Hi i am looking to design a solar cell powered dc-dc boost converter and i am having difficulty finding recent infomation on the latest technology and the issues in this field of power electronics... can anyone please assist?

 

...i am having difficulty finding recent infomation on the latest technology ...

Take a look at the IC manufacturers such as Linear and International Rectifier. They'll have products in this area and may also have pre-commercial, experimental "products" they will share.

 

TI also has a lot of good DC-DC converter chips.

Bob

 

Thanks for your help, i'll look into it. Do you know the most efficient way to boost 0.3v to 3v? I have looked on digikey and read a few power electronic books which gave some ideas how to simulate several designs on multisim but it only stepped up to 0.5v?

 

A Joule Thief circuit might operate as low as .3V, but I am not sure. That is a very low voltage to start with, I don't know of any boost converter chips that go down that low. You might want to look up "energy havesting".

Bob

 

The price for boosting the voltage by a factor of 10 is lowering the current output, at 3 volts, by a factor of more than 10. In simple terms your first "back-of-the-envelope" calculation is that "Power In" is required to be "Power Out" DIVIDED by the Efficiency. Efficiency of a DC-DC converter will ALWAYS be a number in the interval [0, 1). In particular, the efficiency can NEVER be equal to 1.

Example: You want 3V @ 100 milliwatts. That is a current of 33.3... milliamperes. So far so good. Assume a DC-DC converter exists that has an 80% efficiency. So 100 milliwatts / .8 = 125 milliwatts. Still with me? So 125 milliwatts at 0.3 V requires a current of -- are you ready? -- ≈ 417 milliamperes. So finally we see that 417 milliamperes / 33.3 milliamperes ≈ 12.51, and unless I missed something 12.51 is > 10 period, full stop.

Now the question of weather you can build a DC-DC converter that will work down to 0.3V remains to be seen.

 

Thanks Bob I will look into energy harvesting and the joule thief design.

Papa, that was a very interesting and helpful analysis of my problem at hand. I do have room to manoeuvre the input voltage up to 1 V and have researched different circuit designs, which do say 0.3 is too low.... Do you have an idea how to build an efficient circuit that will step up from 1 to 3-5v?

 

Shariar, did a pretty good video on this sort of thing!

HTH Steve

 

Your chances are much better at 1V. A Joule thief would operate pretty effectively at that level. At 0.3V, it would be very difficult to get any reasonable efficiency.

Bob

 

From TI.

http://www.ti.com/lit/ds/symlink/lm2623.pdf

 

Look at LTC3105 and LTC3108

 

The LTC3105 internal schematic shows a low voltage start-up block, but I don't see any such thing in the LTC3108 internals. How does it start up? With only 20 mV input?

 

Thanks for the reply guys, especially loved the video.... Thanks again.

Energy Harvesting is something I have looked into and I would like to know who or where would be the best place to find the most up-to-date published articles on the topic. would it be manufacture websites or magazines.. etc?

 

I take back my comment about not being able to get much efficiency at 0.3V input. Very cool.

Bob