Cell Balancing issue on S32K144 EVK board

[thailivenkatesh]

Hi,

      I am working on Passive Cell balancing feature on S32K144 EVK board. I have modified the S32K144 EVK board to support 12 CELL configuration (Followed the design – AN12536, Figure 4, Filter type C – Full population). And below are the HW and SW details.

Development/HW Setup Details:

Charger – 43.8 DC @ 3.0 A

Resistive Load   - To discharge the CELLs

Battery Pack – 12 LFP CELLS (6Ah)

Test Scenarios and Observations:

Cell 1 Voltage | 3507 mV  increased to 3521 mV 

IDLE (No Load and No Charge):- Cell balancing applied on CELL 1 and could see voltage dissipation.

CHARGING (CHARGER Connected):- Cell balancing applied on CELL 1, no voltage dissipation instead observed CELL is getting charged

Multiple CELLS Balancing (No Load and No Charge):- Cell balancing applied on two CELLs simultaneously on CELL 1 and CELL 8 but no voltage dissipation on both the CELLS.

attached the Cell balancing output data. Please support to resolve this issue  of  how to  do proper cell balancing.

Thanks & Regards

venkatesh

[thailivenkatesh]

Hi JozefKozen,

we enabled CB_DRVEN bit for cell balancing  to activate.
CBx_CFG[CB_TIMER] enabled As an action, this only turns on the MOSFET connected to the balancing resistor but we are getting voltages on all balancing resistors and all  MOSFETs on. Applied cell balancing on only one cell  but why all MOSFETs are on.please support this issue to solve the problem.

[thailivenkatesh]

Hi JozefKozen,
                          Having BCC software driver for MC33771C from elektronika sales and changed the code to meet the requirements and applied cell balancing as per the MC33771C document procedure for individual cell to check the status but cell voltage doesn't change and why i am getting CB_SHORT as logic 1 and driver is off is it related to cell balancing problem or any hardware issues or any register settings required.

Thanks & Regards

venkatesh

[JozefKozon]

Dear Venkathes Thaili,

thank you for your answer. Please download MC33771C/MC33772C Evaluation GUI from this link and please download the MC33771C software from the docstore. If both will work you can eliminate the hardware issue and there is an issue with the adjusted code. 

I would also recommend you to purchase the 14-Cell Battery Pack Emulator to eliminate the hardware issue. Then you can focus on the software.

With Best Regards,

Jozef

[thailivenkatesh]

Hi  JozefKozen,

                          We have got the BCC Driver from your Distributor (Electronika)   already have the NDA with NXP(NDA# 97496) and we are testing the CB using LFP battery pack. Could you please explain when this will set and how to handle this to continue the cell balancing for defined time.

Thanks & Regards

venkatesh

[JozefKozon]

Hi Venkatesh Thaili,

I have checked our NDA database and the NDA# 97496 belongs to another company. I couldn't find the NDA for the SPSOFT. Could you please check the NDA number again? When have you signed the NDA with NXP? If you have signed it only recently its possible, that is still not in our system. If you have valid NDA please ask for access to docstore and please download the GUI and software. This is the easiest way to do the evaluation.

With Best Regards,

Jozef

[JozefKozon]

Dear Venkathes Thaili,

from the output data you have provided I see the shorted load on the cell1 is detected. In the event
of a shorted load, the CB_SHORT_FLT[CBx_SHORT_FLT] is set. When a shorted load is detected, the driver is immediately commanded off. To reactivate the output, the MCU controller must command the driver on again. It looks like the driver is off.

We have a software driver for the MC33771, but is confidential. You would need to have an NDA (Non Disclosure Agreement) signed with NXP. If you already have the NDA with NXP, please share the NDA number to confirm. If not and you would like to sign the NDA please let me know and I will arrange it for you. Please let me know.

With Best Regards,

Jozef

[JozefKozon]

Dear Venkathes Thaili,

1. Could you please confirm which BCC you are using? Is it the MC33771B or MC33771C? 

2. Could you please confirm your company name? When you create a ticket or post a question on the community, please use your company email.

3. There are software drivers for the MC33771B and also for the MC33771C, which could be downloaded from docstore, but you need to register there. Since you have valid NDA there shouldn't be a problem for you. Please use your company email to register on docstore. There is lot of additional useful documents. In case of docstore registration problems please contact the docstore team at: support.docstore@nxp.com

With Best Regards,

Jozef