High Current Inverter Inductor

High Current Inverter Inductor

In the design of filter, it is assumed that the two parts of common mode and differential mode are independent of each other. However, the two parts are not truly independent, as a common mode choke can provide considerable differential mode inductance. This part of differential mode inductance can be simulated by discrete differential mode inductance.

In order to make use of differential mode Inductors, common mode and differential mode should not be carried out simultaneously in the design process of filters, but should be done in a certain sequence. First, common mode noise should be measured and filtered out. By means of Differential Mode Rejection Network, the differential mode components can be removed so that the common mode noise can be measured directly. If the common-mode filter is designed to simultaneously keep the differential mode noise within the allowable range, then the mixed noise of the common-mode and the differential mode should be measured. Because the common mode components are known to be below the noise tolerance, the only components that exceed the limit are the differential mode components, which can be attenuated by the differential mode leakage of the common mode filter. For low power supply systems, the differential mode inductance of a common mode choke is sufficient to solve the problem of differential mode radiation, because the source impedance of differential mode radiation is small, so only a very small amount of inductance is effective.

Although a small number of differential mode inductors is very useful, too large a differential mode inductor can cause magnetic saturation of the choke.