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Superimposed DC Characteristic Analysis

Superimposed DC Characteristic

If direct current is superimposed on an inductor, a magnetic material will come close to the magnetic saturation. It will reduce the permeability and eventually the inductance.

This is called superimposed DC characteristic.

 

Calculation of superimposed DC characteristic

A calculation is performed as follows.

 

1. Nonlinear static analysis is performed with the major loop to obtain the distribution of working points.

2. The distribution of working points is referred to the minor loop and permeability distribution is calculated with dB/dH as permeability.

3. With the given permeability distribution, nonlinear static analysis or linear harmonic analysis is performed to calculate inductance.
   

This calculations above are done with the assumption that the alternating current is small enough against the superimposing direct current.

Definition of minor loop B-H curve

The curve where dB/dH is permeability. (Differential permeability)

Therefore, it is required to set the difference of each step of B-H curve table so as to make it the permeability.

 

Link to examples

• Example 28: Inductor with Superimposed DC (Minor Loop Permeability)

• Example 36: Inductor with Superimposed DC (High Frequency)