How to improve interference immunity in a common ground system for motion controllers (MC)

Improving the overall immunity of the motion controller (MC) system requires optimizing the system grounding. A tree or mesh grounding structure should be adopted to ensure a low-impedance path from each device to the ground. Independent shunt grounding paths should be designed for different types of interference, such as a dedicated grounding busbar for lightning surges. An equipotential bonding busbar should be installed at the device inlet to connect the power ground, signal ground, and chassis ground, eliminating potential differences introduced externally. Isolated interfaces or differential communication should be used between modules within the system.

Common-mode chokes should be used on all incoming and outgoing cables. Tightly coupled signal return should be achieved using a low-impedance ground plane. After completion, comprehensive immunity testing should be conducted, including EFT, surge, and power frequency magnetic field tests. Grounding should be fine-tuned based on the results, such as adding grounding wires or magnetic rings at specific locations. For critical sensors, separate isolated power supply and signal transmission can be used. System grounding should be coordinated with shielding, filtering, and other measures to form a complete EMC protection system.