Boost converter with 28335,matlab2015a and ccsv5

Sir

I am trying to realize the closed loop operation of boost converter with the support of 28335,matlab2015a and ccsv5. My simlink model is shown below. whenever i gave input D.C voltage of 15v, irrespective of the reference voltage value which is set here is 20v, I am getting output of 30v. It is because I set the saturation limit to 50%. I think My pid block is working as i change the P and I values there is fast/slow response. . Why I am not getting the required output. I think it is because of the blocks before PID controller.I am using the voltage sensor as LV-20-p. It sensitivity is 5V/500V. Can anyone help me sir.