JPS616816A - Choke coil - Google Patents

Abstract

PURPOSE:To make it difficult for a current flowing through a choke coil to become discontinuous by employing a structure where windings are provided to a ring-shaped wound iron core having a gap at a part of its section and allowing such structure to have the DC component superposing current characteristic in which an inductance of choke coil increases largely owing to decrease of a DC superposing current. CONSTITUTION:In case a DC superposing current flowing into a choke coil is a DC superposing current value or less where the ring-shaped wound iron core 12 having no gap does not show magnetic saturation by providing a gap to a part of sectional area of iron core of ring-shaped iron core, permeability of the ring-shaped wound iron core becomes equal to a sum of the permeabilities of the ring-shaped wound iron core 11 having a gap and that 12 having no gap, and an inductance of the choke coil becomes a value corresponding to a value of DC superposing current in the range from 0 to I1. Next, when a DC superposing current of choke coil increases and the ring-shaped rolled iron core 12 having no gap is saturated magnetically, a choke coil has an inductance determined by the permeability of the ring-shaped wound iron core 11 having a gap and allowing the DC superposing current to become equal to a value corresponding to the range from I1 to I2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a choke fill that can be used in choke input rectifier circuits and filter circuits of switching regulators, and improves output electronic fluctuation characteristics with respect to load fluctuations during light loads of switching regulators.

The choke coils conventionally used in switching regulators have a small toroidal core with low leakage flux, an outer core material (such as a molybdenum permalloy core) with good DC superimposed current characteristics, and a winding structure as shown in Figure 1. have. In FIG. 1, 1 is the core, 2 is the winding, and FIG. 2 is the DC superimposed current characteristic of the choke coil shown in FIG. 1. The inductance has a constant value up to the DC superimposed current value. When a choke coil configured by the above conventional method is used in a filter circuit of a switching regulator, when the load of the switching regulator changes and the output current decreases, the current flowing through the choke coil becomes discontinuous.

As a result, the stability of the output voltage deteriorates and the output 'FM, l
There was a drawback that the ripple electric ratio component of E increased.

In order to alleviate these drawbacks, the present invention has developed a high-transmission system that includes a gear knob in a part of the cross-sectional area of the iron core to improve the DC superimposed current characteristics so that the inductance increases when the DC superimposed current flowing through the choke coil is small. The purpose is to provide a choke coil using a magnetic annular wound core (permalloy material, etc.).

FIG. 3 shows an embodiment of the present invention, in which 11 is an annular wound core portion with a gap, 12 is an annular wound core portion without a cast, 2 is an oblique winding, 3 is a cast, and FIG. 4 is an embodiment of the present invention. This is the DC superimposed current characteristic of the choke coil. By providing a gap in a part of the core cross-sectional area in the annular wound core as shown in FIG. 3, the direct current superimposed current flowing through this choke coil is reduced to a DC superimposed current 11 in which the annular wound core portion 12 without gaps is magnetically saturated. In the following case, the magnetic permeability of the toroidal core is the sum of the permeability of the toroidal core 11 with a gap and the toroidal core 12 without a gap, and the inductance of the choke coil is the IU flow superposition in Figure 4. t(f, flow is from O to 11
The corresponding value will be obtained between. Next, when the rK superimposed current flowing through the choke coil increases and the gapped toroidal core portion 12 becomes magnetically saturated, the choke coil has an inductance determined by the magnetic permeability of the gapped toroidal core portion 11, and the fourth The DC superimposed current in the figure takes a constant value corresponding to the period from I1 to ■2. In this way, the DC superimposed current value ■l at which the annular wound core portion 12 with no gaps is magnetically saturated is changed to 12
A choke coil having a characteristic that the inductance increases extremely when the direct current superimposed current value at which magnetic saturation is 11 or less is obtained compared to the inductance corresponding to the above. In addition, by changing the dimensions of the annular wound core and the ratio of the cross-sectional area of the gap to the cross-sectional area of the core, a choke coil can be created in which the DC superimposed current has an arbitrary inductance ratio corresponding to 0 to 1 and Il to 2. can be obtained.

As explained above, when a choke coil using a high magnetic permeability ring-wound core with DC superimposed current characteristics as shown in Fig. 4 is used in the filter circuit of a switching regulator, the load of the switching regulator will fluctuate. Even if the output current decreases, the inductance of the choke coil increases dramatically, making it difficult for the current flowing through the choke coil to become discontinuous. Therefore, there is an advantage that the stability of the output pattern does not deteriorate and the ripple voltage component of the output voltage is less likely to increase. Further, similar effects can be expected with a general choke input circuit.

[Brief explanation of the drawing]

Fig. 1 is an example of a conventional choke coil, Fig. 2 is a DC superimposed current characteristic diagram of the choke coil shown in Fig. 1, Fig. 3 is an example of a choke coil using an annular wound core according to the present invention, and Fig. FIG. 4 is a DC superimposed current characteristic diagram of the third choke coil. 1...Core, 2...Winding, 3...
. . . Gap, 11 . . . An annular wound core portion with a gipping, 12 . Agent: Susumu Uchihara, patent attorney ￥1 figure￥2V

Claims (1)

[Claims] In a choke coil using a howl-wound core with high magnetic permeability, a structure in which wires are wound around the annular-wound core with a gap in a part of the cross section, and the inductance of the choke coil with the above-mentioned structure cause a superimposed DC current. 1. A choke coil characterized by having DC superimposed current characteristics that greatly increase due to a decrease in .