83Views5Replies

Author Options:

How to match the load of a DC-converter? Answered

Hi!

I'm having a few TEG-elements (TEP-1264-1.5) that I want to put best use of and plug them in to a circuit in one end and get a 5V USB in the other end!

They are acting somewhat similar to solar panel and a matched load (in this case 2.0 - 2.8 Ω for each) is needed for optimal performance. They will provide during matched load 2.5-4V and 0.5-1.5A and I'm planning on putting two of them in series.

I have been looking at a MPPT design, but those seem to be based on the fact that they are charging a 12V battery that can accept a wide range of input voltages and therefore it's possible to have a DC/DC converter that just adjusts the conversion.

In my case I wan't exactly 5V but I can accept various currents 300mA - 1000mA, so if I know my Ohms law right I should be able to get a load resistance of ~1 - 16 Ω which is quite far out of range.

Is there any way to design a circuit that has a matched load of 2.0-2.8Ω (or will it be twice if they are in series?) while still being able to give a constant output of 5V?

Discussions

0
None
steveastrouk

1 year ago

LInear Technology have quite a name in MPPT silicon, you should look at their design notes for ideas.

0
None
Granstubbesteveastrouk

Answer 1 year ago

Can you specify what kind of circuit I'm looking for? Their design notes page http://www.linear.com/designtools/app_notes.php is quite hefty and my electronic design skills are not something I'm proud of.

0
None
iceng

1 year ago

You do understand that with a variable output voltage, that resistor will also need to change as does the voltage, ergo there is no reasonable single resistor that can fit your need... A TAG like a Solar-panel has variable voltage and available power output..

More to come..

0
None
icengiceng

Answer 1 year ago

You should also be aware that connecting copper wires to single digit resistors has a small but not negligible series resistance...

Regardless, you need an electronic converter that can generate your chosen voltage.. The available current will be a function of power input up to the maximum the electronic device can deliver...

0
None
Granstubbeiceng

Answer 1 year ago

Thank you for taking the time, but you have to excuse me but, I have fairly little knowledge in electronics design, what kind of circuit am I looking for?

A single resistor is out of the question since temperatures will change, as will the optimal resistance. As seen here in the attached image , I need to find the "resistance sweet spot" while I still retain 5V output. But how I do that is beyond my knowledge. Is an ordinary buck-converter my best option here?

TEP1-1264-1-2.jpg