Overview
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A high-frequency reactor, used in equipment such as DC-DC converters, has
a high-frequency current accompanying the switching direct current.
The performance of a reactor is evaluated by a stable inductance in a wide
direct current region superimposed with alternating current components.
The initial magnetization curve is typically used for the magnetization
properties of electromagnetic steel sheet in the magnetic field analysis,
but the operating points are on the miner loops of the hysteresis curve
when a high-frequency alternating current component is superimposed on
the direct current component. (Fig. 1)
Differences in the superimposed direct current characteristics become apparent
when the minor loops differ significantly from the initial magnetization
curve. In this case, the inductance needs to be obtained by taking into
account the minor loop.
This example presents the use of a magnetic field analysis to obtain the
superimposed direct current characteristics of a high-frequency reactor
accounting for the minor hysteresis loop by using the frozen permeability
condition. |
Superimposed direct current characteristics
The superimposed direct current characteristics are indicated in Fig. 2
and the magnetic flux density distribution of the core is indicated in
Fig. 3.
The inductance decreases more rapidly as the direct current increases as
indicated in Fig. 2. This is caused by magnetic saturation as indicated
in Fig. 3. |
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