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# MPPT + Voltage Doubler

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#### ACharnley

##### Member
I have a spreadsheet calculating ideal voltage levels for a MPPT circuit (for a given resistance, inductance, capacitance). The figures are correct.

Given the current source is fixed I've calculated V=IR to produce the voltage levels I should drive the output to.

Questions are:

a. when using a voltage doubler it is right (assume ideal diodes) to half the current so the voltage to be driven to is double?
b. assuming non ideal diodes, is the final voltage [(a) - vDrop] or should the vDrop form part of the MPPT equation?

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The op current will be less than 1/2 the ip, for several reasons, voltage dropp across the cap, Esr of the cap, vdrop in the diode.

Indeed, however these are variable changing based on current draw and heat. I'll work them in if I can. The first cap(s) are ceramic based so ESR will be minimal, and the second will be large so ESR shouldn't be too high (something like 4700uF).

I'm sure you know about low esr caps for smps's, those are the ones to go for.
For prototypes & messing ab out I salvage them from psu's, I have some dell server smps's, the quality of the parts is very good.

A capacitive voltage doubler circuit generally has low efficiency.
Better to use a boost switching converter if you are concerned about efficiency (since it's an MPPT circuit, I assume you are).

I would look into Dickson Charge Pumps also .... Personally I think they are more efficient than a typical Cascade Multiplier. Just my two cents.

Below is a link to a Video of a Dickson Charge Pump that I made awhile back ... "Excuse the miss pronunciation until the very end of the video"

I would look into Dickson Charge Pumps also .... Personally I think they are more efficient than a typical Cascade Multiplier. Just my two cents.

But not that much more efficient, the OP has been pretty vague about what he's trying to do (and why), but redesigning the complete project properly would be better than trying to bodge things with voltage multipliers. Failing that, a standard switch-mode boost converter would probably be a much better idea than multipliers.

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