How to suppress switching noise in industrial servo drives?

Servo driver switching noise is mainly generated by the high-speed switching of power devices (such as IGBTs). Their high-frequency dv/dt and di/dt, through parasitic parameters, form common-mode and differential-mode conducted interference, which radiates and affects surrounding sensitive circuits. Based on EMC design experience from EAST Electronics, a three-stage suppression scheme is recommended:

First, connect a low-ESL DC bus capacitor in parallel on the DC bus side, such as a CMZ7060A-701T series common-mode inductor (70μH) to suppress common-mode current; second, connect a PBZ2012E-060Z0T ferrite bead (60Ω@100MHz) in series at the output of the switching device to absorb high-frequency harmonics; simultaneously, use an ESDSV05-4H multi-channel TVS array in the drive circuit to protect the gate drive from electrostatic discharge and transient overvoltage interference.

Tests show that this combined scheme can reduce conducted interference (CE) by 15-20dB, meeting the EN55032 Class A limit requirements. By optimizing the PCB layout, placing filtering components close to the noise source, and using star grounding, loop impedance can be further reduced, ensuring stable operation of the system in industrial environments.