Variable integration limits for plotting

Hello, I would like to know how I can set "alpha" as a variable between 0 and 2*pi, and plot "Pload" against "alpha". I have tried to set alpha as linspace(0,2*pi) but the integral requires a scalar for its limits. That is the limit of my knowledge of matlab! I have checked other peoples answers, but can't find the method to fit my specific question.

For those interested, the script is for a simple triac controlling a lamp, where "alpha" is the firing angle of the triac. I have set alpha to pi/3 to obtain the power in the load "Pload" at that specific angle, by want to apply this to all angles from 0 - 2*pi.

Any help appreciated. Chris

Code :

Pbulb = 100;

Vsource = 230;

Vpeak = Vsource*sqrt(2);

T = 2*pi;

alpha = pi/3;

Ifull = Pbulb/Vsource;

Rbulb = Vsource/Ifull;

P = @(x) (((Vpeak*sin(x)).^2)/Rbulb);

Pload = (1/T)*(((integral((P),alpha,(3*alpha))))+(integral((P),(4*alpha),(6*alpha))))

Answer 1

[the cyclist]

Use the linspace command to define the range of possible alpha values, then use a loop to calculate Pload for each value of alpha:

Pbulb = 100;
Vsource = 230;
Vpeak = Vsource*sqrt(2);
T = 2*pi;

alphaRange = linspace(0,2*pi);
numberAlphas = numel(alphaRange);

Pload = zeros(1,numberAlphas);
for na = 1:numberAlphas
    alpha = alphaRange(na);
    Ifull = Pbulb/Vsource;
    Rbulb = Vsource/Ifull;
    P = @(x) (((Vpeak*sin(x)).^2)/Rbulb);
    Pload(na) = (1/T)*(((integral((P),alpha,(3*alpha))))+(integral((P),(4*alpha),(6*alpha))));
end

figure
plot(alphaRange,Pload)

[Christopher Lamb]

Fantastic, thank you very much. Now I shall teach myself more about For loops!

Chris

[the cyclist]

The best form of thanks is accepting the answer, signifying its usefulness to you (and potentially others).