How to meet the MCCISPR11 limit for motion controllers?

To ensure the motion controller MC meets the emission limits of CISPR 11/GB 4824, systematic suppression of conducted and radiated noise is necessary.

First, pre-testing is performed to pinpoint outlying frequencies. For conducted emissions, optimize the input filter of the switching power supply, increasing the common-mode inductor or X-capacitor value. Check the shielding and grounding of all external cables. For radiated emissions, check the integrity of the chassis shielding, using conductive pads for gaps and waveguides for ventilation holes. Suppress internal noise sources, such as adding shielding to the clock circuit and using series ferrite beads for the high-speed bus. Optimize the PCB layout to reduce the area of high-speed loops. For outlying frequencies, analyze their source, which may be a harmonic of the switching power supply or the clock, and add targeted filtering or adjust the frequency. Achieving compliance is an iterative process that requires combining filtering, shielding, grounding, and other methods, ensuring that all frequencies are below the Class A or Class B limits with sufficient margin during final testing.