Automotive inductors high frequency inductors

Automotive Inductors high frequency inductors

The common mode choke is useful because μcm is several orders of magnitude larger than μdm, because the common mode current is usually small and smaller μdm can be obtained by keeping L/D lower.

In order to obtain the common mode inductance and minimize the differential mode inductance, it is better to make a multi-turn coil with a large cross-sectional magnetic core. By using a larger coil core, which is not necessary, an effective differential mode inductor can be incorporated into a common mode choke. Because the differential mode flux is away from the magnetic core (annular structure), it can produce extremely strong radiation. Especially when the filter is installed on the PCB board, this radiation can be coupled to the power line, so that the conduction emission is enhanced. When a magnetic material is brought to the field (for example, a ring core is placed in an iron shell), the differential mode permeability may be significantly increased, resulting in saturation of the core due to the differential mode current.