Mean (Variable Frequency)

Compute mean value of signal

Library

Simscape / Electrical / Specialized Power Systems / Sensors and Measurements

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Description

The Mean (Variable Frequency) block computes the mean value of the signal connected to the second input of the block. The mean value is computed over a running average window of one cycle of the frequency of the signal:

$$\begin{array}{l}Mean\left(f(t)\right)=\frac{1}{T}{\displaystyle \underset{(t-T)}{\overset{t}{\int }}f(t)\cdot dt}\\ f(t):\text{input signal, T = 1/ frequency}\end{array}$$

This block uses a running average window. Therefore, one cycle of simulation must complete before the block outputs the computed mean value. For the first cycle of simulation, the output is held constant to the specified initial value.

Parameters

Initial frequency (Hz)

Specify the frequency of the first cycle of simulation. Default is 60.

Minimum frequency (Hz)

The minimum frequency value determines the buffer size of the Variable Time Delay block used inside the block to compute the mean value. Default is 45.

Initial input (DC component)

Specify the initial value of the input during the first cycle of simulation. Default is 0.

Sample time

Specify the sample time of the block, in seconds. Set to 0 to implement a continuous block. Default is 0.

Inputs and Outputs

Freq

The frequency of the signal.

In

Connects to the signal to be analyzed.

X

The mean value of the signal.

Characteristics

Sample Time	Specified in the Sample Time parameter Continuous if Sample Time = 0
Scalar Expansion	Yes, of the parameters
Dimensionalized	Yes

Examples

The power_MeanVariableFrequency model compares the Mean block to the Mean (Variable Frequency) block for three identical input signals. It shows that, even if the frequency of the input signals varies during the simulation, the Mean (Variable Frequency) block outputs correct values.

The model sample time is parameterized by the Ts variable with a default value of 50e-6 s. Set Ts to 0 in the command window to simulate the model in continuous mode.

Version History

Introduced in R2013a