Getting bode plot for a circuit in Simulink

I followed the example mentioned at the link below to construct a dc-dc converter in Simulink (ver 8.1 R2013a) and tried getting the bode plot for the Vout with input perturbation at Vin.

https://www.mathworks.com/help/slcontrol/gs/bode-response-of-simulink-model.html

When I try getting bode plot through the Linear Analysis tool, I cannot see any bode plot! I am confused about how this works. Please see attached a snapshot of my Simulink circuit (Circuit.png) and the snapshot of the Bode I get (BodeOutput.png). Please advise!

[Amit Agrawal]

as i thnk bode block is not implemented in 2013 version

Answer 1

[Carla]

Looking at your screenshot of the Linear Analysis tool, it appears that you trying to obtain a linear model using the Model I/Os. Looking at your model, however, it appears that there is no path from the input analysis point (at the output of the Voltage Measurement1 block) and the output analysis point (output of the Voltage Measurement block).

The Linear Analysis tool computes the linear model from the input analysis point(s) to the output analysis point(s). If a signal injected at the input point doesn't affect the response at the output point, then the computed linear model is simply zero at all frequencies. That seems to be the case here.

Check where you placed the input perturbation - you want to remove the input analysis point from the output of Voltage Measurement1, and put it somewhere else. Perhaps you want to place it at an input of the Ideal Switch block - just make sure that the switch is closed at the operating point you choose for linearization.

[Amit Agrawal]

Dear Carla, As i notice in MATLAB2013, A example name "watertank" is given there and running very well but there is no powergui block. I am using powergui block to run simulation, but its is not showing any bode. How i can get bode with simulation?