plz help me in resolving the error.

# Error: Incorrect use of '=' operator. To assign a value to a variable, use '='. To compare values for equality, use '=='.

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MANSOOR SOOMRO
on 20 Jul 2020

Commented: Azariah Seblu
on 19 Jul 2021

Error evaluating 'InitFcn' callback of block_diagram 'DFIG_SMC'. Callback string is '% Parametrs for DFIG with SMC

% Parametrs for DFIG with SMC

f=50;

Ps=2e6;

n=1500;

Vs=690;

Is=1760;

Tem=12732;

Vr=2070;

p=2;

u=1/3;

smax=1/3;

Vr_stator=(Vr*smax)*u;

Rs=2.6e-3;

Ls=2.587e-3;

Rr'=26.1e-3;

Lr'=2.587e-3;

Lm=2.51e-3;

Rm=1.0805e6;

Vbus=Vr_stator*sqrt(2);

sigma=(1-Lm^2)/(Ls*Lr);

Vs=690*sqrt(2/3);

ws=f*2*pi;

J=127/2;

D=1e-3;

fsw=4e3;

Ts=1/fsw/50;

F=0.058;

%% Maximum and Minimum wind speeds

wt_nom=18;

wt_min=9;

%% Three Blade wind turbine model

N=100;

Radio=42;

ro=1.225;

%% Cp and Ct curves

beta=0;

ind2=1;

%% Kopt for MPPT

Cp_max=0.44;

lambda_opt=7.2;

Kopt=((0.5*rho*pi(Radio^5)*Cp_max)/(lambda_opt^3));

%% Torque and speed inputs

Temm=Torque/N;

wmm=wt*(50/2/pi)*N;

sss=(1500-wmm)/1500;

%% Grid side converter

Cbus=80e-3;

Cg=20e-6;

Lg=400e-6;

Kpg=1/(1.5*Vs*sqrt(2/3));

Kqg=-Kpg;

%% Mechanical Inputs

Theta=20;

Speed=1500;

Caused by:

##### 5 Comments

Azariah Seblu
on 19 Jul 2021

### Accepted Answer

Walter Roberson
on 20 Jul 2020

Rr'=26.1e-3;

Apostrophe cannot be part of a variable name in MATLAB Function Block or Callbacks.

### More Answers (1)

John D'Errico
on 20 Jul 2020

A simple rule in MATLAB: You cannot assign a result to a result.

What is Rr' then? This is the conjugate transpose of the array or vector Rr. MATLAB does not truly care that Rr is apparently a scalar.

Rr'=26.1e-3;

Lr'=2.587e-3;

My guess is you wanted to name a variable like that. Sorry, but Rr' is not a valid variable name. So, what error arises? MATLAB thinks the left hand side is the conjugate transpose of something called Rr, that is, it sees the result of an operation. Therefore, it thinks you may want to compare the two results for equality, thus the error message.

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