JP5653120B2 - Magnetic element - Google Patents

Description

  The present invention relates to a magnetic element in which a magnetic body and a winding are integrally formed, and is particularly suitable for use in a booster circuit of an inverter that is a power conversion device for a vehicle driving power motor such as an electric vehicle or a hybrid vehicle. The present invention relates to a magnetic element such as a reactor that can be used for energizing a large current or applying a high voltage.

  Conventionally, this type of magnetic element is composed of a magnetic body and windings. Magnetic materials such as laminated electrical steel sheets, compacted dust, and cast bodies using Fe-Si alloys with good direct current superposition characteristics are used, and rectangular wires are wound in an edgewise shape. What is turned is known.

  For such a magnetic element, not only the magnetic characteristics, but also an optimum design including an adaptation to an allowable space in a device such as an inverter and a cooling efficiency is required. Further, from the viewpoint of future environmentally friendly products, there is a demand for magnetic elements that are smaller and less expensive.

  One of the performances required as a magnetic element is cooling performance. For example, there is a reactor in which a cooling member is added to improve cooling performance (Patent Document 1).

  Also, from the aspect of magnetic properties, there is known a method of forming windings by forming aggregate wires in which litz wires are covered and fixed in parallel bundles in order to reduce AC resistance, and winding rectangular wires in an edgewise shape. (Patent Document 2).

  Furthermore, an inductor wound in multiple layers using a round wire advantageous in terms of cost reduction is disclosed (Patent Document 3).

JP 2007-335833 A Japanese Patent Laid-Open No. 10-22131 JP-A-5-291046

  However, winding with a rectangular wire has a high space factor and is effective in reducing the size of the winding itself, but has various problems. For example, there are FIGS. 5 and 6 as winding methods. FIG. 5 is a cross-sectional view of a magnetic element in a first conventional example. FIG. 6 is a cross-sectional view of a magnetic element in a second conventional example. The magnetic element 30 in FIG. 5 includes a winding 21, an insulating member 23 such as a bobbin around which the winding 21 is wound, and a magnetic body 2 that casts them. Further, the magnetic element 40 of FIG. 6 includes a winding 31, an insulating member 33 such as a bobbin around which the winding 31 is wound, and the magnetic body 2 that casts them. When the floor area must be reduced as an allowable space, as shown in FIG. 5, it is necessary to consider the heat dissipation performance from the side surface and the inner surface as the element with an outer diameter ratio close to that of a cube. In the case where a large amount can be secured, as shown in FIG. 6, it is desirable to have an outer diameter ratio like a rectangular parallelepiped whose surface to be grounded on the cooling surface is the maximum surface, in other words, a configuration that is flat with respect to the cooling surface.

  Also, as in Patent Document 1, when winding a rectangular wire in an edgewise shape, for example, a rectangular wire having a cross-sectional aspect of up to about 10 as shown in FIG. 5 can be wound edgewise. However, as shown in FIG. 6, it is difficult to wind a cross-section having a high aspect ratio edgewise, so that it can be wound while being deformed into the aspect ratio of the cross section of the rectangular wire itself and the edgewise shape. Since there are restrictions on the range and the winding height is determined by the required number of windings in a range where the outer diameter is limited, the degree of freedom in the height direction is small, and there is also a restriction on the direction of taking out the terminal. Therefore, as a result, the height of the winding is increased, and there is a problem that it is difficult to obtain an optimum shape with respect to the cooling efficiency as described above.

  Furthermore, the flat wire is expensive. On the other hand, the round wire is low in cost, but the space factor when it is wound is low, and if a wire with the same DC resistance diameter as that of a flat wire is used, the AC resistance is reduced by the skin effect and the proximity effect. There was a problem of becoming higher.

  In patent document 2, the structure which relieves alternating current resistance is employ | adopted. However, in the structure of Patent Document 2, the cost itself is produced by manufacturing the aggregated wire covered and fixed in parallel bundles, and the space factor is reduced by the surrounding covering members for maintaining parallelism. In the case of rectangular wires, the shape is maintained as an edgewise winding because there is a resin-coated aggregate wire that maintains the shape using plastic deformation and high elasticity of metals such as copper. It was difficult to hold itself.

  Furthermore, in terms of magnetic properties, in the cross section of the winding including the winding axis of the winding, when the dimension in the direction parallel to the winding axis is the vertical dimension and the dimension in the vertical direction is the horizontal dimension, the vertical dimension / When the ratio of the lateral dimensions is about 1, the inductance is the highest, and the volume of the magnetic element itself including the magnetic material can be reduced. However, in the case of a rectangular wire, it is difficult to configure with the optimum ratio of vertical dimension / horizontal dimension as described above.

  In the magnetic element, the voltage corresponding to (voltage between terminals / number of turns) is the line voltage per turn. When a rectangular wire is wound in an edgewise shape, each wire is inevitably arranged sequentially from the winding start side, and the line voltage is a fraction of the number of turns. When winding a round wire like this, the circumference on the winding start side and the circumference on the winding end side are in contact, and the voltage between these lines is high, which may cause a layer short-circuit. Needed to be careful.

  In order to obtain such a small and low-cost magnetic element, it is possible to easily manufacture a low-profile winding to improve magnetic characteristics and cooling performance, and to use an AC resistance while using a low-cost round wire. It is important to satisfy the requirements such as not worsening the layer short.

  An object of the present invention is to solve the above-described problems, and to provide an optimal magnetic element that can obtain an optimum inductance, does not cause a layer short, has a good cooling performance, and is small and inexpensive.

According to the present invention, the relative permeability is 640 or less of the magnetic material, the magnetic body inside which is formed of, is constituted by the windings of the wire made of round wire by turning two or more simultaneous winding, pre Symbol element lines, skin thickness = 1 / ^{(πfμσ) 1/2} (frequency f, relative permeability mu, the conductivity sigma) is 0.9 or less when the 1 conductor diameter which is calculated by the winding shaft In a cross section of the winding, the winding is aligned in an arrangement parallel to the winding axis, wound from the inner periphery to the outer periphery of the winding, the dimension in the direction parallel to the winding axis, the vertical dimension, A magnetic element characterized in that the ratio of the vertical dimension / horizontal dimension is 0.3 to 5 when the dimension in the direction perpendicular to the winding axis is the horizontal dimension is obtained. The horizontal dimension is (outer diameter−inner diameter) / 2 of the winding.

  In addition, according to the present invention, there is obtained the magnetic element described above, wherein the winding wound by the aligned winding is constituted by two or more layers of the strands.

  In addition, according to the present invention, it is possible to obtain the above-described magnetic element obtained by casting the magnetic material.

  According to the present invention, an optimal inductance can be obtained, a layer short-circuit can be prevented, a cooling performance can be improved, and a small and inexpensive magnetic element can be provided.

  That is, according to the magnetic element of the present invention, the height of the winding can be reduced. Moreover, even if an inexpensive round wire is used, the AC resistance and the layer short-circuit are not deteriorated. Even if the space factor decreases, an optimum inductance can be obtained. In addition, since the configuration is flat with respect to the cooling surface, the cooling performance is good. From the above, a small, inexpensive and high-performance magnetic element can be obtained.

  The present invention can be applied not only to inductors but also to transformers and motors.

The perspective view explaining the method of winding to the bobbin used for the magnetic element in one embodiment of the present invention. Fig.1 (a) is a figure which shows the state of a winding start. FIG.1 (b) is a figure which shows the state in the middle of winding. FIG.1 (c) is a figure which shows the state of the end of winding. 1 is a cross-sectional view of a magnetic element according to an embodiment of the present invention. The perspective view which shows the state which gave the winding to the bobbin used for the magnetic element in other embodiment of this invention. The figure which shows the relationship of the inductance with respect to the vertical dimension / horizontal dimension of a winding, a magnetic element volume, and DC resistance. Sectional drawing of the magnetic element in the conventional 1st example. Sectional drawing of the magnetic element in the conventional 2nd example. Sectional drawing of the magnetic element in the conventional 3rd example.

  Embodiments of the present invention will be described below. FIG. 1 is a perspective view illustrating a method of winding a bobbin used in a magnetic element according to an embodiment of the present invention. FIG. 1 (a) is a diagram illustrating a state of starting winding, and FIG. b) is a diagram showing a state in the middle of winding, and FIG. 1 (c) is a diagram showing a state at the end of winding. FIG. 2 is a cross-sectional view of a magnetic element according to an embodiment of the present invention.

  As shown in FIG. 2, a magnetic element 10 according to an embodiment of the present invention is composed of a winding 1, an insulating member 3 such as a bobbin around which the winding 1 is wound, and a magnetic body 2 for casting them. It is. After setting the insulating member wound with the winding 1 in a case (not shown), a predetermined amount of magnetic slurry is poured, and then heated and cured to obtain the magnetic element 10.

  As the magnetic body 2 in the present invention, for example, a composite magnetic body in which an iron-based magnetic powder such as Fe-Si or Fe-Si-Al is mixed with a liquid resin such as thermosetting is used as a slurry. it can. Iron-based magnetic powders contain a non-ferrous component and have a composition that reduces saturation magnetostriction and magnetocrystalline anisotropy, and iron loss can be reduced, but conversely as the non-ferrous component increases, the saturation magnetic flux density decreases and the magnetic element Therefore, the non-ferrous component species and content are appropriately selected depending on the application. The thermosetting resin is preferably a low-viscosity resin so as to have sufficient fluidity when made into a slurry. In addition, the mechanical properties of the thermosetting resin after curing, such as elastic modulus, fracture strength, and elongation at break, are sufficient for heat generation due to energizing conditions used as magnetic elements and temperature rise due to usage environment, cooling mechanism, etc. It is necessary to have heat resistance and cold resistance and not to be broken by thermal stress. For example, an epoxy resin having a high breaking strength or a silicone resin having a high breaking elongation can be used.

  As shown in FIG. 1A, the insulating member 3 is provided with three flanges 3a, 3b, and 3c at both ends of the cylindrical body and at a central position obtained by dividing the both ends into two. Fixing portions 3a1 and 3b1 having holes through which the winding wire 1 passes are provided so as to extend in the outer peripheral direction of the flange 3a at one end and the central flange 3b. In addition, a fixing portion 3b2 having a hole through which the winding wire 1 passes is provided at a portion of the central flange 3b that contacts the cylindrical body. The fixed portions 3a1, 3b2 and 3b2, 3b1 are formed at an angle of about 20 degrees from the center.

  The winding to the insulating member used for the magnetic element of the present invention is performed as follows. First, as shown in FIG. 1 (a), one end of the winding 1 composed of a plurality of strands (six wires in the figure) is placed one turn between the lower winding portions of the insulating member 3, that is, the flanges 3b and 3c. After applying, the other end of the winding 1 is passed through the hole of the fixing portion 3b2 in the direction from the flange 3c to the flange 3a, and is introduced between the upper winding portions, that is, between the flanges 3a and 3b. Next, as shown in FIG. 1 (b), the insulating member 3 is wound so as to be opposite to each other between the flanges 3b and 3c and between the flanges 3a and 3b. Finally, as shown in FIG. 1 (c), one end of the winding 1 is inserted into the hole of the fixing portion 3b1 provided in the flange 3b of the insulating member 3, and the other end of the fixing portion 3a1 provided in the flange 3a. Each terminal is passed through the hole, and the terminal is processed with a crimp terminal or the like to form a terminal 4.

  For the insulating member 3 in the present invention, for example, phenol resin, epoxy resin or the like can be used.

  Next, an example of one stage is shown. FIG. 3 is a perspective view showing a state in which a bobbin used in a magnetic element according to another embodiment of the present invention is wound. As shown in FIG. 3, the insulating member 13 is provided with two ridges 13a and 13b at both ends of the cylindrical body. Fixed portions 13a1 each having a hole extending through the winding 1 and extending in the inner peripheral direction of the flange 13a at one end are provided.

  One end of the winding wire 11 composed of a plurality of strands (six wires in the figure) is applied between the winding portions of the insulating member 13, that is, the flanges 13a and 13b, and then the hole from the flange 13b to the hole of the fixing portion 13a1. Winding is performed by passing in the direction of 13a.

  Hereinafter, magnetic elements according to embodiments of the present invention will be described with reference to the drawings.

( Reference Example 1)
In this reference example, a copper wire having a diameter of 0.8 mm was wound around a toroidal core having an outer diameter of 27 mm, an inner diameter of 15 mm, and a height of 12 mm, and the inductance was measured by winding 20 turns so as to obtain a substantially uniform line spacing. Next, a copper wire having a diameter of 0.8 mm was similarly used on the same toroidal core, and 20 turns were concentratedly wound so that the windings were in close contact, and the inductance was measured. At this time, the winding is intensively wound in a range of about 1/3 around the entire circumference of the toroidal core. Next, in a state where the toroidal core was wound, a toroidal core not wound with the same material was disposed outside the toroidal core subjected to the winding, and the inductance was measured. Table 1 shows μ of the magnetic material used for the toroidal core.

  As shown in Table 1, in the core with high μ, the change in inductance when winding is uniformly wound and when it is intensively wound is as small as about 2.5%, and a toroidal core is arranged outside. However, there is almost no change in inductance. However, in the core having a low μ, the increase in inductance when the winding is intensively wound is large, and the increase in inductance when the toroidal core is arranged outside is also large.

  This is because, in a core with a high μ, the magnetic resistance that circulates around the core is sufficiently small, so that the magnetic flux circulates inside the core, whereas in a core with a low μ, the magnetic resistance circulates in the core. This is because the number of elements that lower the magnetic resistance increases when short circuiting around the air with μ of 1 outside the winding. This is clear from the fact that the inductance increases when the toroidal core is disposed outside the winding.

  That is, when using a magnetic material with μ of 640 or less, if a winding is arranged around the entire core of the magnetic path, leakage magnetic flux can be reduced, but no winding can be arranged around the entire core of the magnetic path. In this case, as in this example, a core shape such as a pot type in which a magnetic material is arranged outside the winding to form a magnetic path is advantageous.

( Reference Example 2)
The area of the winding window (vertical dimension × horizontal dimension) is 270 mm ² , the winding has an average diameter of 70 mm (the winding average diameter is constant), and the winding inductance for any vertical / horizontal dimension. FIG. 4 shows calculated values of the magnetic element volume and the DC resistance of the winding. Volume and direct current resistance are geometric calculations. Inductance calculation was performed by Kyushu University [Kyoto University [Cryogenic Engineering, Vol. 30, no. 7 (1995) p. 324-332]. At that time, the thickness of the magnetic body in the magnetic element was 8 mm with respect to the outer diameter of the winding, and a constant pot type core shape was used. Basically, the higher the winding inductance, the higher the inductance when the magnetic element is used.

  As shown in FIG. 4, the inductance is maximum when the aspect ratio is 1, and when the ratio is less than 0.3 and exceeds 5, the decrease in inductance becomes 10% or more, which is not preferable.

Example 3
Using a round wire of a diameter and a number of bifilar windings having a cross-sectional area substantially equal to a 0.8 × 9 mm rectangular wire, winding about 27 turns with an inner diameter of 56 mm and a height of 18 mm, the magnetic element of FIG. Inductance was measured. The results are shown in Table 2. The skin depth of copper at 10 kHz is 0.66 mm, and the influence of skin loss should be small when the diameter is 1.3 mm. However, at 1.3 mm, the AC resistance actually exceeds 10 times the DC resistance. There is a problem in practical use, and it is desirable that it is 1.2 mm or less corresponding to 0.9 times in calculation.

Example 4
The diameter of the round wire is 1 mm, the number of bifilar windings is 6, and the windings are made with aligned windings as shown in FIG. 1 and loose windings as shown in FIG. 7, and a composite magnetic material is cast around them. 10 inductors were manufactured for each, and a layer short test was conducted. The magnetic element 50 in FIG. 7 is composed of a winding 41, an insulating member 43 such as a bobbin around which the winding 41 is wound, and the magnetic body 2 that casts them. The number of windings was 28 turns, the inner diameter was 56 mm, the winding height was 14 mm, and the aligned winding had 14 turns as one layer, and two layers (two layers stacked) were connected in series.

  As shown in Table 3, it can be seen that the inductor produced by the aligned winding according to the present invention does not cause a layer short circuit.

  The present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the gist of the present invention.

1, 11, 21, 31, 41 Winding 2 Magnetic bodies 3, 13, 23, 33, 43 Insulating members 3a, 3b, 3c, 13a, 13b 鍔 3a1, 3b1, 3b2, 13a1 Fixed portion 4 Terminals 10, 20, 30, 40, 50 Magnetic element

Claims (3)

A magnetic material having a relative permeability of 640 or less, and a winding formed by winding two or more strands made of a round wire at the same time inside the magnetic material;
Before Kimoto line,
Skin thickness = 1 / (πfμσ) ^1/2 (frequency f, relative magnetic permeability μ, conductivity σ) When the conductor diameter calculated as 1 is 0.9 or less,
In the cross section of the winding including the winding axis, the winding is aligned and arranged in an array parallel to the winding axis, and is wound from the inner circumference toward the outer circumference of the winding,
When the dimension in the direction parallel to the winding axis is the vertical dimension and the dimension in the direction perpendicular to the winding axis is the horizontal dimension, the ratio of the vertical dimension / horizontal dimension is 0.3 to 5. A magnetic element characterized by the above. The magnetic element according to claim 1, wherein the winding wound by the aligned winding is composed of two or more layers of the strands. Magnetic element according to claim 1 or 2, characterized in that it is obtained by casting the magnetic material.

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