Geno Gargas
ECE 548
Prof. Khaligh
Solar MPPT
Techniques
Purpose of Presentation
I. Provide general description of solar
MPPT techniques
II. Describe design of solar MPPT
MATLAB model constructed
III. Present results of MATLAB simulation
IV. Give analysis of results with
recommendation for future work
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%
Common MPPT methods

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
Increased Efficiency
Cheaper and Easier
Cheap and Easy Implementation
Basic Perturb and Observe

Implemented through a DC/DC converter
Logic
1. Change duty cycle
2. Observe
consequences on
power output
3. Decide direction of
next change in duty
cycle
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
where
Constraints
Δd
II – Creation of MATLAB model

Boost converter with a typical 12V, 64W solar
panel, using the P&O algorithm for MPPT
3 Subsystems
1. Solar Panel
2. Boost
Converter
3. MPPT controller
1 - PV model design
Important equations
Equivalent
Circuit
Vpv
1
Temp
Ipv
Ih
Ipv s
Temp
I/P -> Sun and
Temperature
Ipv control

ih
+
i
-
O/P -> Panel
voltage
s
+
-
Ih
Photocurrent 1
+
i
- 1
IpvVout +
+ v
-
+

Rs
Diode
Rh
-
s
Photocurrent
Uses controlled
current sources
2
Vout -

Temp
Ih s
2
Suns
Suns
Ih control
Vpv
MATLAB
Model
PV model simulation
P-V characteristics for varying irradiance conditions
60
I-V characteristics for varying irradiance conditions
S = 300 W/m2
4.5
S = 300 W/m2
4
S = 500 W/m2
S = 800 W/m2
50
S = 1000 W/m2
S = 800 W/m2
3.5
S = 1000 W/m2
3
40
Panel Power (W)
Panel Current (A)
S = 500 W/m2
2.5
2
30
1.5
20
1
0.5
10
0
0
5
10
15
Panel Voltage (V)
20
0
0
5
10
Panel Voltage (V)
15
I-V and P-V characteristics of simulated PV model
with various levels of irradiance


Very similar to characteristics of real solar panels
20
2 – Boost converter design
Parameters
L = 20 mH
1
g
1
Vin +
2
m
Load
Cout = 125 μF
Cin
2
Vin -
Rload = 10Ω
triangle
<=
Relational
Operator
.2
Duty cycle

Cin = 1000 μF
Freq = 25 kHz
Large L to reduce size of current ripple
Simple PWM generator through use of ramp and
comparator

Boost model simulation
Panel voltage at various Duty cycles in Boost converter
Panel current at various Duty cycles in Boost converter
20
3.5
19
3
18
2.5
PV current (A)
PV voltage (V)
17
16
2
1.5
D = .1
15
D = .2
D = .1
14
1
D = .3
D = .2
D = .3
0.5
13
12
0
0.02
0.04
0.06
0.08
time (s)
0.1
0.12
0.14
0.16
0
0
0.02
0.04
0.06
0.08
time (s)
0.1
0.12
0.14
Voltage and current of input vs. time for various duty
cycles


Quick transient decay

Low ripple

Input source is model of solar panel
0.16
Logic
3 – MPPT controller
1. Get Power and Duty values of
K and K+1 periods
2. Figure out direction of
change in duty cycle
3. Change duty cycle
4. Repeat
Timing Sequence
1. Sample new values
after transient
decays
2. Sample for direction
of new Δd
3. Sample values for
use in next period
4. Make change in Δd
Model of controller
Given values from comparing Pk+1 and Pk and Dk+1
and Dk


Performs logic and outputs new duty cycle
2
P comp
1
D comp
NOT
3
K
AND
OR
NOT
AND
NOT
AND
D
In S/H
OR
1
Dout
direction
AND
.1
NOT
-1
delta D
Memory
2
Dire
1
III - Simulation
Test the system during three types of irradiance
Fast changing irradiance
0.96
Fast Changing (50 W/m2s)
2.
Slow Changing (15 W/m2s)
3.
No Change (0 W/m2s)
0.95
0.94
Irradiance (W/m2)
1.
0.93
0.92
0.91
0.9
0.89
0
0.2
0.4
0.6
time (s)
0.8
1
1.2
0.8
1
1.2
Slow changing Irradiance
0.95
Test with different Δd
2. Small Δd (Δd = .005)
0.93
Irradiance (W/m2)
1. Large Δd (Δd = .02)
0.94
0.92
0.91
0.9
0.89
0
0.2
0.4
0.6
time (s)
Fast Changing Irradiance
Power with D=.005 and fast changing irradiance
56
54
54
52
52
50
50
Power (W)
Power (W)
PV power
Power with D=.02 and fast changing irradiance
56
48
48
46
46
44
44
42
42
40
0
0.2
0.4
0.6
time (s)
0.8
1
40
1.2
0
0.2
0.6
time (s)
0.8
1
1.2
Duty cycle with D=.005 and fast changing irradiance
Duty cycle with D=.02 and fast changing irradiance
0.36
0.39
0.355
0.38
0.35
0.37
0.345
0.36
duty cycle
0.34
duty cycle
Duty Cycle
0.4
0.35
0.34
0.335
0.33
0.33
0.325
0.32
0.32
0.31
0.315
0.3
0.31
0
0.2
0.4
0.6
time (s)
0.8
(Δd = .02)
1
1.2
0
0.2
0.4
0.6
time (s)
0.8
1
(Δd = .005)
1.2
Slow Changing Irradiance
Power with D=.005 and slow changing irradiance
51
50
50
49
49
Power (W)
Power (W)
PV power
Power with D=.02 and slow changing irradiance
51
48
48
47
47
46
46
45
45
0
0.2
0.4
0.6
time (s)
0.8
1
1.2
0
0.2
Duty cycle with D=.02 and slow changing irradiance
0.6
time (s)
0.8
1
1.2
1
1.2
Duty cycle with D=.005 and slow changing irradiance
0.39
0.36
0.355
0.38
0.35
0.37
0.345
0.36
duty cycle
0.34
duty cycle
Duty Cycle
0.4
0.35
0.335
0.33
0.34
0.325
0.33
0.32
0.32
0.315
0.31
0
0.2
0.4
0.6
time (s)
0.8
(Δd = .02)
1
1.2
0.31
0
0.2
0.4
0.6
time (s)
0.8
(Δd = .005)
No Change in Irradiance
Power at constant irradiance and D=.005
53
52
52
51
51
50
50
Power (W)
Power (W)
PV power
Power at constant irradiance and D=.02
53
49
49
48
48
47
47
46
46
45
0
0.05
0.1
0.15
0.2
0.25
time (s)
0.3
0.35
(Δd = .02)
0.4
0.45
0.5
45
0
0.05
0.1
0.15
0.2
0.25
time (s)
0.3
0.35
(Δd = .005)
0.4
0.45
0.5
IV - Results
Average Power in each simulation
Δd
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
Max Power
Fast change in S
Slow change in S
No change in S
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.

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

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