Depending on how you are going to model your averaged value model. For instance, you can model the average value model using 'ss' (https://www.mathworks.com/help/control/ref/ss.html). You can then analyze this state-space model.
Alternatively, you can model the power electronics circuit in Simulink with higher fidelity. Based on the Simulink model, you can then use the linearization and frequency response estimation approaches from Simulink Control Design: https://www.mathworks.com/help/slcontrol/ug/linearize-simulink-model.html
