How to suppress common-mode interference at the power line interface of a power line carrier PLC?

Suppressing common-mode interference at the power line interface of a power line carrier PLC requires the deployment of common-mode filtering and shielding measures. A common-mode choke CML4532A-510T with an inductance of 51μH and an impedance greater than 500Ω at 1MHz is installed at the interface. A safety Y capacitor (2.2nF/250VAC) is connected in parallel to ground to provide a low-impedance path for common-mode noise. Shielded cables are used for connection, with the shielding layer terminated 360 degrees to the metal casing. On the PCB, the interface area is surrounded by a ground plane to isolate noise. Common-mode rejection ratio (CMRR) is analyzed through simulation, and filter parameters are optimized to achieve a rejection ratio greater than 30dB. In actual testing, conducted interference tests are performed, and common-mode interference in the 150kHz-30MHz frequency band should be lower than the EN55032 Class B limit. Suppressing common-mode interference can improve the system signal-to-noise ratio by 20dB, making communication more reliable.