JPS6213013A - Choke coil - Google Patents

Abstract

PURPOSE:To prevent the stability of an output voltage from deteriorating by forming a gap at a part of the inner peripheral side of the section of a toroidal core, and inserting a high magnetic permeable member into the gap. CONSTITUTION:A toroidal core 10 has a core section 11 having a gap 15, and a core section 12 having no gap. A high magnetic permeable member 14 is inserted to the gap 15, and a winding 13 is wound on the core 10. Thus, a choke coil which obtained. Further, when the gap is increased, a DC superposing current can be increased, and an arbitrary inductance can be obtained by altering the sizes of the toroidal core and the gaps, and the high magnetic permeable material to be inserted.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a choke coil used in a choke input rectifier unit, a filter circuit of a switching regulator, etc., and particularly relates to a choke coil used in a choke input rectifier unit, a filter circuit of a switching regulator, etc. This invention relates to a choke coil with improved characteristics.

(Prior Art) Conventionally, choke coils that can be used in switching regulators, etc. are generally composed of a toroidal core 1 and a winding 2 as shown in FIG. A choke coil composed of a 4' type core 3, a winding 5, and an insulating spacer 6 is used. The former choke coil is small and has little leakage magnetic flux, and if a molybdenum permalloy core is used, the DC superimposition characteristics can be improved. Further, the latter choke coil has improved DC superimposition characteristics by the gear A/tube formed by the insulating spacer 6 between the cores 4 and 4'. The inductance characteristics of these choke coils with respect to DC superimposed current are as shown in FIG. 5, and the inductance is constant up to a certain DC superimposed current.

(Problem to be solved by the invention) In such a conventional choke coil, when the load of the switching regulator fluctuates and the output current decreases, the W current flowing through the coil becomes discontinuous, and as a result, , the ripple voltage at the output of the switching regulator increases and the output voltage becomes unstable. In addition, in a choke coil like the one shown in Figure 4, the gap creates an open magnetic path, which generates leakage magnetic flux that affects components mounted around the choke coil, and in some cases may damage the circuit made up of these components. The disadvantage is that it may malfunction.

(Means for Solving the Problems) In order to eliminate the above-mentioned drawbacks, the choke coil of the present invention provides a gap in a part of the inner peripheral side of the cross section of the toroidal core, and fills the gap with a high magnetic permeability member. It is inserted and winding is applied.

(Embodiment) FIG. 1 is a plan view showing a choke coil according to an embodiment of the present invention. In FIG. 1, a toroidal core 10 is composed of a core portion 11 having a gap 15 and a core portion 12 having no gap. A high permeability member 14 is inserted into this gap 15, and a toroidal core 1 is inserted into the gap 15.
0 is provided with a winding 13.

Such a toroidal core 10 has inductance/DC superimposed current characteristics as shown in FIG. That is,
The direct current I flowing through this choke coil is so small that the high magnetic permeability member 14 inserted into the gap of the core portion 11 does not saturate the magnetic flux.

In the following cases, the composite magnetic permeability of the toroidal core including the input core portion 11 and the core portion 12 is the sum of the magnetic permeabilities determined by the cross-sectional area of the high magnetic permeability member 14 and the cross-sectional area of the core portion 12, and this composite magnetic permeability The inductance of the choke coil is determined by: The inductance H1 at this time is the DC type i0-1. It becomes a constant value between.

Next, when the DC current flowing through the choke coil increases and the high magnetic permeability member 14 becomes saturated, the composite magnetic permeability of the toroidal core becomes the sum of the magnetic permeabilities determined by the cross-sectional area of the core portion 11 and the cross-sectional area of the core portion 12. Inductance due to magnetic permeability is obtained. The inductance at this time has a value H2 when the DC current in FIG. 2 is in the range of 11 to 11.

Furthermore, when the current flowing through the choke coil increases and the core part 12 becomes magnetically saturated, the composite magnetic permeability becomes the permeability determined by the cross-sectional area of the core part 11, and as shown in FIG. , indicates the inductance H8.

In FIG. 1, the dimensions of the gap 15, the high magnetic permeability member 1
By changing the magnetic permeability etc. of No. 4, the inductance and DC superimposed current characteristics can be changed. Further, since the outer peripheral portion of the toroidal core 10 forms a closed magnetic path by the core portion 12 without a gap, leakage magnetic flux is generated only inside the choke coil and not outside.

(Effects of the Invention) As explained above, according to the present invention, a choke coil can be obtained in which the inductance increases extremely as the direct current decreases. Furthermore, by increasing the gap, the DC superimposed current can be increased, and by changing the dimensions of the toroidal core, the dimensions of the gap, and the high magnetic permeability member inserted, it is possible to obtain an arbitrary inductance.

If a choke fill with such direct current superimposition characteristics is used in the filter circuit of a switching regulator, when the load fluctuates and the output current decreases, the inductance of the choke coil will increase. The current flowing through the coil is less likely to become discontinuous,
This has the effect that the ripple voltage component of the output voltage does not increase and the stability of the output voltage does not deteriorate.

Furthermore, since leakage magnetic flux is generated only inside the choke coil and not outside, even if other components are mounted near the choke coil, there is little influence on the circuit through the components. Therefore, the choke coil of the present invention is very effective when mounting small, high-density components. Moreover, this choke coil can be constructed from inexpensive materials.

[Brief explanation of drawings]

Fig. 1 is a plan view showing an embodiment of the choke coil according to the present invention, Fig. 2 is an inductance/DC superimposed current characteristic diagram of the embodiment shown in Fig. 1, and Fig. 3 is an example of a conventional toroidal core type choke coil. FIG. 4 is a front view showing an example of a conventional El-type core choke coil, and FIG.
FIG. 5 is an inductance/DC superimposed current characteristic diagram in the conventional choke coil shown in FIG. DESCRIPTION OF SYMBOLS 10... Toroidal core, 11... Core part with a gap, 12... Core part without a gap, 13
...Winding wire, 14...High magnetic permeability member, 15...Ki~
・7bu. Representative Patent Attorney Shinsuke Honjo Figure 1 Figure 2 Direction 1 Telephone 9

Claims (1)

[Claims] A choke coil formed by winding a wire around a toroidal core, characterized in that a gap is provided in a part of the inner circumferential side of the cross section of the toroidal core, and a member with high magnetic permeability is inserted into the gap. .