i want to calculate the power output of a 3 phase inverter. Therefore i have to do a FFT on my voltage Signals, to get the amplitude of the fundamental.
In comparison to the FFT Tool from the Simulink powergui, my amplitude is always lower. I searched for some examples for a correct scaled FFT, but i cant find differences to my code.
f1 = ac_voltage_a.data(SteadyState:1:SteadyState+2^15);
g1 = hanning(length(f1)).*f1;
vac_fenstera_Nfft = length(g1);
J = fft(g1);
vac_fenstera_sfft = 2*abs(J)/vac_fenstera_Nfft;
plot(1/dt * (0:(vac_fenstera_Nfft/2-1)) / vac_fenstera_Nfft, (vac_fenstera_sfft(1:vac_fenstera_Nfft/2)));
In comparison to the FFT analysis tool from powergui, the value of my fundamental amplitude is only half the size, even i mutiplied the abs*2.
Where is my fault?
Is it nessesary that the length of g1 is a multiple of 2? I think a DFT could also work out.