Look for

IET power Electronics

"Medium voltage 12-pulse converter: ac side compensation using a shunt active power filter in a novel front end transformer configuration"

Dear Venkat,

I've it made in 1998 with Simplorer (ANSYS).Please look my paper :

https://www.researchgate.net/publication/235974451_Komplexe_Optimierung_der_Kondensatorbatterie_des_Zwischenkreisfrequenzumrichters?ev=prf_pub

Excuse me, it's only in German ! 

Regards Christian

Conference Paper Komplexe Optimierung der Kondensatorbatterie des Zwischenkre...

@ Mahmoud I. Masoud

Thanks for your answer and the paper.

@Christian E. Jacob

Thanks a lot for answer. I will try to convert German into English and then I will try to read.

I also  found a good article by Michael Salcone and Joe Bond entitled, "Selecting Film Bus Link Capacitors For High Performance Inverter Applications".  Which helped me to do the above job.

Dear Venkat,

have you a link to this article? It's interesting for me.

Thank you for download my paper and best regards Christian

@Christian E. Jacob

Dear Christian 

Thanks for your response. Its an IEEE paper. the link is given bellow

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5075431&tag=1

Dear Venkat,

I see the "Bus Link circuit" is only for single phase inverters!

Have you any idea to use this technologie for three-phase bridges?

Dear  Christian,

This analysis of single phase can be extended to three phase star connected load. There are total eight switching states for the converter. if we do a single pulse with a variable duty ratio with phase difference of 120 degrees to each leg, we may observe the variation in currents and corresponding effect on capacitor ripple current. I am not sure but such analysis may help us to find the exact relation. 

Beautiful! Best wishes and good luck from Christian 

@Christian 

Thank you sir.

Please consider that classical three phase system does not need huge capacitor in the DC link, because it does not suffer from huge instantaneous power oscillation, like in case of single phase. In this case value depends on your requirements of voltage sag withstanding, etc.

@Andrii Chub

Thanks Andrii.

you are absolutely right. in three phase system, DC is of six pulse one. therefore each switch conducts maximum of 1/6th time period. which reduces ripple current and accordingly capacitor rating too. 

Dear Andrii,

the active three phase rectifier need normally for commutation between IGBT and reverse diode a capacitor. This capacitor is (parallel to) the DC link and should bee very small. Because it must be discharge, then is an error in power stack. 

Regards Christian