Peak power tracking... (sorry if this shouldn't be posted)

[dwstudd]

Hello everyone,

I am working on a small satellite project (undergraduate work) and am the team leader for the power subsystem. I would like to implement peak power tracking into our system but am unsure of how to do it. I know this can be done in hardware, but it doesn't seem very dynamic with the environment. The digital ppt is intriguing and I'd like to know more about how to implement it.

My system has 4 panels (+x, -x, +y, and +z directions). Is a PPT needed for each panel or can I just tie the panels together and use a single PPT?

This sort've ties into my charging system too. I will basically be building my own switching DC/DC converter to control the amount of current going into teh NiCd cells. My current plan is to basically implement an algorithm like the following:

-Start the pwm to the fet of the charging regulator at some set value (like 50%)
-measure the current through the array
-measure the voltage of the bus
-calculate the power
-increment the turn on period of the pwm
-measure the solar array current and bus voltage again
-calculate the new power value
-if the power has dropped, reduce the duty cycle of the pwm
-if the power has increased, increase the duty cycle of the pwm
-repeat the steps

The above algorithm is known as perturbation and observation if I'm not mistaken.

So basically, my charging regulator is dictating the operating voltage of the solar array by choking off current to the battery.

If you guys have answers to my questions and suggestions to my design please fire away as I'm very new to this!

If questions like this shouldn't be in this forum please let me know... I just don't know where else to go to get support for this...

Thanks!
D-wayne

[quium]

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www.timnolan.com