Bingo !! Very good, dear Bill ! I am very grateful to you for the great help !
I must confess I didn´t "take the risk" in suppressing the evaluation t1 = to + Delta since every simulation takes too long time and I was in a kind of a hurry to find coherent results.
From now on I will have an opportunity for doing this. Thank you immensely!

Dear Bill, maybe you help me for my last lap ! During each iteration, I need to take the rms value of the current iL2 at that time, for evaluating the power and thus the torque given by the motor. I mean, I cannot wait until the end of all the calculations for taking the general rms value of iL2. I need to do it during each iteration.Please, how can I do that ? Thank you in advance, Scabral

iL10 = iL11 = iL20 = iL21 = 0.0;
iL2ef0 = 0.0001; Delta = 0.0001;
J = 0.5;
wr0 = 0.0;
tau = 0.03;
L1 = 5.0/(120.0*Pi); L2 = 5.0/(120.0*Pi); Lm = 20.0/(120*Pi); m = 0;
R1 = 1.5; R2 = 5; s = 1.0;
Vmax = 220.0*Sqrt[2];
w = 120.0 Pi; tmax = 0.01; Phi = 0.0; t1 = 0.0; to = 0.0;
z = Table[to = t1; iL10 = iL11; iL20 = iL21; wr0 = wr1;
   iL11 = 
    iL10 + (Delta *( L2 + Lm)/( L1*L2  + L2*Lm + L1*Lm))*(Vmax *
         Sin[w *to + Phi* Pi/180.0] - 
        R1*iL10 - (Lm/(L2 + Lm))*R2 *iL20 /s);
   iL21 = 
    iL20 + (Delta /( L2 + Lm))*(   
       Lm*( L2 + Lm)/( 
           L1 *L2 + L2 *Lm + L1*Lm)*(Vmax *
            Sin[w *to + Phi* Pi/180.0] - 
           R1*iL10 - (Lm/(L2 + Lm))*R2 *iL20 /s) - R2* iL20 / s ); 

   il2sq = z[[All, 2]]^2;
   rmsiL2 = 
    Table[{z[[i, 1]], Sqrt[Mean[Take[il2sq, i]]]}, {i, 1, Length[z]}];
   wr1 = wr0 + 
     Delta*((3*R2*rmsiL2[[1, 1]]^2)/(120.0*Pi*s) - tau*wr0)/J;
   s = (120*Pi - wr1)/(120*Pi);
   t1 = to + Delta;
   {to, iL11, iL21, rmsiL2, wr1}, {to, 0, tmax, Delta}];
how[{ListPlot[z[[All, {1, 3}]], PlotStyle -> Green], 
  ListPlot[z[[All, {1, 2}]], PlotStyle -> Orange], 
  ListPlot[rmsiL2, PlotStyle -> Blue]}, 
 PlotRange -> {{0, tmax}, {-50, 50}}]
Show[{ListPlot[z[[All, {1, 3}]], PlotStyle -> Green], 
  ListPlot[z[[All, {1, 4}]], PlotStyle -> Orange]}]

Messages of errors :
Mean::rectt: Rectangular array expected at position 1 in Mean[{0.,{}}].
Mean::rectt: Rectangular array expected at position 1 in Mean[{0.,{},{}}].
Mean::rectt: Rectangular array expected at position 1 in Mean[{0.,{},{},{}}].
General::stop: Further output of Mean::rectt will be suppressed during this calculation.

.

il2sq = z[[All, 2]]^2;
rmsiL2 = Table[{z[[i, 1]], Sqrt[Mean[Take[il2sq, i]]]}, {i, 1, Length[z]}];
Show[{ListPlot[z[[All, {1, 3}]], PlotStyle -> Green], 
   ListPlot[z[[All, {1, 2}]], PlotStyle -> Orange],
   ListPlot[rmsiL2, PlotStyle -> Blue]}]

Dear Bill. Thank you very much and again, for your holy help.
I really got confused with the resulting graphics from my proposition. One of them was correct, while the other not. You are right with the need in respecting the structure. But I thought a message of error should appear to my proposition... I suppose your suggestion creates a table of numbers that is somehow stored anywhere and I wonder if this can be a problem if the number of iterations goes too far. Gonna try it. Your proposition for the RMS gives a general result. But what if I want to evaluate the accumulated RMS value at each iteration? This is what I need. thank you so much !!!!!