plot the electrical power of a motor having for a time t=20s the values of u(ur,us,ut) and i(ir,is,it))

 how can i plot the electrical power P of a motor, having for a time t=20s  differents values of u(ur,us,ut) and i(ir,is,it)?

[Stephan]

Do you have the values for i(t) and u(t) for the wanted range of 20 sec? Do you also have the equation to calculate power?

[Maura]

Yes. U and I are matrices. And I know that the power P=U.I

Answer 1

[Stephan]

Hi,

this is an example which should work for your purpose:

% some values for U(t) and I(t) --> i take random values for I(t)...
% and i assume a 24 V DC machine, to have data for the example. 
U = 24 *ones(1,201);
I = 3 * rand(1,201) + 1.5;

% lets say you have measured values every 100 ms from 0-20 secs...
% Then build a time vector which is used as x-axis for the plot
t = linspace(0,20,201);

% calculate the power ELEMENTWISE with '.*' operator gives a...
% vector of the same size as wanted
P = U.*I;

% plot P against t and give labels and a title
plot(t,P)
ax = gca;
xlabel('Time in sec')
ylabel('Power in W')
title('Power against time diagram')

which gives:

I think if you modify t for your case and insert your variables of U(t) and I(t) this should work for you.

Best regards

Stephan