How to separate the power ground and signal ground in industrial servo systems?

In servo systems, power ground (high-current loops) and signal ground (control and sampling loops) must be properly separated to prevent noise coupling. However, after separation, they still need to be connected at a single point to maintain equipotential. Etymotic's separation solution: In PCB design, use a physical gap (at least 3mm) to separate the power ground layer from the signal ground layer. Power ground includes the negative terminal of the DC bus capacitor, the IGBT emitter, the current sampling resistor ground, etc.; signal ground includes the control IC ground, ADC reference ground, communication interface ground, etc. The two ground layers are connected at one point through a zero-ohm resistor or ferrite bead (such as PBZ1608A-102Z0T), which is usually chosen near the reference ground of the signal sampling circuit (such as the op-amp). After separation, ensure that all signal lines do not cross the separation gap. If crossing is necessary, use a common-mode choke (such as CML3225A-510T) or optocoupler for isolation. Proper separation can reduce the impact of power switching noise on ADC sampling by more than 20dB, improving control accuracy and stability.