What effect does the air gap design of the magnetic core have on the saturation characteristics of common mode inductance?

Air gap can enhance saturation resistance (by reducing effective permeability) but decrease inductance (roughly inversely proportional to air gap length). Typical air gap designs range from 0.1-0.5mm for power applications. A magnetic core air gap (a small gap reserved in the magnetic circuit of the core) can reduce the effective permeability of the magnetic core and increase its saturation flux density.

In the absence of air gaps, the magnetic core is prone to saturation under relatively small DC or AC magnetic flux, resulting in a sharp decrease in inductance and loss of filtering capability;

When there is an air gap, the magnetic core's ability to resist saturation is enhanced, allowing it to withstand higher DC currents or alternating magnetic flux. This ensures that the inductance value remains stable and the filtering effect is maintained in high-current scenarios, such as power input circuits.