Patent Application
20130063237
The present invention relates to a reactor, which is suitably used in, e.g., an electronic circuit and an electric circuit and, in particular, which is more suitably used in an electric power system.
A reactor is a passive element using, e.g., windings with intent to introduce reactance in a circuit. The reactor is used in various electronic circuits and electric circuits, etc. for, e.g., preventing harmonic currents in a power-factor improvement circuit, smoothing current pulsations in a current type inverter and chopper control, and boosting a DC voltage in a converter. Further, in the electric power system, the reactor is used as, e.g., a shunt reactor for compensating for a phase-advanced reactive current and boosting a receiving-end voltage, a serial reactor (current limiting reactor) for increasing impedance in the system to reduce the short-circuit capacity, and a arc suppression coil (neutral reactor) for distinguishing a fault current generated in the event of a one-line ground fault.
The reactor includes a coil and an iron core (core member) serving as a path for magnetic flux that is generated when electric power is supplied to the coil. The iron core is fabricated, for example, by layering magnetic steel sheets in the circumferential direction as an integral unit to form a disk-shaped block iron core (also called an iron core packet, a radial block iron core, or a radial core), and by stacking the plurality of disk-shaped block iron cores in the axial direction (see, e.g., Patent Literature (PTL) 1, PTL 2, and PTL 3). More specifically, for example, a cylindrical block iron core is fabricated by successively layering thin iron sheets with different widths to form a sub-block, which has the shape of a sector in section, and by arranging the plurality of sub-blocks in a circular form (see, e.g., PTL 3).
Additionally, the reactor is a device to introduce reactance in a circuit, as described above, and it basically includes one winding per phase. On the other hand, a transformer includes two or more windings per phase and differs from the reactor.
With the related-art reactor, however, because the block iron core is manufactured, as described above, by successively layering thin iron sheets with different widths to form a sub-block, which has the shape of a sector in section, and by arranging the plurality of sub-blocks in a circular form, more man-hours have been required to manufacture the reactor and a cost reduction of the reactor has been difficult to realize.
PTL 1: Japanese Unexamined Patent Application Publication No. 57-049213
PTL 2 Japanese Unexamined Patent Application Publication No. 59-229809
PTL 3: Japanese Unexamined Patent Application Publication No. 2005-347535
The present invention has been made in view of the above-described situation, and an object of the present invention is to provide a reactor that can be more easily manufactured.
In the reactor according to the present invention, a core member is formed of a wire made of a magnetic material and is arranged outside a plurality of coils. With the reactor thus constructed, since the core member is formed of the wire and is arranged outside the plurality of coils, the core member can be formed by winding the wire. Hence the reactor can be more easily manufactured.
The above and other objects, features, and advantages of the present invention will be apparent from the following detailed description and the accompanying drawings.
An embodiment of the present invention will be described below with reference to the drawings. It is to be noted that components denoted by the same reference symbols throughout the drawings represent the same components, and duplicate description of those components is omitted as appropriate. Further, in this specification, when a component is described as a generic term, it is denoted by a reference symbol without a suffix, and when a component is described as one of individual components, it is denoted by a reference symbol with a suffix.
In
In this embodiment, the coils 1 are constituted, for example, by winding a plurality of long band-like conductor members, which are layered with an insulating member (not illustrated) interposed between the conductor members, such that the width direction of the conductor members is matched with the axial direction of the coils 1. Those long band-like conductor members have a sheet shape, a ribbon shape, or a tape shape in which a ratio of the thickness (length in the thickness direction) t to a width (length in the width direction) W is less than 1 (0<t/W<1).
The coils 1 may be formed in a desired plural number, e.g., a number determined in design as appropriate depending on use of the reactor Da. For example, the number of plural coils 1 is set as a number corresponding to the number of phases of AC power supplied to the reactor Da. The coils 1 are constituted by, e.g., two band-like conductor members that are layered with an insulating member interposed therebetween, and the reactor Da is used for 2-phase AC power. Alternatively, the coils 1 are constituted by, e.g., three band-like conductor members that are layered with an insulating member interposed therebetween, and the reactor Da is used for 3-phase AC power.
In this embodiment, as illustrated in
The core member 2 is a member serving as a path for magnetic flux that is generated when electric power is supplied to the coils 1. The core member 2 is formed using a wire made of a magnetic material and is disposed outside the coils 1. In such an arrangement, the magnetic flux generated when electric power is supplied to the coils 1 circulates in a way starting from one end portion of each coil 1 in the axial direction, passing through the core member 2, and returning to the other end portion of the coil 1 in the axial direction. The magnetic material is, for example, pure iron or an iron-based alloy (such as a Fe—Al alloy, a Fe—Si alloy, sendust, or permalloy), and it is processed into a wire by, e.g., rolling or drawing. While it is preferable that all of the magnetic flux generated when electric power is supplied to the coils 1 passes through the core member 2, the magnetic flux may leak in practice.
In more detail, in the example illustrated in
The core member 2 may have a predetermined sectional shape that is optionally selected. In order to reduce an eddy current loss in each of the conductor members of the coils 1, however, a sectional shape of the core member 2, taken along a plane including an axis of the coils 1, is preferably substantially rectangular as illustrated in
Further, the reactor Da of the first embodiment includes, as illustrated in
The central core member 3 has, for example, isotropy and a predetermined magnetic characteristic (permeability) depending on specifications, etc. From the viewpoint of easiness in shaping to the above-described desired shape, the central core member 3 is preferably formed by compacting soft magnetic powder. In the reactor Da thus constructed, the central core member 3 can be easily formed and an iron loss generated in the central core member 3 can also be reduced. More preferably, the central core member 3 is formed by compacting a mixture of soft magnetic powder and non-magnetic powder. A mixing ratio of the soft magnetic powder and the non-magnetic powder can be comparatively easily adjusted, and the predetermined magnetic characteristic in the central core member 3 can be easily realized by appropriately adjusting the mixing ratio.
The soft magnetic powder is ferromagnetic metal powder. More specifically, the soft magnetic powder is, for example, pure iron powder, powder of an iron-based alloy (such as a Fe—Al alloy, a Fe—Si alloy, sendust, or permalloy), amorphous powder, or iron powder having an electrical insulating coating, e.g., a phosphate chemical conversion coating, formed on the surface thereof. The above-mentioned soft magnetic powder can be produced by a known method, such as pulverizing a material with, e.g., atomization, or finely grinding, e.g., iron oxide and reducing the same. Further, it is particularly preferable that the soft magnetic powder is the above-mentioned metal-based material, such as pure iron powder, powder of an iron-based alloy, or amorphous powder, because that metal-based material generally has a larger saturation magnetic flux density when the magnetic permeability is same.
The central core member 3 made of the above-mentioned soft magnetic powder can be formed by a known ordinary process, e.g., powder compacting.
From the viewpoint of downsizing, the central core member 3 is preferably made of a material having higher magnetic permeability than the wire of the core member 2.
The above-described reactor Da can be manufactured, for example, through the following steps. First, as illustrated in
Then, respective one ends of the three conductor members layered as description above (i.e., the layered conductor members) are attached to the circumferential surface of the central core member 3 between both the depressions DP-1 and DP-2 and are started to be wound around the above-mentioned circumferential surface in such a state that the width direction of each of the conductor members (i.e., the layered conductor members) is matched with the axial direction of the central core member 3. As illustrated in
Then, as illustrated in
Thus, the reactor Da of the so-called pot type is fabricated in a state where the wire WL of the core member 2 is wound into a shape like a ball (mass) of string or yarn while surrounding the coils 1. In the reactor Da thus fabricated, the 3-phase commercial AC power is supplied to the three coils 1.
When the AC power is supplied to the coils 1, magnetic flux B of a magnetic field formed by the coils 1 generates, as denoted by arrows in
In the reactor Da of this embodiment, as described above, since the core member 2 is formed of the wire WL and is disposed outside the coils 1, the core member 2 can be formed by winding the wire WL, and the reactor Da can be more easily manufactured. As a result, it is possible to increase productivity and to reduce the cost of the reactor Da of this embodiment.
Although, in the reactor Da of this embodiment, magnetostrictive vibration may occur in the core member 2, the magnetostrictive vibration can be mitigated in the entire core member 2 because the core member 2 is formed of the wire WL and the wire WL is wound in various directions in the whole of the reactor Da.
Since the reactor Da of this embodiment includes the central core member 3, the central core member 3 can be utilized as not only a winding core for the coils 1, but also a winding core for the wire WL of the core member 2. Thus, higher productivity can be obtained.
Further, in the reactor Tra of this embodiment, since the coils 1 are constituted by winding the band-like conductor members that are layered with the insulating member interposed therebetween, the plurality of coils 1 can be formed in one winding step. Accordingly, the reactor Da having the above-described structure can be more easily manufactured.
Here, the three coils 11u, 11v and 11w constituting the plurality of coils 1 may be layered in the radial direction. With such an arrangement, the reactor having a reduced height (thickness) is provided.
In the reactor Tra described above, the central core member 3 may have various shapes in addition to the above-described columnar shape including the depressions DP formed in the circumferential surface of both the end portions thereof.
As illustrated in
As illustrated in
As illustrated in
With the central core members 31 to 33 having the structures described above, since they include respectively the flange members 312, the first disk-like members 322, and the second disk-like members 332, the diameters of the central core members 31 to 33 over which the wire WL of the core member 2 is engaged can be changed. Therefore, the design for setting the lengthwise direction of the wire WL to be almost matched with the direction of the magnetic flux is facilitated.
Further, with the central core member 33, since the diameters of the second disk-like members 332 gradually increase toward the outer side of the layered direction, the wire WL engaged over one second disk-like member 332 on the inner side (e.g., the second disk-like member 332-1) can be retained (held) by the other second disk-like member 332 on the outer side (e.g., the second disk-like member 332-2 in the illustrated example). Accordingly, the shape of the core member 2 can be stably maintained.
As illustrated in
In use of the central core member 34 having the structure described above, the core member 2 is disposed even on both the end surfaces of the central core member 34. When the wire WL of the core member 2 is closely wound, the coils 1 can be completely surrounded by the core member 2.
Another embodiment will be described below.
The coils 12 in the reactor Db of the second embodiment are each constituted, for example, by winding a band-like conductor member to be layered with an insulating member interposed between windings of the conductor member such that the width direction of the conductor member is matched with the axial direction of the coil 12. Further, the coils 12 are constituted by stacking the plurality of wound band-like conductor members in the axial direction. In an example illustrated in
The thus-constructed reactor Db of the second embodiment can also provide similar advantageous effects to those obtained with the reactor Da of the first embodiment.
In the reactor D (Da, Db) of each of the first and second embodiments, the diameter of the wire WL of the core member 2 is preferably ⅓ or less of a skin thickness with respect to the frequency of the AC power supplied to the reactor D. In the reactor D thus constructed, since the diameter of the wire WL is ⅓ or less of the skin thickness with respect to the frequency of the AC power, an eddy current loss can be reduced. Additionally, given that the angular frequency of the AC power is ω, the magnetic permeability of the wire is μ, and the electrical conductivity of the wire is ρ, a skin thickness δ is generally expressed by δ=(2/ωμρ)1/2.
Further, in the reactor D of each of the first and second embodiments, when the 3-phase commercial power is supplied to the reactor D, the wire WL of the core member 2 preferably has a predetermined diameter corresponding to the commercial AC frequency of 50 Hz or 60 Hz. By setting the diameter of the wire WL of the core member 2 to the predetermined diameter corresponding to the commercial AC frequency, the reactor D can be provided to be more suitably adapted for the 3-phase commercial AC.
In the reactor D of each of the first and second embodiments, the central core member 3 may be a hollow cylindrical core member having a wall thickness not smaller than the skin thickness with respect to the frequency of the AC power supplied to the reactor Tr. The hollow cylindrical core member enables the reactor D to be cooled by causing a medium for cooling, e.g., air or oil, to flow through a hollow portion of the hollow cylindrical core member.
In the reactor D of each of the first and second embodiments, the central core member 3 may be a plurality of split core members, i.e., a plurality of pieces split in the circumferential direction thereof. Such an arrangement can also provide the reactor D of the embodiment.
In the reactor D of each of the first and second embodiments, the wire WL of the core member 2 may be one or may be divided into a plurality of wires. When the core member 2 is formed using the plurality of wires WL, the core member 2 can be formed by a first method of winding one wire WL (WL1) as described above, replacing the one wire WL (WL1) with the other wire WL (WL2) midway the winding, and winding the other wire WL (WL2) as described above, or by a second method of winding a plurality of wires WL (WL3) as described above. In the second method, the plurality of wires WL3 can be used in the form where the wires are arrayed parallel to each other and are encapsulated with resin or loosely twisted.
In the reactor D of the embodiment, the wire WL of the core member 2 is arranged such that the lengthwise direction of the wire WL is almost matched with the direction of the magnetic flux generated when the AC power is supplied to the coils 1. When the lengthwise direction of the wire WL is not completely matched with the direction of the magnetic flux, an induced electromotive force is generated in the wire WL with the magnetic flux. However, the core member 2 formed using the plurality of wires WL, as described above, can make comparatively small the potential difference between the ends of the wires WL, the potential difference being caused due to the induced electromotive force generated in the wires WL.
While this specification discloses techniques in the above-described various forms, primary ones of those techniques are as follows.
The reactor according to one form comprises a plurality of coils, and a core member serving as a path for magnetic flux that is generated when electric power is supplied to the coils, wherein the coils are constituted by respectively winding band-like conductor members to be layered with an insulating member interposed between windings of the conductor members such that a width direction of the conductor members is matched with an axial direction of the coils, and the core member is formed of a wire made of a magnetic material and is arranged outside the coils. In the reactor thus constructed, preferably, the coils are surrounded by the core member.
With the structure described above, since the core member is formed of the wire and is arranged outside the plurality of coils, the core member can be formed by the winding the wire, whereby the reactor can be more easily manufactured. As a result, it is possible to obtain higher productivity and to reduce the cost.
According to another form, in the above-described reactor, the wire of the core member is arranged such that a lengthwise direction of the wire is substantially matched with a direction of the magnetic flux generated when AC power is supplied to the coils.
Magnetic resistance of the wire of the core member increases at a larger number of times the wire traverses the magnetic flux produced by the coils to which the AC power is supplied. In view of that point, the wire of the core member is preferably positioned such that the lengthwise direction of the wire is matched with the direction of the magnetic flux as close as possible. With that arrangement, since the wire of the core member is arranged such that the lengthwise direction of the wire is almost matched with the direction of the magnetic flux, the wire of the core member traverses the magnetic flux at a smaller number of times, whereby the magnetic resistance is reduced. The above expression “almost matched with” implies that the lengthwise direction of the wire of the core member is substantially matched with the direction of the magnetic flux, i.e., that an angle θ formed by the lengthwise direction of the wire of the core member and the direction of the magnetic flux satisfies −10°≦θ≦+10°. The angle θ satisfies preferably −7°≦θ≦+7° and more preferably −5°≦θ≦+5°.
According to still another form, the above-described reactors further comprise a central core member made of a magnetic material, the central core member being arranged within a minimum inner diameter of the coils and being magnetically coupled to the core member.
With the structure described above, since the reactor includes the central core member, higher productivity can be obtained by using the central core member as not only a winding core for the coils, but also as a winding core for the core member.
According to still another form, in the above-described reactors, the coils are constituted by winding a plurality of band-like conductor members, which are layered with an insulating member interposed between the conductor members, such that a width direction of the conductor members is matched with an axial direction of the coils.
With the structure described above, since the coils can be manufactured in one winding step, manufacturing of the reactor of that type is facilitated.
According to still another form, in the above-described reactor, the coils are layered in a radial direction of the coils.
With the structure described above, since the coils are layered in the radial direction, the reactor having a reduced height (thickness) can be provided.
According to still another form, in the above-described reactors, the coils are stacked in the axial direction of the coils.
With the structure described above, since the coils are stacked in the axial direction, the reactor having a smaller diameter can be provided.
According to still another form, in the above-described reactors, a diameter of the wire of the core member is ⅓ or less of a skin thickness with respect to a frequency of AC power supplied to the reactor.
With the structure described above, since the diameter of the wire is ⅓ or less of the skin thickness with respect to the frequency of AC power, an eddy current loss can be reduced in the reactor having that structure. Additionally, given that the angular frequency of the AC power is ω, the magnetic permeability of the wire is μ, and the electrical conductivity of the wire is ρ, a skin thickness δ is generally expressed by δ=(2/ωμρ)1/2.
According to still another form, in the above-described reactor, the coils are three in number to be adapted for 3-phase commercial AC. Further, in the reactor thus constructed, the wire of the core member preferably has a predetermined diameter corresponding to the commercial AC frequency of 50 Hz or 60 Hz.
With the structure described above, the reactor for 3-phase commercial AC is provided. Further, since the diameter of the wire of the core member is set to the predetermined diameter corresponding to the commercial AC frequency, the reactor D can be provided to be more suitably adapted for the 3-phase commercial AC.
This application is on the basis of Japanese Patent Application No. 2010-113854 filed May 18, 2010, which is incorporated by reference herein in its entirety.
While the present invention has been adequately and sufficiently described above in connection with embodiments by referring to the drawings for the purpose of expressing the present invention, it is to be recognized that the foregoing embodiments can be easily modified and/or improved by those skilled in the art. Accordingly, it is to be construed that modified forms or improved forms carried out by those skilled in the art are involved within the scope of patent right defined in claims insofar as those forms do not depart from the scope of patent right defined in the claims.
According to the present invention, a reactor can be provided.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-113854 | May 2010 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2011/002646 | 5/12/2011 | WO | 00 | 11/15/2012 |
