• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 64 subscribers
  • Views 604 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ25756: Managing battery charging current along with the system load current and solar MPPT

Cyril Sebastian
Prodigy 190 points
Part Number: BQ25756

Hi, 

I am designing a solar mppt battery charger which also powers a load through an inverter. Block diagram below gives an overall view of this.

The Solar panel has a max power of 450W.The battery is a 24V, 10Ah battery that can charge at max current of 10A (ie:~240W). I would like the remaining power from the panel to be fed to the load.

Is this possible with BQ25756? 

I am trying to understand how I can safely limit the charge current to 10A, while the overall load (Battery + invertor) is much higher. I am having this concern as the controller is not differentiating between Battery charge current and the load current due to the location of the sense resistor.

Please help me with how to go about this problem.

Regards,

Cyril

  • 0
    TI__Mastermind 21200 points

    Hello Cyril,

    Thanks for working with us on this.

    You are right. Our IC can't distinguish between the battery current and the system current. Do you have a way to know whether or not the inverter is enabled?

    You could increase the charge current when the inverter is enabled and decrease the charge current when the inverter is disabled.

    Do you know what the max load expected from the inverter is?

    Best Regards,
    Ethan Galloway

  • 0 in reply to Ethan Galloway
    Prodigy 190 points

    Thanks for your response.

    We have mechanism to monitor and control load and intend to do exactly like you said by increasing the charge current as required.

    Best Regards,

    Cyril

  • 0 in reply to Cyril Sebastian
    Prodigy 190 points

    Hi, 

    I am finding a discrepancy in the documentation. Can you help me?

    Please see the attached image below.

    For recommended inductor DCR range, The excel calculator recommendation has contradictions with itself while also not aligning with the Datasheet recommendation.

    Datasheets suggests 1.75 ~60 milli ohm.

    Excel Calculator suggests 2.6 - 60 milli ohm. While the "comment" in the same excel suggest 5-25 milli ohms.

    I am planning to follow the Datasheet recommendation for this, but would like to know if it is better to follow the Excel. Please comment.

    Best Regards,

    Cyril

  • +1 in reply to Cyril Sebastian
    TI__Mastermind 21200 points

    Hello Cyril,

    Thanks for bringing this to our attention. We'll get this fixed soon. Please follow the datasheet recommendations on DCR for now.

    I'm going to marked this thread as resolved, but please let me know if you have any more questions.

    Best Regards,
    Ethan Galloway