Choke with iron cores and coils

Abstract

choke (6) comprising an outer circumferential iron core (20) and at least three iron core coils (31 to 34) inside the outer circumferential iron core, wherein which at least three iron core coils are composed of iron cores (41 to 44) and coils (51 to 54) which are each wound on the iron cores, wherein the iron cores (41 to 44) are each coupled to the circumferential core (20) at a radially outer end, wherein Columns (101 to 104), which are magnetically coupleable, are formed between the respective radially inner ends of the at least three iron cores and the radially inner ends of the respective further, adjacent iron cores, wherein the coils are arranged in coil spaces (51a to 54a) which are formed between the iron cores and the outer circumferential iron core, wherein one surface of the coil space is parallel to an inner circumferential surface of the coil and another surface of the coil space is parallel to an outer circumferential surface of the coil, and two corner regions (51c to 53c) arranged on the outer circumferential iron core are rounded in the cross-section of the coil spaces in the axial direction, and wherein a radius of the round corner regions (51c to 53c) corresponds at least approximately to half a width (W) of the coil spaces (51a to 54a).

Description

1. Field of the invention

[0001] The invention relates to a choke (motor choke) with iron cores and coils. 2. State of the art

[0002] Chokes (reactor coils) have multiple iron core coils, each of which has an iron core and a coil wound around the iron core. Predetermined gaps are formed between the multiple iron cores. More recently, chokes have been manufactured in which multiple iron cores and coils wound on them are arranged in an annular outer peripheral iron core. See, for example, published Japanese patent application JP 2017-59805 A.

[0003] Document DE 10 2016 010 901 A1 discloses a three-phase reactor with an outer iron core surrounding a central iron core. The iron cores interact to surround at least three coil spaces shaped like circular sectors in a radial cross-section. Furthermore, document JP 2013 - 74 084 A also discloses a reactor with an iron core and three coil spaces shaped like circular sectors in a radial cross-section.

[0004] Document JP 2005 - 303 229 A discloses a transformer whose iron core has rounded corners to reduce magnetic flux concentration in an axial cross-section. Furthermore, document KR 10 2011 0 061 935 A discloses a transformer with an iron core having cavities for accommodating induction coils with rounded corners in an axial cross-section to reduce magnetic flux concentration. Document US 2009 / 0 261 939 A1 also shows an arrangement with an iron core having cavities for partially accommodating induction coils.

[0005] Document WO 2010 / 119324 A2 discloses a multi-phase on-board converter having a plurality of boost coils and including annular self-inductance cores provided for each of the boost coils, each of which has a corresponding one of the boost coils wound thereon, and annular mutual inductance cores provided for each pair of boost coils selected from the plurality of boost coils, each of which has the paired boost coils wound thereon, each of which includes a portion of each self-inductance core corresponding to the paired boost coils. Each of the self-inductance cores and the mutual inductance cores has a gap dividing a line in its circumferential direction. BRIEF DESCRIPTION OF THE INVENTION

[0006] The invention is defined by a device according to the main claim. The subclaims each define advantageous developments.

[0007] In such chokes, coils are arranged in choke gaps formed between the outer peripheral iron core and the iron cores. The coil spaces are at least partially rectangular in an axial section through the choke.

[0008] However, when the choke is energized, the main magnetic flux flowing through the coils passes through the outer peripheral iron core, resulting in a local increase in magnetic flux at the corners of the rectangular coil gaps. This causes a problem in that the magnetic flux increases. Iron losses also increase, and the magnetic flux saturates. Iron losses also increase with increasing frequency.

[0009] The aim should therefore be a choke in which the magnetic flux concentration at the corners of the coil spaces is (largely) avoided.

[0010] According to a first combination of features, a choke is provided, inter alia, with an outer peripheral iron core and at least three iron core coils within the outer peripheral iron core, wherein the at least three iron core coils are composed of iron cores and coils wound thereon, magnetically coupleable gaps are formed between one of the at least three iron cores and a further iron core adjacent thereto, the coils are arranged in coil spaces formed between the iron cores and the outer peripheral iron core, and at least one corner region in the cross section of the coil spaces is rounded in the axial direction.

[0011] Since the corner areas of the coil spaces are rounded in the first feature combination, the concentration of the magnetic flux at the corner areas can be weakened and, as a result, the iron losses can be reduced and saturation of the magnetic flux can be avoided.

[0012] These objects, features and advantages as well as further objects, features and advantages of the invention will become even clearer from the following description of embodiments of the invention with reference to the figures. BRIEF DESCRIPTION OF THE CHARACTERS Fig. 1A is a perspective view of a throttle according to a first embodiment not belonging to the invention. Fig. 1B is a sectional view of a throttle according to the first embodiment. Fig. 1C is a representation of the magnetic flux density of the choke corresponding to Fig. 1B. Fig. 1D is an enlarged partial view of Fig. 1C. Fig. 2A is a sectional view of a prior art choke. Fig. Figure 2B is a representation of the magnetic flux density of the choke according to the prior art. Fig. 2C is an enlarged partial view of Fig. 2B. Fig. 3A is a sectional view of a throttle according to a second embodiment. Fig. 3B shows the magnetic flux density at the choke according to Fig. 3A. Fig. 3C is an enlarged partial view of Fig. 3B. Fig. 4 is a sectional view of a throttle according to a third embodiment not belonging to the invention. Fig. 5 is a sectional view of a throttle according to a fourth embodiment. DESCRIPTION OF DETAILS

[0013] Embodiments of the invention will now be described in more detail with reference to the figures. In the figures, identical components are provided with the same reference numerals. The scales in the figures have been modified to facilitate understanding.

[0014] The following description primarily uses a three-phase choke as an example. However, the description is not limited to the use of a three-phase choke, but can be directly applied to any multi-phase choke that has a constant inductance in each phase. Furthermore, the choke according to this description is not limited to those used on the primary or secondary side of inverters in industrial robots or machine tools; rather, the choke can be used in a variety of machines.

[0015] Fig. 1A is a perspective view of a throttle according to a first embodiment of the invention and Fig. 1B shows a section through the throttle according to the first embodiment. According to the Fig. 1A and Fig. 1B, a core body 5 of a reactor 6 includes an annular outer peripheral iron core 20 and at least three iron core coils 31 to 33 arranged in the outer peripheral iron core 20 at equal intervals in the circumferential direction thereof. The number of iron cores is preferably a multiple of three, so the reactor 6 can be used as a three-phase reactor. Note that the outer peripheral iron core 20 may also have a shape other than circular. The iron core coils 31 to 33 include iron cores 41 to 43 and coils 51 to 53 wound around the iron cores 41 to 43.

[0016] The outer peripheral iron core 20 consists of a plurality of, for example, three, outer peripheral iron core pieces 24 to 26 distributed in the circumferential direction. The outer peripheral iron core pieces 24 to 26 are integrally formed with the iron cores 41 to 43, respectively. The outer peripheral iron core pieces 24 to 26 and the iron cores 41 to 43 are formed by stacking a plurality of iron plates, carbon steel plates, or electromagnetic steel discs, or they are formed from a powder core. If the outer peripheral iron core 20 is formed from a plurality of outer peripheral iron core pieces 24 to 26, it can be easily manufactured even with large dimensions. Note that the number of iron cores 41 to 43 and the number of iron core pieces 24 to 26 do not necessarily have to be the same.

[0017] As can be seen from Fig. 1B, the iron cores 41 to 43 have at least approximately the same dimensions and are arranged at at least approximately equal intervals in the circumferential direction of the outer peripheral iron core 20. Accordingly Fig. 1B, the radially outer ends of the iron cores 41 to 43 are coupled to the iron core parts 24 to 26, respectively.

[0018] The radially inner ends of the iron cores 41 to 43 converge toward the center of the outer peripheral iron core 20, and the angles formed by the tips are at least approximately 120 degrees. The radially inner ends of the iron cores 41 to 43 are separated from each other by gaps 101 to 103, through which the magnetic connection can be established.

[0019] In other words, in the first embodiment, the radially inner end of the iron core 41 is separated from the radially inner ends of the two adjacent iron cores 42 and 43 by gaps 101 and 103. The same applies to the other iron cores 42 and 43. Ideally, the dimensions of the gaps 101 to 103 are equal to each other, but this need not be the case. As can be seen from Fig. As can be seen in Figure 1B, the intersection point of the columns 101 to 103 lies in the center of the throttle 6. The core body 5 is rotationally symmetrical around this center.

[0020] In the first embodiment, the iron core coils 31 to 33 are arranged inside the outer peripheral iron core 20. In other words, the iron core coils 31 to 33 are enclosed by the outer peripheral iron core 20. In this way, the magnetic flux leakage from the coils 51 to 53 to the outside of the outer peripheral iron core 20 can be reduced.

[0021] How Fig. As shown in Fig. 1B, the coils 51 to 53 are arranged in coil spaces 51a to 53a formed between the outer peripheral iron core portions 24 to 26 and the iron cores 41 to 43. In the coil spaces 51a to 53a, the inner peripheral surfaces and the outer peripheral surfaces of the coils 51 to 53 are adjacent to the inner walls of the coil spaces 51a to 53a.

[0022] The coil spaces 51a to 53a each contain four corner sections 51c to 53c, which extend in the axial direction in the cross-section of the choke 6. In the first embodiment, at least one of the corner regions 51c to 53c is rounded. In the embodiment according to Fig. 1B, all corner regions 51c to 53c are rounded. In the first embodiment, the radius (of curvature) of the rounded corner region is between half the length L of the columns 101 to 103 and half the width W of a coil space 51A. If the length L of the columns 101 to 103 is greater than the width W of the coil space 51a, then the radius (of curvature) of the rounded corner region is less than or equal to half the width W of a coil space 51a.

[0023] Fig. 2A is a cross-section through a prior art choke. The configuration of the prior art choke 6' is essentially the same as the configuration of the choke 6 according to the first embodiment. However, the choke 6' differs from the choke 6 in that the corner regions 51c to 53c of the coil spaces 51a to 53a of the choke 6' form right angles in the cross-section of the choke 6'.

[0024] The Fig. 1C and Fig. 2B show the magnetic flux density curves in chokes according to the first embodiment and according to the prior art. Fig. 1D and Fig. 2C are enlarged views of sections of the Fig. 1C and 2B, respectively. To facilitate understanding, the reference symbols of some components have been omitted in these and other similar figures.

[0025] According to the Fig. 2B and Fig. 2C, the magnetic flux at the corner regions 51c of the coil space 51a is relatively dense. In contrast, according to the Fig. 1C and Fig. 1D, the magnetic flux at the corner region 51c of the coil space 51a is less dense (lower magnetic flux density). In the first embodiment, the corner regions 51c of the coil space 51a are rounded with a radius of 1 mm, thereby reducing the concentration of the magnetic flux lines at the corner regions 51c. The same applies to the other corner regions 52c, 53c.

[0026] This allows the so-called iron loss to be reduced and magnetic flux saturation to be suppressed in the first embodiment. The effect of reducing iron losses is further enhanced when higher-frequency current flows.

[0027] Fig. Figure 3A is a cross-sectional view of a choke according to a second embodiment. In the second embodiment, round corner regions 51d to 53d are formed at the outer ends of the coil spaces 51a to 53a, extending in the axial direction in the cross section of the choke 6. The cross section of the corner region 51d according to Fig. 3A is semicircular and one corner area 51d corresponds to two rounded corner areas 51c according to Fig. 1B. In the second embodiment, the radius (radius of curvature) of the round corner regions 51d to 53d is at least approximately half the width W of the coil spaces 51a.

[0028] Fig. Figure 3B shows the magnetic flux density of the Fig. 3A and Fig. 3C shown throttle. Fig. 3C shows Fig. 3B on an enlarged scale. If these figures are compared with the representations of the magnetic flux densities described above according to the configurations according to the Fig. 3B and Fig. 3C, it can be seen that the concentration of the magnetic flux is particularly reduced here. In general, the so-called iron losses increase with frequency. Thus, the configuration according to the second embodiment is particularly advantageous for chokes used at higher frequencies.

[0029] Fig. Figure 4 shows a cross section through a throttle according to a third embodiment of the invention. The corner regions 51c' to 53c' according to Fig. 4 are each part of a hexagon. In particular, the corner regions 51c' of the coil space 51a and the side between them correspond to one side of a hexagon, and accordingly, the regions at both ends of said one side form the internal angles.

[0030] In such a configuration, the magnetic flux densities are substantially the same as those of a choke with corner regions 51c to 53c that are rounded to essentially form parts of a polygon. Thus, it can be understood that the same effects as described above are achieved. In the third embodiment, the corner regions 51c' to 53c' can be manufactured relatively easily compared to the production of rounded corner regions. Furthermore, the corner regions 51c' to 53c', each forming part of a polygon, can also be subjected to the above-mentioned rounding.

[0031] Fig. 5 is a cross-sectional view of a reactor according to a fourth embodiment. The core body 5 according to Fig. 5 has a substantially octagonal outer peripheral iron core 20 and four iron core coils 31 to 34, which correspond to the above-mentioned iron core coils, arranged inside the outer peripheral iron core 20. These iron core coils 31 to 34 are arranged at substantially equal intervals in the circumferential direction of the reactor 6. The number of iron cores is preferably an even number of four or more, so that the reactor 7 can be used as a single-phase reactor.

[0032] As can be seen from the figure, the outer peripheral iron core 20 is composed of four outer peripheral iron core parts 24 to 27 distributed in the circumferential direction. The iron core coils 31 to 34 have iron cores 41 to 44 extending in radial directions and coils 51 to 54 wound around the iron cores, respectively. The radially outer ends of the iron cores 41 to 44 are integrally formed with the respective outer peripheral iron core parts 24 to 26. Note that the number of iron cores 41 to 44 does not necessarily have to be the same as the number of outer peripheral iron core parts 24 to 27. The same applies to the Fig. 1A shown nuclear body.

[0033] Each of the radially inner ends of the iron cores 41 to 44 is positioned near the center of the outer peripheral iron core 20. According to Fig. 5, the radially inner ends of the iron cores 41 to 44 converge toward the center of the outer peripheral iron core 20, and their apex angles are in the range of 90 degrees. The radially inner ends of the iron cores 41 to 44 are separated from each other by gaps 101 to 104, which can be magnetically coupled.

[0034] Rounded corner areas 51d to 54d are provided at the outer ends of the coil spaces 51a to 54a according to Fig.5. The corner regions 51d to 54d have the same shapes as the corner regions 51d to 53d described above. The radius of the rounded corner regions 51d to 54d in the fourth embodiment corresponds substantially to half the width W of a coil space 51a. Thus, the same effects as described above are achieved in this case as well. Note that suitable combinations of some of the above-described embodiments are included in the present description. SPECIAL FEATURES OF THE PRESENT DESCRIPTION

[0035] According to the first combination of features, a choke (6) is provided, inter alia, with an outer peripheral iron core (20) and at least three iron core coils (31 to 34) inside the outer peripheral iron core, wherein the at least three iron core coils are formed from iron cores (41 to 44) and coils (51 to 54) which are each wound on the iron cores, gaps (101 to 104) which can be magnetically coupled are formed between one of the at least three iron cores and another, adjacent iron core, the coils are arranged in coil spaces (51a to 54a) which are formed between the iron cores and the outer peripheral iron core, and at least one corner region (51c to 53c) in the section of the coil spaces is rounded in the axial direction.

[0036] According to the second feature combination, the number of at least three iron core coils in the first and second feature combinations is a multiple of 3.

[0037] According to a third combination of features, in the first or third combination of features, the number of at least three iron core coils is an even number not less than 4. EFFECTS OF FEATURE COMBINATIONS

[0038] Since the corner areas of the coil spaces are rounded in the first feature combination, the concentration of the magnetic flux at the corner areas can be widened (reduced) and iron losses can be reduced, as well as the probability of saturation of the magnetic flux can be reduced.

[0039] The second combination of features enables the choke to be used as a three-phase choke.

[0040] The third combination of features enables the choke to be used as a single-phase choke.

Claims

[1] Choke (6) comprising an outer peripheral iron core (20) and at least three iron core coils (31 to 34) inside the outer peripheral iron core, wherein the at least three iron core coils are composed of iron cores (41 to 44) and coils (51 to 54) which are each wound on the iron cores, wherein the iron cores (41 to 44) are each coupled with a radially outer end to the peripheral core (20), wherein Gaps (101 to 104), which can be magnetically coupled, are formed between the respective radially inner ends of the at least three iron cores and the radially inner ends of the respective further, adjacent iron cores, wherein the coils are arranged in coil spaces (51a to 54a) formed between the iron cores and the outer peripheral iron core, wherein one surface of the coil space is parallel to an inner peripheral surface of the coil and another surface of the coil space is parallel to an outer peripheral surface of the coil, and two corner regions (51c to 53c) arranged on the outer peripheral iron core are rounded in the cross section of the coil spaces in the axial direction, and wherein a radius of the round corner regions (51c to 53c) corresponds at least approximately to half a width (W) of the coil spaces (51a to 54a). [2] A reactor according to claim 1, wherein the number of at least three iron core coils is a multiple of 3. [3] A reactor according to claim 1, wherein the number of said at least three iron core coils is an even number not less than 4.

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