Bode plot of simulink model

Hi there, I have a simulink model for motor control. I need to plot its bode diagram. Is there a command to plot the bode plot for a simulink model? could you tell what is it (if any)? furthermore, I would be happier if you could tell me commands which may draw pole-zero plot.

thanks,

Answer 1

[Fangjun Jiang]

To plot the Bode plot, you need the transfer function.

[A,B,C,D]=LINMOD('SYS') obtains the state-space linear model of the system of ordinary differential equations described in the block diagram 'SYS' when the state variables and inputs are set to the defaults specified in the block diagram.

If your Simulink model is just a transfer function of the controller connected with the transfer function of the motor plant model in a unit feedback, it might be better if you do it in MATLAB.

You can use tf(),ss() or zpk() to specify the controller and the motor model. Then you can use connect() to connect the model with feedback and close the loop. use step() ans stepinfo() to see the step response.

Check the help documentation for all the functions mentioned above. Sometimes its easy to do it in MATLAB without Simulink. But Simulink also has advantages. It's graphical, interactive and can easily add non-linear and time-variant components.

To draw zero-pole plot, use pzmap().

Most of the functions require the Control System Toolbox. If you have that, sisotool(), ltiview() may be very useful.

[Alzapoa]

perfect answer dude

thank you

Answer 2

[Arkadiy Turevskiy]

You might also look at Simulink Control Design. It gives you many tools for trimming and linearizing Simulink models. You can do that using a nice user interface, or command line functions (which can be automatically generated from the GUI).

Take a look at linearization page for more details.

HTH. Arkadiy