doubt about pfc in smps

I am a newbie to SMPS...
I learnt that PFC can improve the efficiency of the SMPS...
Does it also reduce EMI of the SMPS?

thanks in advance

PFC is just meant to improve power factor, not much else. From the perspective of the AC power distribution system, having a load with a high PF improves the efficiency of the power transmission (from the power generation to the load input). However, this transmission efficiency is completely independent of the power efficiency of the PFC itself. Whether the PFC performs better in terms of EMI or efficiency depends on what specifically you're comparing to.

The main advantage of this method is greater efficiency because the switching transistor dissipates little power when it is outside of its active region (i.e., when the transistor acts like a switch and either has a negligible voltage drop across it or a negligible current through it). Other advantages include smaller size and lighter weight (from the elimination of low frequency transformers which have a high weight) and lower heat generation due to higher efficiency. Disadvantages include greater complexity, the generation of high-amplitude, high-frequency energy that the low-pass filter must block to avoid electromagnetic interference (EMI), a ripple voltage at the switching frequency and the harmonic frequencies thereof.
Very low cost SMPSs may couple electrical switching noise back onto the mains power line, causing interference with A/V equipment connected to the same phase. Non-power-factor-corrected SMPSs also cause harmonic distortion.

Higher input voltage and synchronous rectification mode makes the conversion process more efficient. The power consumption of the controller also has to be taken into account. Higher switching frequency allows component sizes to be shrunk, but can produce more RFI. A resonant forward converter produces the lowest EMI of any SMPS approach because it uses a soft-switching resonant waveform compared with conventional hard switching.

https://en.wikipedia.org/wiki/Switched-mode_power_supply



Spread Spectrum Techniques to Reduce EMI in SMPS Devices
https://www.onsemi.com/pub_link/Collateral/AND8428-D.PDF

EMI and Layout Fundamentals for Switched-Mode Circuits
**broken link removed**


Check Microchips EMI filters products.

:wink: