How to design the power frequency magnetic field immunity for industrial servo systems?

Servo systems need to consider immunity to power frequency magnetic fields (50/60Hz), especially in applications using Hall current sensors or resolvers. Eintraelectronics' design methods include:

1) Magnetic field shielding: Use high-permeability materials (such as permalloy) for local shielding of sensitive sensors or circuits.

2) Circuit design: Utilize differential sensing technology (such as differential Hall sensors) to leverage their common-mode rejection capability. For resolvers, whose output signal is differential, the receiver should have high CMRR.

3) Keep wiring away from magnetic field sources: Keep sensitive signal lines away from transformers, motors, and other strong magnetic field sources. If unavoidable, ensure cables are perpendicular to the magnetic field direction.

4) PCB layout: Avoid creating large current loops around sensitive amplifiers. According to IEC 61000-4-8, industrial environments typically require tolerance to power frequency magnetic fields of 30A/m.

These measures ensure that the current or position detection error of the servo system in strong magnetic field environments (such as near high-current buses) is <1%, guaranteeing control accuracy.