Selected Frequency Amplitude

R2026b

Measure amplitude or power at a specified harmonic frequency

Since R2026b

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Libraries:
Power Converter Control with Motor Control Blockset / Measurement

Description

The Selected Frequency Amplitude block measures the amplitude or power of a time-domain signal at a specified harmonic order of the fundamental frequency. Use this block to extract the magnitude of individual harmonic components from a periodic signal, such as for total harmonic distortion analysis or selective harmonic filtering. You can configure the harmonic order, measurement mode, and whether the block outputs the amplitude or signal power at that frequency.

Ports

Input

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Input signal to analyze, specified as a scalar. The block extracts the amplitude or power at the selected harmonic frequency from this signal.

Data Types: single | double

Reset trigger signal, specified as a scalar. A rising edge on this port resets the measurement window.

Dependencies

To enable this port, set Measurement mode to Moving window (default).

Data Types: single | double | Boolean

Fundamental frequency input signal, specified as a positive scalar in Hz. The block uses this frequency and the harmonic order to determine the target measurement frequency.

Dependencies

To enable this port, set Fundamental input frequency type to Input port.

Data Types: single | double

Measurement restart trigger signal, specified as a scalar. A rising edge on this port restarts the fixed-window measurement cycle.

Dependencies

To enable this port, set Measurement mode to Fixed window.

Data Types: single | double | Boolean

Output

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Amplitude at the selected harmonic frequency, returned as a scalar.

Dependencies

To enable this port, set Block output to Amplitude (default).

Data Types: single | double

Power at the selected harmonic frequency, returned as a scalar.

Dependencies

To enable this port, set Block output to Power.

Data Types: single | double

Measurement window completion status, returned as a scalar. The signal indicates whether the fixed-window measurement cycle is complete.

Dependencies

To enable this port, set Measurement mode to Fixed window.

Data Types: single | double | Boolean

Parameters

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To edit block parameters interactively, use the Property Inspector. From the Simulink® Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.

Type of measurement output. Select Amplitude to output the signal amplitude at the selected harmonic frequency. Select Power to output the signal power at that frequency.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: BlkOutput
Values: "Amplitude" (default) | "Power"

Example: set_param(gcb,"BlkOutput","Power")

Simulation discrete sample time, specified in seconds. This value determines how often the block executes and updates the measurement output. Set this to match the fixed-step solver step size of your model. A smaller value increases measurement resolution but adds computational cost.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: BlkSampleTime
Values: "50e-6" (default) | positive scalar in quotes
Data Types: char | string

Example: set_param(gcb,"BlkSampleTime","100e-6")

Source for the fundamental frequency value. Select Specify via dialog to use the Fundamental frequency value (Hz), f₁ parameter. Select Input port to supply the fundamental frequency from an input port.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: InputFrequencyType
Values: "Specify via dialog" (default) | "Input port"

Example: set_param(gcb,"InputFrequencyType","Input port")

Fundamental frequency of the input signal, specified in Hz. The block computes the measurement at the harmonic frequency k * f₁, where k is the harmonic order. For a 50 Hz grid, set this to 50; for a 60 Hz grid, set this to 60. The measurement window spans one complete cycle at this frequency.

Dependencies

This parameter is visible when Fundamental input frequency type is set to Specify via dialog.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: FundamentalFrequency
Values: "50" (default) | positive scalar in quotes
Data Types: char | string

Example: set_param(gcb,"FundamentalFrequency","60")

Harmonic order at which to measure, specified as a positive integer. A value of 1 measures the fundamental component, 2 measures the second harmonic, and so on. The block extracts the amplitude at the frequency k * f₁, so increasing this value targets higher-frequency harmonics.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: OrderMeasure
Values: "1" (default) | positive integer in quotes
Data Types: char | string

Example: set_param(gcb,"OrderMeasure","3")

Windowing method for amplitude computation. Select Moving window to continuously update the measurement over a sliding window. Select Fixed window to compute the measurement over a fixed number of cycles and hold the result until restarted.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: MeasurementMode
Values: "Moving window" (default) | "Fixed window"

Example: set_param(gcb,"MeasurementMode","Fixed window")

Lower bound for the input frequency range, specified in Hz. The block uses this value to allocate the internal buffer that stores samples for one measurement window. A lower frequency requires more buffer memory because the measurement window spans more samples. Set this to the lowest frequency your application needs to measure accurately.

Dependencies

This parameter is visible when Fundamental input frequency type is set to Input port.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: MinimumFrequency
Values: "40" (default) | positive scalar in quotes
Data Types: char | string

Example: set_param(gcb,"MinimumFrequency","30")

Number of signal cycles in the fixed measurement window. The block computes the measurement over this many complete cycles before holding the output. Increasing this value improves measurement accuracy by averaging over more cycles, but increases the time before the first valid output is available.

Dependencies

This parameter is visible when Measurement mode is set to Fixed window.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: NumCycle
Values: "1" (default) | positive integer in quotes
Data Types: char | string

Example: set_param(gcb,"NumCycle","2")

Extended Capabilities

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C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2026b

See Also

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