gui program

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ANALYZING MAXIMUM POWER TRANSFER TO A LOAD RESISTANCE USING

MATLAB, SIMULINK, AND GUI.

Objective:

1. To calculate and plot maximum power against load resistance, using M-file.2. Use of GUI and Simulink to plot maximum power against load resistance.3. Analyzing and discussing on my plotted graphs.

DONE BY: AMINU ILIYASU BUGAJE.


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INTRODUCTION:

In electrical engineering, the maximum power transfer theorem states that, to

obtain maximum external power from a source with a finite internal resistance, the resistance of

the load must be made the same as that of the source. If the load resistance is smaller than the

source resistance, then most of the power ends up being dissipated in the source, and although

the total power dissipated is higher, due to a lower total resistance, it turns out that the amount

dissipated in the load is reduced.Maximum power is transferred from an active device such as a

power supply orbattery to an external device occurs when the impedance of the external device

matches that of the source. (http://en.wikipedia.org/wiki/Maximum_power_theorem#References).

Fig 1. A voltage and an internal resistance Rs supplying a load resistance RL

In the diagram above opposite power is being transferred from the source, with voltage 240v

and fixed source resistance Rs of 100, to a load with resistance RL, find the value of the load

resistance RL, resulting in a current I. By Ohm's law, I is simply the source voltage divided by

the total circuit resistance:

The power PL dissipated in the load is the square of the current multiplied by the resistance:

*Plot the power supply to the load as a function of the load resistance.


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M-File Program

Aim: Tocalculateandplotpoweragainsttheloadresistance.

%date programmer

%******** ***********

%30/7/2010 Aminuiliyasu bugaje

%variables

V=240;%voltagesupplied

Rs=100;%sourceresistance

Rl=1:10:1000; % loadresistancearray

I=V./(Rs+Rl) % calculatecurrent

P=(I.^2).*Rl; %calcultethepowersuppliedtotheload.

plot(Rl,P,'R'); %plotingpowersuppliedasfunctionofloadresistance.

title('poweragainstloadresistance');

xlabel('resistance(Rl)');

ylabel('(power(Pl)');

fprintf('thisisthepower value%d',P)

I =

Columns 1 through7


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2.3762 2.1622 1.9835 1.8321 1.7021 1.5894 1.4907

Columns8through 14

1.4035 1.3260 1.2565 1.1940 1.1374 1.0860 1.0390

Columns 15 through21

0.9959 0.9562 0.9195 0.8856 0.8541 0.8247 0.7973

Columns22through28

0.7717 0.7477 0.7251 0.7038 0.6838 0.6648 0.6469

Columns29through 35

0.6299 0.6138 0.5985 0.5839 0.5701 0.5568 0.5442

Columns 36through42

0.5322 0.5206 0.5096 0.4990 0.4888 0.4790 0.4697

Columns43 through49

0.4607 0.4520 0.4436 0.4356 0.4278 0.4203 0.4131

Columns 50 through 56


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0.4061 0.3993 0.3928 0.3865 0.3803 0.3744 0.3687

Columns 57through63

0.3631 0.3577 0.3524 0.3473 0.3424 0.3376 0.3329

Columns64through70

0.3283 0.3239 0.3196 0.3154 0.3113 0.3073 0.3034

Columns71 through77

0.2996 0.2959 0.2923 0.2888 0.2854 0.2820 0.2787

Columns78through84

0.2755 0.2724 0.2694 0.2664 0.2634 0.2606 0.2578

Columns85 through91

0.2550 0.2524 0.2497 0.2472 0.2446 0.2422 0.2398

Columns92through98

0.2374 0.2351 0.2328 0.2305 0.2284 0.2262 0.2241

Columns99through 100


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0.2220 0.2200

thisisthepower value5.646505e+000thisisthepower value5.142440e+001thisisthepower

value8.261731e+001thisisthepower value1.040499e+002.

I observed that the power is increasing and the load resistance is increasing, and the power

started decreasing when the resistance is value was going higher . Maximum power is 150watt

when load resistance is 100. So this shows that the higher the resistance the lower the power

supplied. I can see that the Maximum PowerTransferoccurs in the load when the load

resistance, RL is equal to the source resistance, RS so then: RS = RL = 100.


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GUI PROGRAM

function varargout = Aminu(varargin)

% AMINU M-file for Aminu.fig% AMINU, by itself, creates a new AMINU or raises the existing% singleton*.

%% H = AMINU returns the handle to a new AMINU or the handle to% the existing singleton*.%% AMINU('CALLBACK',hObject,eventData,handles,...) calls the local% function named CALLBACK in AMINU.M with the given input arguments.%% AMINU('Property','Value',...) creates a new AMINU or raises the% existing singleton*. Starting from the left, property value pairs are% applied to the GUI before Aminu_OpeningFunction gets called. An% unrecognized property name or invalid value makes property application% stop. All inputs are passed to Aminu_OpeningFcn via varargin.%% *See GUI Options on GUIDE's Tools menu. Choose "GUI allows only one% instance to run (singleton)".%% See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help Aminu

% Last Modified by GUIDE v2.5 29-Jul-2010 21:51:58

% Begin initialization code - DO NOT EDITgui_Singleton = 1;gui_State = struct('gui_Name', mfilename, ...

'gui_Singleton', gui_Singleton, ...'gui_OpeningFcn', @Aminu_OpeningFcn, ...'gui_OutputFcn', @Aminu_OutputFcn, ...'gui_LayoutFcn', [] , ...'gui_Callback', []);

if nargin && ischar(varargin{1})gui_State.gui_Callback = str2func(varargin{1});

end

if nargout[varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});

elsegui_mainfcn(gui_State, varargin{:});

end% End initialization code - DO NOT EDIT

% --- Executes just before Aminu is made visible.function Aminu_OpeningFcn(hObject, eventdata, handles, varargin)% This function has no output args, see OutputFcn.% hObject handle to figure% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)% varargin command line arguments to Aminu (see VARARGIN)


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% Choose default command line output for Aminuhandles.output = hObject;

% Update handles structureguidata(hObject, handles);

% UIWAIT makes Aminu wait for user response (see UIRESUME)% uiwait(handles.figure1);

% --- Outputs from this function are returned to the command line.function varargout = Aminu_OutputFcn(hObject, eventdata, handles)% varargout cell array for returning output args (see VARARGOUT);% hObject handle to figure% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)

% Get default command line output from handles structurevarargout{1} = handles.output;

% --- Executes on button press in pushbutton1.function pushbutton1_Callback(hObject, eventdata, handles)% hObject handle to pushbutton1 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)V=240;%voltage suppliedRs=100;%source resistanceRl=1:10:1000; % load resistance arrayI=V./(Rs+Rl) % calculate currentP=(I.^2).*Rl; %calculte the power supplied to the load.plot(Rl,P,'R'); %ploting power supplied as function of load resistance.title('power against load resistance');xlabel('resistance(Rl)');ylabel('(power(Pl)');


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started decreasing when the resistance is value was going higher . Maximum power is 150 when

load resistance is 100. So this shows that the higher the resistance the lower the power

supplied.RL is equal to the source resistance, RS so then: RS = RL = 100. The maximum poweris transferred from an active device such as a power supply orbattery to an external device

occurs

when the impedance

of the external device matches that

of the s

ource


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.

Simulink program


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started decreasing when the resistance is value was going higher. So this shows that the higher

the resistance the lower the power supplied.

CONCLUSION:

In the circuit above the maximum power is transferred from source resistance to a load

resistance when the resistance of the load is same as that of the source (Rs=RL). The powerwas

at maximum point (150) when the resistance value was low (100), and the power value started

decreasingw

hen the resistance valuew

as increasing. So

this implies that the higher theresistance the lower the power supplied and the lower the resistance the higher the power.

The Maximum PowerTransferTheorem is another useful analysis method to ensure that the

maximum amount of powerwill be dissipated in the load resistance when the value of the load

resistance is exactly equal to the resistance of the power source.


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Reference:

1. H.W. Jackson (1959)Introduction to Electronic Circuits, Prentice-Hall.2. Sedra Adel. (1991). Microelectronic Circuits. 3 ed. Saunders College Publishing.3. http://en.wikipedia.org/wiki/Maximum_power_theorem#Maximizing_power_transfer_versus_

power efficiency. Last accessed: 28 July 2010.

4.

William J. Palm III. (2005).Introduction to

MATLAB7 for Engineers. Prentice hall

5. Wayne storr (2010).Electronics Tutorial aboutMaximum PowerTransfer : Availableat http://www.electronics-tutorials.ws/dccircuits/dcp_9.html. last accesed:28 july 2010.

gui program

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