Libre Solar Community Forum

BQ76952 - High Voltage System

I will design an energy storage system using BQ76952. 5 Slave cards and 1 Master card will be in the system. Each slave card will balance the 51.2V 100A system. These systems will be connected in series with each other. 256V in total.
Slave cards will contain Mcu to communicate with the Master. Recommended protection circuits will not be on the board.
The master will manage this system connected in series. There will be circuit breaker contactors, precharge circuit, charge/discharge circuits and a current sensor to measure the current passing through the system. It will also collect all the information by communicating with the Slave cards. It will activate circuit breakers, charging circuits etc. when necessary.

The proposed design of the BQ76952 device includes additional circuits such as protection circuits, precharge circuits and charge/discharge circuits. Some ICs do not include these designs (usually daisy chain designs). I will simplify the BQ76952 circuit like them.

So in my design I want to make all these circuits on the Master. I do not want to make CHG, DSG, PDSG connections on the slave cards I use BQ76952. I want to read these outputs of BQ76952 device with MCU. Thus, I want to transmit the data to the Master and activate/deactivate the relevant circuit over the Master.

I am sharing a simple block diagram (I drew 3 Slaves as a representation). The red crossed mosfets are the part that I will remove from the slave card.

In short, when I remove the protection circuits etc in the BQ76952 recommended circuit, will the device work normally? Or does it have to be FET connections (CHG, DSG PDSG)?

Thanks in advance.

You can use the bq75952 just for cell monitoring and balancing and ignore the FET driving capabilities. However, I would not recommend it. This IC is not meant to be used for HV packs and you would have to develop the galvanically isolated communication yourself. Why not take a chip that has the daisy-chain communication on-board, like the LTC68xx chips?

There was only BQ76952 when buying the BMS chip. We need 16S battery management.That’s why we bought the BQ series.
In terms of price, it is very advantageous than other chips.