how can solve breakingpoint in simulink ?

hi,

I am using SIMULINK, and I keep seeing this error

"The problem occurs at element 3. Change the breakpoints data or use the fixed-point tools such as Auto Scaling or Fixed-Point Advisor to determine a different parameter dialog type".

when i change "cp1,cp2,cp3,cp4" in my code :

i saw this problem

By the way,

my max step size=0.02;

min step size= auto

relative tolerance=1e-3

absolute tolerance=auto

solver=ode45, variable step

er=40;
cp1=0.833*10^6; cp2=1.67*10^6; cp3=7.84*10^6; cp4=14.7*10^6;

lookup_in=[0 (cp1+cp2)/2 (cp1+cp2)/2+er*eps (cp2+cp3)/2 ...
          (cp2+cp3)/2+er*eps (cp3+cp4)/2 (cp3+cp4)/2+er*eps 100];
lookup_out=[cp1 cp1 cp2 cp2 cp3 cp3 cp4 cp4];

can anyone please help me with that ?

thanks in advance,

Answer 1

[Fangjun Jiang]

The values in lookup_in must be monotonically increasing. Right now it is not.

The third value is not regarded as larger than the second value becuase the difference is so small. The resolution must have been lost. The last value (100) is also problematic.

[ADNAN KIRAL]

thanks for your quick reply, i have changed that

now it is working but i was wondering if i change that to the following case, will it affect my output. cheers.

er=4000000;
cp1=0.833*10^6; cp2=1.67*10^6; cp3=7.84*10^6; cp4=14.7*10^6;

lookup_in=[0 (cp1+cp2)/2 (cp1+cp2)/2+er*eps (cp2+cp3)/2 ...
          (cp2+cp3)/2+er*2*eps (cp3+cp4)/2 (cp3+cp4)/2+er*3*eps 18e+6];
lookup_out=[cp1 cp1 cp2 cp2 cp3 cp3 cp4 cp4];

[Fangjun Jiang]

The output should not be affected.

A better way is to specify

lookup_in2=[0 (cp1+cp2)/2 (cp2+cp3)/2 (cp3+cp4)/2]

lookup_out2=[cp1 cp2 cp3 cp4]

And specify the "Interpolation method" as "Flat" in the "Algorithm" panel of the lookup table block.

[ADNAN KIRAL]

ı see, cheers.