#### metamisers

##### Junior Member level 1

The closed loop bode plot is shown below

While designing the Type-3 controller in MATLAB, I chose the corner frequency as 2350Hz, phase margin of 45 degrees with a double pole resonance at 716 Hz. After designing the controller the following results were obtained

Which is almost what I wanted. Now, after implementing the PID controller as shown in the first picture, this is the output voltage result.

The simulation continues while the output voltage is increasing indefinately. About the reference voltage at the positive terminal of the OPAMP, since D = 0.445, hence my reference voltage should be 5x0.445 = 2.225 Volts. Is this correct? I can't figure out where the problem is in the circuit.

For the Boost converter, esr zero is at 19.9kHz, R.H.P. zero is at 8600 Hz, the double zeros of the PID compensator are at 500Hz, the first pole of the compensator is at 10.79 kHz and the 2nd pole is at half the switching frequency of 50 kHz. I chose the voltage divider ratio to be 0.1, hence 2 volts should appear at the negative terminal, but i am not sure what reference voltage should be selected. Any help will be greatly appreciated.

Zahid.