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HIPER PFS-3 PFC parallel operation

Posted by: Kanwar on

Can we use two PFS-3 chip "modules" in parallel to increase the power output ?

Input rectifier-->>feeding both PFC modules with separate inductors-->>cathodes of both output diodes of PFS-3 joined together and sharing one large bulk cap along with negative tied to S pin [with small series current sharing resistor]of both modules serving as COM return path.

Thereby keeping the sensing/control element pins FB/V/REF/G/PGT/C and connected components such as resistors/capacitors individual to each module , though PG could be combined, since its an open drain output.

Since the current sensing is inherent in the PFC chip itself, there is no means for current sharing check if it is happenning properly, can we rely on natural sharing by inserting a small resistor 0.1 or lesser in series with S pin of each module in order to force current sharing, perhaps we can join FB nodes of both modules to midpoint of voltage divider between bulk V+ and return across capacitor ?  

 

what say?

Comments

Submitted by PI-Neela on 11/30/2016

our PFS does not develop to work with parallel scheme. I am concern about the transient conditons or protection senarios such as over current, over votlag eand over temperature etc. Also during strat up transient the inrush current is high and the engine has certain protections. THose control pins particular FB pin is sensitive. Also external current balance resistor signal will not be feedback to controller. I am thinking some commercial N+1 parpallel monitoring chip used in telecom applicaiton could help?