JPS6322660Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of the core structure of a DC reactor.

Conventionally, this type of DC reactor is connected to a DC power supply containing ripple components and used to remove the ripple components, and its inductance and DC current characteristics are such that the inductance remains constant regardless of the DC current value. It remained almost constant.

However, with the recent development of semiconductor devices, thyristors have come to be used as a rectifying means to form direct current from alternating current, but thyristors control the phase angle of the main electrode current waveform using gate current. Therefore, there is a problem in that the rectified current contains ripples with an extremely high content rate. Moreover, the amount of ripple contained in this ripple is larger when the rectified current value is small than when the rectified current value is large, so for example, when controlling the speed of a DC motor using this rectified current, When the voltage was reduced, direct current with high ripple content flowed through the motor's brushes, causing spark discharge, damaging the brushes and causing a major accident.
To prevent this accident, the rectified current applied to the DC motor should have a large inductance at a small DC current value, and should be connected to the DC motor via a DC reactor that has a small inductance at the rated current value. .

As described above, it has become desirable to have various types of DC reactors having different inductance and DC current characteristics depending on the purpose of use.

A DC reactor that satisfies this requirement has conventionally been constructed by providing an appropriate gap in an iron core around which a coil is wound. That is, as shown in FIG. 1, the iron core 1 is made of laminated thin steel plates 2a.
, and iron cores 3, 4, and 5 made by laminating thin steel plates 3a, 4a, and 5a, respectively, and iron cores 2 and 3,
Gaps 6, 7, and 8 are provided between 3 and 4, and 4 and 5 through insulating spacers (not shown), respectively, and coils (not shown) are wound in series or parallel around the legs 1a and 1b of the iron core 1. Then, each of the cores 2 to 5 is tightened with bolts through the bolt insertion holes 2b, 3b, and 4b, respectively, and the cores 2 to 5 are tightened with fasteners (not shown), or fasteners are placed on both ends of the laminated core. The bolts were then tightened to form a DC reactor. However, as shown in curve 9 of FIG. 2, the DC reactor with the above configuration has a large inductance at a small value of DC current, and although the inductance is small at the rated current, the current value The change in inductance value is not large with respect to the change in . Furthermore, if the characteristics of inductance and DC current shown in curve 10 are obtained, an iron core for generating the inductance in the shaded area surrounded by curves 9 and 10 becomes unnecessary, so the DC reactor can be made smaller. At the same time, the cost will also be reduced. Further, one of the conventional methods is disclosed as a conventional example in Japanese Patent Laid-Open No. 139959/1983. That is, a pair of chevron-shaped flat steel plates of the same shape are arranged facing each other on the same plane with a gap g between the chevrons, and these are laminated to form a frame, and a plurality of these laminated iron core frames are stacked. This is a method of configuring the iron core of a swinging yoke. That is, in this method, the gap g between the frames is selected in advance, and three core frames each having gaps g ₁ , g ₂ , and g ₃ are stacked on top of each other and assembled to obtain desired characteristics. However, although this method is theoretically correct, in practice it may not be possible to achieve the desired result due to variations in the magnetic properties of each core frame, magnetic interference between frames, errors in gaps g ₁ , g ₂ , g _3, etc. In order to obtain the inductance-DC current characteristics, processing and adjustment are required again. Therefore, the manufacturing work is troublesome, and it is necessary to adjust the machine during manufacturing, resulting in an unreasonable result.

The present invention was developed in view of solving the above problems, and aims to provide a DC reactor that not only can increase the rate of change in inductance with respect to DC current, but also allows the rate of change to be set arbitrarily, and is also miniaturized. The laminated core has a coil wound around a leg with a gap, and its both end faces are tightened with fasteners, and the laminated core has at least a predetermined ratio in the lamination direction. In addition to being partitioned into three laminated cores through insulators, the tightening can be loosened to adjust the length of the gap in one of the laminated cores, and each of the laminated cores has a structure in which the magnetic permeability does not suddenly decrease. It is characterized by having voids that produce a predetermined inductance vs. DC current characteristic at a void length or number of voids.

Prior to describing embodiments of the present invention, the principle of the present invention will be explained. FIG. 3 is a perspective view showing the core structure of a DC reactor consisting of a single core of laminated steel plates having a gap length _G1 . When a DC reactor is formed by winding a coil around the above-mentioned iron core and a DC current containing a ripple component is passed through this coil, the characteristics of the inductance and DC current of this DC reactor become curve a in FIG. 4. Next, the void length G ₁
If we increase the dimension of _G2 and obtain similar characteristics, we obtain curve b in Fig. 4. These curves a and b show that when the air gap length of the iron core in the DC reactor is increased, the magnetic permeability of the iron core decreases, and the decrease in inductance with respect to an increase in DC current increases.

Next, a first embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a perspective view of the core structure of the first embodiment. In the figure, the core of the DC reactor has a laminated core 11 having a laminated thickness S ₁ and a gap length G ₁ , and a laminated core 11 having a laminated thickness S ₂ and a gap length G ₂ (however, G ₂ > _G1 ). Note that 13 is an insulating member between the iron cores 11 and 12.

When a coil is wound around the iron core configured as described above, and a DC current containing ripples obtained by rectifying the commercial power supply using a thyristor element is passed through the wound coil, the inductance of the DC reactor and the characteristics of the DC current are as described above. Curve c shown in FIG. 6 is obtained by combining curve a and curve b in FIG. 4, which were described in the explanation of the principle of the present invention. This curve c shows that the inductance is extremely large when the DC current value is small, and that the inductance decreases as the DC current value increases toward the rated current value.
Moreover, since the curve c in FIG. 6 is similar to the characteristic curve 10 explained in FIG. 2, by comparing it with the curve 9 in FIG. 2 (the characteristic curve of the conventional DC reactor), The DC reactor of the first embodiment has the effect of reducing the amount of laminated steel plates required for forming the iron core. Furthermore, the device of the first embodiment has a laminated core 11.
and the laminated iron core 12,
If you want to fine-tune the shape of curve c in FIG. 5, for example, remove only the laminated core 12 and
Adjusting G ₂ also has the effect of easily adjusting this characteristic curve.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a perspective view of the core structure of the second embodiment of the present invention. In the figure, the core 20 of the DC reactor includes a laminated core 21 having a lamination thickness S ₂₁ and a laminated core ₂₂ having a lamination thickness S 22 .
The laminated core 23 is divided into laminated cores 23 having a lamination thickness S ₂₃ , and the laminated core 21 has one gap G ₂₁ , the laminated core 22 has two gaps G ₂₂ a and G ₂₂ b, and the laminated core 2 has one gap G 21 .
3 is formed to have one void _G23 .
In addition, 21a, 22a, 22b, 22c, 23a
is a thin steel plate, 24 is an insulating member between the iron cores 21 and 22, and 25 is an insulating member between the iron cores 22 and 23.

A coil is wound around the leg portion of the iron core 20 configured as described above, and a direct current containing a ripple component obtained by rectifying a commercial power source using a thyristor element is passed through the wound coil. In this case, the voids G ₂₁ , G ₂₂ a,
If the dimensions of G ₂₂ b and G ₂₃ are selected as shown below, the inductance and DC current characteristics shown in FIG. 8 can be obtained. In addition, the void G ₂₁ ,
In the methods of G ₂₂ a, G ₂₂ b, and G _23, all void lengths do not necessarily have to be different as long as the following conditions are met.

If the gaps G ₂₂ a and G ₂₂ b are set to values larger than the set dimensions, and the gaps G ₂₁ and G ₂₃ are set to values smaller than the set dimensions, a curve d in FIG. 8 is obtained.

When the gaps G ₂₂ a and G ₂₂ b are made smaller than the set dimensions, and the gaps G ₂₁ and G ₂₃ are made larger than the set dimensions, a curve e in FIG. 8 is obtained.

Make the gaps G ₂₂ a and G ₂₂ b larger than the set dimensions,
If the gaps G ₂₁ and G ₂₃ are also made larger than the set dimensions,
This becomes the curve f in FIG.

The above characteristic curves d, e, and f are obtained by dividing the iron core 20 into three parts, each with the laminated thickness S ₂₁ of each core 21, 22, and 23,
Although the characteristics are shown when S ₂₂ and S ₂₃ are constant, more characteristic curves can be obtained by changing the ratio of the lamination direction of the laminated core in combination with the above characteristics. That is, from the second embodiment, it is possible to obtain various types of inductance and DC current characteristics that could not be obtained using the conventional method. For this,
By determining the inductance and DC current characteristics of the DC reactor prototyped in advance by changing the core gap length, the number of gaps, and the lamination thickness, it is possible to obtain a DC reactor that has the required characteristic curve. A reactor can be easily manufactured.

Note that the reason for providing two gaps, G ₂₂ a and G ₂₂ b, in the iron core 22 and not providing one gap whose size is the sum of the gaps G ₂₂ a and G ₂₂ b is because of the latter. This is because, in this case, the magnetic permeability of the iron core 22 will drop rapidly to an extent that is inappropriate for the iron core.

Further, in the characteristic curve d, the inductance becomes extremely large when the DC current is small, and in the characteristic curves d and f, the inductance decreases as the DC current increases. This means that the amount of iron core used can be saved compared to the conventional method.
Further, when it is desired to finely adjust the characteristic curves, for example, by removing only the iron core 22 and adjusting the dimensions of the gaps G ₂₂ a and G ₂₂ b, the shapes of the characteristic curves d, e, and f can be finely adjusted.

In summary, the present invention divides the core of a DC reactor into at most three laminated cores, each having a predetermined laminated size, through an insulator, and provides each of the divided cores with a predetermined gap length or number of gaps. , there is no magnetic interference between the cores separated by insulators, and there is no need to readjust the air gap as in the conventional method. In addition to making it possible to have a particularly large inductance in a small current range, the above characteristics only need to be fine-tuned in one laminated core, making the work easier compared to the conventional method. Since the work mode is to loosen three or less tightened laminated cores and take out only one, in the case of the present application where there are at most three laminated cores, compared to the case where there are four or more laminated cores. Easy to work with. Furthermore, the ratio of inductance to DC current can be changed significantly, and the ratio of this change can be arbitrarily selected.Furthermore, since inductance is reduced in proportion to DC current, inductance does not decrease in proportion to DC current. Compared to the conventional method, it is possible to save the required amount of iron cores and reduce the cost of the product, and it also has the practically important effect of making the product smaller.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the schematic configuration of a conventional DC reactor, Fig. 2 is a characteristic curve diagram of inductance and DC current of a conventional DC reactor, and Fig. 3
4 and 4 are schematic perspective views of the core configuration and characteristic curves of inductance and DC current for explaining the principle of the present invention, and FIGS. 5 and 6 are of the first embodiment according to the present invention. A perspective view of the iron core structure and a characteristic curve diagram of inductance and DC current,
FIG. 7 and FIG. 8 are a perspective view of a schematic core configuration of a second embodiment of the present invention and a characteristic curve diagram of inductance and direct current. 11, 12... Iron core, 13... Insulating member, 2
0, 21, 22, 23... iron core, 24, 25...
Insulating members, G ₁ , G ₂ , G ₂₁ , G ₂₂ a, G ₂₂ b, G ₂₃ ...
Gap length, S ₁ , S ₂ , S ₂₁ , S ₂₂ , S ₂₃ ...Lamination thickness,
a, b, c, d, e, f...Characteristic curves of inductance and direct current.

Claims (1)

[Scope of utility model registration request] In a laminated core in which a coil is wound around a leg with a gap and its both end faces are tightened with fasteners, the laminated core has at least three laminated layers having a predetermined ratio in the lamination direction. In addition to partitioning the core with an insulator, the length of the gap in one laminated core can be loosened to adjust the length of the gap, and each of the laminated cores has a gap length that does not cause a sudden decrease in magnetic permeability. Alternatively, a DC reactor characterized in that it has air gaps that produce a predetermined inductance vs. DC current characteristic depending on the number of air gaps.