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Buck Converter with Loop Gain Multitone Analysis

This demonstration shows how to obtain the loop gain of a voltage-regulated buck converter with a resistive load using Multitone Analysis. Multitone Analysis is similar to an AC Analysis where the response of the system to a small perturbation signal is analysed. However, instead of multiple sinusoidal signals of different frequencies, only one multitone signal is applied. It is composed of several sinusoidal signals and therefore contains all investigated frequencies at once.

The Multitone Analysis is faster than the AC Analysis because it only needs to compute the response to one signal instead of a set of signals for each frequency. The caveat with Multitone Analysis, however, is that the value for the initial simulation period parameter should be sufficiently large enough for the system to have reached steady-state conditions from a transient simulation.

To run a Loop Gain Analysis double-click on the Loop Gain Analysis block to open the dialog and click on the Start analysis button. The progress of the analysis is displayed in the MATLAB Command Window. When the analysis has finished a new Bode plot will be displayed showing the corresponding transfer function.

A demonstration of the loop gain calculated using Loop Gain Analysis is given in the demo model Buck Converter with Loop Gain Analysis.

A demonstration of an open-loop Multitone Analysis is given in the demo model Buck Converter with Multitone Analysis.