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I know there are several commercial products for maximum power point tracking for a single power source (solar cells for example). But does anyone know any solution for the case where there are several sources? For example, solar combined with piezoelectric generator?
These are two suggested architectures that I can come up with; but the optimal solution may be different from these. Specifically, connecting the sources in series may not be a good idea.

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where I have multiple sources (in the figures above two sources) of power and need to have the combined maximum power from each source in the output.

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    \$\begingroup\$ Show block diagram. \$\endgroup\$ – winny May 4 '18 at 18:03
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    \$\begingroup\$ There are dual-string solar controllers. \$\endgroup\$ – Brian Drummond May 4 '18 at 18:17
  • \$\begingroup\$ Thermal? What is thermal? Do you have a thermoelectric generator (thermopile) or Stirling engine or??? Are the sources connected to each other in parallel? Or are you looking for a product with multiple independent MPPT inputs? \$\endgroup\$ – mkeith May 4 '18 at 18:37
  • \$\begingroup\$ @mkeith I added more details \$\endgroup\$ – vmontazeri May 4 '18 at 19:40
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    \$\begingroup\$ I will caution you that maximum power point trackers make a lot of assumptions about the source of power. I think most of them are designed to track maximum power when connected to solar panels. I am not at all sure they will work correctly when connected to other power sources. MPPT is not generic. \$\endgroup\$ – mkeith May 5 '18 at 4:35
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What you need is two MPPT controllers. You might be able to find two in one box with some shared components, to implement your first diagram (I don't know and product selection is off-topic here), but inevitably what you're doing, electrically, will be two MPPT controllers because you have two power sources, each with their own source impedances which must be tracked separately.

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A PV is a solar power controlled current source and a PZT is an acceleration controlled charge generator. You would never put these two sources in series or parallel so separate conversion to and impedance matched voltage is required.

Ideal Watts power maximum conversion like DC motors for Hp or thermal piles and PV, is derived by choose a voltage about 80% of Voc but is impirically found by matching load incremental impedance to source. Some use pulsed Voc/Isc to arrive this and others by hunting and sensing Vo*Io changes and finding the peak which has a derivative Pd. vs delta Z of zero. So for a simple solution start with 82%Voc and reduce to 72% of Voc when Pin/Pmax is low.

Ideally each current source will be regulated by either the intermediate charge Cap voltage or battery if “matched” but often this is not the case so dc-dc converters may be needed for each by PWM to LC charge sink for matched impedance loads to each source since each source is unlikely to have the same dynamic impedance

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  • \$\begingroup\$ any -1 without a question is just ignorance \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 4 '18 at 20:23
  • \$\begingroup\$ This a poorly defined question with an intelligent answer \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 4 '18 at 20:25
  • \$\begingroup\$ Why is it not a good idea to put the two sources in series? I know it wont work, but theoretically speaking I don't understand. \$\endgroup\$ – vmontazeri May 5 '18 at 20:08
  • \$\begingroup\$ you cannot put in series until they are voltage sources after conversion \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 5 '18 at 21:20

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