# Smoothing Capacitor Sizing for VFD

#### AlexMalkin

May 17, 2016
1
Hi Everyone , I'm designing a VFD for final year project ,
Just wondering if anyone could shed some light on calculations for a smoothing capacitor for for a 6 IGBT H bridge , with 3 Phase Diode Rectifier , converting ac to dc bus .

The input AC V is 175 50 Hz at 44A across 3 phase at 0 , -30 , -60 degrees . My IGBT's are rated for 600v 100 A .

I would like to have the ripple voltage around 4 % .

#### Minder

Apr 24, 2015
3,366
3 ph is normally 120° apart, and the 360Hz ripple % level is close to what you are looking for before smoothing.
M.

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