Power converter

Abstract

A power conversion device according to the present disclosure comprises: at least one insulation structure (20); and a plurality of power conversion units (10). The at least one insulation structure has a plurality of step structures (30) stacked along a first direction (DR1). Each of the step structures has a first bottom wall (31), a first upper wall (32), a first side wall (33), a second side wall (34), and a first back wall (35). The first bottom wall and the first upper wall are opposite to each other at an interval in the first direction. The first side wall and the second wall are opposite to each other at an interval in a second direction (DR2) orthogonal to the first direction. The upper end and the lower end of the first side wall are respectively connected to one-side ends of the first bottom wall and the first upper wall in the first direction. The upper end and the lower end of the second side wall are respectively connected to the other-side ends of the first bottom wall and the first upper wall in the first direction.

Description

Technical Field

[0001] The present disclosure relates to a power conversion device.

Background Art

[0002] For example, Japanese Patent No. 6995259 (Patent Document 1) describes a power conversion device. The power conversion device described in Patent Document 1 has a plurality of sub-modules and an insulating structure. The plurality of sub-modules are arranged in a grid pattern along a first direction and a second direction. The first direction and the second direction are a horizontal direction and a vertical direction, respectively. Between two adjacent sub-modules in the first direction and between two adjacent sub-modules in the second direction, they are insulated by an insulating structure.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the power conversion device described in Patent Document 1, there is room for improvement in suppressing the occurrence of discharge. The present disclosure has been made in view of the problems of the prior art as described above. More specifically, the present disclosure provides a power conversion device capable of suppressing the occurrence of discharge.

Means for Solving the Problems

[0005] The power conversion device of the present disclosure comprises at least one insulating structure and a plurality of power conversion units. The at least one insulating structure has a plurality of tiered structures stacked along a first direction. Each of the plurality of tiered structures has a first bottom wall, a first top wall, a first side wall, a second side wall, and a first back wall. The first bottom wall and the first top wall are spaced apart and facing each other in the first direction. The first side wall and the second side wall are spaced apart and facing each other in a second direction perpendicular to the first direction. The upper and lower ends of the first side wall are connected to one end of the first bottom wall and the first top wall in the first direction, respectively. The upper and lower ends of the second side wall are connected to the other end of the first bottom wall and the first top wall in the first direction, respectively. The first back wall is connected to one end of the first bottom wall, the first side wall, and the second side wall in a third direction perpendicular to the first and second directions. The first and second side walls are divided into multiple parts spaced apart from each other in the third direction. The multiple power conversion units are spaced apart along the first direction within each of the multiple tiered structures. Each of the multiple power conversion units has a bottom surface, a top surface, a first side surface, a second side surface, and a back surface. The bottom surface is in contact with the first bottom wall. The top surface is spaced apart from the first top wall. The first and second side surfaces face one side and the other side in the second direction, respectively. The back surface faces one side in the third direction. In the first power conversion unit adjacent to the first side wall of the multiple power conversion units, the corner between the first side surface and the back surface is covered by the corner between the first side wall and the first back wall. In the second power conversion unit adjacent to the second side wall of the multiple power conversion units, the corner between the second side surface and the back surface is covered by the corner between the second side wall and the first back wall. [Effects of the Invention]

[0006] According to the power conversion device of this disclosure, it is possible to suppress the generation of discharge. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic circuit diagram of the power converter 100. [Figure 2] This is a schematic circuit diagram of the power conversion unit 10. [Figure 3] This is a front view of the power converter 100. [Figure 4] This is a rear view of the power converter 100. [Figure 5] This is a first side view of the power converter 100. [Figure 6] This is a second side view of the power converter 100. [Figure 7] This is a cross-sectional view of section VII-VII in Figure 3. [Figure 8] This is a perspective view of the power converter 100. [Figure 9] This is a front view of the insulating enclosure 40. [Figure 10] This is a rear view of the insulating enclosure 40. [Figure 11] This is a first side view of the insulating enclosure 40. [Figure 12] This is a second side view of the insulating enclosure 40. [Figure 13] This is a perspective view of the insulating enclosure 40. [Figure 14] This is a perspective view of a power converter 100 having multiple insulating structures 20. [Figure 15] This is a first side view of a power converter 100 having multiple insulating structures 20. [Figure 16] This is a second side view of a power converter 100 having multiple insulating structures 20. [Figure 17] This is a perspective view of the insulating enclosure 40 in the power converter 100A. [Figure 18] This graph shows the electric field strength at the ridge between the base surface 10a and the side surface 10c. [Figure 19] This is a perspective view of the power converter 200. [Figure 20] This is a side view of the power converter 200. [Figure 21] This is a perspective view of the power converter 300. [Figure 22] This is a rear view of the insulating structure 20 in the power converter 300. [Figure 23] It is a perspective view of the power conversion device 400. [Figure 24] It is a front view of the power conversion device 500. [Figure 25] It is a plan view of the power conversion device 500. [Figure 26] It is an exploded perspective view of the power conversion device 500. [Figure 27A] It is a perspective view showing the position of the maximum electric field portion of the conductive member 70 when the shield member 71 is provided. [Figure 27B] It is a perspective view showing the position of the maximum electric field portion of the conductive member 70 when the shield member 71 is not provided. [Figure 28] It is a perspective view of the power conversion device 600. [Figure 29] It is a plan view of the power conversion device 600. [Figure 30] It is a plan view of the power conversion device 600 according to the modified example.

Mode for Carrying Out the Invention

[0008] Details of the embodiments of the present disclosure will be described while referring to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations will not be repeated.

[0009] Embodiment 1. The power conversion device according to Embodiment 1 will be described. The power conversion device according to Embodiment 1 is referred to as the power conversion device 100.

[0010] (Configuration of Power Conversion Device 100) The configuration of the power conversion device 100 will be described below.

[0011] The power conversion device 100 is, for example, an MMC (Multilevel Modular Convertor) type HVDC (High Voltage DC) converter. However, the power conversion device 100 is not limited thereto.

[0012] Figure 1 is a schematic circuit diagram of the power converter 100. As shown in Figure 1, The power converter 100 is It has multiple sets of upper arms 110 and lower arms 120. The upper arms 110 and lower arms 120 are connected in series. Each of the multiple sets of upper arms 110 and lower arms 120 is connected in parallel. A transformer 130 is connected between the upper arms 110 and lower arms 120. The upper arms 110 and lower arms 120 have multiple power conversion units 10 connected in series.

[0013] Figure 2 is a schematic circuit diagram of the power conversion unit 10. As shown in Figure 2, the power conversion unit 10 includes, for example, switching elements 11a and 11b, diodes 12a and 12b, a capacitor 13, and connecting wires 14a and 14b.

[0014] Switching elements 11a and 11b are, for example, IGBTs (Insulated Gate Bipolar Transistors). Switching elements 11a and 11b are connected in series.

[0015] Diodes 12a and 12b are connected in parallel to the switching elements 11a and 11b, respectively, so as to be reverse-biased. Capacitor 13 is connected in parallel to the switching elements 11a and 11b, which are connected in series.

[0016] The connecting line 14a is connected to the emitter of the switching element 11a and the collector of the switching element 11b. The connecting line 14b is connected to the emitter of the switching element 11b. The connecting line 14a of one power conversion unit 10 is connected to the connecting line 14b of another adjacent power conversion unit 10. In this way, the power conversion unit 10 constitutes a half-bridge type converter cell. However, the power conversion unit 10 may also constitute a full-bridge type converter cell.

[0017] Figure 3 is a front view of the power converter 100. Figure 4 is a rear view of the power converter 100. Figure 5 is a first side view of the power converter 100. Figure 6 is a second side view of the power converter 100. Figure 7 is a cross-sectional view taken between VII and VII in Figure 3. Figure 8 is a perspective view of the power converter 100. As shown in Figures 3 to 8, the power converter 100 has an insulating structure 20.

[0018] The insulating structure 20 is formed from an electrically insulating material. The insulating structure 20 is formed from, for example, FRP (Fiber Reinforced Plastic), glass epoxy resin, cast epoxy resin, polyethylene, polyvinyl chloride, silicone, fluoropolymer synthetic rubber, nylon, electrically insulating ceramics, etc. The insulating structure 20 has a plurality of stepped structures 30.

[0019] Multiple tiered structures 30 are stacked along a first direction DR1. The first direction DR1 corresponds, for example, to the vertical direction. Each tiered structure 30 has a bottom wall 31, a top wall 32, side walls 33, side walls 34, a back wall 35, and multiple partition walls 36. The top wall 32 of one tiered structure 30 is connected to the bottom wall 31 of another tiered structure 30 adjacent to that tiered structure 30 by adhesive, bolts, or the like.

[0020] The bottom wall 31 and the top wall 32 are spaced apart and facing each other in the first direction DR1. The side walls 33 and 34 are spaced apart and facing each other in the second direction DR2. The second direction DR2 is perpendicular to the first direction DR1. The second direction DR2 corresponds to, for example, the horizontal direction. The lower and upper ends of the side wall 33 are connected to one end (the right end in Figure 3) of the bottom wall 31 and the top wall 32 in the second direction DR2, respectively. The lower and upper ends of the side wall 34 are connected to the other end (the left end in Figure 3) of the bottom wall 31 and the top wall 32 in the second direction DR2, respectively.

[0021] The third direction DR3 is perpendicular to the first direction DR1 and the second direction DR2, and corresponds to, for example, the horizontal direction. The back wall 35 is connected to one end (the right end in Figure 5) of the bottom wall 31, side wall 33, and side wall 34 in the third direction DR3. However, the back wall 35 is not connected to one end of the top wall 32 in the third direction DR3, and there is an opening between the back wall 35 and the top wall 32. Multiple partition walls 36 are lined up along the second direction DR2 between the side wall 33 and side wall 34. The lower and upper ends of the partition walls 36 are connected to the bottom wall 31 and the top wall 32, respectively. One end of the partition wall 36 in the third direction DR3 is connected to the back wall 35.

[0022] Power conversion units 10 are arranged inside the space defined by the bottom wall 31, top wall 32, side wall 33, back wall 35 and partition wall 36, inside the space defined by the bottom wall 31, top wall 32, side wall 34, back wall 35 and partition wall 36, and inside the space defined by the bottom wall 31, top wall 32, back wall 35 and two adjacent partition walls 36. From another perspective, the multiple power conversion units 10 are lined up along the second direction DR2 inside the stepped structure 30. Two adjacent power conversion units 10 in the second direction DR2 are electrically connected to each other. A power conversion unit 10 at one end or the other end of the second direction DR2 (power conversion unit 10A or power conversion unit 10B, described later) may also be electrically connected to power conversion units 10 other than the adjacent power conversion units 10 in the second direction DR2.

[0023] The side wall 33 is divided into multiple parts in the third direction DR3. The side wall 33 has, for example, a first part 33a and a second part 33b. The first part 33a and the second part 33b are located at one end and the other end of the side wall 33 in the third direction DR3, respectively. The first part 33a and the second part 33b are spaced apart in the third direction DR3. In other words, the side wall 33 is open between the first part 33a and the second part 33b.

[0024] The side wall 34 is divided into multiple parts in the third direction DR3. The side wall 34 has, for example, a first part 34a and a second part 34b. The first part 34a and the second part 34b are located at one end and the other end of the side wall 34 in the third direction DR3, respectively. The first part 34a and the second part 34b are spaced apart in the third direction DR3. In other words, the side wall 34 is open between the first part 34a and the second part 34b.

[0025] The partition wall 36 is divided into multiple parts in the third direction DR3. The partition wall 36 has, for example, a first part 36a and a second part 36b. The first part 36a and the second part 36b are located at one end and the other end of the partition wall 36 in the third direction DR3, respectively. The first part 36a and the second part 36b are spaced apart in the third direction DR3. In other words, the partition wall 36 has an opening between the first part 36a and the second part 36b.

[0026] The stepped structure 30 has a plurality of insulating housings 40. The plurality of insulating housings 40 are arranged along a second direction DR2. Figure 9 is a front view of the insulating housing 40. Figure 10 is a rear view of the insulating housing 40. Figure 11 is a first side view of the insulating housing 40. Figure 12 is a second side view of the insulating housing 40. Figure 13 is a perspective view of the insulating housing 40. As shown in Figures 10 to 13, the insulating housing 40 has a bottom wall 41, a top wall 42, a side wall 43, a side wall 44, and a back wall 45.

[0027] The bottom wall 41 and the top wall 42 are spaced apart and facing each other in the first direction DR1. The side walls 43 and 44 are spaced apart and facing each other in the second direction DR2. The lower and upper ends of the side wall 43 are connected to one end of the bottom wall 41 and the top wall 42 in the second direction DR2, respectively. The lower and upper ends of the side wall 44 are connected to the other end of the bottom wall 41 and the top wall 42 in the second direction DR2, respectively. The back wall 45 is connected to one end of the bottom wall 41, the side walls 43 and the side walls 44 in the third direction DR3. The back wall 45 is not connected to one end of the top wall 42 in the third direction DR3, and there is an opening between the back wall 45 and the top wall 42.

[0028] The side wall 43 is divided into multiple parts in the third direction DR3. The side wall 43 has, for example, a first part 43a and a second part 43b. The first part 43a and the second part 43b are located at one end and the other end of the side wall 43 in the third direction DR3, respectively. The side wall 43 is divided into multiple parts in the third direction DR3. The side wall 44 has, for example, a first part 44a and a second part 44b. The first part 44a and the second part 44b are located at one end and the other end of the side wall 44 in the third direction DR3, respectively.

[0029] The side wall 43 of one insulating enclosure 40 is connected to the side wall 44 of another insulating enclosure 40 adjacent to that one insulating enclosure 40 by adhesive, bolts, etc. The bottom wall 41 is part of the bottom wall 31, and the top wall 42 is part of the top wall 32. The side wall 43 at one end in the second direction DR2 is part of side wall 33, and the side wall 44 at the other end in the second direction DR2 is part of side wall 34. Adjacent side walls 43 and side walls 44 form a partition wall 36. A power conversion unit 10 is located inside the insulating enclosure 40.

[0030] The power conversion unit 10 has a bottom surface 10a and a top surface 10b. The power conversion unit 10 also has a side surface 10c, a side surface 10d, and a rear surface 10e. The bottom surface 10a, top surface 10b, side surfaces 10c, side surfaces 10d, and rear surface 10e are surfaces of the case of the power conversion unit 10. This case is, for example, gold It is made of metal. The bottom surface 10a is in contact with the bottom wall 31 (bottom wall 41). The top surface 10b is spaced apart from the top wall 32 (top wall 42). The side surfaces 10c and 10d face one and the other side in the second direction DR2, respectively. The back surface 10e faces one side in the third direction DR3.

[0031] Among the multiple power conversion units 10 located inside the stepped structure 30, the one adjacent to the side wall 33 is designated as power conversion unit 10A. Among the multiple power conversion units 10 located inside the stepped structure 30, the one adjacent to the side wall 34 is designated as power conversion unit 10B.

[0032] In power conversion unit 10A, the corner (first corner) between the side surface 10c and the back surface 10e is covered by the corner (second corner) between the side wall 33 and the back wall 35. In power conversion unit 10B, the corner (third corner) between the side surface 10d and the back surface 10e is covered by the corner (fourth corner) between the side wall 34 and the back wall 35. Preferably, in power conversion unit 10A, the side surface 10c is spaced apart from the side wall 33 in the second direction DR2, and the back surface 10e is spaced apart from the back wall 35 in the third direction DR3. Preferably, in power conversion unit 10B, the side surface 10d is spaced apart from the side wall 34 in the second direction DR2, and the back surface 10e is spaced apart from the back wall 35 in the third direction DR3.

[0033] Figure 14 is a perspective view of a power converter 100 having multiple insulating structures 20. Figure 15 is a first side view of the power converter 100 having multiple insulating structures 20. Figure 16 is a second side view of the power converter 100 having multiple insulating structures 20. As shown in Figures 14 to 16, the power converter 100 may have multiple insulating structures 20. In the example shown in Figures 14 to 16, the power converter 100 has two insulating structures 20. These two insulating structures 20 are called insulating structure 20A and insulating structure 20B. Insulating structures 20A and 20B are arranged back-to-back with a gap between them. That is, insulating structures 20A and 20B are arranged so that their back walls 35 are spaced apart and facing each other.

[0034] In the examples shown in Figures 14 to 16, the potential difference between two adjacent power conversion units 10 is smallest in the second direction DR2, while the potential difference between two adjacent power conversion units 10 is largest in the third direction DR3. In the examples shown in Figures 14 to 16, the insulating structures 20A and 20B are arranged back-to-back with a gap between them. However, if the potential difference between two adjacent power conversion units 10 is small in the third direction DR3, the insulating structures 20A and 20B may be arranged back-to-back without a gap.

[0035] (Effects of power converter 100) The effects of the power converter 100 are explained below.

[0036] As described above, the upper surface 10b is separated from the upper wall 32, while the bottom surface 10a is in contact with the bottom wall 31. Therefore, the area where the bottom surface 10a and the bottom wall 31 are in contact becomes a triple junction of air, metal, and insulator, where electric field concentration occurs and it is likely to become a discharge initiation point. Extending the back wall 35 to reach one end of the upper wall 32 in the third direction DR3 improves the dielectric strength due to barrier insulation. However, if an insulator with a higher dielectric constant than air is present near the electric field concentration point, the electric field at the concentration point will be stronger than in the case where such an insulator is not present.

[0037] In the power converter 100, since there is an opening between the upper wall 32 and the back wall 35, an insulator is present only in the vicinity of the electrolytic concentration point, and there is no insulator in areas that are unlikely to become discharge starting points. As a result, with the power converter 100, the electric field concentration near the electric field concentration point is mitigated, making it less likely for discharge to occur.

[0038] Since the back surface 10e is the surface facing another power conversion unit 10 where the potential difference is maximum, the first and third corners are prone to electric field concentration and become discharge initiation points. In the power conversion device 100, the first and third corners are covered by the second and fourth corners, respectively, and the side walls 33 and 34 are divided into multiple parts. As a result, the insulator is present only near the electric field concentration points and is not present in areas that are less likely to become discharge initiation points. Consequently, with the power conversion device 100, electric field concentration near the electric field concentration points is mitigated, making discharge less likely to occur.

[0039] The power converter relating to the comparative example is power converter 100A. The configuration of power converter 100A is the same as that of power converter 100, except for the insulating housing 40. Figure 17 is a perspective view of the insulating housing 40 in power converter 100A. As shown in Figure 17, in the insulating housing 40 of power converter 100A, the side walls 43 and 44 are not divided into multiple parts. Also, in the insulating housing 40 of power converter 100A, the back wall 45 extends to one end of the top wall 42 in the third direction DR3.

[0040] Figure 18 is a graph showing the electric field strength at the ridge between the bottom surface 10a and the side surface 10c. The vertical axis in Figure 18 represents the electric field strength at the ridge between the bottom surface 10a and the side surface 10c. The horizontal axis in Figure 18 represents the distance from the point where the bottom surface 10a, side surface 10c, and back surface 10e intersect. As shown in Figure 18, in power converter 100 and power converter 100A, the point where the bottom surface 10a, side surface 10c, and back surface 10e intersect is the electric field concentration point. However, in power converter 100, A In comparison, the electric field strength at the electric field concentration point is reduced. Thus, in the power converter 100, the electric field concentration near the electric field concentration point is reduced, making it less likely for discharge to occur.

[0041] Embodiment 2. A power converter according to Embodiment 2 will be described. The power converter according to Embodiment 2 will be referred to as power converter 200. Here, we will mainly describe the differences from power converter 100, and will avoid repeating redundant explanations.

[0042] (Configuration of power converter 200) The configuration of the power converter 200 is described below.

[0043] Figure 19 is a perspective view of the power converter 200. Figure 20 is a side view of the power converter 200. As shown in Figures 19 and 20, the power converter 200 has a plurality of power conversion units 10 and a plurality of insulating structures 20 (insulating structures 20A and insulating structures 20B). In this respect, the configuration of the power converter 200 is the same as that of the power converter 100.

[0044] The power converter 200 further includes a plurality of insulating connecting members 50. The insulating connecting members 50 are made of an electrically insulating material. The insulating connecting members 50 connect the insulating structure 20A and the insulating structure 20B. More specifically, the insulating connecting members 50 connect each of the plurality of tiered structures 30 constituting the insulating structure 20A to each of the plurality of tiered structures 30 constituting the insulating structure 20B. Some of the plurality of tiered structures 30 constituting the insulating structure 20A do not need to be connected to some of the plurality of tiered structures 30 constituting the insulating structure 20B by the insulating connecting members 50. In these respects, the configuration of the power converter 200 differs from the configuration of the power converter 100.

[0045] (Effects of power converter 200) The effects of the power converter 200 are explained below.

[0046] In the power converter 200, the insulating structure 20A and the insulating structure 20B are connected by an insulating connecting member 50, so that the distance between the insulating structure 20A and the insulating structure 20B is mechanically kept constant. Therefore, even when vibrations such as earthquakes are applied, the insulating distance between the insulating structure 20A and the insulating structure 20B is prevented from becoming smaller than expected.

[0047] Embodiment 3. A power conversion device according to Embodiment 3 will be described. 3 Let's assume it's 00. Here, we will mainly explain the differences from the power converter 200, and will avoid repeating redundant explanations.

[0048] (Configuration of power converter 300) The configuration of the power converter 300 is described below.

[0049] Figure 21 is a perspective view of the power converter 300. Figure 22 is a rear view of the insulating structure 20 in the power converter 300. As shown in Figures 21 and 22, the power converter 300 has a plurality of power conversion units 10, a plurality of insulating structures 20 (insulating structure 20A and insulating structure 20B), and a plurality of insulating connecting members 50. In this respect, the configuration of the power converter 300 is the same as the configuration of the power converter 200.

[0050] In the power converter 300, the stepped structure 30 has a bottom wall 31, an upper wall 32, side walls 33, side walls 34, and a back wall 35, but it does not have a partition wall 36 and is not composed of multiple insulating housings 40. In this respect, the configuration of the power converter 300 differs from the configuration of the power converter 200. In the example shown in Figures 21 and 22, the stepped structure 30 does not have any partition walls 36, but a partition wall 36 may be placed in part between two adjacent power converter units 10 in the second direction DR2.

[0051] (Effects of power converter 300) The effects of the power converter 300 are explained below.

[0052] The potential difference between two adjacent power conversion units 10 is smallest in the second direction DR2. When the potential difference between two adjacent power conversion units 10 in the second direction DR2 is small, dielectric breakdown between the two adjacent power conversion units 10 in the second direction DR2 can be suppressed even without the partition wall 36. Therefore, in the power conversion device 300, it is possible to reduce the weight of the stepped structure 30 while suppressing dielectric breakdown between two adjacent power conversion units 10 in the second direction DR2.

[0053] Embodiment 4. A power converter according to Embodiment 4 will be described. The power converter according to Embodiment 4 will be referred to as power converter 400. Here, we will mainly describe the differences from power converter 100, and will avoid repeating redundant explanations.

[0054] (Configuration of power converter 400) The configuration of the power converter 400 is described below.

[0055] Figure 23 is a perspective view of the power converter 400. As shown in Figure 23, the power converter 400 has a plurality of power conversion units 10 and a plurality of insulating structures 20 (insulating structure 20A and insulating structure 20B). In this respect, the configuration of the power converter 400 is the same as that of the power converter 100.

[0056] The power converter 400 further has a plurality of insulating pillars 60. The insulating pillars 60 are formed of an electrically insulating material. The insulating pillars 60 are formed of, for example, FRP, glass epoxy resin, other epoxy resins, polyethylene, polyvinyl chloride, silicone, fluoropolymer synthetic rubber, nylon, polymer insulators, ceramic insulators, etc. The insulating pillars 60 extend along a first direction DR1. The plurality of insulating pillars 60 are arranged, for example, in a grid pattern in a plan view. The insulating structure 20A and the insulating structure 20B are arranged on the plurality of insulating pillars 60. In these respects, the configuration of the power converter 400 differs from the configuration of the power converter 100.

[0057] (Effects of power converter 400) The effects of the power converter 400 are explained below.

[0058] When a surge voltage is applied due to malfunctions during operation, the operation of peripheral equipment, lightning strikes, etc., a discharge may occur from the power conversion unit 10 toward the ground. In the power conversion device 400, the distance between the power conversion unit 10 and the ground is ensured by the fact that the insulating structures 20A and 20B are supported by multiple insulating pillars 60, so the occurrence of such discharges can be suppressed.

[0059] Embodiment 5. A power converter according to Embodiment 5 will be described. The power converter according to Embodiment 5 will be referred to as power converter 500. Here, the differences from power converter 400 will be mainly explained, and redundant explanations will not be repeated.

[0060] (Configuration of power converter 500) The configuration of the power converter 500 is described below.

[0061] Figure 24 is a front view of the power converter 500. Figure 25 is a plan view of the power converter 500. Figure 26 is an exploded perspective view of the power converter 500. In Figure 26, two power conversion units 10, two insulating housings 40, and one conductive member 70 are shown as excerpts. As shown in Figures 24 to 26, the power converter 500 has multiple power conversion units 10, multiple insulating structures 20 (insulating structure 20A and insulating structure 20B), and multiple insulating support columns 60. In this respect, the configuration of the power converter 500 is the same as the configuration of the power converter 400.

[0062] The power converter 500 has a plurality of conductive members 70 and a plurality of shielding members 71. Two adjacent power converter units 10 in the second direction DR2 are electrically connected by the conductive members 70. More specifically, the conductive members 70 are connected to connecting wires 14a or 14b. However, in Figure 26, the connection wires 14a or 14b and the conductive members 70 are not shown. The conductive members 70 are attached to the front surface 10f of the power converter unit 10. The conductive members 70 are attached, for example, by bolts or adhesive.

[0063] The conductive member 70 is formed of an electrically conductive material. The conductive member 70 is formed of, for example, aluminum, copper, iron, tin, stainless steel, alloys thereof, or other metallic materials. The conductive member 70 may also be formed of a conductive plastic mixed with carbon-based materials (carbon, graphite, carbon nanotubes, graphene, etc.), a conductive plastic mixed with metallic materials (silver, nickel, copper, aluminum, tin, stainless steel, iron, etc.), or a conductive plastic mixed with both carbon-based materials and metallic materials.

[0064] The conductive member 70 has a first portion 70a, a second portion 70b, and a third portion 70c. The first portion 70a is connected to one power conversion unit 10, and the second portion 70b is connected to another power conversion unit 10 adjacent to the first power conversion unit 10 in the second direction DR2. The first portion 70a and the second portion 70b extend along the third direction DR3. The third portion 70c is connected to the end of the first portion 70a on the opposite side of the power conversion unit 10 and to the end of the second portion 70b on the opposite side of the power conversion unit 10. The third portion 70c extends along the second direction DR2.

[0065] The conductive member 70 is formed, for example, by bending a plate, so that it stands independently without contacting the components or surrounding structures of the power converter 500. However, the conductive member 70 is not limited to this. The conductive member 70 may be, for example, braided wire.

[0066] The shielding member 71 is made of an electrically conductive material. The shielding member 71 has, for example, a cylindrical portion 71a, a hemispherical portion 71b, and a hemispherical portion 71c. The cylindrical portion 71a is cylindrical and extends along the second direction DR2. The hemispherical portions 71b and 71c are hemispherical and are connected to both ends of the cylindrical portion 71a in the second direction DR2, respectively. The diameters of the hemispherical portions 71b and 71c are greater than the width of the conductive member 70. The shielding member 71 covers the corners of the conductive member 70. More specifically, the corner between the first portion 70a and the third portion 70c is covered by the hemispherical portion 71b, and the corner between the second portion 70b and the third portion 70c is covered by the hemispherical portion 71c. In these respects, the configuration of the power converter 500 differs from the configuration of the power converter 400.

[0067] (Effects of power converter 500) The effects of the power converter 500 are explained below.

[0068] Since the conductive member 70 protrudes to the outside of the power converter 500, when voltage is applied to the power conversion unit 10, electric field concentration is likely to occur at the corners of the conductive member 70. In the power converter 500, the corners of the conductive member 70 are covered by the shield member 71, which can mitigate electric field concentration at the corners of the conductive member 70. Figure 27A is a perspective view showing the location of the maximum electric field of the conductive member 70 when the shield member 71 is present. Figure 27B is a perspective view showing the location of the maximum electric field of the conductive member 70 when the shield member 71 is not present. In Figures 27A and 27B, the location of the maximum electric field of the conductive member 70 is indicated by an arrow. As an example, in the power converter 500, the electric field strength at the maximum electric field of the conductive member 70 can be reduced to about 1 / 3 compared to when the shield member 71 is not present.

[0069] Embodiment 6. A power converter according to Embodiment 6 will be described. The power converter according to Embodiment 6 will be referred to as power converter 600. Here, the differences from power converter 400 will be mainly explained, and redundant explanations will not be repeated.

[0070] (Configuration of power converter 600) The configuration of the power converter 600 is described below.

[0071] Figure 28 is a perspective view of the power converter 600. Figure 29 is a plan view of the power converter 600. As shown in Figures 28 and 29, the power converter 600 has a plurality of power conversion units 10, a plurality of insulating structures 20 (insulating structures 20A and insulating structures 20B), and a plurality of insulating support columns 60. In this respect, the configuration of the power converter 600 is the same as that of the power converter 400.

[0072] The power converter 600 has a plurality of shielding members 80 and a plurality of shielding members 81. Of the plurality of stepped structures 30 that make up the insulating structure 20, the one closest to the insulating support column 60 is designated as stepped structure 30A. Of the plurality of stepped structures 30 that make up the insulating structure 20, the one furthest from the insulating support column 60 is designated as stepped structure 30B. The power converter unit 10 located inside stepped structure 30A is designated as power converter unit 10C. The power converter unit 10 located inside stepped structure 30B is designated as power converter unit 10D.

[0073] Shield member 80 extends along the second direction DR2 so as to cover the corner between the bottom surface 10a and the front surface 10f of the power conversion unit 10C. Shield member 81 extends along the second direction DR2 so as to cover the corner between the top surface 10b and the front surface 10f of the power conversion unit 10D. In other words, shield members 80 and 81 cover the corners of the power conversion unit 10 that face the ground surface. Shield members 80 and 81 are at the same potential as either power conversion unit 10. The connection between shield member 80 and power conversion unit 10 is not shown in the diagram.

[0074] The shield members 80 and 81 each have a cylindrical portion 82 extending along the second direction DR2, and hemispherical portions 83 and 84 connected to both ends of the cylindrical portion 82. However, the shape of the shield members 80 and 81 is not limited to this. The shield members 80 and 81 may, for example, be plate-shaped with rounded ends.

[0075] Figure 30 is a plan view of a modified power conversion device 600. As shown in Figure 30, both ends of the shield member 81 may be curved to follow the corners between the top surface 10b and the side surface 10c and between the top surface 10b and the side surface 10d of the power conversion unit 10D in order to protect those corners. Although not shown, both ends of the shield member 80 may also be curved to follow the corners between the bottom surface 10a and the side surface 10c and between the bottom surface 10a and the side surface 10d of the power conversion unit 10C in order to protect those corners.

[0076] Shield members 80 and 81 are formed of an electrically conductive material. Shield members 80 and 81 are formed of, for example, aluminum, copper, iron, tin, stainless steel, alloys thereof, or other metallic materials. Shield members 80 and 81 may also be formed of conductive plastic mixed with carbon-based materials (carbon, graphite, carbon nanotubes, graphene, etc.), conductive plastic mixed with metallic materials (silver, nickel, copper, aluminum, tin, stainless steel, iron, etc.), conductive plastic mixed with both carbon-based materials and metallic materials, etc. In these respects, the configuration of the power converter 600 differs from the configuration of the power converter 500.

[0077] (Effects of power converter 600) The effects of the power converter 600 are explained below.

[0078] When a surge voltage is applied due to malfunctions during operation, the operation of peripheral equipment, lightning strikes, etc., discharge may occur from the corners of power conversion units 10C and 10D toward the grounded object. In the power converter 600, the corners of power conversion units 10C and 10D are covered by shielding members 80 and 81, respectively, which mitigates electric field concentration at these corners and thus suppresses the occurrence of such discharge.

[0079] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The basic scope of this disclosure is indicated by the claims rather than by the embodiments described above, and all modifications within the meaning and scope of the claims are intended to be included. [Explanation of Symbols]

[0080] 10,10A,10B,10C,10D Power conversion unit, 10a Bottom, 10b Top, 10c,10d Side, 10e Rear, 10f Front, 11a,11b Switching element, 12a,12b Diode, 13 Capacitor, 14a,14b Connecting wire, 20,20A,20B Insulating structure, 30,30A,30B Stage structure, 31 Bottom wall, 32 Top wall, 33 Side wall, 33a First part, 33b Second part, 34 Side wall, 34a First part, 34b Second part, 35 Back wall, 36 Partition wall, 36a First part, 36b Second part, 40 Insulating enclosure, 41 Bottom wall, 42 Top wall, 43 Side wall, 43a First part, 43b Second part, 44 Side wall, 44a first part, 44b second part, 45 back wall, 50 insulating connection member, 60 insulating support column, 70 conductive member, 70a first part, 70b second part, 70c third part, 71 shield member, 71a cylindrical part, 71b, 71c hemispherical part, 80, 81 shield member, 82 cylindrical part, 83, 84 hemispherical part, 100, 200, 300, 400, 500, 600 power converter, 100A power converter, 110 upper arm, 120 lower arm, 130 transformer, DR1 first direction, DR2 second direction, DR3 third direction.

Claims

1. At least one insulating structure, Equipped with multiple power conversion units, The at least one insulating structure has a plurality of stepped structures that are stacked along a first direction, Each of the aforementioned multi-tiered structures has a first bottom wall, a first top wall, a first side wall, a second side wall, and a first back wall. The first bottom wall and the first top wall are separated and facing each other in the first direction. The first side wall and the second side wall are separated and facing each other in a second direction perpendicular to the first direction. The upper end of the first side wall is connected to one end of the first upper wall in the second direction, The lower end of the first side wall is connected to one end of the first bottom wall in the second direction, The upper end of the second side wall is connected to the other end of the first upper wall in the second direction, The lower end of the second side wall is connected to the other end of the first bottom wall in the second direction, The first back wall is connected to one end of the first bottom wall, the first side wall, and the second side wall in a third direction perpendicular to the first and second directions. The first side wall and the second side wall are divided into a plurality of parts that are spaced apart from each other in the third direction. The plurality of power conversion units are arranged at intervals along the second direction within each of the plurality of tiered structures. Each of the aforementioned power conversion units has a bottom surface, a top surface, a first side surface, a second side surface, and a back surface. The bottom surface is in contact with the first bottom wall, The aforementioned upper surface is spaced apart from the first upper wall, The first side and the second side face one side and the other side in the second direction, respectively. The aforementioned back surface faces one side in the third direction, In the first power conversion unit adjacent to the first side wall among the plurality of power conversion units, the corner between the first side and the rear is covered by the corner between the first side wall and the first back wall. A power conversion device in which, in a second power conversion unit adjacent to the second side wall among the plurality of power conversion units, the corner between the second side surface and the rear surface is covered by the corner between the second side wall and the first rear surface.

2. In the first power conversion unit, the first side surface is spaced apart from the first side wall in the second direction, and the rear surface is spaced apart from the first back wall in the third direction. The power conversion device according to claim 1, wherein the second power conversion unit has a second side surface that is spaced apart from the second side wall in the second direction, and a rear surface that is spaced apart from the first rear wall in the third direction.

3. Further comprising insulating connecting members, The aforementioned at least one insulating structure is a first insulating structure and a second insulating structure, The first insulating structure and the second insulating structure are arranged such that the first back wall faces the first structure with a gap between them. The power conversion device according to claim 1, wherein the first insulating structure and the second insulating structure are connected to each other by the insulating connecting member.

4. Each of the aforementioned multi-tiered structures has a plurality of insulating housings arranged along the second direction, One of the multiple power conversion units is placed inside the multiple insulating enclosures. Each of the plurality of insulating housings has a second bottom wall that forms part of the first bottom wall, a second upper wall that forms part of the first upper wall, a third side wall, a fourth side wall, and a second back wall that forms part of the first back wall. The third side wall of one of the plurality of insulating housings at one end in the second direction constitutes the first side wall, The power conversion device according to claim 1, wherein the fourth side wall of one of the plurality of insulating housings at the other end in the second direction forms the second side wall.

5. Further equipped with multiple insulating supports, The plurality of insulating support columns extend along the first direction, The power conversion device according to claim 1, wherein each of the at least one insulating structure is arranged on the plurality of insulating supports.

6. The system further comprises a conductive member electrically connecting two adjacent power conversion units in the second direction, and a first shielding member covering the conductive member, The first shield member has a cylindrical portion and a first hemispherical portion and a second hemispherical portion connected to both ends of the cylindrical portion. The power conversion device according to any one of claims 1 to 5, wherein the diameter of the first hemisphere and the diameter of the second hemisphere are greater than or equal to the width of the conductive member.

7. Further comprising a second shield member, The power conversion device according to any one of claims 1 to 5, wherein the second shielding member covers the corners of the plurality of power conversion units facing the ground surface.

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