1. Geno Gargas
ECE 548
Prof. Khaligh
Solar MPPT Techniques

2. Purpose of Presentation
Provide general description of solar MPPT techniques
Describe design of solar MPPT MATLAB model constructed
Present results of MATLAB simulation
Give analysis of results with recommendation for future work

3. I – Basics of MPPT
Solar panel characteristic has non-linear relationship with Temperature and Irradiance
MPP also moves non-linearly
MPPT can improve efficiency by 15-20%

4. Common MPPT methods Increased Efficiency Cheaper and Easier
Cheap and Easy Implementation
Fractional Open-Circuit Voltage
Fractional Short-Circuit Current
Intermediate Price and Implementation
Perturb and Observe
Incremental Conductance
Expensive and Difficult Implementation
Fuzzy Logic Control
Neural Networks
Cheaper and Easier
Increased Efficiency

5. Basic Perturb and Observe
Implemented through a DC/DC converter
Logic
Change duty cycle
Observe consequences on power output
Decide direction of next change in duty cycle

6. P & O Design Parameters
Balance Δd between size of the oscillation across MPP, and inability to not get confused
Two degrees of freedom: Δd and Ta
Ta Constraints Δd
where

7. II – Creation of MATLAB model
Boost converter with a typical 12V, 64W solar panel, using the P&O algorithm for MPPT
3 Subsystems
Solar Panel
Boost Converter
MPPT controller

8. 1 - PV model design Important equations Equivalent Circuit
I/P -> Sun and Temperature
O/P -> Panel voltage
Uses controlled current sources
MATLAB Model

9. PV model simulation
I-V and P-V characteristics of simulated PV model with various levels of irradiance
Very similar to characteristics of real solar panels

10. 2 – Boost converter design
Parameters
L = 20 mH
Cout = 125 μF
Rload = 10Ω
Cin = 1000 μF
Freq = 25 kHz
Large L to reduce size of current ripple
Simple PWM generator through use of ramp and comparator

11. Boost model simulation
Voltage and current of input vs. time for various duty cycles
Quick transient decay
Low ripple
Input source is model of solar panel

12. 3 – MPPT controller Logic Timing Sequence
Get Power and Duty values of K and K+1 periods
Figure out direction of change in duty cycle
Change duty cycle
Repeat
Timing Sequence
Sample new values after transient decays
Sample for direction of new Δd
Sample values for use in next period
Make change in Δd

13. Model of controller
Given values from comparing Pk+1 and Pk and Dk+1 and Dk
Performs logic and outputs new duty cycle

14. III - Simulation Test the system during three types of irradiance
Fast Changing (50 W/m2s)
Slow Changing (15 W/m2s)
No Change (0 W/m2s)
Test with different Δd
Large Δd (Δd = .02)
Small Δd (Δd = .005)

15. Fast Changing Irradiance
PV power
Duty Cycle
(Δd = .02)
(Δd = .005)

16. Slow Changing Irradiance
PV power
Duty Cycle
(Δd = .02)
(Δd = .005)

17. No Change in Irradiance
PV power
(Δd = .02)
(Δd = .005)

18. IV - Results Average Power in each simulationΔd
Fast change in S
Slow change in S
No change in S
.02
48.68 W
47.95 W
47.2 W
.005
48.87 W
48.14 W
48.05 W
These results were found using the mean statistical data provided by MATLAB in each simulation
Average Maximum power available from solar panel
Fast change in S
Slow change in S
No change in S
Max Power
49.22 W
48.44 W
48.1 W
These results were found by simulating the panel at the average insolation for each form of change in irradiation, and finding the maximum point on the power curve.

19. Analysis Efficiency of MPPT algorithm for various parameters Δd
Fast change P
Slow change P
No change P
.02
98.9 %
99 %
98.1%
.005
99.3 %
99.4 %
99.9%
Higher efficiency with small Δd, regardless of how the sun is changing
I observed that the smaller Δd takes much longer to get to the MPP from a step change in irradiance
The step change is a very rare occurrence, so this may not be an issue
Design the system for the smallest Δd possible for the best efficiency

20. Future Work
Design a controller that can vary the size of the perturbation with respect to how far from the MPP it is
Leave Δd at a small value and adjust the sampling time to see if that has any effect.
Simulate the MPPT controller for other converter types, possibly in line with a battery charge controller