How to avoid ground loop interference in motion controller MC

To avoid ground loops in the motion controller (MC), the grounding strategy should be selected based on the signal frequency and system architecture. For low-frequency analog circuits and sensors, single-point grounding is used, with all ground wires converging at a single point on the controller. For high-frequency digital circuits and communication interfaces, multi-point grounding is used, implemented through a low-impedance ground plane. Differential signal transmission, such as RS-422, is preferred between the controller and remote devices like drivers and encoders, as it is inherently insensitive to ground loops.

If single-ended signals must be used, an isolation scheme should be employed, such as using an isolation amplifier or digital isolator, disconnecting the direct ground connection. The shield of shielded cables should only be grounded at the controller end, with the other end left floating. During system installation, ensure all devices have a good common ground; if potential differences exist between devices, equipotential bonding conductors should be used. Potential ground loops can be identified by measuring the noise voltage and current between ground wires, and current probes can be used to locate the circulating current path. During the design phase, the impedance of the grounding system is analyzed through simulation to optimize the location and number of grounding points.