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Harmonic Analyzer

Analyze and plot harmonic spectrum of Simscape logging nodes

Since R2022a


The Harmonic Analyzer app calculates the harmonic orders, magnitudes, and fundamental frequency of a simscape.logging.Node of an AC or periodic variable and plots a bar chart of the percentage of fundamental magnitude versus harmonic order.

The Harmonic Analyzer app allows you to:

  • Import the simulation data of a model stored in a simscape.logging.Node variable.

  • Analyze and plot the harmonic spectrum of the selected simscape.logging.Node object.

  • Export the data in MATLAB® as a script or a function.

The app finds the points in the selected leaf node, or a node at the very end of the tree navigation, where the Simscape™ log crosses a threshold specified by the DC offset parameter. It then uses the crossing points to find the required number of periods, specified by the Number of periods parameter, preceding the value specified by the Simulation time (s) parameter. Finally it inputs the selected data to the Goertzel algorithm, which calculates the harmonic magnitudes up to the value in the Harmonic order parameter.

Harmonic Analyzer app

Open the Harmonic Analyzer App

To open the app, at the MATLAB Command Window, enter: ee_HarmonicAnalyzer.


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Open the model. At the MATLAB command prompt, enter:


Run the model. In the Simulation tab, click the Run button.

The base workspace now contains the simlog_ee_harmonics_rectifier Node object.

Open the Harmonic Analyzer app by entering:


To load the simulation data variable of the ee_harmonics_rectifier model, in the app, click Import.

In the Simulation data dialog, set Inputs to the simlog_ee_harmonics_rectifier Node object to import from the base workspace.

Harmonic Analyzer node import window

The app imports all Simscape logging nodes contained in the simlog_ee_harmonics_rectifier Node object.

Harmonic Analyzer simulation data tree

For more information about data logging, see Enable Simscape Data Logging for the Whole Model.

To analyze and plot the signal and the harmonic spectrum of a logging node, open the Harmonic Analyzer app, click the Simulation Data tab, then select a node. You can only plot the harmonic spectrum of a leaf node.

Follow the steps in Load Simulation Data Variable for the Current Model to open the model, open the app, and load the Node object for simlog_ee_harmonics_rectifier.

Then select the V(2) node to plot the b-phase of the AC node in the Signal Plot tab, as well as its harmonic spectrum in the Harmonic Plot tab.

Harmonic Analyzer App harmonic spectrum plot

The Panned Signal Plot tab plots the panned signal. Drag the panner in the Signal Plot tab to interactively focus on a specific part of the signal. To increase or decrease the size of the panner, specify the Number of periods parameter.

To export the MATLAB commands required to plot the harmonic spectrum of the selected node outside of the Harmonic Analyzer app, click the Export button and then Script or Function to generate a script or a function, respectively.

Related Examples


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Number of periods of fundamental frequency in the harmonic analysis. The value of this parameter also affects the size of the panner box in the Signal Plot tab.

DC offset in the input signal. The app uses this value to find the periods of interest.

Number of harmonics to include in the analysis.

Time of the last period panned to compute the harmonic spectrum. The final permissible simulation time is equal to the simulation time specified in the model.


The Harmonic Analyzer app does not support simscape.logging.Node objects generated by variable step size models.

Version History

Introduced in R2022a