JPS598325Y2 - inductance element - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a biased magnetic inductance element that applies a magnetic bias by inserting a permanent magnet into a gap provided in a magnetic core.

In an inductance element such as a choke coil, since direct current and alternating current are superimposed, an air gap has been provided in the magnetic core to avoid magnetic saturation due to the direct current magnetic field.

However, when a gap is provided in the magnetic core, the inductance value decreases, and in order to compensate for this, the inductance element must be made larger.

To overcome this drawback, a biased magnetic inductance element was devised in which a permanent magnet is inserted into a soft magnetic core to cancel out the DC magnetic field.

A front sectional view and a side view of this conventional biased magnetic inductance element are shown in FIGS. 1a and 1).

The magnetic core is made up of a core 11 and an E core 12, and a permanent magnet 13 for applying a magnetic bias is inserted into a gap created by making the center leg of the E core 12 shorter than both legs.

The direction of magnetization of the permanent magnet 13 is opposite to the direction of the magnetic field generated by the current flowing through the coil 14.

However, if an impact current of several tens to hundreds of times the running current flows through a smoothing circuit using a choke coil due to a load short circuit or a component failure, this conventional biased magnetic inductance element cannot be used permanently. Since a large demagnetizing field is applied to the magnet 13 and the permanent magnet 13 is demagnetized, there is a drawback that the inductance value becomes small.

The present invention aims to overcome the above-mentioned drawbacks and provide an inductance element whose inductance value does not deteriorate.

In order to achieve the above object, the present invention is characterized in that a permanent magnet for applying a magnetic bias is inserted into the air gap provided in the side legs other than the central leg in the coil axis direction of the magnetic core. .

In other words, the present inventors have found that when the coil current is increased, almost the same magnetic flux flows through each part of the magnetic core until the magnetic core is saturated, but once the magnetic core is saturated, the increase in magnetic field is mainly caused by Focusing on the fact that it only occurs in the legs,
Permanent magnets that apply magnetic bias are disposed in side leg portions other than the center leg in the axial direction of the coil, thereby limiting the influence of the demagnetizing field caused by the impulse current.

The front sectional view and side view of the embodiment of the present invention are shown in Figures 2a and l.
).

The inductance element of the present invention is constructed almost in the same way as a conventional biased magnetic inductance element.

The magnetic core consists of a (1) core 11 and an E core 12, and a coil 14 is provided inside the core.

A feature of the present invention that differs from conventional biased magnetic inductance elements is that permanent magnets 21 and 22 that provide magnetic bias are inserted into gaps provided on both legs of the E core 12.

Now, let us consider a case 1 in which an impact current several tens to hundreds of times the rated current flows through the coil 14 of this embodiment.

The impact current generates a magnetic field in the magnetic core corresponding to the saturation magnetic flux density of the magnetic core.

In the case of a soft magnetic core, a magnetic field corresponding to the saturation magnetic flux density is generated with a small current value, so naturally a magnetic field is generated due to the current flowing through the coil.

If a permanent magnet that applies a magnetic bias is provided at a position as shown in this embodiment, even if an impact current flows, the magnetic field due to the current flowing through the coil will not be applied to this permanent magnet.

Therefore, the permanent magnet is not demagnetized and the inductance value does not deteriorate.

It is of course necessary to select a magnetic material for the permanent magnets 21 and 22 that will not be demagnetized even by a magnetic field equal to the saturation magnetic flux density of the magnetic core.

FIG. 3 shows the deformation of the inductance L with respect to direct current (IDC) of the inductance element of the present invention and the conventional biased magnetic inductance element.

When no impulse current is applied, the conventional biased magnetic inductance element and the inductance element of the present invention have similar characteristics, as shown by the solid line 33. Ivy.

When an impact current is applied, the characteristics of the conventional biased magnetic inductance element change to those shown by the dotted line 34, but the inductance element of the present invention maintains the characteristics when no impact current is applied, and the inductance shifts to the left. It did not occur.

As is clear from the above, according to the present invention, a highly reliable small inductance element that does not cause any change in inductance characteristics even if a large shock current flows due to an accident such as a short circuit on the load side or a component failure can be obtained. It will be done.

[Brief explanation of the drawing]

Figures 1a and b are a front sectional view and a side view of a conventional inductance element, Figures 2a and 1) are a front sectional view and a side view of an embodiment of the present invention, respectively, and Figure 3 is a direct current FIG. 3 is a diagram showing inductance characteristics. 11, 12: Magnetic core, 14... Coil, 13
, 21, 22: Permanent magnet.

Claims (1)

[Scope of utility model registration request] An inductance element characterized in that a gap is provided in a side leg portion of a magnetic core other than the center leg in the coil axis direction, and a permanent magnet is inserted into the gap to apply a magnetic bias.