This model of a buck converter uses a “state-average” abstraction (i.e. the actual switching effect is removed by averaging), so that it simulates very quickly. It can be used for iterative compensator tuning because it supports small-signal AC analysis. Performance metrics include line and load transient response (time-domain), as well as the open-loop phase margin (frequency-domain).
Two companion design examples show similar results for a switching circuit implementation of this buck converter. The first, "Step-Down (Buck) DC to DC Converter - Switching", shows the line and load transient performance. The second, "TDFS Loop Stability for Step-Down (Buck) DC to DC Converter - Switching", shows the open-loop frequency response. This effective "AC" analysis is performed using the TDFS method, at time-domain simulation technique for measuring frequency response.