FFT analysis using simscape power_fftscope, analytical expression.

Hi guys,

I am trying to use the power_fftscope analysis as an input for my ansys fem simlation. Therefore, I need the current or voltage as an analytical expression including the harmonic components. So I wanted to ask what the analytical expression would look like. I got order, phase and magnitude. Does the analytical expression look something like sin(order*fundamental_freq*2pi*t+phase)? Or how is it supposed to look like? And how can I make sure that the fundamental frequency phase is zero?

Thanks in advance!

Answer 1

[Divit]

Hi Dom,

I understand that you would like to know how you can express current or voltage analyticlally containing harmonic components.

To express the current or voltage waveform with harmonic components analytically, you can use a Fourier series representation. The analytical expression for the waveform would be a sum of sine or cosine functions at different frequencies, each with a specific order, phase, and magnitude.

The general form of the analytical expression for a waveform with harmonic components can be written as:

or

where:

or represents the voltage or current waveform as a function of time.

or is the DC offset or average value of the waveform.

N is the number of harmonic components or orders.

is the magnitude or amplitude of the nth harmonic component.

ω is the fundamental angular frequency ().

is the phase shift or phase angle of the nth harmonic component.

To ensure the fundamental frequency phase is zero, set () in the expression. This means that the first harmonic component will have no phase shift relative to time, and the fundamental frequency phase will be zero.

By specifying the values of , , , and for each harmonic component, you can obtain the analytical expression for the waveform that includes the harmonic components.

Hope it helps!