JP2013128057A - Scott connection transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Scott connection transformer exhibiting excellent energy consumption efficiency while reducing the no-load loss.SOLUTION: As the core of a Scott connection transformer 1, a wound core 8b consisting of two inner cores 86, 87, each formed by winding a thin magnetic steel sheet in multiple, and an outer core 88 is used. In the wound core 8b, two inner cores 86, 87 of the same shape are juxtaposed in the hollow part of the outer core 88.

Description

  The present invention relates to a Scott connection transformer used when converting three-phase AC power into single-phase AC power.

  There are two types of AC power supplies that supply single-phase AC power and three-phase AC power. Single-phase AC power is used to move electrical products in general households, and three-phase AC power is used as a power source for three-phase motors in factories and the like.

  On the other hand, there are cases where single-phase AC power is required where only three-phase AC power is available. Specifically, there is a case where power is supplied from a three-phase three-wire power source to a large-capacity single-phase load (for example, a single-phase electric furnace or a single-phase AC train).

  In such a case, it is common to convert three-phase AC power into single-phase AC power using a Scott connection transformer (see, for example, Patent Document 1). Hereinafter, a method for converting three-phase AC power into single-phase AC power using a Scott connection transformer will be described with reference to FIG.

  FIG. 3 shows an example of a connection diagram of the Scott connection transformer. The Scott connection transformer 1 is composed of a main seat transformer 2 and a T seat transformer 3. In the main transformer 2, the primary winding 4 and the secondary winding 5 are wound around the iron core 8, and in the T seat transformer 3, the primary winding 6 and the secondary winding 7 are wound around the iron core 8. Yes.

  The primary winding 4 and the secondary winding 5 of the main transformer 2 are magnetically coupled to each other via an iron core 8. Further, both ends of the primary winding 4 are connected to terminals U and W, and both ends of the secondary winding 5 are connected to terminals u1 and ou.

  Similarly, the primary winding 6 and the secondary winding 7 of the T seat transformer 3 are magnetically coupled to each other via an iron core 8. One end of the primary winding 6 is connected to the midpoint of the primary winding 4 of the main transformer 2 and the other end is connected to the terminal V. Both ends of the secondary winding 7 are connected to terminals ov and v1.

  In the Scott connection transformer shown in FIG. 3, when the terminals U and W of the primary winding 4 of the main transformer 2 and the terminal V of the T transformer 3 are respectively connected to a three-phase AC power source, the main transformer Two-phase single-phase AC power is obtained from the terminals u1 and ou at both ends of the secondary winding 5 of the transformer 2 and the terminals ov and v1 at both ends of the secondary winding 7 of the T-seater transformer 3.

  Next, with reference to FIG. 4, the structure of the conventional Scott connection transformer (for example, refer patent document 2) which employ | adopted the iron core as an iron core is demonstrated. The stacked iron core 8a is formed by laminating thin magnetic steel sheets in a direction perpendicular to the paper surface, and includes upper and lower yoke portions 81 and 82, left and right side leg portions 83 and 84, and a central leg portion 85. A rectangular hollow portion into which a winding is inserted is formed between the portion 85 and the left and right side leg portions 83 and 84.

  The main seat primary winding 4 and the main seat secondary winding 5 are wound around the left side leg portion 83 toward the paper surface to constitute the main transformer 2, and the right side leg portion 84 has the T seat primary winding. The wire 6 and the T seat secondary winding 7 are wound to constitute the T seat transformer 3. Although not shown in FIG. 4, lines are drawn from the respective windings and connected to the terminals of FIG.

JP-A-8-335520 JP 2004-88834 A

In general, transformer loss is divided into no-load loss and load loss. Of these, the load loss is obtained as I ² R from the resistance (R) of the winding of the transformer and the load current (I) flowing through the device, and the loss varies depending on the magnitude of the load.

  On the other hand, the no-load loss is a loss that occurs when a voltage is applied to the input side of the transformer, and is not related to the size of the load, as is the case with a general standby power supply loss. A transformer is a device that supplies power, and the primary input is rarely interrupted, so no-load loss always occurs.

  In recent years, there has been an increasing demand for energy saving for electrical products, and transformers are no exception. However, since the conventional Scott connection transformer using the stacked iron core as shown in FIG. 4 has a large no-load loss and poor energy consumption efficiency, it cannot sufficiently meet the demand for energy saving.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a Scott connection transformer that can sufficiently meet the demand for energy saving.

In order to achieve the above object, the Scott connection transformer according to the present invention has a primary winding and a secondary winding wound around one of the two side legs provided on the iron core, The primary winding and the secondary winding of the T seat are wound on the other side leg, and the midpoint of the primary winding of the main seat and one end of the primary winding of the T seat are connected, A Scott connection transformer in which a three-phase alternating current is applied to both ends of the primary winding of the main seat and the other end of the primary winding of the T seat,
The iron core is composed of two inner iron cores and one outer iron core each of which a thin plate made of a magnetic material is wound in multiple layers, and the two inner iron cores having the same shape are juxtaposed in the hollow portion of the outer iron core. It is characterized by.

  Here, when the width of the side leg portion is W, the width of the first and second inner iron cores is √2 / 2 W, and the width of the outer iron core is (1−√2 / 2) W. It is preferable that Further, it is preferable to use an amorphous magnetic thin plate as the thin plate made of the magnetic material.

  The Scott connection transformer according to the present invention significantly reduces no-load loss by using a wound iron core, and as a result, achieves energy saving by improving energy consumption efficiency.

It is a front view which shows the structure of the Scott connection transformer concerning embodiment of this invention. It is a perspective view which shows the external appearance of the iron core (A) of the Scott connection transformer concerning this Embodiment, and the iron core (B) of the conventional Scott connection transformer. It is a connection diagram of a Scott connection transformer. It is a front view which shows the structure of the conventional Scott connection transformer.

  Hereinafter, a Scott connection transformer according to an embodiment of the present invention will be described with reference to the drawings.

<Configuration of Scott connection transformer>
In FIG. 1, the external appearance of the Scott connection transformer 1 concerning this Embodiment is shown. The Scott connection transformer 1 according to the present embodiment employs a wound core 8b as an iron core. The wound iron core 8b includes first and second inner iron cores 86 and 87 having the same shape and an outer iron core 88.

  Inner cores 86 and 87 are obtained by winding a thin plate made of a magnetic material (in this embodiment, a thin plate of an electromagnetic steel plate) in multiple turns so that a rectangular hollow portion is formed on the inner side. No. 88 is obtained by winding a thin sheet of an electromagnetic steel sheet in a square shape so that two inner iron cores 86 and 87 can be juxtaposed in the inner hollow portion.

  The main transformer 2 is configured by winding the main primary winding 4 and the main secondary winding 5 (see FIG. 3) around the first inner iron core 86 and the outer iron core 88 located on the left side of the drawing. The T seat primary winding 6 and the T seat secondary winding 7 (see FIG. 3) are wound around the second inner iron core 87 and outer iron core 88 located on the right side to constitute the T seat transformer 3. Yes. Although not shown in FIG. 1, lines are drawn from the respective windings and connected to the terminals of FIG.

<Comparison of characteristics by core type>
Next, the difference in characteristics between the case where the wound core 8b of the present invention is used for the iron core of the Scott connection transformer 1 and the case where the conventional stacked core 8a (see FIG. 4) is used will be described. FIG. 2A shows a perspective view of the wound core 8b of the Scott connection transformer according to the present embodiment, and FIG. 2B shows a perspective view of the product core 8a of the conventional Scott connection transformer. In the figure, W1 to W6 are widths, H1 and H2 are heights, and D1 is a depth.

  First, the reason why the wound core having the configuration shown in FIG. In the case of an iron core having the same volume, it is known that a wound iron core has less no-load loss than a stacked iron core. Further, since the flow of magnetic flux hardly occurs outside the iron core, the iron core at the corner portion is wasted when the stacked iron core is used. On the other hand, when the wound core is used, since the corner portion is formed in an arc shape, there is less waste core portion than the stacked core. Mainly for these reasons, the inventors examined whether a wound core could be used as the core of the Scott connection transformer.

  In the Scott connection transformer, the coil is wound around the left and right side legs of the iron core. Therefore, two iron cores having the same shape as the inner iron core 86 shown in FIG. Thought to do. When such a structure is employed, the width (thickness of the laminated thin plates) W2 of the central leg portion 85 is twice the width W5 of the side leg portion 86.

  On the other hand, in the Scott connection transformer employing the stacked iron core having the configuration shown in FIG. 2B, from the viewpoint of the magnetic flux density passing through the central leg 85, the width W2 of the central leg 85 is set to the side leg 83 (or 84). It is known that the transformer efficiency is maximized and the amount of iron core can be reduced when the width W1 is √2 times. However, when a structure in which two iron cores having the same shape as the inner iron core 86 described above are employed as the wound iron core, the width W2 of the central leg 85 is inevitably twice the width W5 of the side leg 86. Therefore, waste is generated in the electromagnetic steel sheet to be used.

  Therefore, the inventors examined a configuration in which the two inner cores 86 and 87 juxtaposed as shown in FIG. 2A are surrounded by the outer core 88 as the wound core 8b. In this configuration, the width W5 of the inner iron cores 86 and 87 is √2 / 2 × W1 with respect to the width W1 of the side legs 83 and 84, and the width W6 of the outer iron core 88 is (1−√2 / 2). If set to × W1, the width W2 of the central leg portion 85 is √2 times the width W1 (= W5 + W6) of the side leg portion 83, and therefore it is possible to avoid waste in the electromagnetic steel sheet.

  The above-described width W5 of the inner cores 86 and 87 and the width W6 of the outer iron core 88 are optimum values. Even if these values increase or decrease slightly, the efficiency of the transformer gradually decreases, so there is no practical problem. Therefore, the employable widths W5 and W6 are values having a certain width.

  Next, with reference to FIG. 2, the difference in no-load loss when the wound core 8b is employed and when the stacked core 8a is employed will be described. In FIG. 2, the volume of the wound core 8b and the stacked core 8a is set to be the same as a premise. That is, the wound core 8b and the stacked core 8a have the same width W4, height H1, and depth D1. Further, the hollow portions of the inner iron cores 86 and 87 have the same shape and volume (W3 × H2 × D1).

  The wound iron core 8b and the stacked iron core 8a having the dimensions shown in FIG. 2 are manufactured by using electromagnetic steel plates made of the same material, and the primary winding and the secondary winding are wound on the left and right side legs 83 and 84 the same number of times. The magnetic flux density is 1.49T to constitute the Scott connection transformer 1.

When an iron core having the dimensions shown in the following (1) and (2) is manufactured using a thin plate having a specific gravity of 7.65 and a space factor of 0.96 as the electromagnetic steel sheet, the weight of the wound core 8b is 117.5 kg, and the stacked core 8a. The weight of is 136.3 kg. Under the same conditions, the no-load loss decreases as the weight of the magnetic steel sheet used decreases, so the no-load loss of the wound core 8b is about 24% less than that of the product core 8a.
(1) Wound core 8b: W1 = W5 + W6 = 75 mm, W5 = 53 mm, W6 = 22 mm, W2 = 106 mm, W4 = 356 mm, H1 = 400 mm, H2 = 250 mm, D1 = 158 mm
(2) Product core 8a: W1 = 75mm, W2 = 106mm, W4 = 356mm, H1 = 400mm, H2 = 250mm, D1 = 158mm

  Further, when the stacked iron core 8a is used, as shown in FIG. 2 (B), a single thin plate is formed by combining four different types of shapes, a total of six strip-shaped electromagnetic steel plates. For this reason, four joints of the iron core are generated for each of the main transformer 2 and the T transformer 3, and the flow of magnetic flux is disturbed at the joint, and the no load loss is increased by the resistance generated thereby.

  As a countermeasure for this, in the conventional transformer, the flow of magnetic flux is prevented from being disturbed by shifting the place where the seam is generated in the adjacent electromagnetic steel sheet. However, when such a method is adopted, it is necessary to change the dimensions of the strip-shaped electrical steel sheet, which complicates the cutting process and the arrangement process, and increases the manufacturing cost of the transformer.

  On the other hand, when the wound iron core 8b is used, since the wound iron core is produced by bending the electromagnetic steel sheets cut into strips and superimposing them, the seam of each thin plate is one place. There is little loss of magnetic flux. As a result, the wound core 8b has a no-load loss caused by the seam of 50% or less as compared with that of the stacked core 8a.

  When the no-load loss was measured for the wound core 8b and the stacked core 8a having the above dimensions, it was 140W for the wound core 8b and 175W for the stacked core 8a. That is, the no-load loss of the wound core 8b was 80% of that of the stacked core 8a. From this result, it is understood that a Scott connection transformer with high energy consumption efficiency can be realized by using the wound core 8b of the present invention.

  In this embodiment, the Scott connection transformer is manufactured using an electromagnetic steel sheet. However, instead of the electromagnetic steel sheet, a thin plate made of an iron-based amorphous magnetic material (hereinafter referred to as “amorphous magnetic thin plate”) is used. A Scott connection transformer may be fabricated. Since the amorphous magnetic thin plate has a low no-load loss of about 20% as compared with the electromagnetic steel plate, the standby power can be greatly reduced.

  Furthermore, the amorphous magnetic thin plate is thinner and more flexible than the electromagnetic steel plate. When manufacturing a wound core, a strip-shaped magnetic thin plate is wound in a state where both ends are overlapped, and only the operation is repeated, thereby simplifying the manufacturing process of the core and shortening the assembly time. . Further, unlike the case of using the electromagnetic steel sheet, no seam is generated, and the manufacturing cost can be reduced because the joining position of the adjacent thin plates is slightly shifted in order to adjust the thickness of the overlapped portion.

  As a reference, a wound core 8b having a shape shown in FIG. 2A is manufactured using an amorphous magnetic thin plate and a Scott connection transformer having a capacity of 30 kVA, and a stacked iron core 8a having a shape shown in FIG. The electrical characteristics at 50 Hz and a load factor of 40% were measured for Scott connection transformers of the same capacity manufactured using

  In the Scott connection transformer using the amorphous magnetic thin plate, the no-load loss was 32.4 W, the load loss was 119 W, the total loss was 151.4 W, and the efficiency was 98.8%. On the other hand, the Scott connection transformer using the electromagnetic steel sheet had no load loss 175 W, load loss 109 W, total loss 284.0 W, and efficiency 97.7%. “Efficiency” is the ratio between the effective output of the transformer and (effective output + total loss) expressed as a percentage.

  Similarly, at a load factor of 100%, the Scott connection transformer using an amorphous magnetic thin plate had no load loss 32.4W, load loss 742W, total loss 774.4W, and efficiency 97.5%. On the other hand, in the Scott connection transformer using the electromagnetic steel sheet, the no-load loss was 175.0 W, the load loss was 680.0 W, the total loss was 855.0 W, and the efficiency was 97.2%.

  Even if it sees the above-mentioned result, the Scott connection transformer of the present invention using a wound iron core has less no-load loss compared with the conventional Scott connection transformer using a load iron core, and has realized high efficiency. I understand.

DESCRIPTION OF SYMBOLS 1 Scott connection transformer 2 Main seat transformer 3 T seat transformer 4 Main seat primary winding 5 Main seat primary winding 6 T seat primary winding 7 T seat secondary winding 8, 8b Iron core 83, 84 Side leg 85 Center leg 86, 87 Inner core 88 Outer core

Claims (3)

The primary winding and secondary winding of the main seat are wound on one side leg of the two side legs provided on the iron core, and the primary winding and secondary winding of the T seat are mounted on the other side leg. A wire is wound, and a midpoint of the primary winding of the main seat and one end of the primary winding of the T seat are connected, and both ends of the primary winding of the main seat and the primary winding of the T seat A Scott connection transformer in which a three-phase alternating current is applied to the other end of
The iron core is composed of two inner iron cores and one outer iron core each of which a thin plate made of a magnetic material is wound in multiple layers, and the two inner iron cores having the same shape are juxtaposed in the hollow portion of the outer iron core. Scott connection transformer, characterized by   When the width of the side legs is W, the width of the first and second inner iron cores is √2 / 2 W, and the width of the outer iron core is (1−√2 / 2) W. The Scott connection transformer according to claim 1, wherein:   The Scott connection transformer according to claim 1, wherein an amorphous magnetic thin plate is used as the thin plate made of the magnetic material.

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