How can I make a duty cycle vary in a state-space model?

I have the following state space for a boost supply:

As we can see the model has a varying duty cycle(d^). I have converted the state space to a transfer function using:

SS =ss(Aac,Bac,Cac,Dac)

TFs=tf(SS2)

To test my system I have copied the transfer function and but it in Simulink block. My problem is that I want to vary only my (d^). How can I do that?

[David K.]

Can you show how you implemented it? Because in your equations (d^) is an input to the state space system. Therefore, you just need to change the input. If you are using the state space block, since there are two inputs to the system you will likely need to take the (vg^) and (d^) signals and join them into a bus before inputting to the state space block.

[Amina Mokhtar]

That it true I can insert the (d^) as a constant but I wanted to vary its value like a step but the statespace block in simulink has only one input and that will be my (Vg)