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I'm new here but I have read a lot of topics here about my question. I am designing a solar battery charger with MPPT algorithm but I don't know if I am doing it well.

First of all my specs are here:

Solar Panel:

  • 10 W peak power
  • Maximum Power Current: IMP = 0.57 A
  • Maximum Power Voltage: VMP = 17.49 V
  • Short Circuit Current: ISC = 0.61 A
  • Open Circuit Voltage: VOC = 21.67 V

Battery:

  • One cell Lithium-Polymer
  • Nominal Voltage: 3.7 V
  • Capacity: 1700 mAh (max 1C)

This is my actual schematic:

Schematic

The µC is working from 3.3 V.

Secondly:

I've designed a buck converter with the following values:

schematic

simulate this circuit – Schematic created using CircuitLab

The problem is controlling the MOSFET with PWM in full-closed and full-opened states. Should I use a gate driver IC or another method?

Thereafter:

When the night comes, or the PV doesn't generate enough power, I have to stop the charging and MPPT. How do I know that the sun gives enough power to start MPPT, without starting it? (I was thinking about measuring the ISC to know the possible IMPP).

Finally:

  • Do I have to use a charger IC to protect the battery form bad charging behavior?
  • What do you think about the MP2615 charger? Is it good in this case?

I hope you can help.

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  • \$\begingroup\$ 10 W into a single cell will not play nicely. Do you have other loads in the system or are you not going to run full current? \$\endgroup\$ – winny Oct 29 '18 at 18:03
  • \$\begingroup\$ No. It is just a standalone charger. If I'm right, I would like to make the system work on a lower power (not use the whole 10 W) when the irradiance is high. I would use the MPP on cloudy days (when irradiance is lower). I know it is energy wasting but when I have started this project, I did not choose the parts very well so I work with my current parts :D \$\endgroup\$ – Andrew S. Oct 29 '18 at 18:16
  • \$\begingroup\$ Well, you sort of have to or your battery will explode :-) \$\endgroup\$ – winny Oct 29 '18 at 19:59
  • \$\begingroup\$ What is your opinion? Would this setup work (without explode anything)? \$\endgroup\$ – Andrew S. Oct 29 '18 at 20:51
  • \$\begingroup\$ It you implement a suitable constant current limit in your control loop, it should. But it also begs the question, why all the trouble? Why not just buy a commercial switch regulator? \$\endgroup\$ – winny Oct 30 '18 at 6:32

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