How should power supply filtering be designed for a power DTU?

The design of the DTU power-side power supply filtering needs to be determined based on the grid noise spectrum and current capacity. For the 220VAC input, a three-stage filtering architecture is adopted: the first stage is differential-mode filtering, using an X2 safety capacitor (0.47μF/275VAC) connected in parallel between the L and N lines; the second stage is common-mode filtering, using a common-mode inductor CML4532A-510T (51μH, rated current 6A); the third stage is high-frequency noise suppression, using a series ferrite bead PBZ1608E600Z0T. For the DC power supply, a π-type filter is added, using a power inductor PWR6045R6R8M0T and a low-ESR electrolytic capacitor (220μF). Simulation verification shows that the filtering effect is greater than 40dB in the 150kHz-30MHz frequency band, meeting the EN55032 Class B conducted emission limits.