This one is about the MPPT I've been working on. The first of it's kind developed by our team. It should effectively be able to interface between our solar cell array and our battery pack, while at the same time track the maximum power point of our array.
Here's what it looks like right now. I ended up making two mistakes on the board layout that I had to fix but hey it's a first rev (I guess technically not even a first revision as it's not complete yet).
Lately I have been testing the power conversion efficiency of the boost converter portion of it. It takes a low voltage input from the solar cell array and "boosts" it up to battery pack voltage.
In the chart below output voltage was 109V and input current was 3-5 amps. I don't have enough data points as of right now to make a really nice graph all at one input current so this is what you get for now.
The y axis is efficiency and the x axis is boost ratio...
I tested mostly at high boost ratios as that's what I expect us to encounter on Axiom. Looking at this Graph it looks like we will be in the 94-95% efficiency range with the setup we are thinking of going with right now which is pretty darn good.
But really the power conversion is only half of the equation. Next is to program in a tracking algorithm to "track" the maximum power point of the array modules. This will be the next critical part of the design as a lot of energy can be gained or lost due to a good or bad tracking algorithm.
To implement the tracking algorithm the on board micro controller reads in input current and input voltage and uses those two parameters to figure out where the maximum power point of the array module is.
The MPPT also has full communication with our chase vehicle so that we know at all times if the tracker is working or not as well as contribute useful data that we can use for race strategy.
See Ya
Tim Gamber
Electrical Engineering Manager