THD simulation results issue

satyanarayana BN

Hi 

we are simulating buck topology based PFC circuit, we are measuring input source voltage VTHD. The Sim View results showing  around 5%. but we calculated the THD manually and observed the VTHD value is 0.003%. Why simview measurements not matching with manual calculations.

we have calculated THD manually, below steps followed

         Click on FFT button in simview

          export the data points to .csv file 

         calculated the THD manually

Please check attached files for your reference.

FFT-v.xlsx

Simview FFT.JPG

Simview VTHD.JPG

Rhonda_20369

Hi, satyanarayana BN,

 

There are several factors affect the precision of the THD measurement (and any other measurement) in Simview.  One of them is the simulation step size. 

 

The simulation result data are discrete. All the measurements in Simview are calculated from each of the data point.

If your simulation step is smaller, your THD calculation in Simview could be more accurate.