UCC28180: Line to Line boost PFC for delta three phase AC input

Hello Dhananjay, 

Your proposed 3-phase arrangement (shown above) is not technically feasible and will not work. In fact it will damage one or more components, usually one of the diodes in each diode bridge and the fuses will blow. 

This arrangement does not work because the three GNDs of each PFC stage are NOT common and cannot be connected directly together.  Each GND will rise and fall with the positive and negative peaks of the input line and since the 3 lines are 120 degrees out of phase, the three GNDs are never all the same voltage at the same time.   

There are three ways around this problem: 
1.  Use a "Vienna Rectifier" which generally requires and MCU to control it; 
2.  Use 3 separate LLC stages (one for each PFC) and connect their isolated outputs together (with load-sharing, if necessary);
3.  Use a 6-diode rectifier bridge at the input and feed all 3 lines into it.  This is simplest, however, the PF will be lower and THDi will be higher.  Many users still find this arrangement to be sufficiently high-enough PF and sufficiently low-enough THDi to pass requirements. 

Regards,
Ulrich