WHYT0630 Series | VOOHU |
Resources & downloads
Board bill of materials
Reference designators, zones, VOOHU categories, recommended parts and availability for all 20 positions. Opens directly in Excel.
Datasheet collection
Datasheet PDFs for the VOOHU parts recommended on this board.
Design files & footprint library
Schematic, PCB, and VOOHU part footprints and 3D models.
Coming soonRequest the BMS master controller (BCU) reference design full package
Includes the full-board position list, datasheets for the recommended VOOHU parts and position-by-position selection notes. For advice tailored to your battery cluster voltage (1000 / 1500 V), BMU count or communication protocol, please include it in your requirements. We reply within 24 hours on working days.
