simulink sum wrong output

Hi,

I'm simulating my discrete controller but got one problem with the sum function (in red circle). The two inputs are plotted with the purple and yellow lines and the output is the blue line. At 0.3s the sum outputs a very large result about -7*10^7 even after I set the output limit to +-50. But from the inputs, the result shouldn't be that large. I tried different time steps but that didn't help. Did I set something wrong? Any advice will be appreciated.

Regards, Jiaqi

Answer 1

[Abhishek GS]

Hi Jiaqi,

The Output Minimum and Output Maximum do not saturate or clip the output signal. Use a saturation block after the Sum block if you intend it for that purpose. The Output Min and Max values are used for Parameter range checking, Simulation range checking and Automatic scaling of fixed-point data types. Refer the below link for more information.

http://in.mathworks.com/help/simulink/slref/sumofelements.html?

[jiaqi]

Hi Abhishek,

After adding a saturation block after the sum, the result keeps the same, still very large. Am I doing something wrong?

Thanks, Jiaqi