Boosting Filters with Leakage Inductance

Introduction：

In an ideal inductance model, the magnetic flux is entirely concentrated at the center of the coil after winding. However, in practice, loop coils may not be wound completely or tightly enough, leading to magnetic flux leakage.

 

A common-mode inductor features two windings separated by a significant gap, which creates flux leakage and forms a differential-mode inductor. As a result, common-mode inductors typically exhibit some ability to attenuate differential-mode interference.

 

In filter design, leakage inductance can also be utilized. For instance, in a standard filter, a common-mode inductor alone may be used, with its leakage inductance providing an appropriate amount of differential-mode inductance to suppress differential-mode currents. In some cases, the leakage inductance of a common-mode choke is intentionally increased to enhance differential-mode inductance, thereby improving the filter's performance