Hello,

In SMPS circuits, why and what is the purpose of using the LLC converters after the PFC stage ?

The output of PFC stage we have a DC, so we can directly fed this DC to the load right ! instead of LLC converter !

Why there are inverting the DC signal again in the LLC converter by using the Resonant Network and then that sinusoidal signal fed to the transformer and then rectifying the signal which is connecting to the Load ?

Why doing this long process ? We can do simply by connecting the output of PFC to the Load !

 

PFC = Power Factor Correction
LLC = inductor + inductor + capacitor

The DC output from the PFC is at the wrong DC voltage for what the load expects.
You need the inverter to bring the voltage to the desired DC voltage. The LLC is a resonant converter in the inverter stage to go from DC to AC and back to DC.

https://www.nxp.com/docs/en/reference-manual/DRM119.pdf