DRAFT: This module has unpublished changes.

 

Desired Voltage

Buck Output Vin= 20 V

Buck Output Vin= 19 V

Buck Output Vin= 18 V

Buck Output Vin= 17 V

Buck Output Vin= 16 V

Buck Output Vin= 15 V

Buck Output Vin= 14 V

Buck Output Vin= 13 V

Buck Output Vin= 12 V

12 V

12.26

11.6

11

10.3

9.7

9.1

8.5

7.9

7.2

13 V

13.51

12.8

12.1

11.4

10.7

10

9.4

8.7

3.9

14 V

14.28

13.5

12.8

12

11.4

10.6

9.9

4.3

Error

15 V

15.29

14.5

13.7

12.9

12.2

11.3

Error

Error

Error

16 V

16.22

15.4

14.6

13.7

12.9

Error

Error

Error

Error

17 V

17.24

16.3

15.5

14.6

Error

Error

Error

Error

Error

18 V

18.24

17.3

16.4

Error

Error

Error

Error

Error

Error

19 V

19.07

18.2

Error

Error

Error

Error

Error

Error

Error

20 V

Error

Error

Error

Error

Error

Error

Error

Error

Error

 

 

 

 

 

 

 

 

 

 

The table above demonstrates the decreasing accuracy of the DC-DC buck converter circuit as the input voltage decreases from the ideal 20 V down to 12 V. Figure 12 is a plot of the data, and clearly shows that operating at a solar panel voltage of 20 V provides the best DC-DC buck performance in terms of accuracy. The buck circuit would provide fluctuating values when asked to output a voltage equal to the input voltage.

 


Signal

Rise Time

Fall Time

Percent Overshoot

Average Voltage

PMOS Input

 55.6us 472.0 ns

1.1 %

7.2 V

PMOS Output

56 ns

 17.20 us

1.0 %

13.4 V

 Current Divider:

 


The 3.35 V is read into the Arduino Uno analog input pin A5 from the voltage divider at the load attached to the DC-DC buck converter circuit. Using the 1kresistors, their ratio of the voltage divider translates 3.35 volt to 13.4 volts. This matches with the desired output of 13.2 volts.

 


Through Ohm’s Law, Input Current IIN in can be measured with a series resistor at the DC-DC Buck Circuit input : 

 

The power from the solar panel can then be calculated: 

 




DRAFT: This module has unpublished changes.