08/31/2020 rework MPPT circuitboard

A project log for solar powered boat

low-cost methods to power boats from solar power

sean-depagniersean d'epagnier 09/01/2020 at 03:150 Comments

I have improved the MPPT by adding 5 filter capacitors.

These capacitors greatly stabilize the voltage and current readings.  This allows for quicker peak power tracking, although the algorithm sometimes gets confused if the light level is increasing or decreasing with changing cloud cover and doesn't get back to the optimal setting until the power level stabilizes.

I also reduced the mosfet gate capacitors from 33 ohms to 6.8 ohms and was able to realize an 18% power increase over a direct battery connection up from 15% previously because of reduced dead time.  I was only able to cut the dead time in half from 1.25uS to .625uS   I wonder if using a more powerful gate driver or using mosfets with lower gate charge (but higher on resistance) might help allow for a shorter dead time.

I  need to try with a parallel schottky diode to the mosfet, as it may conduct during switching and slightly increase performance, it will be interesting to see how significant it is.

I still need to experiment with different inductors as well.