JPH0362007B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrical induction device made of grain-oriented silicon steel. Since the loss rating levels specified by users of power and power transmission and distribution transformers are currently high, it is becoming extremely important to reduce the no-load loss, or core loss, of power and power transmission and distribution transformers. For this reason, efforts are being made to reduce core losses in power and power transmission and distribution transformers. In the past, electrical steel manufacturers have increased the permeability of steel by increasing the degree of directionality in order to reduce core losses in electrical steel. As a result of these efforts, we have developed (1) regularly grained silicon steels such as AISI M-3 to M-8, and (2) high-grade silicon steels with higher magnetic permeability and lower iron loss than regularly grained silicon steels. Magnetic permeability oriented silicon steel was developed. Iron loss W _I is further improved by the use of insulating stress coatings on the major faces of grain-oriented steels, and by scribing transversely (i.e. transverse to the rolling direction) to reduce the domain dimensions of these materials. Further improvements have been made in grain-oriented steel coated in an insulative manner by scratching. However, the measured core loss W _C (watts/pound of iron (or Watts/Kg)) in a commercial transformer core is equal to the measured core loss W _I (watts/pound of iron) of the electrical steel that makes up the core. ) has been experienced in the industry. Therefore, the reduction in core loss achieved by the above-mentioned improvements in grain-oriented electrical steel has not been completely realized as an equivalent reduction in core loss in commercial transformers using these materials. Changes in reluctance between the various parallel magnetic paths in the transformer core cause large changes in magnetic flux density between these paths. Changes in reluctance are determined by core geometry (path length, cross section),
This can be caused by changes in the magnetic permeability of the core steel itself. As a result, if the magnetic flux density is non-uniform,
The loss will be large. However, with proper control of the non-uniform distribution, the losses in a core made of two different steels can be smaller than expected. To take advantage of this phenomenon, various combinations of steel core schemes have been proposed. For example, U.S. Pat.
No. 4205288 combines regular grain-oriented silicon steel and high permeability grain-oriented silicon steel. Reference is made herein to the specification of US Pat. No. 4,205,288. Furthermore, laser scribing in parallel to the rolling direction has been disclosed as a method of reducing core loss at the T-joint portion of a three-phase stack type transformer core (French Patent Application No. 8022231, April 1981).
(See Public Notice No. 2468191, which was viewed by the public on the 30th). The inventors have proposed an improvement by combining grain-oriented electrical steels laterally scribed in two or more ways in a transformer to vary the magnetic properties between a single transformer core laminate or laminates of the same electrical steel. discovered that it is possible to manufacture transformers and cores for transformers. According to one embodiment of the invention, a transformer is obtained which is designed to operate at a magnetic flux density B and has a ferromagnetic core and an electrical winding arranged inductively. The ferromagnetic core is composed of layered grain-oriented steel plates coated with an insulating coating.One group or first part of the above-mentioned steel plates has a significantly reduced A _C peak magnetic permeability in the direction of easy magnetization. In addition, it has a plurality of scribe lines spaced apart from each other and scribed laterally so as to make the iron loss W _IS smaller by ΔW _IS than the iron loss W _I before scribing. A second group or portion of these steel plates is substantially conventional in the direction of easy magnetization.
Characterized by A _C peak permeability and iron loss W ₂ . This second group of steel plates may be unscribed, but is preferably laterally laser scribed to reduce core losses without significantly reducing permeability. This ferromagnetic core has a core loss W _CS , which is greater than the core loss of the same ferromagnetic core made entirely of grain-oriented steel with an insulating coating in the specified state.
ΔW _CS is smaller than W _C. The present inventors have determined that in these ferromagnetic cores, the core loss improvement amount ΔW _CS by laser scribing is greater than or equal to the weighted average value of the iron loss improvement amounts of the two groups of steel plates that make up the ferromagnetic core. was found to be equal to. Expressed mathematically, it becomes ΔW _CS W _I − [X ₁ W _IS +X ₂ W ₂ ]. Here, X ₁ is the weight of the steel plates in the first group, X ₂ is the weight of the steel plates in the second group,
It is preferable that ΔW _CS 1.1 [W _I −(X ₁ W _IS +X ₂ W ₂ )]. These and other features of the invention will become more apparent from the following detailed description in conjunction with the accompanying drawings. In the present invention, the inventors describe grain-oriented electrical steel that has been laterally laser scribed and grain-oriented electrical steel of the same grade that has not been scribed but has an insulating coating (wherein the laterally laser scribed steel is significantly We have discovered that the core loss of a transformer can be significantly improved by combining the A _C peak permeability (which has been reduced to 20%) and the core loss improved by laser scribing during the induction. Further according to the invention, the original A _C
Combining the above laterally laser scribed material with the same grade of grain-oriented electrical steel with an insulating coating that has been laser scribed in another direction to improve core loss while substantially maintaining peak permeability. You may. . The lateral laser scribing method used in this specification means that the scribe line is approximately ± in the direction perpendicular to the rolling direction of the steel sheet (i.e., the direction in which it is easily magnetized).
30°, and as used herein, a significant decrease in _peak permeability means:
This means that the original magnetic permeability of the steel sheet at a given induction before laser scribing is reduced to between about 30% and about 85%. The above-mentioned features of the invention will become clearer on consideration of the following examples, which are intended only to illustrate the invention. First, it was coated with CARLITE-3.
A nominally 0.28 mm (0.011 inch) thick steel plate consisting of TRAN-COR H was obtained. TRAN-COR H is
CARLITE-3 is a trademark of ARMCO, Inc. of Middletown, Ohio, for high permeability grain-oriented silicon steel in which the promotion of secondary recrystallization is inhibited using AIN.
is a trademark of ARMCO Corporation for an insulating glass stress coating consisting of aluminum-magnesium-phosphite-chromium-silica. This stress paint applies tension to the underlying silicon steel, causing subdivision of the magnetic domains. This starting material is divided into three groups: a control group, a second control group laser scribed on one surface according to the B-section treatment method (see Table 1) which does not result in large permeability changes, and a second control group with significant permeability changes. A third group was divided into one surface which was laser scribed according to the treatment method in Section A (see Table 1) which caused the degradation.

[Table] * is approximate value. The rest time, incident energy density, and incident power density are: (1) The beam spot is
Must be a rectangle of 0.013cm x 1.3cm (0.005″ x 0.5″)
(2) It is based on the simplified assumption that the beam power density is constant over the entire beam spot surface.
The laser used for these treatments was a model V500 CO ₂ CW laser manufactured by Foton Source, Inc. of Livonia, Michigan. A and B group materials are approximately 0.013 cm (0.005 inch);
The laser beam was focused on an elongated oval spot approximately 1.3 cm (0.5 in.) wide and long, and scribed at essentially a 90° angle to the rolling direction.
The longitudinal direction of the spots at this time was aligned in the laser scanning direction. The scribe line generated is approx.
They were separated by 0.32 cm (0.125 inch) without adversely affecting either the insulation value of the coating or the stacking factor of the material. Pending U.S. Patent Application No.
No. 435444, No. 435822 and No. 435443 (all
(filed October 20, 1980) will more clearly demonstrate the extensive capabilities of laser scribing technology used as well as comparable technology. These applications describe a method for laser scribing ferromagnetic steel sheets with an insulating coating and the products produced as a result, as well as apparatus for laser scribing. The specifications of U.S. Patent Application Nos. 435,444 and 435,822 also describe (1) lowering iron loss (i.e., core loss) without significantly reducing or decreasing magnetic permeability, and (2) without significantly changing iron loss. A laser scribing method for reducing magnetic permeability is disclosed. The specifications of all three applications mentioned above are incorporated herein by reference. The table shows the % change in permeability and iron loss characteristics caused by laser scribing according to Sections A and B. Although the materials treated according to Section A did not have as much improvement in core loss (i.e., single sheet core loss) as the material treated under Section B at 15 and 17 kilogauss, or the maximum commercial flux density, these The material of the A term in the magnetic flux density is B
Although there was no significant change in the original magnetic permeability of the material, the magnetic permeability decreased significantly.

[Table] To form the core element for a small three-leg type three-phase laminated transformer, the plan view of which is shown in Figure 1.
Material from each of the two groups was sheared. Both ends of each element are aligned with respect to the rolling direction shown by arrow 5 in Fig. 1 (i.e., the direction in which it is easily magnetized)
Sheared at 45°. The core 1 of the transformer was constructed by stacking seven layers. In FIG. 1, only the top layer 10 and bottom layer 70 (shown in dotted lines) are shown for clarity. Each element or strip of steel that makes up each layer is approximately 7.6 and 14.0 cm (3.0 and 5.5 inches)
of sufficient length and 7.6 cm (3.0 in.) to form a window with dimensions a and b, respectively, equal to
It had a width W of . As shown in FIG. 1, the joints 75 formed at adjacent longitudinal ends of the steel all form an angle of 45° with respect to the rolling direction, as shown schematically by a phantom line in FIG. Pairs of primary and secondary electric windings 77, 78, 79 are arranged around each leg of the core of the transformer so as to be freely inducible. The ferromagnetic layers 1 are stacked to form a stepped lap joint shape 80 as shown in FIG.
0, 20, 30, 40, 50, 60 and 70, joint portions 75 formed between adjacent ends of highly permeable grain-oriented silicon steel insulatively coated within
is located. The stepped lap joint configuration 80 means that the joint formed in each superimposed layer is offset by a substantially fixed distance l in the same direction from the position of the joint in the next adjacent layer. In this way, e.g. an elongated coated steel 201 in layer 20
is the corresponding element 3 in the layer 30 immediately below it
0 and uncoated end 30
5 element 303 is adjacent to the uncoated end 307 of element 301. In the layer 10 immediately above the layer 20, the element 201 is connected to the corresponding element 1 in this joint shape 80.
01, and in this model transformer core 1 manufactured in this example, l is approximately 2.3 mm.
(0.09 inch). An opening or gap 90 is formed between adjacent longitudinal uncoated ends of the insulatively coated grain-oriented electrical steel in a layer. The dimensions or distances of the gap 90 can vary from joint to joint and from layer to layer.
In the model transformer tested, gap 90 contained air. Although other joint shapes are possible, a stepped lap joint shape is preferred to minimize core loss. Having described the geometry of the model cores tested in these examples, the table provides the results of tests performed on cores formed entirely from each group of materials. From the table, for 15 and 17 kilogauss, A
The term treated material (reduced permeability) exhibits superior core loss measurements compared to the term B material (substantially conventional permeability), and the difference is approximately at 15KG.
It is 0.018W/Kg (0.008 Watts/lb) and at 17KG it is approximately 0.033W/Kg (0.015 Watts/lb).
It will be recalled that in single sheet testing, the Section A material had inferior core loss compared to the Section B material (see table).

【table】

[Table] Materials from three groups are combined as shown in the table so that the center leg 81 is composed of laminates from different groups with the materials of the other parts of the core, namely the top and bottom yokes and the outer legs. As shown in FIGS. 1 and 2, the transformer core was shaped like a three-legged transformer. Examination of the table shows that when the B term material (substantially original or conventional permeability) is placed in the center leg 81 and the remainder of the core is constructed from the A term material (low permeability), It can be seen that the core loss ΔW _CS is improved to the maximum extent compared not only to the core made entirely of one group of materials shown, but also to the other combination cores shown in the table. Considering the combined core results in the table, it is possible to combine laser scribed material with unscribed material, construct the center leg with unscribed material, and construct the remainder of the core with scribed material. , it can be seen that the maximum ΔW _CS can be obtained. However, unexpectedly, when the scribed material forming the remainder of the core is of group A type (low permeability), 15 and
The core loss improvement rate at 17KG clearly exceeds the single sheet weighted average improvement rate ΔW _I by 1.1 and 1.2, respectively. As shown in the table, if the remainder of the core is made of Part B scribed material, an improvement of only about 0.6 to 0.7 is obtained. The table shows that when the center leg is constructed from scribed material and the rest of the core is formed from non-scribed material, the absolute value of ΔW _CS is relatively low, but 13 and
The improvements for these core geometries at 15KG are relatively large and are greatest when the center leg is made of a low permeability material. Another embodiment configures the top and bottom yokes and center legs with laterally scribed laminates (e.g., A-term materials) that have both improved core loss and significantly reduced permeability; On the other hand, implementing a three-phase laminated core in which the outer legs are constructed from laterally scribed (e.g., Section B material) with improved core losses but with substantially the original (pre-scribed) permeability. . The previous examples illustrated some of the embodiments of the invention in connection with a combination of laminates with different magnetic permeabilities between the laminates. The following examples serve to illustrate the invention in connection with the processing and use of laminates having A _C peak permeability in the easily magnetized direction that varies from position to position in each laminate. Probably. We have discovered that in laser scribed grain-oriented silicon steel, the A _C peak permeability can be varied over a wide range in the direction of easy magnetization while keeping the iron loss improvement rate relatively constant. This effect shows the iron loss improvement (%) and A _C peak permeability as a function of scribe speed when other scribe parameters such as power, beam shape and dimensions and scribe line spacing are held constant.
This is schematically illustrated by the graph in the figure. For example, between points 402 and 404, the iron loss improvement rate is 40
It can be seen that permeability 408 decreases with laser scribe speed while 6 remains relatively constant near its maximum value. It is observed that when the laser scribe speed is slowed down, the width of the damage zone generated in the laser scribe line increases, resulting in a decrease in magnetic permeability. Magnetic permeability can also be reduced by increasing the incident power of the beam while holding other parameters constant. Permeability can also be varied by scribe spacing or beam spot size or geometry. Some of these effects are clearly demonstrated in the table and the following examples. In the following example, all specimens are CARLITE
A 12 mil TRAN-CORH stress-relieved epoxy inset with a -3 coating was used with a continuous wave _CO2 laser. All data is
It is 15KG, 60Hz and is expressed as a percentage change. Unless otherwise noted, the scribe lines were in corresponding locations on each side of the strip and spaced 0.25 inches apart. Example 1 The scanning speed was varied while keeping other conditions constant. Beam Power: 2 Watts Lens Focal Length: 2.5 inches Defocus: Focus Position ( ) Input Beam Dimensions: (0.002 inch diameter) Table shows percent change in core loss and peak permeability for various scan speeds.

[Table] In this series, the magnetic permeability can be varied over a wide range while keeping the core loss improvement rate constant. In practice, this effect can be exploited by varying the scanning speed at different locations within the stack. For example, when using a rotating scan mirror with varying magnetic permeability across the width, the scan mirror can be shaped to allow the beam to scan faster in some parts of the width than in other parts without changing the rotational speed of the mirror assembly. can be designed. Example 2 The beam spot diameter was changed by changing the amount of defocus (spot size), and other conditions were kept constant. Beam Power: 5 Watt Lens Focal Length: 5 inches Table shows percent change in core loss and peak permeability for two defocus conditions and two scan speeds.

[Table] Changing the amount of defocus is a simple method to control the magnetic permeability along the width and/or length of the steel plate.To change the permeability as desired, simply tilt the steel plate from the focal plane. SUFFICIENT FIG. 4 shows one embodiment of a core 420 for a single-phase stacked transformer according to the present invention. This ferromagnetic core has a top yoke 422, a bottom yoke 4
24, and two legs 426 and 428 joining said top and bottom yokes. The junction of each of these portions is a joint region 430. Each member is preferably comprised of grain-oriented silicon steel plates with an insulating coating in superimposed layers 440, and the superimposed ferromagnetic steel plates 440 in each member are
The overlapped ferromagnetic steel plates 440 in the adjacent member within the joint region 430 mate, preferably forming a stepped lap joint shape. In this embodiment of the invention, each laminate is preferably non-uniformly lateral laser scribed. For example, in FIG. 5, an enlarged plan view of stack 440 showing lateral laser scribe lines 450 is shown. Although the scribe lines 450 are preferably invisible to the naked eye, they can be easily observed and their widths A can be measured using magnetic domain image sensitization methods known to those skilled in the art. These scribe lines are generated by repeatedly scanning a laser beam in a direction transverse to the rolling direction of a grain-oriented ferromagnetic steel sheet coated with an insulating coating, thereby generating scribe lines 450 having a width A and spaced apart by a distance L in the rolling direction. It is formed by Width A of each scan line
changes in a predetermined relationship along the longitudinal direction of the scribe line. In the embodiment shown in FIGS. 4 and 5, the width A is greatest at the inner edge of the laminate 440 adjacent the window 460 of the core 420 and extends across each scribe line 4 until it reaches the outer edge 465 of the laminate.
Preferably, it decreases continuously along the length of 50. In this embodiment, the permeability increases as one moves from the inner edge 455 to the outer edge 465 of each laminate forming the core 420. For example, the magnetic permeability of the material near the inner edge 455 can be reduced to about 1/3 to 1/2 of its value before laser scribing, but the permeability of the material near the outer edge 46
Materials near 5 have the same magnetic permeability as before, or have decreased from about 2/3 to about 3/4 of the previously mentioned magnetic permeability. FIG. 6 shows another embodiment of the invention. This figure shows one layer of the stack in the central leg joint region (or T-joint) of a three-phase transformer core. The center leg laminate 601 intersects the bottom yoke laminates 603 and 605, and each laminate is laterally scribed such that the _AC peak permeability varies in the direction of easy magnetization along the length of each laminate. did. This change in magnetic permeability is indicated by the change in width of the scribe line shown. The scribe line 607 is
Scribe line 6 away from the T-joint area
A lower permeability was generated in the joint region compared to the permeability in the laminates 601, 603 and 605 in the region with 0.09. Each laminate in each T-joint of the core is preferably scribed as shown in FIG. Both regions of the laminate with scribe line 607 and scribe line 609 have improved core loss. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification or practice of the invention disclosed herein. The specification and examples are considered to be exemplary only, with the scope and spirit of the invention being indicated by the claims.

[Brief explanation of drawings]

FIG. 1 is a plan view of one embodiment of the transformer according to the present invention, and FIG. 2 is a plan view of the transformer core in FIG. 1 showing a preferred embodiment of the joint shape.
Figure 3 is a schematic graph showing the effect of laser scribe speed on percent improvement in core loss and peak permeability with other scanning parameters held constant; Figure 4 is a partial cross-sectional view along a single-phase stacked transformer core. A perspective view showing an embodiment of the fifth embodiment.
The figure is an enlarged partial plan view showing one embodiment of the grain-oriented steel plate coated with insulation according to the present invention constituting the ferromagnetic core shown in FIG. 4, and FIG. 6 is a three-phase stack according to the present invention. FIG. 3 is a partial plan view showing the area around the central leg joint area of the transformer core. 5...Rolling direction, 10...Top layer, 70...Bottom layer,
72...Window, 75...Joint part, 77, 78, 7
9... Winding wire.

Claims (1)

[Scope of Claims] 1. A ferromagnetic core; and an electrical winding disposed in an inductive relationship with respect to the ferromagnetic core, the ferromagnetic core comprising a directional ferromagnetic wire coated with an insulating coating in superimposed layers. The first portion of the steel plate has a plurality of scribe lines extending laterally and spaced apart from each other;
It is characterized by A _C peak magnetic permeability that is significantly reduced in the direction of easy magnetization at magnetic flux density B, and iron loss W _IS that is lower than iron loss W _I before scribing at magnetic flux density B by the amount of △W _IS . , the second portion of the steel plate is characterized by a substantially conventional A _C peak permeability and iron loss W ₂ in a direction that is easily magnetized at a magnetic flux density B, and the ferromagnetic core is characterized by the coating in a specified state. △W _CS at magnetic flux density B than the core loss W _C of the same ferromagnetic core made entirely of grain-oriented steel
△W _CS is △W _CS ≧W _I − [X ₁ W _IS +X ₂ W _{2 ]} (where _, X ₂ is equal to the weight of the second portion of the steel plate constituting the core). 2. The electric induction device according to claim 1, wherein the second portion of the steel plate is laterally scribed in order to reduce iron loss. 3. The width of the scribe line varies linearly along the longitudinal direction of the scribe line,
The electric induction device according to claim 1, wherein the magnetic permeability is varied in the longitudinal direction of the scribe line.