• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 78 subscribers
  • Views 1124 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.

TIDA-00120: Charge Li-Ion 4S battery (11-16.8VDC ) with 12-22VDC PV panel

Alex Dukhovny94
Prodigy 70 points
Part Number: TIDA-00120
Other Parts Discussed in Thread: TIDA-00049, TIDA-00657, TIDM-BUCKBOOST-BIDIR, TIDM-SOLAR-DCDC

Dear Experts,

I came across the TI’s TIDA-00120 reference design and I’d like to ask you if there is possibility to make a slight changes to the MCU code ( or HW, or both ) and turn this interleaved buck into buck-boost MPPT-Charger. Let’s say the panel is 12-22VDC  with VMP: 17.5VDC and IMP: 4.52A and the battery is 11-16.8VDC ( the voltages are overlapping so the DC/DC conversion should be buck-boost, as I understand) From the HW point of view the topology of TIDA-00120 should be OK ( correct me if I am wrong ) , the problem is the SW to perform the buck-boost. Is that correct ?

Any advice would be greatly appreciated!

Alex Dukhovny 

  • 0
    TI__Intellectual 2760 points

    Alex,
    To clarify a core assumption you’ve made, TIDA-00120 is not capable of acting as a boost converter. This is because the current maximum power point of solar panel resides below the open circuit voltage. There is never a reason to boost the output when doing just MPPT, like this design does.

    In addition, TIDA-00120 is designed for lead acid batteries, which have a much simpler charge profile than the Li-Ion batteries you want to charge and wouldn’t be compatible. You would need an external Li-Ion charger with a DC input.

    There are a few things you can do to potentially implement a solar 4S charger with MPPT:

    • Check out TIDA-00049, it might do everything you need already.

    • Set the output voltage of the MPPT to never drop below the input voltage of your charger in software. You might be operating outside the maximum power point for some of the time, but you’ll at least be in an acceptable voltage range.

    • Use a charger with a wide input voltage (an integrated Boost Controller) like TIDA-00657.

    • Add a boost converter to the output of the TIDA-00120 based MPPT. If you go to the TIDesigns home page and “Search power designs by parameters” you should be able to easily find one that works. The output of this can feed your charger and you can maintain MPPT.

    • Lastly, you can move to the more complex buck/boost MPPT solutions. We have two TIDesigns you can take a look at: TIDM-BUCKBOOST-BIDIR, and TIDM-SOLAR-DCDC You would still need an external charger with these, but you can maintain MPPT across the full panel output range.

  • 0 in reply to Bart Basile
    Prodigy 70 points

    Thank you for the clarification.

    Another question for a new scenario: 

    I have PV panel with the voltage high enough to perform charging of 4S Li-Ion battery (11-16.8VDC)  in a pure step-down mode, with the IMPP of 3A and VMPP of 35VDC, so the dedicated Li-Ion MPPT-chargers ICs are not available from TI's portfolio because of input voltage limitation. Despite the original TIDA-00120  intended to charge the Lead-acid battery , the difference between Li-ion battery charge profile and Lead-acid battery charge profile is not so complicated - the Li-ion battery has even simpler profile without float charge stage. Do you think I'll be able to introduce slight SW changes and modify TIDA-00120 to perform charging of 4S Li-ion battery ?

    Thanks

**Attention** This is a public forum