How to meet the CISPR 11 limits for industrial servos?

To ensure a servo system meets CISPR 11 (GB 4824) limits, it must be designed for Class A (industrial environments) or the more stringent Class B (residential environments).

The compliance path for Audiotech is as follows: For conducted emissions (150kHz-30MHz), the key is to optimize the input filtering network: use a combination of high-performance CMZ common-mode inductors (such as CMZ7060A-701T) and X2 capacitors, adding a second stage of common-mode filtering if necessary.

For radiated emissions (30MHz-1GHz), focus on addressing motor cable radiation and chassis leakage: use shielded motor cables with grounding at both ends, use conductive gaskets in cabinet gaps, and use waveguide plates for ventilation openings. Control loop area in the internal PCB layout and shield switching nodes.

Pre-testing and iteration: Conduct pre-compliance testing during the R&D phase to locate out-of-specification frequencies and make targeted adjustments, such as adding magnetic rings or adjusting filter parameters.

Typically, a systematically designed servo driver can meet Class A standards; to meet Class B standards, more stringent filtering and shielding are required, increasing costs accordingly.