JPH09213546A - Dc reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a d.c. reactor having a biasing permanent magnet which is not demagnetized. SOLUTION: This reactor comprises a first core 1 having a winding 2 wound round a leg 11, second core 3 combined with the first core 1 to form a closed magnetic circuit, and biasing permanent magnet 4 magnetized so as to face at the flux made by the winding 2. The second core 3 has an opening 3G into which the leg 11 of the core 1 is inserted and lips 3L which are formed at both sides of the opening 3G and have sections not saturated even with an overcurrent flowing on the winding 2. A magnetic gap 13 is formed between the side face of the opening 3G and that of the leg 11 of the core 1, the winding 2 is disposed in an internal space of the core 3 and the permanent magnet 4 is disposed outside the lips 3L of the core 3 so that the magnetic flux Φe made by the winding 2 and that Φm made by the permanent magnet are branched at the lips 3L.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in switching power supplies and inverters for improving the current waveform of power supplies.
The present invention relates to a DC reactor having a bias magnet.

[0002]

2. Description of the Related Art Conventionally, as a DC reactor having a bias magnet for obtaining a large inductance in a region where a smoothing current is small and a small inductance in a region where a smoothing current is large, a coil wound around a central magnetic leg and a central magnet are used. A first magnetic core having a leg and a side magnetic leg, 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, and a first magnetic body There is one in which a permanent magnet for bias is inserted between the body and the second magnetic core (for example, Japanese Patent Publication No. 61-19098).

[0003]

However, in the prior art, the magnetic flux created by the winding causes the first magnetic material to saturate,
Since an excessive magnetic flux is made to flow to the second magnetic core via the biasing permanent magnet, if a sudden large current flows due to a momentary power failure or equipment failure, the permanent magnet will be demagnetized. Alternatively, when a permanent magnet having a high conductivity such as a rare earth magnet is used, there is a problem that iron loss occurs inside the permanent magnet.

[0004]

In order to solve the above problems, the present invention divides a magnetic path in which a magnetic flux generated by a winding flows and a magnetic path in which a magnetic flux generated by a permanent magnet flows in front of a permanent magnet,
The magnetic flux φe created by the winding is prevented from flowing in the permanent magnet 4, and the permanent magnet for bias is not demagnetized.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION A first magnetic core having a winding wound around a leg, a second magnetic core forming a closed magnetic circuit in combination with the first magnetic core, and a magnetic flux formed by the winding are opposed to each other. In a DC reactor having a biasing permanent magnet magnetized as described above, the permanent magnet being interposed between the first magnetic core and the second magnetic core, the second magnetic core is a 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 the side surface of the opening and the leg of the first magnetic core. A magnetic gap is formed between the side surfaces of the second magnetic core, the winding is provided in the inner space of the second magnetic core, the permanent magnet is provided outside the lip of the second magnetic core, and the magnetic flux generated by the winding is The magnetic flux generated by the permanent magnet is branched at the lip portion. The first and second magnetic cores are formed by laminating a plurality of electromagnetic steel plates punched into a predetermined shape, the first magnetic cores are T-shaped magnetic cores, the second magnetic cores are C-shaped magnetic cores, and First
And the second magnetic core is a sintered magnetic core, the first magnetic core is a T-shaped magnetic core in which a column serving as the leg is upright at the center of a disk portion, and the second magnetic core is a disk core and a pot core. Or a hole serving as the opening is provided at the center of the disc core, the pot core is covered with the disc core, and the permanent magnet is inserted between the T-shaped magnetic core and the disc core. Is provided in the bottom of the pot core, the disk 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 project from the bottom of the pot core. The disk core is brought into contact with the upper surface of the 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 portion 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 portions, thereby adjusting the size of the magnetic gap.

[0006]

Embodiments 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 the leg 11 of the T-shaped magnetic core 1 in which a plurality of electromagnetic steel plates punched into a predetermined shape are laminated. The leg 11 has a height H1 and a width Bt. On the lower surface of the head of the T-shaped magnetic core 1, a pair of rectangular permanent magnets 4 having a thickness H2 are provided symmetrically with respect to the side surfaces of the legs 11 with the same polarity in the vertical direction. is there. A leg 11 is provided on top of the C-shaped magnetic core 3 formed by laminating a plurality of electromagnetic steel plates punched into a predetermined shape.
Width B so that a predetermined magnetic gap 13 is maintained when the
The groove 3G of u is provided, and the lip portion 3L is formed with a thickness H4 that can ensure a cross-sectional area where the magnetic flux generated by the winding wire 2 is not saturated. Here, the height between the inner bottom and the upper surface of the C-shaped magnetic core 3 is H
When it is set to 3, H1 = H2 + H3. From the side opening of the C-shaped magnetic core 3 toward the internal space,
Insert the T-shaped magnetic core 1 around which the winding 2 is wound, and insert 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 both sides of the magnetic air gap 13 necessary to obtain a predetermined inductance.

FIG. 2 is a side sectional view showing a second embodiment of the present invention. In this example, the magnetic cores of the first embodiment are 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 columnar leg 11 having a diameter Dt and a height H1 which is upright in the center of the disc portion 10.
Are provided to form the T-shaped magnetic core 1. A ring-shaped permanent magnet 4L is provided on the lower surface of the disc portion 10. Permanent magnet 4
L has a thickness H2 in which a hole 3H having a diameter much larger than the diameter Dt of the leg 11 is provided in 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 wire 2. A disc core 5 is provided on the lower surface of the permanent magnet 4L.
The disk core 5 has a predetermined magnetic gap 13 between the leg 11 and the leg 11.
A hole 3H having a diameter Du is provided so as to maintain the above, and a thickness H4 is provided so as to ensure a cross-sectional area where the magnetic flux generated by the winding 2L is not saturated. A pot core 31 having a depth H5 is provided on the lower surface of the disc core 5. A ring-shaped winding 2L is provided on the inner bottom of the pot core 31 with the leg 11 inserted through the center thereof.

FIG. 3 is a side sectional view showing a third embodiment of the present invention. This example is a pot core of the second embodiment,
The arrangement of the disk core and the permanent magnet is changed. T
The disk portion 10 of the shaped magnetic core 1 is provided with a hole 3 having a diameter Du at the center of the bottom.
It directly contacts the opening surface of the pot core 31 provided with H.
Here, between the leg 11 and the hole 3H, the area facing the magnetic gap 13 required to obtain a predetermined inductance is maintained. The winding 2L is housed in the inner bottom of the pot core 31. A permanent magnet 4L is provided on the outer bottom of the pot core 31. A disk core 5 is provided by directly contacting 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 made of a normal soft iron plate, so that it is cheaper than the second embodiment.

FIG. 4 is a sectional view showing a fourth embodiment of the present invention, in which (a) is a side sectional view and (b) is a view taken along the line AA of (a) in the case of the first embodiment. is there. In this example, the first and second
In this embodiment, the magnetic gap is changed so that the inductance can be adjusted. The leg 11 having the height H6 has a root width of Br, a width from the middle to the top is Bt, and a taper portion 11T thinner than the thickness of the lip portion 1L is provided on the middle. The lip portion 1L (or the disc core 5) of the C-shaped magnetic core 3 is provided with a taper portion 31T at a position corresponding to the taper portion 11T provided in the middle of the leg 11. At the bottom of the thickness H7 of the C-shaped magnetic core 3 (bottom of the pot core 31), the leg 11
A groove 3Gg or a hole 3Gh is provided so that the tops of the two fit together with a slight gap. Here, the height H6 of the leg 11
Is H6 <H1 + H7 within a range in which 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, since the C-shaped magnetic core 3 is separated into the right and left by the groove 3Gg, side plates 7 are provided on both side surfaces of the C-shaped magnetic core 3 in the stacking direction, as shown in FIG. 4B. It is integrated with the C-shaped magnetic core 3 by welding or the like, and the groove 3Gg is cut on the bottom of the C-shaped magnetic core 3 by machining. For assembly, the winding 2 is set in the inner space of the C-shaped magnetic core 3 (or the pot core 31), and the shim 6 having a high magnetic permeability such as amorphous and the permanent magnet 4 are provided on the upper surface of the C-shaped magnetic core 3 (or the disk core 5). Set, space in the core of winding 2, groove 3Gg or hole 3
Insert the leg 11 into Gh. By changing the thickness of the shim 6, the leg 11 is moved up and down to change the magnetic air gap of the tapered portion, and the inductance is adjusted.

FIG. 5 is a sectional view showing a fifth embodiment of the present invention. In this example, the magnetic gap of the third embodiment is changed to adjust the inductance. 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. Shim 6 on the mating surface of the pot core 31 and the T-shaped magnetic core 1.
And the legs 11 are moved up and down to sandwich the tapered portions 1 facing each other.
The inductance is adjusted by adjusting the size of the air gap of 1T and 31T. 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 shown in FIG. 6 when the gap between the opposed tapered portions is large and when the gap is small, it is represented by c.

[0011]

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 is not generated in the permanent magnet. (2) Since the magnetic flux generated by the winding and the magnetic flux generated by the permanent magnet flow in the magnetic core in opposition to each other, the magnetic core is not saturated 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 the inductance suitable for the usage state.

[Brief description of 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.

FIG. 4A is a side sectional view showing a fourth embodiment of the present invention, and FIG. 4B is an A- in the case of being applied to the first embodiment.
FIG.

FIG. 5 is a sectional side view showing a fifth embodiment of the present invention.

FIG. 6 is a graph showing the performance of the 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)

[Claims] 1. A first magnetic core having a winding wound around a leg, a second magnetic core forming a closed magnetic circuit in combination with the first magnetic core, and a magnetic flux formed by the winding facing each other. A magnetized biasing permanent magnet is provided, and the permanent magnet is used as the first magnet.
In the DC reactor inserted between the magnetic core and the second magnetic core, the second magnetic core has an opening through which the leg of the first magnetic core is inserted, and the winding is excessive on both sides of the opening. A lip portion having a cross-sectional area that does not saturate even when a large current flows, forming a magnetic gap between the side surface of the opening and the side surface of the leg of the first magnetic core, and forming the winding into the second magnetic core. In the inner space of the second magnetic core, the permanent magnet is provided outside the lip of the second magnetic core, and the magnetic flux produced by the winding and the magnetic flux produced by the permanent magnet are branched at the lip. DC reactor to be. 2. The first and second magnetic cores are formed by stacking a plurality of electromagnetic steel plates punched into a predetermined shape,
2. The DC reactor according to claim 1, wherein said magnetic core is a T-shaped magnetic core, and said second magnetic core is a C-shaped magnetic core. 3. The first and second magnetic cores are sintered magnetic cores, and the first magnetic cores are T-shaped magnetic cores in which the columns serving as the legs are provided upright in the center of a disk portion. The DC reactor according to claim 1, wherein the magnetic core of (1) comprises a disk core and a pot core. 4. A hole for forming the opening is provided at 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 magnetic core and the disk core. DC reactor described in. 5. The bottom of the pot core is provided with a hole to serve as the opening, and the disk portion of the T-shaped magnetic core is brought into contact with the opening of the pot core so that the leg projects from the bottom of the pot core. 4. The direct current according to claim 3, wherein the disk core is covered as described above, 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. Reactor. 6. The size of the magnetic air gap is adjusted by providing a taper portion in the middle of the leg and the opening and moving the leg up and down to change the air gap between the respective taper portions. The DC reactor according to any one of 2 to 5.