Static electromagnetic equipment and bidirectional DC-DC converter using static electromagnetic equipment

Abstract

To provide a stationary electromagnetic apparatus having a winding structure capable of setting a wide range of leakage inductance without applying special structures and methods.SOLUTION: In a stationary electromagnetic apparatus, first primary winding 11 and first secondary winding 21 are arranged to overlap each other while maintaining a certain distance across a spacer 7, on a first magnetic leg 2a of a single-phase iron core 2 obtained by molding a magnetic material into a ring shape, and second primary winding 12 and second secondary winding 22 are arranged side-by-side while maintaining a certain distance across a spacer 8 in a center axis B1 direction on a second magnetic leg. The first primary winding 11 and the second primary winding 12 are connected in series by connection means 11a, and the first secondary winding 21 and the second secondary winding 22 are connected in series by connection means 21a.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to static electromagnetic devices, and more particularly to a technique for adjusting leakage inductance by a winding structure in a high-frequency transformer used in a switching power supply, a power converter, and the like.

Background Art

[0002] In recent years, there has been an increase in power transmission and distribution equipment that handles DC power, such as solar power generation systems, emergency battery charging and discharging systems during power outages, and charging systems for electric vehicles. There is an increasing demand for a DC converter (DC-DC converter) that converts an input DC voltage into an AC voltage by an inverter circuit, transforms this by a high-frequency transformer, and then converts this into a DC voltage by a rectifier circuit and outputs it. Depending on the application of the DC-DC converter, a function of controlling the operation timing of switching elements that constitute an inverter and a rectifier circuit and sending DC power bidirectionally is required. Furthermore, since the switching loss generated in the switching element is one of the causes that reduce the conversion efficiency of the DC-DC converter, it is required to utilize the resonance phenomenon of the inductor component L and the capacitor component C in the circuit to realize zero-voltage switching or zero-current switching operation and suppress the switching loss.

[0003] In order to provide the above-described bidirectional control function of DC power and the zero-voltage switching or zero-current switching function required for improving the performance of the DC-DC converter, it is necessary to provide an inductor component L having an appropriate value in series with the high-frequency transformer (see, for example, Patent Document 1). The inductor component L generally has a method of providing a reactor device or the like separately from the high-frequency transformer, and a method of incorporating the leakage inductance Ls into the high-frequency transformer by devising the winding structure of the high-frequency transformer. Compared with the former method, the latter method can reduce the number of parts and the cost.

[0004] In this regard, technologies relating to winding structures for high-frequency transformers having a desired leakage inductance Ls have been disclosed. For example, Patent Document 2 discloses a transformer (static electromagnetic device) configuration comprising a primary winding section arranged on one magnetic leg of a single-phase iron core, at least one first secondary winding section on the same magnetic leg as the primary winding section and magnetically close to the primary winding section, and at least one second secondary winding section arranged on the other magnetic leg of the iron core that is magnetically loose from the primary winding section. Furthermore, Patent Document 3 discloses a configuration for a high-frequency magnetic leakage transformer in which a primary winding and a secondary winding are arranged on an iron core with a required spacing between them, and a ferrite powder molded plate with low magnetic permeability is interposed between the two windings as a pass core to obtain an appropriate value of leakage inductance Ls. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-103257 [Patent Document 2] Japanese Patent Publication No. 2013-98189 [Patent Document 3] Japanese Patent Publication No. 2004-39847 [Overview of the project] [Problems that the invention aims to solve]

[0006] The static electromagnetic device disclosed in Patent Document 2 is a technology that controls the leakage inductance value Ls of the static electromagnetic device by providing a first secondary winding on the same magnetic leg as the primary winding and a second secondary winding on a different magnetic leg, thereby dividing it into magnetically dense and sparse parts. However, since the primary winding is provided on only one magnetic leg, the range of possible values ​​for Ls is narrow, the same as in conventional configurations. On the other hand, the high-frequency magnetic leakage transformer disclosed in Patent Document 3 has a wider range of possible values ​​for Ls compared to conventional configurations, but because it combines a magnetic material with low magnetic permeability in the iron core, it requires more material costs than conventional methods.

[0007] This invention has been made in view of the above background, and its purpose is to provide a stationary electromagnetic device that allows for setting a wide range of leakage inductance Ls. Another object of the present invention is to provide a static electromagnetic device suitable for use in a bidirectional DC-DC converter. [Means for solving the problem]

[0008] The following are some of the representative features of the invention disclosed in this application. According to one feature of the present invention, in a stationary electromagnetic device in which first and second primary windings and first and second secondary windings are wound around two magnetic legs of a single-phase iron core formed from a magnetic material into an annular shape, and the primary windings and secondary windings are connected in series, the first primary winding and the first secondary winding are wound on the first magnetic leg with a constant spacing between them, and the second primary winding and the second secondary winding are wound on the second magnetic leg in a vertical direction with a constant spacing between them. In the first magnetic leg where the windings are wound on top of each other, the first primary winding, which is the high-voltage side, is arranged on the outer circumference, and the first secondary winding, which is the low-voltage side, is arranged on the inner circumference. The primary winding and the secondary winding each consist of strands wound multiple times, and these strands are sealed in a cylindrical shape with a first insulating material and a second insulating material.

[0009] According to another feature of the present invention, the wires constituting the primary winding and secondary winding wound around the magnetic leg are aligned parallel to the axial direction of the magnetic leg and sealed with an insulating material such as resin, and a spacer made of an insulator is interposed in the gap between the structures to maintain a constant distance. Alternatively, the wires constituting the first primary winding and the first secondary winding wound on top of the first magnetic leg may be aligned at a certain angle with respect to the axial direction of the magnetic leg, the insulating material such as resin sealing them may have a tapered structure, and a spacer may be interposed in the gap between them to maintain a constant distance.

[0010] According to another feature of the present invention, the invention comprises the above-mentioned static electromagnetic device, a first inverter circuit connected to the primary winding of the static electromagnetic device, and an inverter circuit connected to the secondary winding. When the first inverter circuit converts the input DC to AC, it controls the AC voltage converted by the static electromagnetic device to be converted back to DC by the second inverter circuit. When the second inverter circuit converts the input DC to AC, it controls the AC voltage converted by the static electromagnetic device to be converted back to DC by the first inverter circuit, thereby performing DC-DC conversion in the reverse direction from the secondary side to the primary side. [Effects of the Invention]

[0011] According to the configuration of the present invention, a wide range of leakage inductance Ls can be incorporated into the high-frequency transformer (static electromagnetic equipment) within a DC-DC converter used in various applications, without requiring the application of special structures or manufacturing methods. Furthermore, since the volume of the high-frequency transformer is reduced compared to conventional structures, the effects of miniaturization and cost reduction can be obtained. In addition, since a static electromagnetic equipment having a high-frequency transformer suitable for bidirectional control of DC power can be realized, it is possible to realize a static electromagnetic equipment and a bidirectional DC-DC converter using the same that have excellent overall conversion efficiency, suppress power loss and promote energy saving. [Brief explanation of the drawing]

[0012] [Figure 1] This is a longitudinal cross-sectional view of a stationary electromagnetic device 1 according to a first embodiment of the present invention. [Figure 2] This is a top view of a stationary electromagnetic device 1 according to a first embodiment of the present invention. [Figure 3] This is a longitudinal cross-sectional view showing the internal structure of the winding of a static electromagnetic device 1 according to the first embodiment of the present invention. [Figure 4] This graph shows the correlation between the volume of a static electromagnetic device 1 and its leakage inductance in a first embodiment of the present invention and a conventional example. [Figure 5] This is a longitudinal cross-sectional view showing the internal structure of the winding of a static electromagnetic device 1A according to a second embodiment of the present invention. [Figure 6] It is a longitudinal sectional view of a static electromagnetic device 1B showing a modified example in which the structure of the winding in FIG. 5 is changed. [Figure 7] It is a schematic diagram showing a method of assembling a static electromagnetic device 1A according to a second embodiment of the present invention. [Figure 8] It is a schematic diagram showing a method of assembling a static electromagnetic device 1C which is a modified example of the assembling method shown in FIG. 7. [Figure 9] It is a longitudinal sectional view of a static electromagnetic device 1D according to a third embodiment of the present invention. [Figure 10] It is a longitudinal sectional view of a static electromagnetic device 1E according to a fourth embodiment of the present invention. [Figure 11] It is a diagram showing an application example of a static electromagnetic device 1F showing a fifth embodiment of the present invention, and is a circuit diagram of a DC-DC converter combining inverter circuits 60 and 70. [Figure 12] It is a longitudinal sectional view of a static electromagnetic device 101A in Conventional Example 1. [Figure 13] It is a longitudinal sectional view of a static electromagnetic device 101B in Conventional Example 2.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following figures, the same parts are denoted by the same reference numerals, and repeated explanations are omitted. Also, in this specification, the directions of front, back, left, right, up, and down are described as the directions shown in the figures.

Examples

[0014] The configuration and effects of the first embodiment of the present invention will be described using Figures 1 to 4. Before describing the first embodiment, the configurations of conventional static electromagnetic devices 101A and 101B will be described using Figures 12 and 13. Figure 12 is a longitudinal cross-sectional view of a conventional static electromagnetic device in a vertical plane. The vertical plane is the plane passing through the central axes of the two first magnetic legs 2a and the second magnetic leg 2b. In Figure 12, the static electromagnetic device 101A has a ring-shaped single-phase iron core 2, and primary windings 11 and 12 and secondary windings 21 and 22 are wound around the two magnetic legs 2a and 2b formed on the single-phase iron core 2, respectively, overlapping each other. In this specification, the method of winding the primary winding and secondary winding on the side closer to (inside) and the side farther from (outside) the magnetic leg, as in the case of the magnetic leg 2a, so that the entire primary winding and secondary winding overlap when viewed radially from the central axis of the magnetic leg, is called "overlapping winding". In this "overlapping winding" configuration, it is common practice to wind the primary windings 11 and 12, through which high-voltage current flows, on the outside, away from the magnetic legs 2a and 2b, while windings 21 and 22, through which low-voltage current flows, on the inside, closer to the magnetic legs 2a and 2b. The primary windings 11 and 12 are connected by a connecting means 11a, and the ends of the primary windings are connected to electrodes 14a and 14b. Similarly, the secondary windings 21 and 22 are connected by a connecting means 21a, and the ends of the secondary windings are connected to electrodes 24a and 24b. A constant radial gap length d is provided between the primary winding 11 and the secondary winding 21, and between the primary winding 12 and the secondary winding 22. The gap length d is set to be constant in the direction of the central axes A1 and B1 of the magnetic legs 2a and 2b. Conventionally, the desired leakage inductance Ls was achieved between the primary and secondary windings by adjusting the size of the gap length d.

[0015] Figure 13 shows another conventional example of a static electromagnetic device 101B. This static electromagnetic device 101B has a ring-shaped single-phase iron core 2, and of the two magnetic legs 2a and 2b formed on the single-phase iron core 2, a primary winding 11 and a secondary winding 21 are wound around magnetic leg 2a with a gap d in the vertical direction, and a primary winding 12 and a secondary winding 22 are wound around magnetic leg 2b with a gap d in the vertical direction. In this specification, the method of forming windings such that the primary winding and the secondary winding are adjacent in a non-contact state when viewed in the direction of the central axis of a single magnetic leg by winding the primary winding and the secondary winding side by side on one side (here, the lower side) and the other side (here, the upper side) when viewed in the direction of the central axis of the magnetic leg is called "parallel winding". The primary windings 11 and 12, wound around the two magnetic legs 2a and 2b, are connected in series by a connecting means 11a, and the secondary windings 21 and 22 are connected in series by a connecting means 21a. The first primary winding 11 and the first secondary winding 21 are arranged to have a constant gap length d in the direction of the central axis of the magnetic legs 2a, and the second primary winding 12 and the second secondary winding 22 are arranged to have a constant gap length d in the direction of the central axis B1. The gap length d is set to be constant at any position in the circumferential direction. Electrodes 14a and 14b are provided at the ends of the primary windings 11 and 12, and electrodes 24a and 24b are provided at the ends of the secondary windings 21 and 22.

[0016] Next, the stationary electromagnetic device 1 of this embodiment will be described using Figure 1. Figure 1 is a vertical cross-sectional view of the stationary electromagnetic device 1 according to the first embodiment. This cross-section (vertical plane) is the plane passing through the central axis A1 of the first magnetic leg portion 2a and the central axis B1 of the second magnetic leg portion 2b. The stationary electromagnetic device 1 has a ring-shaped single-phase iron core 2. The single-phase iron core 2 is manufactured by stacking many thin plates of magnetic material such as thin amorphous or nanocrystalline materials. Eddy current losses can be reduced by using a stacked iron core. In Figure 1, the division surface of the single-phase iron core 2 is omitted from the illustration, but it may be configured as a one-piece iron core without a division surface in the ring portion as shown in Figure 1, or the single-phase iron core 2 may be configured in a divided form as will be explained in Figures 7 and 8 below. Furthermore, the single-phase iron core 2 may be made of sintered (ceramic) ferrite, which is manufactured by mixing, sintering, and molding insulating magnetic materials such as ferrite as powder raw materials.

[0017] A first primary winding 11 and a first secondary winding 21 are wound in overlapping order around the first magnetic leg portion 2a formed on the single-phase iron core 2, and a second primary winding 12 and a second secondary winding 22 are wound adjacent to each other in the direction of the central axis B1 around the second magnetic leg portion 2b (parallel winding). The primary windings 11 and 12 wound over the two magnetic leg portions 2a and 2b are connected in series by a connecting means 11a, and electrodes 14a and 14b are provided at the other ends of each winding. Similarly, the secondary windings 21 and 22 wound over the two magnetic leg portions 2a and 2b are connected in series by a connecting means 21a, and electrodes 24a and 24b are provided at the other ends of the secondary windings 21 and 22 (the ends away from the connecting means 21a). In the schematic diagram of Figure 1, the connecting means 11a and connecting means 21a appear to be wired inside the iron core 2, but in reality they are wired on the outside of the iron core 2. In this embodiment, the first primary winding 11 and the second primary winding 12 can have the same number of turns or different numbers of turns. Similarly, the first secondary winding 21 and the second secondary winding 22 can have the same number of turns or different numbers of turns. The connecting means 11a and connecting means 21a may be connected by pulling out the ends of the primary and secondary windings and connecting them without cutting them, or by cutting them and then reconnecting them, or by preparing connecting wires, or by other methods of electrical connection.

[0018] On the first magnetic leg portion 2a side, the first primary winding 11 and the second secondary winding 21 are arranged such that they have a constant gap d in the radial direction with respect to the central axis A1. A constant gap is also formed between the inner surface of the first secondary winding 21 and the outer surface of the magnetic leg portion 2a. Furthermore, the positional relationship between the inner surface of the first secondary winding 21 and the outer surface of the first magnetic leg portion 2a is such that there is a predetermined gap. On the second magnetic leg portion 2b side, the primary winding 12 and the secondary winding 22 are arranged apart such that they have a constant gap in the axial direction with respect to the central axis B1 (overlapping winding). In other words, in the "overlapping winding" state as described in this embodiment, the regions where the primary winding 12 and the secondary winding 22 are located do not overlap in the direction of the central axis B1 of the second magnetic leg portion 2b. On the second magnetic leg portion 2b side, the second secondary winding 22 and the second primary winding 12 are arranged such that they have a constant gap d in the direction of the central axis B1. The gap length d is set to be constant at both the upper surface of the primary winding 12 and the lower surface of the secondary winding 22. In addition, a constant gap is formed between the inner surface of the second secondary winding 22 and the outer surface of the magnetic leg portion 2a, and between the inner surface of the second primary winding 12 and the outer surface of the magnetic leg portion 2a.

[0019] Normally, AC power transformers are configured to minimize leakage inductance Ls, so it was preferable to have the gap d between the primary winding 11 and the secondary winding 21, and the gap d between the secondary winding 21 and the first magnetic leg 2a as small as possible. In AC transformers, the static electromagnetic device 1 of this embodiment performs unidirectional voltage conversion, where AC power is output from the secondary winding at a voltage converted by electromagnetic induction from the primary winding to the secondary winding. On the other hand, the static electromagnetic device 1 of this embodiment needs to perform AC voltage conversion in the reverse direction, from the secondary windings 21 and 22 to the primary windings 11 and 12, in addition to AC voltage conversion from the primary windings 11 and 12 to the secondary windings 21 and 22. Therefore, rather than minimizing leakage inductance Ls, the gap d between the primary windings 11 and 12 and the secondary windings 21 and 22 is adjusted so that the leakage inductance Ls falls within a desired size (range) in order to achieve the best overall bidirectional voltage conversion efficiency.

[0020] In the embodiment shown in Figure 1, the length of the gap d due to the overlapping winding on the first magnetic leg 2a side and the length of the gap d due to the parallel winding on the second magnetic leg 2b side are set to be equal. However, the gap length on the first magnetic leg 2a side may be set to d1 and the gap length on the second magnetic leg 2b side to d2, and d1 and d2 may be set to different values ​​so that a desired leakage inductance Ls is provided between the windings for each magnetic leg 2a and 2b. The static electromagnetic device 1 is configured to have a width W, a depth D (see Figure 2 below for the symbols), and a height H. The sizes of W, H, and D are arbitrary, but for example, if an AC voltage of 6.6KV is converted to a secondary DC voltage of 380V per static electromagnetic device 1 using, for example, seven static electromagnetic devices 1, the size (W, D, H) of the static electromagnetic device 1 will be about 20 to 30 cm. Furthermore, the static electromagnetic device 1 in this embodiment has no restrictions on its size or weight. It may be small, with (W, D, H) dimensions of less than 20 cm each, or large, with dimensions of 30 cm or more, for example, with (W, D, H) dimensions of about 1 m each. The present invention is not limited to various sizes. single phase This can be applied to a stationary electromagnetic device 1 having an iron core 2.

[0021] Figure 2 is a top view of the stationary electromagnetic device 1 shown in Figure 1. The primary winding 12 and secondary winding 22 on the second magnetic leg portion 2b side have the same internal and external shapes, so in the example of Figure 2, only the secondary winding 22 is visible in the top view. Here, the coil is wound around the magnetic legs 2a and 2b of the single-phase iron core 2, a so-called "external iron type" shape. The single-phase iron core 2 is formed by stacking many thin plate-shaped magnetic materials of the same type. Therefore, the external shapes of the first magnetic leg portion 2a and the second magnetic leg portion 2b are approximately rectangular in cross-sectional shape when viewed from above. The primary winding 11 and secondary winding 21, which are wound coaxially with respect to the first magnetic leg portion 2a, are cylindrical, but they do not have a perfectly circular cross-section along the external shape of the single-phase iron core 2. The cross-sectional shape of the outer surface of the primary winding 11 and secondary winding 21, and the cross-sectional shape of the inner surface, are close to rectangular (approximately rectangular). Similarly, the primary winding 12 and secondary winding 22, which are wound coaxially around the second magnetic leg portion 2b, are also cylindrical, and the cross-sectional shapes of their outer and inner surfaces are approximately rectangular, respectively.

[0022] Figure 3 is a longitudinal cross-sectional view showing an example of the winding structure in this embodiment. Figure 3(A) shows a cross-section of the first primary winding 11 and the first secondary winding 21 wound in overlap with the first magnetic leg portion 2a, and Figure 3(B) shows the second primary winding 12 and the second secondary winding 22 wound side by side with the second magnetic leg portion 2b. The first primary winding 11 is wound with thin strands 15 aligned parallel to the central axis A1 (see Figure 1), and the first secondary winding 21 is wound with thicker strands 25 aligned parallel to the central axis A1. Figure 3 shows the state where the strands 15 are double-wound and the strands 25 are wound once, but the number of times the strands 15 and 25 are wound around the first magnetic leg portion 2a is a design matter and can be set as appropriate. The strands 15 and 25 are formed by twisting together multiple thin wires of copper, aluminum, etc., coated with an insulating material on their surface to form a litz wire, or by winding a thin sheet of copper, aluminum, etc., around an iron core, and after winding, they are sealed with insulating materials 16 and 26 such as resin, respectively.

[0023] When manufacturing the stationary electromagnetic device 1, it is assembled with a spacer 7 interposed in the gap between the sealed windings 11 and 21. Similarly, on the second magnetic leg 2b side, the second primary winding 12 around which the strands 15 are wound and the second secondary winding 22 around which the strands 25 are wound are assembled with a spacer 8 interposed between them. The spacers 7 and 8 are manufactured from an electrically non-conductive insulating material, which can be manufactured, for example, by integrally molding synthetic resin into a ring shape. By precisely controlling the dimensions between the spacers 7 and 8 in this way, a desired leakage inductance Ls can be provided between the windings. In this specification, the gap d is described as the distance between the first insulating material 16 and the second insulating material 26, and the distance between the first insulating material 17 and the second insulating material 27. However, from an electrical perspective, the gap d is not measured in the insulating material but rather in the distance between the end faces of wire 15 and wire 25. Therefore, the value of the gap d must be determined by considering the position of the wires and their positions on the outer surface of the insulating material.

[0024] Next, using Figure 4, the correlation between the volume and leakage inductance Ls of the static electromagnetic device in this embodiment will be explained. Figure 4 is a graph showing the relative changes in volume and leakage inductance Ls when the gap length d between the primary and secondary windings is changed for a static electromagnetic device of the same specifications. The dashed line 45 shows the change in leakage inductance Ls in the first conventional example static electromagnetic device 101A shown in Figure 12, and the dashed line 46 shows the change in leakage inductance Ls in the second conventional example static electromagnetic device 101B shown in Figure 13. The solid line 40 is a straight line showing the relationship between the volume (=W×D×H) and leakage inductance Ls of the static electromagnetic device 1 in this embodiment.

[0025] The points marked 'd' on lines 40, 45, and 46 represent the minimum gap length between the primary and secondary windings required to maintain dielectric strength, while the point marked '2d' represents the point where the gap length is twice the minimum value d. The volume of the static electromagnetic device is calculated by the product of the width W, height H, and depth D of the static electromagnetic device 1, as shown in Figures 1 and 2. Furthermore, the leakage inductance Ls of the static electromagnetic device 1 was determined by 3D electromagnetic field analysis of the effective value V of the voltage generated between electrodes 14a and 14b of the primary winding when the secondary winding of the static electromagnetic device 1 was short-circuited and a sinusoidal current of frequency f and effective value I was passed through the primary winding. Ls=V / (2πfI) … (Formula 1) This is the result obtained using [method / method].

[0026] In the first conventional example of static electromagnetic equipment 101A (see Figure 12), the primary and secondary windings are wound in overlapping order, resulting in tight magnetic coupling and the smallest leakage inductance Ls, as shown by the dashed line 45. In this winding structure, increasing the gap length d reduces magnetic coupling and thus increases Ls, but simultaneously increases the width W of the static electromagnetic equipment, thus increasing its volume. In contrast, in the second conventional example of static electromagnetic equipment 101B (see Figure 13), the primary and secondary windings are wound side by side, resulting in loose magnetic coupling and the largest leakage inductance Ls, as shown by the dashed line 46. In this winding structure, increasing the gap length d further reduces magnetic coupling and thus increases Ls. On the other hand, the gap length d cannot be reduced any further in order to maintain the dielectric strength between the primary and secondary windings, and therefore Ls cannot be reduced any further. As can be seen from the static electromagnetic device 101A having the characteristics of dashed line 45 and the static electromagnetic device 101B having the characteristics of dashed line 46, the leakage inductance Ls differs greatly depending on whether the structure of static electromagnetic device 101A or 101B is adopted, and the adjustment range for each by changing the gap length d is limited.

[0027] In this embodiment, a structure is used in which the first magnetic leg portion 2a of the stationary electromagnetic device is wound with the primary winding 11 and secondary winding 21 shown in Figure 12 overlapping, and a structure is used in which the second magnetic leg portion 2b is wound with the primary winding 12 and secondary winding 22 shown in Figure 12 side by side. The value of the leakage inductance Ls in this structure has characteristics that are somewhere between the two conventional examples, as shown by the solid line 40. In this embodiment, the value of the leakage inductance Ls can be further adjusted by changing the ratio of the number of turns of the first and second primary windings 11 and 12, and the ratio of the number of turns of the first and second secondary windings 21 and 22, respectively. The solid line 40 represents the case where the number of turns is the same for both windings. In Figure 4, the solid line 40a shows the correlation between volume and Ls when the ratio of turns between the magnetic leg section 2a, where the primary and secondary windings are wound on top of each other, and the magnetic leg section 2b, where the windings are wound side by side, is 1:2, while the solid line 40b shows the correlation when the ratio of turns is 2:1. By changing the ratio of turns between the two winding structures with different magnetic coupling strengths, the adjustable range of leakage inductance Ls is broadened, and a stationary electromagnetic device 1 with any volume range and leakage inductance Ls within the hatched region 41 in Figure 4 can be designed. Therefore, the stationary electromagnetic device 1 according to this embodiment can achieve a wide range of leakage inductance Ls, including regions that cannot be designed with the characteristics 45 and 46 of the two conventional examples, without unnecessarily increasing the volume of the stationary electromagnetic device 1. [Examples]

[0028] Next, a second embodiment of the present invention will be described with reference to Figures 5 and 6. Figure 5 is a longitudinal cross-sectional view showing the internal structure of the winding of a stationary electromagnetic device 1A according to the second embodiment of the present invention. Figure 5(A) shows the first primary winding 11 and the first secondary winding 21 wound in overlapping order on the first magnetic leg portion 2a. The strands 15 and 25 constituting the first primary winding 11 and the first secondary winding 21, which are wound in overlapping order on the first magnetic leg portion 2a side, are aligned at a constant angle θ with respect to the axial direction of the first magnetic leg portion 2a, and are sealed with a spacer 7a made of resin or the like. The angle θ is, for example, about 0° to 20°. In this case, the inner circumferential surface of the spacer 7a of the primary winding 11 has a tapered structure such that the inner diameter is smaller at the top and increases towards the bottom. On the other hand, on the second magnetic leg portion 2b side, the strands 15 and 25 constituting the second primary winding 12 and the second secondary winding 22, which are wound in overlapping order, are aligned parallel to the direction of the central axis B1 of the second magnetic leg portion 2b, and the primary winding 12 and the second secondary winding 22 are arranged side by side on the magnetic leg portion 2b, similar to Embodiment 1 shown in Figure 3.

[0029] The outer surface of the insulating material 26a of the secondary winding 21 has a conical shape, with a smaller outer diameter at the top and a larger outer diameter towards the bottom. A spacer 7a is interposed in the gap between the inner surface of the insulating material 16a of the primary winding 11 and the outer surface of the insulating material 26a of the secondary winding 21. Three ring-shaped spacers 7a are used here, and by adjusting the dimensions of the spacers 7a and the gap d so that the gap length between the primary winding 11 and the secondary winding 21 is a predetermined value, the desired leakage inductance Ls is achieved between the windings.

[0030] Figure 5(B) shows the second primary winding 12 and the second secondary winding 22 wound side by side around the second magnetic leg portion 2b. The structure of the second magnetic leg portion 2b where the windings are side by side is the same as the structure shown in Figure 3(B), and the second primary winding 12 and the second secondary winding 22 are arranged with a gap between them in the direction of the central axis B1 by two ring-shaped spacers 8 of different diameters.

[0031] Figure 6 is a longitudinal cross-sectional view showing a modified static electromagnetic device 1B of Figure 5, in which the winding structure has been changed. In the static electromagnetic device 1B of Figure 5, the strands 15 and 25 were aligned vertically at a slight angle θ with respect to the central axis A1 of the first magnetic leg 2a. In contrast, in the static electromagnetic device 1B shown in Figure 6, the strands 15 and 25 are aligned parallel to the central axis A1 of the first magnetic leg 2a (see Figure 1). The shape of the inner surface of the insulating material 16b of the primary winding 11 and the shape of the outer surface of the insulating material 26b of the secondary winding 21 are made conical, similar to Figure 5(a), by changing the partial radial thickness, and a predetermined gap d is formed by interposing three spacers 7a of different diameters between them. On the other hand, the structure of the second magnetic leg portion 2b, which is wound side by side, is the same as the structure of the primary winding 12 and secondary winding 22 shown in Figures 3(B) and 5(b), and the second primary winding 12 and the second secondary winding 22 are arranged with a gap between them in the direction of the central axis B1 by two ring-shaped spacers 8 of different diameters.

[0032] Figure 7 is a schematic diagram showing the assembly method of the static electromagnetic device 1A in the second embodiment. In this example, the single-phase core 2 is divided at the upper and lower central positions. This shape has the advantage that the single-phase core 2 can be formed by placing the same part on the upper and lower sides, since the upper and lower parts of the single-phase core 2 are symmetrical. First, the lower single-phase core 2 is placed on a workbench or the like, and the first secondary winding 21 is inserted into the first magnetic leg portion 2a of the single-phase core 2. The secondary winding 21 is held by a jig or the like (not shown) such that a portion of its lower surface is separated by a predetermined distance from the upper surface of the lower connecting portion 2d that connects the lower end of the first magnetic leg portion 2a and the lower end of the second magnetic leg portion 2b of the single-phase core 2. Next, three spacers 7 of different sizes are placed on the outside of the secondary winding 21. Of the three spacers 7, the larger diameter spacer is held by its outer surface on the secondary winding 21 near the bottom, the medium diameter spacer is held near the center, and the small diameter spacer is held by its outer surface on the secondary winding 21 at the upper end. After positioning the three spacers 7 in this way, the first primary winding 11 is inserted from top to bottom. At this time, the tapered shape on the inside of the primary winding 11 restricts its downward movement by the three spacers 7. This state is the positional relationship of the primary winding 11, spacers 7, and secondary winding 21 shown in Figure 6. In summary, on the first primary winding 11 and the first secondary winding 21, a certain angle θ is provided between the inner surface of the first primary winding 11 and the outer surface of the first secondary winding 21, so that even if there are variations in the finished dimensions, the first primary winding 11 is interposed by its own weight when inserted from above. Spacer By using 7, the gap length d can be kept constant. Therefore, the time required to adjust the leakage inductance Ls of the static electromagnetic device 1A can be reduced.

[0033] Next, the second primary winding 12 is inserted into the second magnetic leg portion 2b of the single-phase core 2. The primary winding 12 is held by a jig or the like so that a portion of its lower surface is separated by a predetermined distance from the upper surface of the lower connecting portion 2d that connects the lower end of the first magnetic leg portion 2a and the lower end of the second magnetic leg portion 2b of the single-phase core 2. Next, two ring-shaped spacers 8 of different diameters are placed on the primary winding 12. Next, the second secondary winding 22 is placed on these spacers 8. After this, the upper single-phase core 2 is inserted from top to bottom as shown in the figure, thereby joining the magnetic legs 2a and 2b of the upper single-phase core 2 and the lower single-phase core 2. In this way, the static electric current in the second embodiment is formed. magnetic Device 1A is assembled. Note that static electromagnetic device 1 shown in Figure 1 and static electromagnetic device 1B shown in Figure 8 can be assembled using the same procedure.

[0034] Figure 8 is a schematic diagram showing the assembly method of static electromagnetic equipment 1C, which is a modified version of the assembly method shown in Figure 7. In the method of Figure 7, the dividing surface of the upper single-phase core 2 and the lower single-phase core 2 was located between the second primary winding 12 and the second secondary winding 22, which are wound side by side. When moving the upper single-phase core 2 from top to bottom to join it with the lower single-phase core 2, it must be passed between the second secondary winding 22, which is placed on the second primary winding 12 via a spacer 8. At this time, if the second secondary winding 22 is not held in place by some means (for example, a jig used during manufacturing) to prevent it from shifting laterally (horizontally perpendicular to the central axis B1), there is a risk that the second secondary winding 22 will shift horizontally, making it impossible to insert the upper single-phase core 2 between the first secondary winding 21 and the second secondary winding 22, which worsens the ease of assembly. Therefore, in the static electromagnetic device 1C shown in Figure 8, the upper core 3 and the lower core 4 are made asymmetrical in shape, so that the dividing surface is located at least above the upper surface of the second secondary winding 22.

[0035] In the example shown in Figure 8, by setting the dividing surface to a position where it is located above the upper surface of either the first secondary winding 21 or the second secondary winding 22 after assembly, the ease of assembly of the primary windings 11 and 12 and the secondary windings 21 and 22, particularly the ease of assembly of the secondary windings 21 and 22, can be improved. Furthermore, it becomes easier to route the wiring of the primary windings (11 and 12) connected in series around the extraction cores 3 and 4, and it becomes easier to route the wiring of the secondary windings (21 and 22) connected in series around the extraction cores 3 and 4, making it easier to attach the windings 11, 12, 21, and 22 to the cores 3 and 4. Note that the method of dividing the single-phase core 2 is not limited to the examples in Figures 7 and 8. For example, although the lower core 4 in Figure 8 is U-shaped, it may be made J-shaped, and the upper core 3 may be formed in an inverted J-shape. In that case, if the dividing surface on the first magnetic leg side is the same as the first magnetic leg side in Figure 6, and the dividing surface on the second magnetic leg side is the same as the dividing surface on the second magnetic leg side in Figure 8, the assembly of the second magnetic leg side will not be hindered. Also, the upper iron cores 3 and 4 can be made into common parts. [Examples]

[0036] Figure 9 is a longitudinal cross-sectional view of a stationary electromagnetic device 1D according to a third embodiment of the present invention. In the stationary electromagnetic device 1D, a first primary winding 11 and a first secondary winding 21 are wound around one side of a ring-shaped single-phase iron core 2, i.e., around the first magnetic leg portion 2a, in the longitudinal direction of the magnetic leg portion 2a. A second primary winding 12 and a second secondary winding 22 are wound around a part of the second magnetic leg portion 2b on the other side, overlapping each other. Furthermore, a third primary winding 13 is wound below the second secondary winding 22 of the second magnetic leg portion 2b, in the longitudinal direction of the magnetic leg portion 2b. The primary windings (11, 12, 13) wound around the two magnetic leg portions are connected in series by connecting means 11a and 12a. Here, the high-voltage side connecting means 11a can be formed from strands of wire. On the first magnetic leg portion 2a side, the primary winding 11 is positioned on the upper side, and the primary winding 12 on the second magnetic leg portion 2b side, which is wound in tandem, is positioned on the outer circumference. Therefore, the primary windings 11 and 12 can be connected at the shortest distance between the first magnetic leg portion 2a and the second magnetic leg portion 2b using the connecting means 11a. In addition, the primary windings 12 and 13 can also be connected at the shortest distance on the outside of the magnetic leg portion 2b using the connecting means 12a.

[0037] A constant gap length d1 is provided between the parallel-wound primary winding 11 and secondary winding 21, a constant gap length d2 is provided between the overlapping primary winding 12 and secondary winding 22, and a constant gap length d3 is provided between the parallel-wound primary winding 13 and secondary winding 22. By adjusting the lengths of these gaps d1 to d3, a desired leakage inductance Ls can be provided between the windings. Although not shown in Figure 9, in this embodiment as well, it is preferable to provide insulating spacers 7 and 8 between each winding to reliably maintain the gap length between the windings, similar to embodiments 1 and 2.

[0038] In the third embodiment, the magnetic coupling between the primary winding 12 and the secondary winding 22 becomes tight. This overlapping winding portion is part of the second magnetic leg portion 2b, and the magnetic coupling of the remaining portion is loose. Therefore, the leakage inductance Ls is larger than in the first and second embodiments. Furthermore, while maintaining the configuration of this embodiment, the value of the leakage inductance Ls can be controlled by changing the turns ratio of the windings wound around the first magnetic leg portion 2a and the second magnetic leg portion 2b. In this case, the range of leakage inductance Ls that can be incorporated into the stationary electromagnetic device 1D, i.e., the region 41 shown in Figure 4, can be shifted upward. [Examples]

[0039] A fourth embodiment of the present invention will be described with reference to Figure 10. Figure 10 is a longitudinal cross-sectional view of a stationary electromagnetic device 1E according to the fourth embodiment of the present invention. In the stationary electromagnetic device 1E, a first primary winding 11 and a first secondary winding 21 are wound in overlapping order around a first magnetic leg portion 2a formed on a ring-shaped single-phase iron core 2, and a second primary winding 12 and a second secondary winding 22 are wound side by side around a second magnetic leg portion 2b. Furthermore, a third primary winding 13 is wound on the outside of the second secondary winding 22. The primary windings 11 and 12, and 12 and 13 wound around the two magnetic leg portions are connected in series by connecting means 11a and 13a. A constant gap length d1 to d3 is provided between the primary winding 11 and the secondary winding 21, making it easy to have a desired leakage inductance Ls between the windings by setting d1. Although not shown in Figure 10, in Example 4, as in Examples 1 and 2, it is preferable to provide insulating spacers 7 and 8 between each winding in order to stably maintain the gap lengths d1 to d3 between the windings.

[0040] In the fourth embodiment, in the first magnetic leg portion 2a, the primary winding 11 and the secondary winding 21 are wound in tandem, and the magnetic coupling of these windings is tight. On the second magnetic leg portion 2b side, in the upper portion when viewed in the direction of the central axis B1, the primary winding 1 is wound on the outer circumference of the secondary winding 22. 2 The remaining lower part is wound in layers, and the primary winding 1 3 As a result of the arrangement, the secondary winding 22 and the primary winding 1 2 These are wound side by side. In this case, the second secondary winding 22 and the 2 Primary winding 1 2 The magnetic coupling is tight, and the second secondary winding 22 and the 3 Primary winding 1 3 The magnetic coupling is sparse. Therefore, the leakage inductance Ls is smaller than in the first and second embodiments. Furthermore, while maintaining the configuration of this embodiment, the value of the leakage inductance Ls can be controlled by changing the turns ratio of the windings wound around the first magnetic leg portion 2a and the second magnetic leg portion 2b. In this case, the range of leakage inductance Ls that can be incorporated into the stationary electromagnetic device 1E, i.e., the region 41 shown in Figure 4, can be shifted downwards. [Examples]

[0041] Next, a fifth embodiment of the present invention will be described using Figure 11. Figure 11 is a schematic circuit diagram of a bidirectional DC-DC converter 50 that transforms a DC voltage by combining the static electromagnetic device 1 of the first embodiment, an inverter circuit 60 connected to the primary side (14a, 14b) of the static electromagnetic device 1, and an inverter circuit 70 arranged on the secondary side of the static electromagnetic device 1. The static electromagnetic device 1 is the same configuration as shown in Figures 1 to 3, but this is merely an example, and any of the static electromagnetic devices 1A to 1E shown in Embodiments 2 to 4 may be included in the circuit of Figure 11. The first inverter circuit 60 is connected to the electrodes 14a and 14b of the primary winding of the static electromagnetic device 1, and the second inverter circuit 70 is connected to the electrodes 24a and 24b of the secondary winding of the static electromagnetic device 1. Known circuits can be used for the inverter circuits 60 and 70, so only a brief explanation will be given here.

[0042] The first inverter circuit 60 consists of multiple switching elements (four in this case) 61-64 and one or more capacitors 65. The DC voltage V input to the DC-DC converter 50 dc1 The current is converted into an AC voltage of any frequency by switching elements 61-64 arranged in a bridge configuration and input to the primary windings 11 and 21 of the stationary electromagnetic device 1. Although not shown in Figure 11, the inverter circuit 60 is supplied with AC of a predetermined frequency between the primary windings 11 and 12 by the on / off control of the gate voltage by a control unit (not shown). Field-effect transistors (FETs), insulated-gate bipolar transistors (IGBTs), etc., can be used as switching elements 61-64.

[0043] The static electromagnetic device 1 converts the voltage according to the turns ratio of the primary windings 11 and 12 and the secondary windings 21 and 22, and the transformed AC is output to electrodes 24a and 24b. The AC output to electrodes 24a and 24b is converted back to DC by the second inverter circuit 70, resulting in a DC voltage V dc2The output is as follows. The second inverter circuit 70 can have the same circuit configuration as the first inverter circuit 60, and the gate voltages of four switching elements 71 to 74 connected in a bridge configuration are controlled on and off by a control unit (not shown). One or more capacitors 75 are provided between the positive and negative terminals on the output side of the switching elements 71 to 74.

[0044] In the bidirectional DC-DC converter 50, the input from the secondary winding side is output to the primary winding side, making it possible to return regenerative power from the inductive equipment on the secondary winding side to the supply side on the primary winding side. For this reason, instead of providing a simple rectifier circuit such as a diode bridge on the secondary winding side, an inverter circuit 70 is provided. In such a bidirectional DC-DC converter 50, an optimal leakage inductance Ls value can be set considering not only the forward voltage conversion (voltage conversion from the primary winding side to the secondary winding side) but also the reverse voltage conversion (voltage conversion from the secondary winding side to the primary winding side), so that the conversion loss when returning surplus energy from a storage battery or the like on the secondary side to the primary side can be reduced. Thus, the present invention has made it possible to realize a bidirectional DC-DC converter 50 that can improve the overall energy reuse efficiency and contribute to energy saving, and a static electromagnetic device 1 suitable for use therein.

[0045] Although the present invention has been described above based on several embodiments, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. [Explanation of symbols]

[0046] 1, 1A~1F Stationary electromagnetic equipment 2 (single-phase) iron core 2a, 2b magnetic legs 2d Lower connection part (of the magnetic leg) 3, 4 Iron core 7, 8 Spacers 11, 12, 13 Primary winding 11a, 12b, 13a (connection means for the primary winding) 14a, 14b (electrodes of the primary winding) 15 (Primary winding) strands 16, 16a, 16b, 17, 18 (Insulators for the primary winding) 21, 22 Secondary winding 21a, 22a (Secondary winding) connection means 24a, 24b (electrodes of the secondary winding) 25 (Secondary winding) strands 26, 26a, 26b, 27, 28 (Insulators for the secondary winding) 40, 40a, 40b Volume and leakage inductor of a static electromagnetic device according to the first embodiment of the present invention 41 Designable range of static electromagnetic equipment of the first embodiment of the present invention 45 Correlation between volume and leakage inductance of the first conventional static electromagnetic device 101A 46 Correlation between volume and leakage inductance of a second conventional static electromagnetic device 101B 50 DC-DC Converters 60, 70 inverter circuits d. Gap length between the primary and secondary windings Ls (leakage inductance of static electromagnetic equipment) W (width of stationary electromagnetic equipment) H (height of stationary electromagnetic equipment) D (depth of stationary electromagnetic equipment)

Claims

1. In a stationary electromagnetic device in which a first magnetic leg portion and a second magnetic leg portion of a single-phase iron core formed by shaping a magnetic material into a ring are wound with first and second primary windings and first and second secondary windings, respectively, the first primary winding and the second primary winding are connected in series, and the first secondary winding and the second secondary winding are connected in series, The first magnetic leg portion is wound with the first primary winding and the first secondary winding overlapping while maintaining a constant distance between them. The second magnetic leg portion is wound with the second primary winding and the second secondary winding side by side in the direction of the central axis of the second magnetic leg portion, without overlapping radially, and maintaining a constant distance between them. A stationary electromagnetic device characterized in that the winding structure for the first magnetic leg and the winding structure for the second magnetic leg are different.

2. The static electromagnetic device according to claim 1, characterized in that the first primary winding and the second primary winding have the same or different number of turns, and the first secondary winding and the second secondary winding have the same or different number of turns.

3. In the first magnetic leg portion, The first primary winding includes strands that have been wound multiple times, and the strands are sealed in a cylindrical shape with insulating material. The first secondary winding includes strands that have been wound multiple times and is sealed in a cylindrical shape with insulating material. The static electromagnetic device according to claim 2, characterized in that a constant distance is maintained between the primary winding and the secondary winding while interposing a first spacer in the gap between the two insulating materials, and the primary winding and the secondary winding are aligned coaxially with respect to the center line of the first magnetic leg.

4. In the second magnetic leg portion, The second primary winding includes strands wound multiple times and is sealed with insulating material. The second secondary winding includes strands that have been wound multiple times and is sealed with insulating material. The static electromagnetic device according to claim 3, characterized in that a constant distance is maintained by interposing a second spacer in the central axis direction of the second magnetic legs of the two insulating materials, and the primary winding and the secondary winding are arranged side by side in the central axis direction of the second magnetic legs.

5. In the first magnetic leg portion, The strands constituting the first primary winding and the first secondary winding are sealed with the insulating material so as to be aligned at a certain angle with respect to the center line direction of the first magnetic leg. The inner surface of the sealed first primary winding is formed at an angle θ with respect to the centerline direction of the first magnetic leg, The outer circumferential surface of the sealed first secondary winding is formed parallel to the inner circumferential surface at an angle θ with respect to the centerline direction of the first magnetic leg, The static electromagnetic device according to claim 4, characterized in that the first primary winding and the first secondary winding are held at a constant distance apart by interposing the first spacer between the inner surface of the first primary winding and the outer surface of the first secondary winding.

6. The static electromagnetic device according to claim 4, characterized in that the single-phase iron core is constructed by laminating thin plate-shaped magnetic materials and is divided in a plane perpendicular to the centerline direction of the first magnetic leg and in a plane perpendicular to the centerline direction of the second magnetic leg.

7. It has a single-phase iron core formed by shaping a magnetic material into a ring and having two magnetic legs, The primary winding is divided into first and second sections and wound around both of the two magnetic legs. The secondary winding is divided into first and second sections and wound around both of the two magnetic leg sections. On one side of the two magnetic legs, the primary winding and the secondary winding are wound in a manner that maintains a constant distance between them in the radial direction. On the other side of the two magnetic legs, the primary winding and the secondary winding are arranged and wound at a constant distance from each other in the direction of the center line of the magnetic legs, so as not to overlap. A static electromagnetic device characterized by having different winding structures for one magnetic leg and for the other magnetic leg.

8. In the one of the magnetic legs that is wound in overlapping directions, The static electromagnetic device according to claim 7, characterized in that the first primary winding is located on the high-voltage side and on the outer circumference side, and the first secondary winding is located on the low-voltage side and on the inner circumference side.

9. The first primary winding includes strands that have been wound multiple times and is sealed in a cylindrical shape with a first insulating material. The first secondary winding includes strands wound multiple times and is sealed in a cylindrical shape with a second insulating material. The static electromagnetic device according to claim 8, characterized in that the first primary winding and the second secondary winding are held at a constant distance apart by interposing a spacer between the first and second insulating materials.

10. In a stationary electromagnetic device in which a primary winding divided into three parts, first, second, and third, is wound around both the first and second magnetic legs of a single-phase iron core formed from a magnetic material in an annular shape, and a secondary winding divided into first and second parts is wound around it, In the first magnetic leg portion, the first primary winding and the first secondary winding are wound together while maintaining a constant distance between them. In the second magnetic leg portion, a superimposed winding portion is formed on one side of the second magnetic leg portion as viewed in the direction of the centerline of the second magnetic leg portion, in which the second primary winding and the second secondary winding are superimposed while maintaining a constant distance in the radial direction, and further, the third primary winding is wound around the magnetic leg portion so as to be aligned at a constant distance from the superimposed winding portion on the other side in the direction of the centerline of the second magnetic leg portion. A static electromagnetic device characterized in that the overlapping winding portion formed by the second primary winding and the second secondary winding is arranged so as not to overlap with the third primary winding.

11. In a stationary electromagnetic device in which a primary winding divided into three parts, first, second, and third, is wound around both the first and second magnetic legs of a single-phase iron core formed from a magnetic material in an annular shape, and a secondary winding divided into first and second parts is wound around it, In the first magnetic leg portion, the first primary winding and the first secondary winding are wound side by side, maintaining a constant distance between them so that they do not overlap when viewed in the direction of the central axis of the first magnetic leg portion. In the second magnetic leg portion, a superimposed winding portion is formed on one side of the second magnetic leg portion as viewed in the direction of the centerline of the second magnetic leg portion, in which the second primary winding and the second secondary winding are superimposed while maintaining a constant distance in the radial direction, and further, the third primary winding is wound around the magnetic leg portion so as to be aligned at a constant distance from the superimposed winding portion on the other side in the direction of the centerline of the second magnetic leg portion. A static electromagnetic device characterized in that the overlapping winding portion formed by the second primary winding and the second secondary winding is arranged so as not to overlap with the third primary winding.

12. The stationary electromagnetic device according to any one of claims 1 to 11, A first inverter circuit connected to the primary winding, having a plurality of switching elements and one or more capacitors, It has a second inverter circuit connected to the secondary winding, which has a plurality of switching elements and one or more capacitors, When the first inverter circuit converts the incoming DC to AC, it performs DC-DC conversion from the primary side to the secondary side by controlling the AC voltage converted by the static electromagnetic equipment to be converted back to DC by the second inverter circuit. A bidirectional DC-DC converter using static electromagnetic equipment, characterized in that when the second inverter circuit converts the incoming DC to AC, it controls the first inverter circuit to convert the AC voltage converted by the static electromagnetic equipment back to DC, thereby performing reverse DC-DC conversion from the secondary side to the primary side.

13. A static electromagnetic device characterized in that the winding constituting the static electromagnetic device according to any one of claims 1 to 11 is a litz wire made by twisting together a plurality of fine wires of copper or aluminum coated with an insulating material on their surface, or a thin sheet material of copper or aluminum wound around an iron core.

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