Create power map of motor using xlxread ie Speed Torque and Power

Hi,

I like to create something like this https://www.mathworks.com/matlabcentral/answers/44515-how-to-plot-efficiency-maps

where it is a speed torque graph with power instead of effeciencies. Im trying to pull data from an excel file with a colum for speed, torque and input power.

Im using this but im not sure how to generate the map using contourf(XYZ)

[Data]=xlsread('Table.xlsx');

X=[Data(:,11)]; (Speed)

Y=[Data(:,2)]; (Torque)

Z=[Data(:,50)]; (Power)

Contourf(X,Y,Z);

etc.

Can someone show me the best way to do this? I think i need to create (x,y) before i use the contour function.

Thanks

[dpb]

"...show me the best way to do this?"

readtable, in all likelihood; xlsread has been deprecated for quite a while, now...

Once you have the table, use the references to the desired columns by name from it; don't make more copies of the same data.

Specific help would doubtless ensue if you would attach the input file so folks can see what actually have and do something with it.

Answer 1

[Divyanshu]

Hi rockstar49,

Here are few assumptions I have made based on the description provided:

• The data contains three values probably as columns in the excel sheet i.e., speed, torque & power.
• And you want to plot power on a X-Y grid where X is speed and Y is torque.

Few steps you can follow to achieve the desired plot are:

• Firstly, read the data from the excel-file using “readtable” function.
• Then, create a 2-D grid of speed & torque using “meshgrid” function of Matlab.
• Finally, you can plot the data using “contourf” function.

Here is a sample Matlab script you can refer to:

data = readtable("Book1.xlsx");
[speed,torque] = meshgrid(data.S,data.T);
power = data.S * data.T'
contourf(speed,torque,power)

In the above script, "power" is a 9 * 9 matrix which we got by multiplying each element of "speed" with all the elements of "torque".

Please refer the following documentation for further understanding of the functions used:

Filled 2-D contour plot - MATLAB contourf (mathworks.com)

2-D and 3-D grids - MATLAB meshgrid (mathworks.com)

Create table from file - MATLAB readtable (mathworks.com)