JP3765326B2 - DC reactor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a DC reactor having a bias magnet used for a switching power supply and an inverter in order to improve a current waveform of the power supply.
[0002]
[Prior art]
Conventionally, as a DC reactor having a bias magnet for obtaining a large inductance in a region where the smooth current is small and a small inductance in a region where the smooth current is large, a winding wound around the central magnetic leg, a central magnetic leg and a side magnetic leg A first magnetic core having a first magnetic body, a first magnetic body in direct contact with each magnetic leg of the first magnetic core, a second magnetic core facing the first magnetic body, a first magnetic body, and a second magnetic body There is one in which a permanent magnet for biasing is inserted between magnetic cores (for example, Japanese Patent Publication No. 61-19098).
[0003]
[Problems to be solved by the invention]
However, in the conventional technique, the magnetic flux generated by the winding causes the first magnetic body to be saturated, and an excessive magnetic flux is caused to flow to the second magnetic core via the biasing permanent magnet. When a sudden large current flows due to a power failure or equipment failure, the permanent magnet is demagnetized, or when a permanent magnet with a high conductivity such as a rare earth magnet is used, iron loss occurs inside the permanent magnet. There is a problem of doing.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, the present invention branches the magnetic path through which the magnetic flux generated by the winding flows and the magnetic path through which the magnetic flux generated by the permanent magnet flows before the permanent magnet, and the magnetic flux φe generated by the winding is the permanent magnet 4. This prevents the magnet from flowing through and prevents the permanent magnet for bias from demagnetizing.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
A first magnetic core in which a winding is wound on a leg, a second magnetic core that forms a closed magnetic circuit in combination with the first magnetic core, and a bias magnet that is magnetized so as to face the magnetic flux created by the winding In the direct current reactor in which the permanent magnet is inserted between the first magnetic core and the second magnetic core, the second magnetic core has an opening for inserting the leg of the first magnetic core. And a lip portion having a cross-sectional area that does not saturate even when an excessive current flows through the winding on both sides of the opening, and magnetically between the side of the opening and the side of the leg of the first magnetic core. An air gap is formed, the winding is provided in the internal space of the second magnetic core, the permanent magnet is provided outside the lip portion of the second magnetic core, and the magnetic flux generated by the winding and the magnetic flux generated by the permanent magnet are The lip portion branches off.
A plurality of electromagnetic steel sheets in which the first and second magnetic cores are punched into a predetermined shape are laminated, the first magnetic core is a T-shaped core, and the second magnetic core is a C-shaped magnetic core,
The first and second magnetic cores are sintered magnetic cores, the first magnetic core is a T-shaped magnetic core provided with the column that serves as the leg upright in the center of the disk portion, and the second magnetic core is a disk core. And a pot core,
A hole serving as the opening is provided in the center of the disk core, the pot core is covered with the disk core, and the permanent magnet is inserted between the T-shaped core and the disk core,
A hole serving as the opening is provided at the bottom of the pot core, the disc portion of the T-shaped magnetic core is brought into contact with the opening of the pot core, and the leg is covered so as to protrude from the bottom of the pot core, The disk core is brought into contact with the upper surface of the permanent magnet and the top surface of the leg, and the permanent magnet is inserted between the outer bottom of the pot core and the disk core.
Further, a taper is provided in the middle of the leg and in the opening, and the leg is moved up and down to change the gap between the respective taper to adjust the size of the magnetic gap.
[0006]
【Example】
Embodiments will be described below with reference to the drawings.
FIG. 1 is a perspective view showing a first embodiment of the present invention.
A winding 2 is wound around a leg 11 of a T-shaped magnetic core 1 in which a plurality of electromagnetic steel sheets punched into a predetermined shape are stacked. The leg 11 has a height H1 and a width Bt.
A pair of rectangular permanent magnets 4 having a thickness H2 are provided on the lower surface of the head of the T-shaped magnetic core 1 so as to maintain a relatively large gap from the side surface of the leg 11, have the same vertical polarity, and are symmetrically provided. is there.
A groove 3G having a width Bu is provided above the C-shaped magnetic core 3 in which a plurality of electromagnetic steel sheets punched into a predetermined shape are stacked so as to maintain a predetermined magnetic gap 13 when the legs 11 are inserted. The lip 3L is formed with a thickness H4 that can secure a cross-sectional area in which the magnetic flux produced by the wire 2 is not saturated.
Here, when the height between the inner bottom and the upper surface of the C-shaped magnetic core 3 is H3, H1 = H2 + H3.
The T-shaped magnetic core 1 wound with the winding 2 is inserted from the opening on the side surface of the C-shaped magnetic core 3 toward the internal space, and the magnetism necessary for obtaining a predetermined inductance on both sides of the leg 11 and the groove 3G. The T-shaped magnetic core 1 is fixed in the internal space of the C-shaped magnetic core 3 so as to maintain an area facing the static air gap 13.
[0007]
FIG. 2 is a side sectional view showing a second embodiment of the present invention.
In this example, each magnetic core of the first embodiment is sintered with ferrite or the like, the T-shaped magnetic core is formed into a circular shape, and the C-shaped magnetic core is divided into a pot core and a disk core.
A T-shaped magnetic core 1 is formed by providing a columnar leg 11 having a diameter Dt and a height H1 so as to stand upright in the center of the disc portion 10.
A ring-shaped permanent magnet 4L is provided on the lower surface of the disc portion 10. The permanent magnet 4L has a thickness H2 in which a hole 3H having a diameter much larger than the diameter Dt of the leg 11 is provided at the center, which is magnetized so as to generate a magnetic flux in a direction opposite to the flow of the magnetic flux generated by the winding 2. is there.
A disk core 5 is provided on the lower surface of the permanent magnet 4L. The disk core 5 is provided with a hole 3H having a diameter Du so as to maintain a predetermined magnetic gap 13 between the legs 11, and has a thickness H4 that can secure a cross-sectional area in which the magnetic flux generated by the winding 2L is not saturated.
On the lower surface of the disk core 5, a pot core 31 having a depth H5 is provided.
On the inner bottom of the pot core 31, a winding 2L wound in a ring shape is provided with a leg 11 inserted through the center.
[0008]
FIG. 3 is a side sectional view showing a third embodiment of the present invention.
In this example, the arrangement of the pot core, disk core and permanent magnet in the second embodiment is changed.
The disc portion 10 of the T-shaped magnetic core 1 is in direct contact with the opening surface of the pot core 31 provided with a hole 3H having a diameter Du at the center of the bottom portion.
Here, a space between the leg 11 and the hole 3H is kept opposite to the magnetic gap 13 necessary for obtaining a predetermined inductance.
The winding 2L is housed in the inner bottom of the pot core 31. A permanent magnet 4 </ b> L is provided on the outer bottom of the pot core 31.
The disk core 5 is provided in direct contact with the lower surface of the permanent magnet 4L and the top of the leg 11.
By doing so, the pulsating magnetic flux generated by the windings does not flow in the disk core 5, and the disk core 5 can be formed of a normal soft iron plate, so that it is less expensive than the second embodiment.
[0009]
4A and 4B are cross-sectional views showing a fourth embodiment of the present invention, in which FIG. 4A is a side cross-sectional view, and FIG. 4B is a cross-sectional view taken along line AA in FIG.
In this example, the magnetic air gap of the first and second embodiments is changed to make the inductance adjustable.
The leg 11 having a height H6 has a base width Br, a width from the middle to the top Bt, and a tapered portion 11T thinner than the lip portion 1L.
The lip portion 1L (or the disk core 5) of the C-shaped magnetic core 3 is provided with a tapered portion 31T at a position corresponding to the tapered portion 11T provided in the middle of the leg 11.
At the bottom of the C-shaped magnetic core 3 having a thickness H7 (bottom of the pot core 31), a groove 3Gg or a hole 3Gh is provided in which the top of the leg 11 fits with a slight gap.
Here, the height H6 of the leg 11 is such that H6 <H1 + H7 in a range where the facing area of the groove 3Gg or the hole 3Gh and the leg 11 is not magnetically saturated in this portion.
In the first embodiment, the C-shaped magnetic core 3 is separated into right and left by the groove 3Gg. Therefore, as shown in FIG. 4B, side plates 7 are provided on both side surfaces in the stacking direction of the C-shaped magnetic core 3, It integrates with the C-shaped magnetic core 3 by welding or the like, and the groove 3Gg is cut by machining at the bottom of the C-shaped magnetic core 3.
For the assembly, the winding 2 is set in the internal space of the C-shaped magnetic core 3 (or pot core 31), and a high-permeability shim 6 such as amorphous and the permanent magnet 4 are placed on the upper surface of the C-shaped magnetic core 3 (or disk core 5). The leg 11 is inserted into the space in the center of the winding 2, the groove 3Gg, or the hole 3Gh.
By changing the thickness of the shim 6, the leg 11 is moved up and down to change the magnetic gap of the tapered portion, thereby adjusting the inductance.
[0010]
FIG. 5 is a sectional view showing a fifth embodiment of the present invention.
In this example, the magnetic air gap of the third embodiment is changed so that the inductance can be adjusted.
A tapered portion 11T is provided in the middle of the leg 11, and a tapered portion 31T is provided at a position corresponding to the lip portion 31L of the pot core 31.
The shim 6 is sandwiched between the mating surfaces of the pot core 31 and the T-shaped magnetic core 1, the legs 11 are moved up and down, and the size of the gap between the opposing tapered portions 11T and 31T is adjusted to adjust the inductance.
A magnetic fluid may be interposed between the leg 11 and the groove or hole 3Gb.
In the fourth and fifth embodiments, as shown in FIG. 6, the inductance can be changed as b when the gap between the opposing tapered portions is large and as c when the gap is small.
[0011]
【The invention's effect】
As described above, the present invention has the following effects.
(1) Since the magnetic flux generated by the winding does not flow in the permanent magnet, the permanent magnet is not demagnetized and iron loss does not occur in the permanent magnet.
(2) Since the magnetic flux generated by the winding and the magnetic flux generated by the permanent magnet flow in opposition in the magnetic core, the magnetic core does not saturate until the exciting current reaches a predetermined value, and the size can be reduced.
(3) In the fourth and fifth embodiments, since the inductance can be adjusted, it is possible to obtain an inductance suitable for the state of use.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a first embodiment of the present invention.
FIG. 2 is a side sectional view showing a second embodiment of the present invention.
FIG. 3 is a side sectional view showing a third embodiment of the present invention.
4A is a side cross-sectional view showing a fourth embodiment of the present invention, and FIG. 4B is a view taken along the line AA in FIG. 4A when applied to the first embodiment.
FIG. 5 is a side sectional view showing a fifth embodiment of the present invention.
FIG. 6 is a graph showing the performance of a reactor.
[Explanation of symbols]
1 T-shaped magnetic core 1L, 31L Lip portion 10 Disc portion 11 Leg 11T, 31T Tapered portion 2, 2L Winding 3 C-shaped magnetic core 3G, 3Gg Groove 3H, 3Gh Hole 31 Pot core 4, 4L Permanent magnet 5 Disc core 6 Shim

Claims (6)

A first magnetic core in which a winding is wound on a leg, a second magnetic core that forms a closed magnetic circuit in combination with the first magnetic core, and a bias magnet that is magnetized so as to face the magnetic flux created by the winding A direct current reactor in which the permanent magnet is interposed between the first magnetic core and the second magnetic core,
The second magnetic core includes an opening for interposing the leg of the first magnetic core, and lip portions on both sides of the opening that have a cross-sectional area that does not saturate even if an excessive current flows through the winding. ,
Forming a magnetic gap between a side surface of the opening and a side surface of the leg of the first magnetic core;
Providing the winding in the internal space of the second magnetic core, and providing the permanent magnet outside the lip portion of the second magnetic core;
A DC reactor, wherein a magnetic flux generated by the winding and a magnetic flux generated by the permanent magnet are branched at the lip portion. A plurality of electromagnetic steel sheets obtained by punching the first and second magnetic cores into a predetermined shape are laminated, the first magnetic core is a T-shaped magnetic core, and the second magnetic core is a C-shaped magnetic core. The direct current reactor according to 1. The first and second magnetic cores are sintered magnetic cores,
2. The DC reactor according to claim 1, wherein the first magnetic core is a T-shaped magnetic core in which a columnar column is provided upright in the center of a disc portion, and the second magnetic core is constituted by a disk core and a pot core. . 4. The direct current reactor according to claim 3, wherein a hole serving as the opening is provided in the center of the disk core, the pot core is covered with the disk core, and the permanent magnet is interposed between the T-shaped magnetic core and the disk core. . A first magnetic core in which a winding is wound around a leg, a second magnetic core that forms a closed magnetic circuit in combination with the first magnetic core, and a bias magnetized so as to oppose the magnetic flux created by the winding In a DC reactor equipped with a permanent magnet of
The first magnetic core is a T-shaped magnetic core provided with the column that serves as the leg standing upright in the center of the disc part,
The second magnetic core is composed of a disk core and a pot core,
The pot core is provided with a hole to be the opening at the bottom,
Covering the disc part of the T-shaped magnetic core with the opening of the pot core so that the legs protrude from the bottom of the pot core;
The disc core is in contact with the top of the leg;
The permanent magnet was inserted between the outer bottom of the pot core and the disk core.
DC reactor characterized by that. 6. A taper portion is provided in the middle of the leg and in the opening, and the size of the magnetic gap is adjusted by changing the gap between the tapered portions by moving the leg up and down. The direct current reactor according to claim 1.

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