JP7575896B2 - Transformers - Google Patents

Description

The present invention relates to a transformer.

In a system for supplying power from a power supply system to a load, a configuration is known in which a transformer is provided between the power supply system and a power conversion circuit connected to the load. The power conversion circuit is composed of multiple switching elements (semiconductor elements), and is therefore prone to generating harmonics. For this reason, various systems have been proposed in which a harmonic suppression filter circuit is connected to the transformer to prevent harmonics generated in the power conversion circuit from flowing into the power supply system (see, for example, Patent Documents 1-4 below).

In addition, when an electric motor or the like is connected as a load, multiple power conversion circuits may be connected between the load and the secondary side of the transformer. A known transformer for this purpose is a multiple transformer that includes a primary winding to which a power supply system is connected and multiple secondary windings to which multiple power conversion circuits are connected (see, for example, Patent Document 5 below). In a multiple transformer, more switching elements are included on the secondary side, making it more likely that harmonics will be generated.

Japanese Utility Model Application Publication No. 6-60252 JP 2004-288862 A JP 2017-112747 A Japanese Patent Application Publication No. 6-253544 JP 2011-71190 A

However, there is room for improvement in the above conventional harmonic suppression mode. That is, even if a harmonic suppression filter circuit is simply connected to the tertiary winding of a transformer, the desired harmonic suppression effect cannot be obtained unless the leakage inductance of each winding can be adjusted to an appropriate value. To explain in more detail, in order to obtain a sufficient harmonic suppression effect, the secondary leakage inductance needs to be large and the tertiary leakage inductance needs to be small, but with the above simple connection mode, it is difficult to increase one leakage inductance and reduce the other leakage inductance. Furthermore, in a multiple transformer, even if a harmonic suppression filter circuit is simply connected to the tertiary winding of the multiple transformer, there is also a problem that an imbalance occurs in the harmonic suppression effect of the harmonic suppression filter circuit between multiple power conversion circuits (between multiple secondary windings).

Figure 9 shows an example of the arrangement of a multiple transformer (triple transformer) having three secondary windings to which three power conversion circuits are connected in a comparative example. Note that while only one phase is shown in Figure 9, the same applies when there are multiple phases. For example, in the case of three phases, the configuration shown in Figure 9 is provided for each of the U phase, V phase, and W phase.

In FIG. 9, the multiple transformer 100 includes a primary winding 101 connected to a three-phase power supply system 111, three secondary windings (first secondary winding 102a, second secondary winding 102b, and third secondary winding 102c) respectively connected to three power conversion circuits (first power conversion circuit 112a, second power conversion circuit 112b, and third power conversion circuit 112c), and a tertiary winding 103 connected to a harmonic suppression filter circuit 113. Each winding 101, 102a to 102c, and 103 is wound around a common winding axis X so that they are arranged in sequence at a predetermined interval along a common winding axis direction (X direction). The multiple transformer 100 in FIG. 9 is configured as a shell-type multiple transformer in which the iron core 104 is arranged outside each winding 101, 102a to 102c, and 103.

To equalize the filter effect of the harmonic suppression filter circuit 113 for each secondary winding, it is necessary to equalize the combined leakage inductance between the primary winding 101 and each secondary winding 102a-102c and the combined leakage inductance between the tertiary winding 103 and each secondary winding 102a-102c among the multiple secondary windings. On the other hand, the smaller the distance between the two target windings (the distance in the winding axis X direction), the stronger the coupling between these windings, and therefore the smaller the combined leakage inductance.

Therefore, in the case of an arrangement as shown in FIG. 9, the coupling with the primary winding 101 becomes stronger in the order of the first secondary winding 102a, the second secondary winding 102b, and the third secondary winding 102c, and in the reverse order, the coupling with the tertiary winding 103 becomes stronger. Therefore, in FIG. 9, the combined leakage inductance between the primary winding 101 and each of the secondary windings 102a to 102c and the combined leakage inductance between the tertiary winding 103 and each of the secondary windings 102a to 102c are not equal. Therefore, in an arrangement as shown in FIG. 9, harmonics cannot be appropriately suppressed, and harmonics generated in multiple power conversion circuits flow into the power supply system, causing distortion in the power supply system.

The present invention aims to solve the above problems and provide a transformer that can provide an appropriate harmonic suppression effect in a transformer to which at least one power conversion circuit is connected.

A transformer according to one aspect of the present invention includes a primary winding connected to a power supply system, a plurality of secondary windings connected to a plurality of power conversion circuits, and a tertiary winding connected to a harmonic suppression filter circuit, the primary winding, the plurality of secondary windings, and the tertiary winding are arranged on a common winding axis, the tertiary winding has a plurality of tertiary winding portions arranged in a divided manner so as to be adjacent to each of the plurality of secondary windings in the common winding axis direction, and the primary winding has a plurality of primary winding portions arranged in a divided manner so as to be adjacent to each of the plurality of tertiary winding portions in the common winding axis direction.

According to the above configuration, the primary winding and the tertiary winding are arranged in a divided manner so that the tertiary winding portion is adjacent to each of at least the multiple secondary windings, and the primary winding portion is adjacent to the tertiary winding portion. Therefore, the distance between the primary winding portion and each secondary winding and the distance between each secondary winding and the tertiary winding portion are equalized between the multiple secondary windings. Therefore, the combined leakage inductance between the primary winding portion and the secondary winding portion and the combined leakage inductance between the tertiary winding portion and each secondary winding can be equalized between the multiple secondary windings. Furthermore, by arranging the tertiary winding portion between the primary winding portion and each secondary winding, the coupling between the primary winding portion and the tertiary winding portion and the coupling between the tertiary winding portion and each secondary winding are strengthened, and the leakage inductance of the tertiary winding can be reduced. Therefore, the harmonic suppression effect in the harmonic suppression filter circuit connected to the tertiary winding can be enhanced while eliminating the imbalance of the harmonic suppression effect between the multiple power conversion circuits. As a result, the above configuration can provide an appropriate harmonic suppression effect in a transformer to which multiple power conversion circuits are connected.

Each of the multiple secondary windings may have multiple secondary winding portions arranged in a divided manner in the common winding axis direction, and each of the multiple tertiary winding portions may be arranged between the multiple secondary winding portions. According to the above configuration, each of the tertiary winding portions corresponding to each secondary winding is arranged so as to be sandwiched between the secondary winding portions of the corresponding secondary winding. This makes it possible to reduce the leakage inductance of the tertiary winding.

The multiple tertiary winding parts may be arranged to sandwich each of the multiple primary winding parts from both sides in the common winding axis direction, and each of the multiple secondary winding parts may be arranged to be adjacent to the multiple tertiary winding parts on the opposite side to the side adjacent to the primary winding parts of the multiple tertiary winding parts in the common winding axis direction. According to the above configuration, the secondary winding parts of each secondary winding and the primary winding parts and tertiary winding parts corresponding to each secondary winding are arranged symmetrically around the primary winding parts in the common winding axis direction. That is, for each of the multiple secondary windings, the tertiary winding parts are arranged on both sides of the primary winding part, and the secondary winding parts of the corresponding secondary windings are arranged on both outsides of the primary winding parts. This makes it possible to minimize the leakage inductance of the tertiary winding and to enhance the suppression effect of harmonics. In addition, by adjusting the spacing between the secondary winding portion and the tertiary winding portion and the spacing between the tertiary winding portion and the primary winding portion, the leakage inductance of the primary winding and the leakage inductance of each secondary winding can be adjusted while maintaining equality between multiple secondary windings.

Each of the multiple tertiary winding portions may be disposed between the multiple primary winding portions with respect to the common winding axis direction. According to the above configuration, each of the tertiary winding portions is disposed so as to be sandwiched between the primary winding portions. This makes it possible to reduce the leakage inductance of the tertiary winding.

The multiple primary winding portions may include a primary winding first portion adjacent to the tertiary winding portion on the opposite side of the tertiary winding portion adjacent to any of the multiple secondary windings in the common winding axis direction, and a primary winding second portion adjacent to each of the multiple secondary windings on the opposite side of the multiple secondary windings adjacent to the tertiary winding portion in the common winding axis direction. According to the above configuration, the primary winding portion and the tertiary winding portion are adjacent to each other, thereby increasing the coupling strength between them, and thus reducing the leakage inductance of the tertiary winding.

The plurality of tertiary winding portions may include a tertiary winding first portion disposed between the primary winding first portion and any of the plurality of secondary windings with respect to the common winding axis direction, and a tertiary winding second portion disposed adjacent to the primary winding second portion when another secondary winding is disposed on the opposite side of the side adjacent to the one secondary winding in the primary winding second portion adjacent to one of the plurality of secondary windings with respect to the common winding axis direction. According to the above configuration, the number of adjacent points between the tertiary winding portion and the primary winding portion is increased, so that the coupling strength between them is strengthened and the leakage inductance of the tertiary winding can be reduced. Furthermore, by relatively weakening the coupling strength between the primary winding portion and each secondary winding, the leakage inductance in the secondary winding can be prevented from becoming smaller than necessary. This can enhance the harmonic suppression effect in the harmonic suppression filter circuit connected to the tertiary winding.

The multiple secondary windings may have an outer diameter larger than the outer diameter of the primary winding and the tertiary winding, or may have an inner diameter larger than the inner diameter of the primary winding and the tertiary winding. According to the above configuration, the coupling strength between the tertiary winding portion and each secondary winding and the coupling strength between the primary winding portion and each secondary winding can be weakened without weakening or changing the coupling strength between the primary winding portion and the tertiary winding portion. Therefore, the combined leakage inductance between the tertiary winding and each secondary winding and between the primary winding and each secondary winding can be increased. As a result, only the leakage inductance of each secondary winding can be increased, and the harmonic suppression effect can be further improved.

A transformer according to another aspect of the present invention includes a primary winding connected to a power supply system, a plurality of secondary windings connected to a plurality of power conversion circuits, and a tertiary winding connected to a harmonic suppression filter circuit, the primary winding, the plurality of secondary windings, and the tertiary winding are arranged on a common winding axis, the plurality of secondary windings are lap-wound at the same position with respect to the common winding axis direction, the tertiary winding is arranged adjacent to the plurality of lap-wound secondary windings with respect to the common winding axis direction, and the primary winding is arranged adjacent to the tertiary winding with respect to the common winding axis direction.

According to the above configuration, the primary winding and the tertiary winding are arranged so that the tertiary winding is adjacent to each of at least the multiple lap-wound secondary windings, and the primary winding is adjacent to the tertiary winding. Therefore, the distance between the primary winding and each secondary winding and the distance between each secondary winding and the tertiary winding are equalized among the multiple secondary windings. Therefore, the combined leakage inductance between the primary winding and each secondary winding and the combined leakage inductance between the tertiary winding and each secondary winding can be equalized among the multiple secondary windings. Furthermore, by arranging the tertiary winding between the primary winding and each secondary winding, the coupling between the primary winding and the tertiary winding and the coupling between the tertiary winding and each secondary winding are strengthened, and the leakage inductance of the tertiary winding can be reduced. Therefore, the harmonic suppression effect in the harmonic suppression filter circuit connected to the tertiary winding can be enhanced while eliminating the imbalance of the harmonic suppression effect between the multiple power conversion circuits. As a result, the above configuration can provide an appropriate harmonic suppression effect in a transformer to which multiple power conversion circuits are connected.

Each of the multiple secondary windings may have multiple secondary winding portions arranged in a divided manner in the common winding axis direction, and the tertiary winding may be arranged between the multiple secondary winding portions in the common winding axis direction. According to the above configuration, the tertiary winding is arranged so as to be sandwiched between the multiple secondary winding portions. This makes it possible to reduce the leakage inductance of the tertiary winding.

The multiple secondary windings may include a first secondary winding and a second secondary winding, and the second secondary winding may be disposed radially inward from the first secondary winding at a first position in the common winding axis direction, and may be disposed radially outward from the first secondary winding at a second position in the common winding axis direction. According to the above configuration, the winding lengths of the multiple secondary windings are equalized. Therefore, it is possible to easily equalize the harmonic suppression effect between the multiple secondary windings.

A transformer according to another aspect of the present invention includes a primary winding connected to a power supply system, a secondary winding connected to a power conversion circuit, and a tertiary winding connected to a harmonic suppression filter circuit, the primary winding, the secondary winding, and the tertiary winding are arranged on a common winding axis, the primary winding has a plurality of primary winding portions divided in parallel or in series, the tertiary winding has a plurality of tertiary winding portions divided in parallel or in series, and the plurality of tertiary winding portions are arranged so as to be sandwiched between the plurality of primary winding portions in the common winding axis direction, or the plurality of primary winding portions are arranged so as to be sandwiched between the plurality of tertiary winding portions in the common winding axis direction.

According to the above configuration, the primary winding is divided into a plurality of primary winding portions, and the tertiary winding is divided into a plurality of tertiary winding portions, and each tertiary winding portion is sandwiched between the primary winding portions, or each primary winding portion is sandwiched between the tertiary winding portions. This allows the leakage inductance due to the tertiary winding to be reduced relatively to the leakage inductance due to the secondary winding. Therefore, the harmonic suppression effect in the harmonic suppression filter circuit connected to the tertiary winding can be improved. As described above, according to the above configuration, an appropriate harmonic suppression effect can be added to the transformer.

The secondary winding may have a plurality of secondary winding parts divided in parallel or in series, and each winding part may be arranged such that the number of the plurality of tertiary winding parts sandwiched between the plurality of primary winding parts in the common winding axis direction is greater than the number of the plurality of secondary winding parts sandwiched between the plurality of primary winding parts in the common winding axis direction, or the number of the plurality of primary winding parts sandwiched between the plurality of tertiary winding parts in the common winding axis direction is greater than the number of the plurality of secondary winding parts sandwiched between the plurality of tertiary winding parts in the common winding axis direction. According to this configuration, the number of the tertiary winding parts sandwiched between the primary winding parts is greater than the number of the secondary winding parts sandwiched between the primary winding parts, or the number of the primary winding parts sandwiched between the tertiary winding parts is greater than the number of the secondary winding parts sandwiched between the tertiary winding parts, so that the leakage inductance due to the tertiary winding can be reduced relatively to the leakage inductance due to the secondary winding. Moreover, by dividing the secondary winding, the relationship between the leakage inductance due to the secondary winding and the leakage inductance due to the tertiary winding can be more precisely adjusted.

A transformer according to another aspect of the present invention includes a primary winding connected to a power supply system, a secondary winding connected to a power conversion circuit, and a tertiary winding connected to a harmonic suppression filter circuit, and the secondary winding has an outer diameter larger than the outer diameters of the primary winding and the tertiary winding, or has an inner diameter larger than the inner diameters of the primary winding and the tertiary winding.

With the above configuration, it is possible to increase only the leakage inductance due to the secondary winding. Therefore, the harmonic suppression effect can be further improved. As a result, with the above configuration, it is possible to add an appropriate harmonic suppression effect to the transformer.

According to the present invention, it is possible to provide an appropriate harmonic suppression effect in a transformer to which at least one power conversion circuit is connected.

FIG. 1 is a diagram showing a schematic configuration example of a multiple transformer according to a first embodiment. FIG. 2 is a diagram for explaining leakage inductance in a winding portion group in this embodiment. FIG. 3 is a diagram showing a schematic configuration example of a multiple transformer according to the second embodiment. FIG. 4 is a diagram showing a schematic configuration example of a multiple transformer according to a first modification of the second embodiment. In FIG. FIG. 5 is a diagram showing a schematic configuration example of a multiple transformer according to a second modification of the second embodiment. In FIG. FIG. 6 is a diagram showing a schematic configuration example of a multiple transformer according to the third embodiment. FIG. 7A is a diagram showing an example of the arrangement of each winding in a transformer having one secondary winding. FIG. 7B is a diagram showing an example of the arrangement of each winding in a transformer having one secondary winding. FIG. 7C is a diagram showing an example of the arrangement of each winding in a transformer having one secondary winding. FIG. 7D is a diagram showing an example of the arrangement of each winding in a transformer having one secondary winding. FIG. 7E is a diagram showing an example of the arrangement of each winding in a transformer having one secondary winding. FIG. 8 is a graph showing the waveform of the primary winding voltage when a multiple transformer is used in one embodiment, in comparison with a comparative example. FIG. 9 is a diagram showing an example of the arrangement of a multiple transformer (triple transformer) having three secondary windings to which three power conversion circuits are connected in a comparative example.

The following describes an embodiment of the present invention with reference to the drawings. In the following, elements that are the same or have the same function are given the same reference numerals throughout the drawings, and duplicate descriptions are omitted.

(Embodiment 1)
1 is a diagram showing a schematic configuration example of a multiple transformer in embodiment 1. A transformer 10 in this embodiment includes a primary winding 1 connected to a three-phase power supply system 11, three secondary windings (a first secondary winding 2A, a second secondary winding 2B, and a third secondary winding 2C) respectively connected to three power conversion circuits (a first power conversion circuit 12A, a second power conversion circuit 12B, and a third power conversion circuit 12C), and a tertiary winding 3 connected to a harmonic suppression filter circuit 13. That is, the transformer 10 in this embodiment is a multiple transformer having a plurality of secondary windings 2A, 2B, and 2C (hereinafter, referred to as a multiple transformer 10).

The multiplex transformer 10 in this embodiment is configured to transform three-phase AC from the power supply system 11 and output three-phase AC that is input to each of the power conversion circuits 12A, 12B, and 12C. Note that FIG. 1 shows only one of the three phases (U-phase), and the other two phases (V-phase and W-phase) are not shown. In the multiplex transformer 10, the windings in the other two phases are arranged in the same manner as the U-phase, which will be described below.

The windings 1, 2A-2C, and 3 are wound around the winding axis X in a portion of the core 4 that extends in the winding axis X direction so that they are arranged at a predetermined interval along a common winding axis direction (X direction). The windings 1, 2A-2C, and 3 are arranged in a straight line on the common winding axis X. In this embodiment, the windings 1, 2A-2C, and 3 all have the same outer diameter and inner diameter. The multiple transformer 10 in this embodiment is configured as a shell-type multiple transformer in which the core 4 is arranged outside the windings 1, 2A-2C, and 3. A predetermined refrigerant is circulated between the windings 1, 2A-2C, and 3 to cool the windings 1, 2A-2C, and 3 and the core 4.

The three power conversion circuits 12A to 12C have the same element configuration. For example, each of the power conversion circuits 12A to 12C has the same type and number of semiconductor elements (e.g., switching elements, etc.) and is configured with an inverter driven by a specified control method (e.g., PWM control). At this time, each of the power conversion circuits 12A to 12C is driven at the same control frequency. Note that the power conversion circuits 12A to 12C may be configured as other power conversion circuits such as rectifiers. A specified load such as a motor is connected to the output of the power conversion circuits 12A to 12C.

The harmonic suppression filter circuit 13 may be, for example, an active filter that detects harmonic currents and outputs a compensation current corresponding to the harmonic currents, or it may be a passive filter including an LC circuit. In this embodiment, the power supply system 11, the three power conversion circuits 12A to 12C, the harmonic suppression filter circuit 13, and the multiple transformer 10 are configured as a power supply system for supplying power to a load.

In this embodiment, the tertiary winding 3 has multiple tertiary winding portions 3a1, 3a2, 3b1, 3b2, 3c1, and 3c2 that are arranged in a divided manner with respect to the common winding axis X direction. Each of the tertiary winding portions 3i1 and 3i2 (i = a, b, c) is adjacent to each of the multiple secondary windings 2A, 2B, and 2C.

The primary winding 1 also has multiple primary winding portions 1a, 1b, and 1c that are arranged in a divided manner with respect to the common winding axis X direction. Each primary winding portion 1i (i=a, b, c) is adjacent to each of the multiple tertiary winding portions 3i1 and 3i2.

Furthermore, each of the multiple secondary windings 2A, 2B, and 2C has multiple secondary winding portions 2A1, 2A2, 2B1, 2B2, 2C1, and 2C2 that are divided and arranged in the direction of a common winding axis X. Each of the multiple tertiary winding portions 3i1 and 3i2 is arranged between the multiple secondary winding portions 2I1 and 2I2 (I = A, B, C).

The tertiary winding 3 is divided into two for each secondary winding 2I (i.e., six for the entire multiple transformer 10). The primary winding 1 is divided into one for each secondary winding 2I (i.e., three for the entire multiple transformer 10). The multiple tertiary winding portions 3i1, 3i2 are arranged to sandwich each of the multiple primary winding portions 1i from both sides in the direction of the common winding axis X. In other words, the tertiary winding portions 3i1, 3i2 are arranged adjacent to both sides of each of the multiple primary winding portions 1i.

Furthermore, each secondary winding 2I is divided into two. Each of the multiple secondary winding portions 2I1, 2I2 is arranged adjacent to the multiple tertiary winding portions 3i1, 3i2 on the opposite side to the side of the multiple tertiary winding portions 3i1, 3i2 adjacent to the primary winding portion 1i in the common winding axis X direction.

As a result, for each of the multiple secondary winding portions 2I1, 2I2, the primary winding portion 1i, the tertiary winding portion 3i1, 3i2, and the secondary winding portion 2I1, 2I2 are arranged in this order (or in reverse order) to form a winding portion group. For example, for the first secondary winding first portion 2A1, the first secondary winding first portion 2A1, the tertiary winding first portion 3a1, and the primary winding portion 1a are configured as one winding portion group. Also, for the first secondary winding second portion 2A2, the first secondary winding second portion 2A2, the tertiary winding second portion 3a2, and the primary winding portion 1a are configured as another winding portion group. The same applies to the other secondary winding portions.

Thus, according to the above configuration, the primary winding 1 and the tertiary winding 3 are arranged in a divided manner such that the tertiary winding portions 3i1 and 3i2 are adjacent to at least the multiple secondary windings 2I (secondary winding portions 2I1 and 2I2), and the primary winding portion 1i is adjacent to the tertiary winding portions 3i1 and 3i2. Furthermore, as described above, the secondary winding 2A is also arranged in a divided manner along the common winding axis X. As shown in FIG. 1, in the winding portions 1i, 2I1, 2I2, and 3i of the windings 1, 2A to 2C, and 3 in this embodiment, each winding is divided in parallel. However, instead of this, the winding portions 1i, 2I1, 2I2, and 3i of the windings 1, 2A to 2C, and 3 may be divided in series.

Figure 2 is a diagram for explaining leakage inductance in a winding portion group in this embodiment. In Figure 2, a primary winding portion 1ix, a tertiary winding portion 3ix, and a secondary winding portion 2Ix are illustrated as one winding portion group GI. Note that in Figure 2, the spacing between each winding portion is intentionally made large for clarity of illustration.

In the example of FIG. 2, the width of the primary winding portion 1ix along the winding axis X is W1, the width of the secondary winding portion 2Ix along the winding axis X is W2, and the width of the tertiary winding portion 3ix along the winding axis X is W3. The interval between the primary winding portion 1ix and the tertiary winding portion 3ix is the 1-3 interval δ13, and the interval between the tertiary winding portion 3ix and the secondary winding portion 2Ix is the 2-3 interval δ23. The 1-3 interval δ13 is equal to or smaller than the 2-3 interval δ23 (δ13≦δ23). In this case, if the interval between the primary winding portion 1ix and the secondary winding portion 2Ix is the 1-2 interval δ12, then δ12=δ13+W3+δ23. Therefore, δ12>δ23≧δ13 holds.

In this case, if the combined leakage inductance of the primary winding portion 1ix and the secondary winding portion 2Ix is L12, the combined leakage inductance of the secondary winding portion 2Ix and the tertiary winding portion 3ix is L23, and the combined leakage inductance of the primary winding portion 1ix and the tertiary winding portion 3ix is L13, the combined leakage inductance between each winding portion has the relationship L13≦L23<L12.

Furthermore, if the leakage inductance of the primary winding portion 1ix is L1, the leakage inductance of the secondary winding portion 2Ix is L2, and the leakage inductance of the tertiary winding portion 3ix is L3, the relationship between the leakage inductance of each winding portion and each combined leakage inductance satisfies the following relationship:
L1+L2=L12
L2+L3=L23
L1+L3=L13

From the above relational expressions, when the leakage inductances L1, L2, and L3 are expressed as combined leakage inductances L12, L23, and L13, the following is obtained.
L1=(L12-L23+L13)/2
L2=(L12+L23-L13)/2
L3=(-L12+L23+L13)/2

As described above, since L13≦L23<L12, the leakage inductance of each winding portion has the relationship L3<L1≦L2. Therefore, by disposing the tertiary winding portions 3i1, 3i2 between the primary winding portion 1i and the secondary winding portions 2I1, 2I2 as shown in FIG. 2, the coupling between the primary winding portion 1i and the tertiary winding portions 3i1, 3i2 and the coupling between the tertiary winding portions 3i1, 3i2 and the secondary winding portions 2I1, 2I2 is strengthened, and the leakage inductance L3 in the tertiary winding portions 3i1, 3i2 can be reduced.

In this embodiment, as shown in Fig. 1, a winding portion group similar to that in Fig. 2 is formed for each of the multiple secondary winding portions 2I1, 2I2. Therefore, the leakage inductance L3 in the tertiary winding portions 3i1, 3i2 can be reduced in the multiple secondary winding portions 2I1, 2I2. Moreover, since the same winding arrangement is used between different secondary windings 2A, 2B, 2C, the distance between the primary winding portion 2i and each secondary winding 2I (each secondary winding portion 2I1, 2I2) and the distance between each secondary winding 2I and the tertiary winding portion 3i are uniform between the multiple secondary windings 2A, 2B, 2C. Therefore, the combined leakage inductance L12 between the primary winding portion 1i and each of the secondary winding portions 2I1, 2I2, the combined leakage inductance L23 between the tertiary winding portion 3i and each of the secondary winding portions 2I1, 2I2, and the combined leakage inductance L13 between the primary winding portion 1i and the tertiary winding portion 3i can be equalized between the multiple secondary windings 2A, 2B, 2C.

Therefore, it is possible to improve the harmonic suppression effect in the harmonic suppression filter circuit 13 connected to the tertiary winding 3 while eliminating the imbalance in the harmonic suppression effect between the multiple power conversion circuits 12A, 12B, and 12C. As described above, with the above configuration, it is possible to add an appropriate harmonic suppression effect to the multiple transformer 10 to which the multiple power conversion circuits 12A, 12B, and 12C are connected.

In addition, according to the above configuration, each of the tertiary winding portions 3i1, 3i2 corresponding to each secondary winding 2I is arranged so as to be sandwiched between the secondary winding portions 2I1, 2I2 of the corresponding secondary winding 2I. Furthermore, the secondary winding portions 2I1, 2I2 of each secondary winding 2I and the primary winding portion 1i and the tertiary winding portions 3i1, 3i2 corresponding to each secondary winding 2I are arranged symmetrically with respect to the common winding axis X direction, with the primary winding portion 1i at the center.

That is, for each of the multiple secondary windings 2I, tertiary winding portions 3i1 and 3i2 are arranged on both sides of the primary winding portion 1i, and the secondary winding portions 2I1 and 2I2 of the corresponding secondary winding 2I are arranged on both sides of the primary winding portion 1i. This minimizes the leakage inductance L3 of the tertiary winding 3, and enhances the suppression effect of harmonics.

In addition, by adjusting the 2-3 spacing δ23 between the secondary winding portions 2I1, 2I2 and the tertiary winding portions 3i1, 3i2, and the 1-3 spacing δ13 between the tertiary winding portions 3i1, 3i2 and the primary winding portion 1i, the leakage inductance L1 of the primary winding 1 and the leakage inductance L2 of each secondary winding 2I can be adjusted while maintaining an equal state between the multiple secondary windings 2I.

In this way, by connecting the harmonic suppression filter circuit 13 to the tertiary winding 3 of the multiple transformer 10, the harmonics generated in the multiple power conversion circuits 12A, 12B, and 12C can be appropriately suppressed, eliminating the need for an external filter device and enabling the power supply system to be made more compact. This allows the multiple transformer 10 to be placed in a small space, improving the layout freedom of the power supply system. Furthermore, by eliminating the need for an external filter device, the system costs can be reduced and the environmental load can be reduced by reducing the amount of constituent materials. Furthermore, by dividing each winding 1, 2A-2C, and 3, the surface area of each winding is increased, thereby improving the cooling efficiency of each winding.

In addition, by making the interval (1-3 interval δ13) between the primary winding portion 1i and the tertiary winding portions 3i1, 3i2 smaller than the interval (2-3 interval δ23) between the secondary winding portions 2I1, 2I2 and the tertiary winding portions 3i1, 3i2 (δ13<δ23), the coupling strength between the tertiary winding portions 3i1, 3i2 and each secondary winding portion 2I1, 2I2 becomes weaker than the coupling strength between the primary winding portion 1i and the tertiary winding portions 3i1, 3i2. Therefore, the leakage inductance L1 of the primary winding portion 1i can be made smaller than the leakage inductance L2 of the secondary winding portions 2I1, 2I2 (L1<L2). This makes it possible to increase the combined leakage inductance between the tertiary winding 3 and each secondary winding 2I, thereby further enhancing the harmonic suppression effect.

(Embodiment 2)
Fig. 3 is a diagram showing a schematic configuration example of a multiple transformer according to the second embodiment. In Fig. 3, the same components as those in the first embodiment shown in Fig. 1 are given the same reference numerals, and description thereof will be omitted. The multiple transformer 20 according to the present embodiment differs from the multiple transformer 10 according to the first embodiment in that the secondary windings 2A-2C are not divided, and primary winding portions 1i1 and 1i2 are arranged to sandwich each of the secondary windings 2A-2C and a part of the tertiary winding (each of the tertiary winding first portions 3i1) from both sides in the direction of the common winding axis X.

In this embodiment, the tertiary winding 3 has multiple tertiary winding portions 3a1, 3a2, 3b1, 3b2, 3c1, and 3c2 that are arranged in a divided manner with respect to the common winding axis X direction. Each of the tertiary winding first portions 3i1 (i=a, b, c) is adjacent to each of the multiple secondary windings 2I (I=A, B, C).

The primary winding 1 also has multiple primary winding portions 1a1, 1a2, 1b1, 1b2, 1c1, and 1c2 that are arranged in a divided manner with respect to the common winding axis X direction. The primary winding 1 is divided into two for each secondary winding 2I (i.e., six for the entire multiple transformer 10). The multiple primary winding portions 1i1 and 1i2 are arranged to sandwich the multiple tertiary winding first portions 3i1 and the multiple secondary windings 2I from both sides in the common winding axis X direction.

More specifically, the primary winding first portion 1i1 is adjacent to each of the multiple tertiary winding first portions 3i1 on the opposite side to the side of the multiple tertiary winding first portions 3i1 adjacent to any of the multiple secondary windings 2I. Also, the primary winding second portion 1i2 is adjacent to each of the multiple secondary windings 2I on the opposite side to the side of the multiple secondary windings 2I adjacent to the tertiary winding first portions 3i1 in the common winding axis X direction. In other words, the tertiary winding first portion 3i1 is disposed between the primary winding first portion 1i1 and any of the multiple secondary windings 2I in the common winding axis X direction.

As a result, for each of the multiple secondary windings 2I, the primary winding first portion 1i1, the tertiary winding first portion 3i1, the secondary winding 2I, and the primary winding second portion 1i2 are arranged in this order (or in reverse order) to form a winding portion group. For example, for the first secondary winding 2A, the primary winding first portion 1a1, the tertiary winding first portion 3a1, the first secondary winding 2A, and the primary winding second portion 1a2 are configured as one winding portion group. Also, for example, for the second secondary winding 2B, the primary winding first portion 1b1, the tertiary winding first portion 3b1, the second secondary winding 2B, and the primary winding second portion 1b2 are configured as another winding portion group. The same is true for the third secondary winding 2C.

According to the above configuration, the primary winding 1 and the tertiary winding 3 are arranged in a divided manner such that the tertiary winding first portion 3i1 is adjacent to at least each of the multiple secondary windings 2I, and the primary winding first portion 1i1 is adjacent to the tertiary winding first portion 3i1. Furthermore, as described above, the primary winding 1 is arranged in a divided manner such that the primary winding second portion 1i2 is adjacent to each of the multiple secondary windings 2I. Note that the winding portions 1i1, 1i2, 3i1, and 3i2 of each winding 1 and 3 may be divided in parallel or in series.

In this manner, even in this embodiment, by disposing the tertiary winding first portion 3i1 between the primary winding first portion 1i1 and each secondary winding 2I, the coupling between the primary winding first portion 1i1 and the tertiary winding first portion 3i1 and the coupling between the tertiary winding first portion 3i1 and the secondary winding 2I is strengthened, and the leakage inductance L3 in the tertiary winding first portion 3i1 can be reduced.

Furthermore, according to this embodiment, each of the tertiary winding first portions 3i1 is arranged so as to be sandwiched between the primary winding portions 1i1 and 1i2. This makes it possible to reduce the leakage inductance L3 of the tertiary winding 3. Also, according to this embodiment, the primary winding first portion 1i1 and the tertiary winding first portion 3i1 are adjacent to each other, which strengthens the coupling strength between them, thereby making it possible to further reduce the leakage inductance L3 of the tertiary winding 3.

Furthermore, the tertiary winding portions 3i1 and 3i2 include a tertiary winding second portion 3i2 in addition to the tertiary winding first portion 3i1. The tertiary winding second portion 3i2 is arranged to be adjacent to the primary winding second portion 1i2 when another secondary winding 2I' (when I=A, I'=B, when I=B, I'=C) is arranged on the opposite side to the side adjacent to one secondary winding 2I in the primary winding second portion 1i2 adjacent to one secondary winding 2I among the multiple secondary windings in relation to the common winding axis X direction.

More specifically, the tertiary winding second portion 3a2 disposed between the first secondary winding 2A and the second secondary winding 2B is disposed adjacent to the primary winding second portion 1a2 adjacent to the first secondary winding 2A in the common winding axis X direction. Also, the tertiary winding second portion 3b2 disposed between the second secondary winding 2B and the third secondary winding 2C is disposed adjacent to the primary winding second portion 1b2 adjacent to the second secondary winding 2B in the common winding axis X direction.

Thus, in this embodiment, the tertiary winding 3 is divided into one per secondary winding 2I and one between winding subgroups (i.e., five for the entire multiple transformer 10).

According to the above configuration, the number of adjacent points between the tertiary winding portions 3i1, 3i2 and the primary winding portions 1i1, 1i2 is increased, so that the strength of the coupling between them is strengthened, and the leakage inductance L3 of the tertiary winding 3 can be further reduced. Furthermore, by relatively weakening the strength of the coupling between the primary winding portions 1i1, 1i2 and each secondary winding 2I, it is possible to prevent the leakage inductance L2 in the secondary winding 2I from becoming smaller than necessary. This can enhance the harmonic suppression effect in the harmonic suppression filter circuit 13 connected to the tertiary winding 3.

(Variation 1)
Fig. 4 is a diagram showing a schematic configuration example of a multiple transformer in Modification 1 of Embodiment 2. In Fig. 4, the same components as those in Embodiment 2 shown in Fig. 3 are given the same reference numerals, and description thereof will be omitted. A multiple transformer 30 in this modification differs from the multiple transformer 20 in Embodiment 2 in that the multiple secondary windings 2I have an outer diameter larger than the outer diameters of the primary winding 1 (primary winding portions 1i1, 1i2) and the tertiary winding 3 (tertiary winding portions 3i1, 3i2).

In this modified example, each secondary winding 2I has the same outer diameter. Also, in this modified example, each winding 1, 2A-2C, 3 has the same inner diameter. From the above, if the outer diameter of the primary winding 1 is Ro1, the outer diameter of the tertiary winding 3 is Ro3, and the outer diameter of each secondary winding 2I is Ro2, then the relationship Ro2>Ro1=Ro3 holds.

According to the configuration of this modified example, the coupling strength between the tertiary winding portion (tertiary winding first portion 3i1) and each secondary winding 2I and the coupling strength between the primary winding portions 1i1, 1i2 and each secondary winding 2I can be weakened without weakening or changing the coupling strength between the primary winding portions 1i1, 1i2 and the tertiary winding portions 3i1, 3i2. Therefore, the combined leakage inductance between the tertiary winding 3 and each secondary winding 2I and between the primary winding 1 and each secondary winding 2I can be increased. As a result, only the leakage inductance of each secondary winding 2I can be increased, and the harmonic suppression effect can be further improved.

(Variation 2)
Fig. 5 is a diagram showing a schematic configuration example of a multiple transformer in Modification 2 of Embodiment 2. In Fig. 5, the same components as those in Embodiment 2 shown in Fig. 3 are given the same reference numerals, and description thereof will be omitted. A multiple transformer 40 in this modification differs from the multiple transformer 20 in Embodiment 2 in that the multiple secondary windings 2I have an inner diameter larger than the inner diameters of the primary winding 1 (primary winding portions 1i1, 1i2) and the tertiary winding 3 (tertiary winding portions 3i1, 3i2).

In this modified example, each secondary winding 2I has the same inner diameter as the others. Also, in this modified example, each winding 1, 2A-2C, 3 has the same outer diameter as the others. From the above, if the inner diameter of the primary winding 1 is Rp1, the inner diameter of the tertiary winding 3 is Rp3, and the inner diameter of each secondary winding 2I is Rp2, then the relationship Rp2>Rp1=Rp3 holds.

Even with the configuration of this modified example, the coupling strength between the tertiary winding portion (tertiary winding first portion 3i1) and each secondary winding 2I and the coupling strength between the primary winding portions 1i1, 1i2 and each secondary winding 2I can be weakened without weakening or changing the coupling strength between the primary winding portions 1i1, 1i2 and the tertiary winding portions 3i1, 3i2. Therefore, the combined leakage inductance between the tertiary winding 3 and each secondary winding 2I and between the primary winding 1 and each secondary winding 2I can be increased. As a result, only the leakage inductance of each secondary winding 2I can be increased, and the harmonic suppression effect can be further improved.

In the above-mentioned modified examples 1 and 2, the outer diameter and inner diameter of the primary winding 1 and the outer diameter and inner diameter of the tertiary winding 3 are the same length, but at least one of the outer diameter and inner diameter may be different between the primary winding 1 and the tertiary winding 3. This makes it possible to adjust the leakage inductance of each winding. Also, the above-mentioned modified examples 1 and 2 may be combined. That is, the multiple secondary windings 2I may have an outer diameter larger than the outer diameter of the primary winding 1 (primary winding parts 1i1, 1i2) and the tertiary winding 3 (3i1, 3i2), and an inner diameter larger than the inner diameter of the primary winding 1 (primary winding parts 1i1, 1i2) and the tertiary winding 3 (3i1, 3i2).

In the above-mentioned modified examples 1 and 2, the windings 1, 2A to 2C, and 3 are divided and arranged as in the second embodiment, but the above-mentioned modified examples 1 and 2 can also be applied to the division and arrangement based on the first embodiment. That is, in the division and wiring of the windings 1, 2A to 2C, and 3 shown in FIG. 1, the secondary winding portions 2I1 and 2I2 may have an outer diameter larger than the outer diameter of the primary winding 1 (primary winding portion 1i) and the tertiary winding 3 (tertiary winding portions 3i1 and 3i2). In the division and wiring of the windings 1, 2A to 2C, and 3 shown in FIG. 1, the secondary winding portions 2I1 and 2I2 may have an inner diameter larger than the inner diameter of the primary winding 1 (primary winding portion 1i) and the tertiary winding 3 (tertiary winding portions 3i1 and 3i2).

(Embodiment 3)
Fig. 6 is a diagram showing a schematic configuration example of a multiple transformer according to embodiment 3. In Fig. 6, the same components as those in embodiment 1 shown in Fig. 1 are given the same reference numerals and description thereof will be omitted. A multiple transformer 50 according to this embodiment differs from the multiple transformer 10 according to embodiment 1 in that a plurality of secondary windings 2I (secondary winding portions 2I1, 2I2) are lap-wound at the same positions with respect to the common winding axis X direction.

In this embodiment, each of the multiple secondary windings 2I has multiple secondary winding portions 2I1, 2I2 that are divided and arranged in the direction of a common winding axis X. The tertiary winding 3 is arranged between the multiple secondary winding portions 2I1, 2I2 in relation to the direction of the common winding axis X so as to be adjacent to the multiple lap-wound secondary windings 2I. For this reason, the tertiary winding 3 is divided and arranged into a tertiary winding first portion 3a1 adjacent to each secondary winding first portion 2I1 and a tertiary winding second portion 3a2 adjacent to each secondary winding second portion 2I2.

The primary winding 1 is disposed adjacent to the tertiary winding first portion 3a1 and the tertiary winding second portion 3a2 in the direction of the common winding axis X. In this embodiment, the primary winding 1 is not divided in the direction of the common winding axis X.

As a result, the secondary winding first portion 2I1, the tertiary winding first portion 3a1, the primary winding 1, the tertiary winding second portion 3a2, and the secondary winding second portion 2I2, which is lap wound at the second position, are arranged in this order (or in the reverse order) with respect to the common winding axis X direction.

The secondary winding portions 2I1, 2I2 are configured so that the outer diameter (outer diameter of the first secondary winding first portion 2A1 and the third secondary winding second portion 2C2) in the lap-wound state is the same as the outer diameter of the primary winding 1 and the tertiary winding 3, and the inner diameter (inner diameter of the third secondary winding first portion 2C1 and the first secondary winding second portion 2A2) in the lap-wound state is the same as the inner diameter of the primary winding 1 and the tertiary winding 3. This allows the tertiary winding portions 3a1, 3a2 and the primary winding 1 to be positioned in the direction of the common winding axis X of all the secondary windings 2I (secondary winding portions 2I1, 2I2).

According to the above configuration, the primary winding 1 and the tertiary winding 3 are arranged so that the tertiary winding 3 is adjacent to each of the multiple lap-wound secondary windings 2I, and the primary winding 1 is adjacent to the tertiary winding 3. Therefore, the distance between the primary winding 1 and each secondary winding 2I and the distance between each secondary winding 2I and the tertiary winding 3 (tertiary winding portions 3a1, 3a2) are equalized between the multiple secondary windings 2I. Therefore, the combined leakage inductance between the primary winding 1 and each secondary winding 2I and the combined leakage inductance between the tertiary winding 3 and each secondary winding 2I can be equalized between the multiple secondary windings 2I.

In the above configuration, the tertiary winding 3 is arranged so as to be sandwiched between the multiple secondary winding portions 2I1 and 2I2, as in the first embodiment. This allows the leakage inductance of the tertiary winding 3 to be reduced. Furthermore, by arranging the tertiary winding portions 3a1 and 3a2 between the primary winding 1 and each secondary winding 2I, the coupling between the primary winding 1 and the tertiary winding portions 3a1 and 3a2 and the coupling between the tertiary winding portions 3a1 and 3a2 and each secondary winding 2I is strengthened, and the leakage inductance of the tertiary winding 3 can be reduced. Therefore, the harmonic suppression effect in the harmonic suppression filter circuit 13 connected to the tertiary winding 3 can be enhanced while eliminating the imbalance of the harmonic suppression effect between the multiple power conversion circuits 12A to 12C. As described above, according to the above configuration, an appropriate harmonic suppression effect can be added in the multiple transformer 50 to which the multiple power conversion circuits 12A to 12C are connected.

Furthermore, in this embodiment, since multiple secondary windings 2I are lap-wound, it is not necessary to divide the primary winding 1 and the tertiary winding 3 for each secondary winding 2I, and therefore it is possible to suppress an increase in size in the direction of the winding axis X compared to embodiment 1. However, in embodiment 1, by dividing the primary winding 1 and the tertiary winding 3 into separate secondary windings 2I, it is possible to suppress an increase in size in the radial direction of the winding axis X compared to this embodiment.

Furthermore, in this embodiment, the first secondary winding first portion 2A1 located at a first position in the common winding axis X direction is disposed on the outermost side, and the second secondary winding first portion 2B1 located at the same first position is disposed on the inner side of the first secondary winding first portion 2A1. Furthermore, the third secondary winding first portion 2C1 located at the same first position as the second secondary winding first portion 2B1 is disposed on the inner side of the second secondary winding first portion 2B1. Also, the first secondary winding second portion 2A2 located at a second position in the common winding axis X direction is disposed on the innermost side, and the second secondary winding second portion 2B2 located at the same second position is disposed on the outer side of the first secondary winding second portion 2A2. Furthermore, the third secondary winding second portion 2C2, which is located in the same second position as the second secondary winding second portion 2B2, is disposed radially outward from the second secondary winding second portion 2B2.

For example, if three or more secondary windings are each assigned a number (first, second, third, ...), the three or more secondary winding portions 2I1 located in the first position are arranged so that the larger the number, the closer to the outer diameter, and the three or more secondary winding portions 2I2 located in the second position are arranged so that the larger the number, the closer to the inner diameter.

In this way, each secondary winding 2I is arranged so that the radial positions of the first and second positions where it is divided are staggered. This makes the winding length of each secondary winding 2I equal among the multiple secondary windings 2I. Therefore, it is easy to equalize the harmonic suppression effect among the multiple secondary windings 2I.

In this embodiment, the primary winding 1 and the tertiary winding 3 for each secondary winding 2I are arranged in the same manner as in embodiment 1. Alternatively, the primary winding 1 and the tertiary winding 3 for each secondary winding 2I may be arranged in the same manner as in embodiment 2. That is, the primary winding first portion 1a1, the tertiary winding 3, the secondary winding 2I wound in a lap at the first position, and the primary winding second portion 1a2 may be arranged in this order (or in the reverse order) with respect to the common winding axis X direction.

Other Embodiments
Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various improvements, changes, and modifications are possible without departing from the spirit of the present invention.

For example, in the above embodiment, a three-phase multiple transformer is illustrated, but this is not limited thereto, and for example, a single-phase multiple transformer may be configured. Also, in the above embodiment, a shell-type multiple transformer in which the iron core 4 is disposed on the outside of each of the windings 1, 2A-2C, and 3 is illustrated, but this is not limited thereto, and the transformer may be configured as a core-type multiple transformer in which the iron core 4 is disposed on the inside of each of the windings 1, 2A-2C, and 3.

In addition, in the above embodiment, a multiple (triple) transformer having three secondary windings as the multiple secondary windings 2I is exemplified, but this is not limited to this. The multiple secondary windings 2I may be two, or may be four or more.

In addition, in the above embodiment, only the harmonic suppression filter circuit 13 is connected to the tertiary winding 3, but other devices or circuits such as a pump may be connected in parallel or series to the harmonic suppression filter circuit 13. As a result, harmonics are suppressed in the voltage input to the other devices or circuits due to the effect of the harmonic suppression filter circuit 13.

The division manner of each winding 1, 2A-2C, 3 is not limited to the above embodiment. For example, in embodiment 1, either the tertiary winding first portion 3i1 or the tertiary winding second portion 3i2 may be omitted. In other words, one primary winding portion and one tertiary winding portion may be disposed between the secondary winding portions 2I1 and 2I2 of each secondary winding 2I.

Also, for example, in the second embodiment, the tertiary winding second portion 3i2 may be omitted. In this case, the primary winding second portion 1i2 and the primary winding first portion 1i'1 (when i=a, i'=b, when i=b, i'=c) located on both sides of the tertiary winding second portion 3i2 in FIG. 3 may be a common primary winding portion.

As a divisional aspect similar to that of the second embodiment, each winding may be divided and arranged so as to satisfy the following conditions.
q1>q3>q2 and s3>s2
Here, q1 is the number of divisions of the primary winding 1, q2 is the number of divisions for each of the secondary windings 2I, q3 is the number of divisions of the tertiary winding 3, s2 is the number of times that each of the secondary windings 2I (or the secondary winding portion of the secondary winding) is sandwiched between the primary winding 1 (primary winding portion), and s3 is the number of times that the tertiary winding 3 (or the tertiary winding portion) is sandwiched between the primary winding 1 (primary winding portion).

Furthermore, while the above embodiment illustrates a multiple transformer having multiple secondary windings 2I, the present invention is also applicable to a transformer having one secondary winding 2 to which one power conversion circuit 12 is connected. Figures 7A to 7E are diagrams showing examples of the arrangement of each winding in a transformer having one secondary winding. Figures 7A to 7E only show the arrangement order of the windings in the common winding axis X direction of the transformers 60A to 60E, and other configurations are not shown.

In the transformers 60A to 60E shown in Figures 7A to 7E, the primary winding 1, secondary winding 2, and tertiary winding 3 are also arranged on a common winding axis X. The primary winding 1 has multiple primary winding portions 1D divided in parallel or in series. The tertiary winding 3 has multiple tertiary winding portions 3D divided in parallel or in series. In the examples of the transformers 60A to 60D, the secondary winding 2 is not divided. The multiple tertiary winding portions 3D are arranged so as to be sandwiched between the multiple primary winding portions 1D in the direction of the common winding axis X.

In the transformer 60A shown in FIG. 7A, the primary winding 1 is divided into three primary winding portions 1D, and the tertiary winding 3 is divided into two tertiary winding portions 3D. Each tertiary winding portion 3D is arranged between two primary winding portions 1D. That is, one tertiary winding portion 3D is arranged in each of two sections (spaces between two primary winding portions 1D) defined by the three primary winding portions 1D. The secondary winding 2 is arranged in one of the two sections. That is, the secondary winding 2 is also arranged between two primary winding portions 1D. As a result, the number (2) of multiple tertiary winding portions 3D sandwiched between multiple primary winding portions 1D is greater than the number (1) of secondary winding portions 2 sandwiched between primary winding portions 1D. This configuration satisfies the above formula (q1>q3>q2 and s3>s2).

In the transformer 60B shown in FIG. 7B, the primary winding 1 is divided into four primary winding portions 1D, and the tertiary winding 3 is divided into two tertiary winding portions 3D. Of the three sections (space between two primary winding portions 1D) defined by the four primary winding portions 1D, one tertiary winding portion 3D is arranged in each of the two sections located at both ends, and the secondary winding 2 is arranged in the central section. As a result, the number (2) of multiple tertiary winding portions 3D sandwiched between multiple primary winding portions 1D is greater than the number (1) of secondary windings 2 sandwiched between primary winding portions 1D. This configuration satisfies the above formula (q1>q3>q2 and s3>s2).

In the transformer 60C shown in FIG. 7C, the primary winding 1 is divided into three primary winding portions 1D, and the tertiary winding 3 is divided into three tertiary winding portions 3D. Two tertiary winding portions 3D are arranged in one of two sections (space between two primary winding portions 1D) defined by the three primary winding portions 1D, and one tertiary winding portion 3D is arranged in the other section. The secondary winding 2 is arranged between the two tertiary winding portions 3D arranged in one section. As a result, the number of tertiary winding portions 3D sandwiched between multiple primary winding portions 1D (3) is greater than the number of secondary windings 2 sandwiched between primary winding portions 1D (1).

In the transformer 60D shown in FIG. 7D, the primary winding 1 is divided into four primary winding portions 1D, and the tertiary winding 3 is divided into four tertiary winding portions 3D. Of the three sections (space between two primary winding portions 1D) defined by the four primary winding portions 1D, one tertiary winding portion 3D is arranged in each of the two sections located at both ends, and two tertiary winding portions 3D are arranged in the central section. The secondary winding 2 is arranged between the two tertiary winding portions 3D arranged in the central section. As a result, the number of tertiary winding portions 3D sandwiched between multiple primary winding portions 1D (4) is greater than the number of secondary windings 2 sandwiched between primary winding portions 1D (1).

In the transformer 60E shown in FIG. 7E, the primary winding 1 is divided into three primary winding portions 1D, and the tertiary winding 3 is divided into four tertiary winding portions 3D. Furthermore, the secondary winding 2 is also divided into two secondary winding portions 2D. Two tertiary winding portions 3D are arranged in each of two sections (spaces between two primary winding portions 1D) defined by the three primary winding portions 1D, and one secondary winding 2D is arranged between each of the two tertiary winding portions 3D arranged in each section. As a result, the number of tertiary winding portions 3D sandwiched between multiple primary winding portions 1D (4) is greater than the number of secondary winding portions 2D sandwiched between multiple primary winding portions 1D (2).

The configuration of the above transformers 60A to 60E allows the leakage inductance due to the tertiary winding 3 to be reduced relative to the leakage inductance due to the secondary winding 2. This improves the harmonic suppression effect in the harmonic suppression filter circuit 13 connected to the tertiary winding 3. As described above, the above configuration allows the transformers 60A to 60E to provide an appropriate harmonic suppression effect. Furthermore, the configuration of the transformer 60E allows the secondary winding 2 to be divided, allowing for more fine adjustment of the relationship between the leakage inductance due to the secondary winding 2 and the leakage inductance due to the tertiary winding 3.

The aspects shown in the first and second modifications of the second embodiment (FIGS. 4 and 5) can also be applied to the above-mentioned transformers 60A to 60E having one secondary winding 2. Furthermore, for a transformer having one or more secondary windings 2, even if the windings are not arranged separately, the effects can be obtained by applying the aspects shown in the first and second modifications of the second embodiment. That is, by configuring the transformer so that the secondary winding has an outer diameter larger than the outer diameters of the primary winding and the tertiary winding, or has an inner diameter larger than the inner diameters of the primary winding and the tertiary winding, the leakage inductance due to the tertiary winding can be reduced relative to the leakage inductance due to the secondary winding, and the harmonic suppression effect in the harmonic suppression filter circuit connected to the tertiary winding can be improved.

In addition, in the above transformers 60A to 60E, an example has been shown in which multiple tertiary winding portions 3D are arranged to be sandwiched between multiple primary winding portions 1D in the direction of the common winding axis X, but in the above transformers 60A to 60E, the multiple tertiary winding portions 3D and the multiple primary winding portions 1D may be interchanged. In other words, multiple primary winding portions 1D may be arranged to be included in multiple tertiary winding portions 3D in the direction of the common winding axis X.

(Example)
8 is a graph showing the waveform of the primary winding voltage when a multiple transformer in one embodiment is used, in comparison with a comparative example. Fig. 8(a) is a graph showing the voltage waveform in the embodiment, and Fig. 8(b) is a graph showing the voltage waveform in the comparative example. In this embodiment, a multiple transformer was used in which the windings 1, 2A-2C, and 3 are arranged in the same manner as in the second embodiment (Fig. 3).

On the other hand, in the comparative example, a multiple transformer was used in which the primary winding portion, the first secondary winding, the primary winding portion, the tertiary winding portion, the primary winding portion, the second secondary winding, the primary winding portion, the tertiary winding portion, the primary winding portion, the third secondary winding, and the primary winding portion were arranged in this order in the common winding axis direction. That is, in this comparative example, the primary winding portion is arranged adjacent to each of the multiple tertiary winding portions in the common winding axis direction, but the tertiary winding portion is not arranged adjacent to each of the multiple secondary windings in the common winding axis direction. Also, in the comparative example, the number of divisions of the tertiary winding portion is smaller than in the example, and as a result, the total area of the surface facing the primary winding portion sandwiching the tertiary winding portion is smaller than in the example. The outer diameter, shape, etc. of each winding were the same in the example and the comparative example.

A power supply system, power conversion circuit (inverter), and harmonic suppression filter circuit of the same configuration were connected to such a multiple transformer in each of the examples and comparative examples, and the voltage in the primary winding was measured for each.

As a result, as shown in FIG. 8, the waveform of the primary winding voltage in the embodiment exhibited a waveform closer to a sine wave (with less distortion) with the harmonic components suppressed compared to the comparative example. This shows that the result of this embodiment is that the tertiary winding 3 has a plurality of tertiary winding portions 3i1, 3i2 arranged in a divided manner so as to be adjacent to each of the plurality of secondary windings 2I with respect to the common winding axis X direction, and the primary winding 1 has a plurality of primary winding portions 1i1, 1i2 arranged in a divided manner so as to be adjacent to each of the plurality of tertiary winding portions 3i1, 3i2 with respect to the common winding axis X direction, thereby providing an appropriate harmonic suppression effect in a multiple transformer.

The present invention is useful for providing an appropriate harmonic suppression effect in a multiple transformer to which multiple power conversion circuits are connected.

1 Primary winding 1i (i = a, b, c), 1D Primary winding portion 1i1 (i = a, b, c) Primary winding first portion (primary winding portion)
1i2 (i = a, b, c) Primary winding second part (primary winding part)
2A, 2B, 2C Secondary winding 2I1 (I=A, B, C) Secondary winding first portion (secondary winding portion)
2I2 (I = A, B, C) Secondary winding second part (secondary winding part)
2D Secondary winding portion 3 Tertiary winding 3i1 (i=a, b, c) Tertiary winding first portion (tertiary winding portion)
3i2 (i = a, b, c) Tertiary winding second part (tertiary winding part)
3D tertiary winding portion 10, 20, 30, 40, 50, 60A to 60E transformer 11 power supply system 12A, 12B, 12C power conversion circuit 13 harmonic suppression filter circuit

Claims (2)

A primary winding connected to a power supply system;
a plurality of secondary windings connected to a plurality of power conversion circuits;
a tertiary winding connected to the harmonic suppression filter circuit;
the primary winding, the plurality of secondary windings and the tertiary winding are disposed on a common winding axis;
the tertiary winding has a plurality of tertiary winding portions arranged in a divided manner so as to be adjacent to each of the plurality of secondary windings with respect to the common winding axis direction;
the primary winding has a plurality of primary winding portions arranged in a divided manner so as to be adjacent to each of the plurality of tertiary winding portions with respect to the common winding axis direction;
A transformer, wherein the plurality of secondary windings have an outer diameter larger than an outer diameter of the primary winding and the tertiary winding, or have an inner diameter larger than an inner diameter of the primary winding and the tertiary winding. A primary winding connected to a power supply system;
a plurality of secondary windings connected to a plurality of power conversion circuits;
a tertiary winding connected to the harmonic suppression filter circuit;
the primary winding, the plurality of secondary windings and the tertiary winding are disposed on a common winding axis;
The plurality of secondary windings are lap-wound at the same position with respect to the common winding axis,
the tertiary winding is disposed adjacent to the plurality of lap-wound secondary windings with respect to the common winding axis direction;
the primary winding is disposed adjacent to the tertiary winding with respect to the common winding axis direction;
Each of the plurality of secondary windings has a plurality of secondary winding portions that are divided and arranged in the common winding axis direction,
the tertiary winding is disposed between the plurality of secondary winding portions with respect to the common winding axis direction;
the plurality of secondary windings includes a first secondary winding and a second secondary winding;
the second secondary winding is disposed radially inner than the first secondary winding at a first position in the common winding axis direction, and disposed radially outer than the first secondary winding at a second position in the common winding axis direction.

Images