Information

This information is part of the Modelica Standard Library maintained by the Modelica Association.

This block determines the total harmonic distortion (THD) over the given period 1/f. Consider that the input u consists of harmonic RMS components U₁, U₂, U₃, etc. The total RMS component is then determined by:

The calculation of the total harmonic distortion is based on the parameter useFirstHarmonic. The default value useFirstHarmonic = true represents the standard THD calculation used in electrical engineering. The non-default value useFirstHarmonic = false calculates the THD typically used for the assessment of audio signals.

If useFirstHarmonic = true, the total higher harmonic content (harmonic order numbers > 1) refers to the RMS value of the fundamental wave:

If useFirstHarmonic = false, the total higher harmonic content (harmonic order numbers > 1) refers to the total RMS:

In case of a zero input signal or within the first period of calculation, the boolean output signal valid becomes false to indicate that the calculation result is not valid. Valid calculations are indicated by valid = true.

f	Value: Type: Frequency (Hz) Description: Base frequency
useFirstHarmonic	Value: true Type: Boolean Description: THD with respect to first harmonic, if true; otherwise with respect to total RMS

	u	Type: RealInput Description: Connector of Real input signal
	y	Type: RealOutput Description: Connector of Real output signal
	valid	Type: BooleanOutput Description: True, if output y is valid

Components (9)

	harmonic	Type: Harmonic
	rootMeanSquare	Type: RootMeanSquare
	greaterThreshold	Type: GreaterThreshold
	division	Type: Division
	limiter	Type: Limiter
	pythagoras	Type: Pythagoras
	andValid	Type: And
	booleanExpression	Type: BooleanExpression
	switch1	Type: Switch

TotalHarmonicDistortion

Diagram

Information

Parameters (2)

Connectors (3)

Components (9)

Used in Examples (1)