How to isolate noise in a power line carrier PLC switching power supply?

Isolating power line carrier PLC switching power supply noise requires a multi-stage isolation and filtering strategy. At the power input, a common-mode inductor CMZ3225A-101T is first used to suppress common-mode noise from the switching frequency and its harmonics. Then, a series power inductor such as PWH6045R6R8M0T is used to attenuate differential-mode noise. A key measure is to deploy an isolation transformer between the switching power supply and the carrier circuit, with a 1:1 turns ratio and a primary-to-secondary withstand voltage of over 3000VAC, effectively blocking conducted noise. Simultaneously, a π-type filter is added to the secondary side of the isolation transformer, using a combination of a PBZ1608A-102Z0T ferrite bead and ceramic capacitors. For ground noise, optocouplers are used for signal isolation. In the PCB layout, the switching power supply area and the carrier circuit are separated. Through this comprehensive isolation scheme, the impact of switching power supply noise on carrier communication can be reduced by more than 40dB.