PLECS 2.1 Online Help

Loop Gain Analysis

Purpose

Determine the closed-loop gain of a control loop.

Library

Extras/Analysis Tools

Description

[Picture]

The Loop Gain Analysis block enables you to determine the gain of a closed control loop. To measure the loop gain, insert the block anywhere in the control loop. The loop gain is determined by adding a small sinusoidal signal at various frequencies and extracting the same frequencies from the system before and after the summation point by Fourier analysis.

An analysis can be started either by clicking the button Start analysis or with the MATLAB command

placsweep(block);

where block is the Simulink handle or the full block path of the Loop Gain Analysis block. Otherwise, the block remains inactive and does not influence the control loop.

For additional information see section AC Analysis.


Note  The Loop Gain Analysis block works only on scalar signals. In order to analyze the gain of a vectorized control loop you need to demultiplex the vector signal into individual scalar signals before inserting the Loop Gain Analysis block.

Parameters and Dialog Box

The dialog box and parameters are identical to those of the AC Sweep block.