ERROR : plant linearizes to zero

Dear all,

          I am trying to tune a PI controller with two "fcn" and one "MATLAB" function blocks as plant. Inside the "fcn" blocks are 2 simple equations but inside the "MATLAB" block i have written some code and the output is 1 or 0 (I am actually generating PWM signals based on duty ratios calculated inside the block).

"fcn1" has equation 1.5*u(1)*cos(u(2))*60

"fcn2" has equation asin((2*pi*50*0.00003*60)/(u(1)*u(2)))

"MATLAB" function block has a formula to calculate duty ratios and I generate the PWM signal (SVPWM) by splitting the duty ratio and apply 1 or 0 at different intervals.

The model file (subsystem alone and full model) is attached so please take a look.

thanks.