Power conversion device

Abstract

A power conversion device includes a DC bus that transmits a DC current, a filter capacitor element connected to the DC bus, and a magnetic core having a through-hole for the DC bus to pass through and formed of a single member, wherein the through-hole is formed in the magnetic core in a manner that a first inner diameter along a width direction of the DC bus is longer than a second inner diameter orthogonal to the first inner diameter.

Description

Technical Field

[0001] This invention relates to a power conversion device. Background Technology

[0002] Currently, inverters are required to be miniaturized and have high output. As a result, cooling structures are needed to suppress the heat generation of components, making the improvement of the internal structure of inverters increasingly important.

[0003] As background technology for this application, the following patent document 1 is known. In patent document 1, a magnetic core 35 is described, which is provided with a slit 35B connecting the inner and outer peripheral surfaces in a manner that covers the conductive rod 11. The technology disclosed is that magnetic reluctance can be adjusted by changing the width of the slit 35B, etc., to prevent magnetic saturation. Existing technical documents Patent documents

[0004] Patent document 1: Japanese Patent Application Publication No. 2017-069317. Summary of the Invention The problem the invention aims to solve

[0005] The flat magnetic core described in Patent Document 1 can prevent magnetic saturation through the slit 35B. On the other hand, since it is a segmented core that is not a single core, noise removal loss may occur in the slit where the segmented cores are connected.

[0006] In view of the above, the object of the present invention is to provide a power conversion device that achieves both improved cooling performance and miniaturization while improving noise removal performance. Technical means to solve the problem

[0007] The power conversion device of the present invention comprises: a DC bus for transmitting DC current; a capacitor element for filtering connected to the DC bus; and a magnetic core having a through hole for the DC bus to pass through and formed by a single component, wherein the through hole is formed in the magnetic core with a first inner diameter along the width direction of the DC bus being longer than a second inner diameter orthogonal to the first inner diameter. The effects of the invention

[0008] It can provide a power conversion device that achieves both improved cooling performance and miniaturization while enhancing noise removal performance. Attached Figure Description

[0009] Figure 1 This is an exploded perspective view of a power conversion device according to an embodiment of the present invention. Figure 2 This is a cross-sectional view of a power conversion device according to an embodiment of the present invention. Figure 3 This is an explanatory diagram of the filter section according to an embodiment of the present invention. Figure 4 Is Figure 3 An explanatory diagram showing the filter section with a resin section. Figure 5 This is a side view of the filter section according to an embodiment of the present invention. Figure 6 This is a diagram illustrating the assembly of the filter section according to an embodiment of the present invention. Figure 7 This is an explanation Figure 6 A diagram showing the assembly of a filter section with a resin section. Detailed Implementation

[0010] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following description and drawings are examples for illustrating the present invention; appropriate omissions and simplifications have been made to clarify the description. The present invention may also be implemented in various other ways. Unless otherwise specified, the constituent elements may be singular or plural.

[0011] To facilitate understanding of the present invention, the positions, sizes, shapes, and extents of the constituent elements shown in the accompanying drawings may not represent their actual positions, sizes, shapes, or extents. Therefore, the present invention is not limited to the positions, sizes, shapes, and extents disclosed in the accompanying drawings.

[0012] (Embodiments and their structure of the present invention) Figure 1 This is an exploded perspective view of a power conversion device according to an embodiment of the present invention.

[0013] The power conversion device 1 (hereinafter referred to as inverter 1) converts the DC power input from the battery (not shown) into three-phase AC power, and includes a power conversion module 11, a DC bus 12, an X capacitor (X condenser) 13, a Y capacitor (Y condenser) 14, a filter circuit 15, a housing 18 (hereinafter referred to as housing 18), a DC power input section 19, an EMC core 21 (hereinafter referred to as core 21), and an EMC bus 22.

[0014] EMC bus 22 is a DC bus that transmits direct current. Y capacitor 14 is a filter capacitor element connected to EMC bus 22. Core 21 is a magnetic core formed from a single component.

[0015] The power conversion module 11 uses built-in switching elements to convert DC power input from the battery into AC power and output it. Additionally, the X capacitor 13 attenuates the ripple voltage generated by the power conversion module 11. Furthermore, in Figure 1Six X capacitors 13 are shown, but their number is not particularly limited. In this embodiment, it is sufficient for the power conversion device 1 to have at least one X capacitor 13. In the following description, the six X capacitors 13 will be collectively referred to as X capacitors 13.

[0016] Two Y capacitors 14 and a filter circuit 15 are arranged in the X-axis direction. At least two Y capacitors 14 are provided in the power conversion device 1. The Y capacitors 14 and the filter circuit 15 are assembled on an EMC bus 22 having a core 21, forming an EMC filter section 20 (hereinafter referred to as filter section 20). The filter section 20 attenuates DC power noise generated by the wiring connected to the power conversion device 1 via the DC power input section 19.

[0017] The EMC core 21 and EMC bus 22, which are magnetic components of the EMC filter component that effectively counteract noise (emission) from the inverter 1, are provided near the DC power input section 19, which serves as the power input side. This improves the noise cancellation effect on the inverter 1 from the outside.

[0018] Compare existing inverters with the inverter 1 of this invention. In existing inverters, the core has a circular structure, and in order to correspond to the insertion part of the core, the shape of the EMC bus must be made thinner. As a result, by shrinking the EMC bus, the resistance of the bus increases, causing it to heat up.

[0019] Therefore, in this invention, the shape of the EMC bus 22 is not made thinner, but the hole of the core 21 is made to have the same width as the EMC bus 22, and its size increases along the width direction of the EMC bus 22. Thus, the hole shape of the core 21 can be made to allow insertion without changing the size of the EMC bus 22. By adopting this structure, heat suppression and miniaturization of the EMC bus 22 can be achieved. Details will be described later.

[0020] In addition, there is no specific specification for the placement of core 21, but if it is placed between Y capacitor 14 and filter 15, it will form a π-type filter, which will improve the noise removal effect. Therefore, it is preferable to place it between Y capacitor 14 and filter 15.

[0021] Figure 2 This is a cross-sectional view of a power conversion device according to an embodiment of the present invention.

[0022] The housing 18 has a water channel 24, which cools the inverter 1 as a whole by means of refrigerant flowing inside the water channel 24. The X capacitor 13 and the core 21 are cooled by contacting the housing 18 and dissipating heat through the housing 18 to the refrigerant flowing in the water channel 24. The DC power input section 19 is connected to the EMC bus 22.

[0023] EMC bus 22 has weld ribs 23 (hereinafter referred to as ribs 23) that connect the aforementioned Y capacitor 14 and filter 15 by welding. Core 21 requires the EMC bus 22, which serves as a DC bus, to pass through a through hole inside the core 21. Therefore, core 21 has a through hole with an inner diameter larger than the outer diameter of the EMC bus 22 and ribs 23.

[0024] Here, since the core 21 needs to be housed within the housing 18, it has a flat shape. To prevent the temperature of the core 21 from exceeding the component's guaranteed temperature due to heat generation from the core 21 and residual heat from the EMC bus 22, it is important to improve cooling performance by increasing the contact area between the core 21 and the housing 18. In this embodiment, the outer peripheral surface of the core 21 has a flat portion along the width direction of the EMC bus 22. By dissipating heat directly from this flat portion or via a thermally conductive member to the housing 18, which functions as a heat dissipation member, heat dissipation of the core 21 can be effectively achieved even without a special shape on the housing 18 consistent with conventional circular cores. Furthermore, due to the large contact area, the heat dissipation effect of the core 21 is improved compared to conventional core shapes.

[0025] Furthermore, this also improves the cooling performance of the refrigerant in the component. In the case of a conventional circular core, the thermal resistance increases because the contact area with the cooling surface becomes smaller or the distance from the cooling surface becomes longer. However, in this invention, by forming the core 21 from a circular shape to a generally elliptical shape, the contact area with the cooling surface is increased, and the core 21 can be cooled more effectively.

[0026] Furthermore, since the core 21 has a through-hole with an inner diameter larger than the width of the EMC bus 22, it is not necessary to use a special shape like a split core when assembling the core 21 onto the EMC bus 22, and the assembly can be performed without constraints in terms of configuration. Therefore, an ideal filter can be constructed, avoiding the noise removal loss at the connection points of the split core sections that would occur with split cores, thus improving the noise removal effect. At the same time, it is not necessary to split the EMC bus 22 before or after this assembly.

[0027] Figure 3 This is an external view of the filter section according to one embodiment of the present invention. Figure 3 (a) is a three-dimensional view of the filter section. Figure 3 (b) is a cross-sectional view of the filter section.

[0028] The structure of the existing filter section will be described. In the EMC filter section of existing inverters, the core temperature is sometimes exceeded during temperature measurement tests. In view of this problem, a method to suppress the heating of inverter 1 and not exceed the guaranteed temperature of the components used has been studied, and the present invention has been realized. For example, from the point of view of cooling, methods such as using a refrigerant to cool the EMC bus 22 itself or using a refrigerant to cool the surrounding components can be considered. The object of the present invention is a structure that does not exceed the guaranteed temperature of the components through a cooling structure without limiting the output torque.

[0029] Furthermore, while improving the cooling performance of inverter 1, miniaturization must also be addressed. For example, in order to house the core 21 within the housing 18, the core 21 needs to be as small as possible, but the shape of the EMC bus 22 needs to be wide to suppress heat generation. Therefore, a shape for the core 21 that facilitates cooling is required. Additionally, due to EMC countermeasures, the shape of the core 21 requires the EMC buses 22 on the P-side and N-side to be stacked. Therefore, it is also important to avoid narrowing, bending, or stretching the EMC bus 22 when miniaturization is desired. The filter section 20 of the present invention will be explained based on the above considerations.

[0030] The EMC bus 22 of the filter section 20 is configured on the + side (P side) and - side (configuration side) of the DC power supply. As described above, the EMC bus 22 is mounted on the housing 18 to suppress heat generation, and therefore has a shape that is as wide as possible, and has a shape that is not narrow, not bent, or not drawn.

[0031] The EMC busbar 22 is characterized by having ribs 23, which facilitates the connection between the EMC busbar 22 and other components (Y capacitor 14, filter 15). Furthermore, to ensure clearance, the EMC busbar 22 is formed as a double-layer structure with alternating layers of busbar and resin board. This allows the EMC busbar 22 to achieve creepage distance as a high-voltage busbar and forms a stacked structure with minimal height. Additionally, by making the busbar wide, the resistance of the EMC busbar 22 is reduced, suppressing heat generation. Since the EMC busbar 22 has positioning ribs 33 for individual mounting to the housing 18, it can be easily mounted to the housing 18 via the post-installation positioning ribs 33.

[0032] exist Figure 3The through-hole of core 21 will be described in section (b). The through-hole is formed in core 21 such that the inner diameter 28 along the width direction of EMC bus 22 is longer than the inner diameter 29 orthogonal to the inner diameter 28. The inner diameter 28 along the length direction of the through-hole is wider than the inner diameter of EMC bus 22. Therefore, core 21 can be inserted into the stacked EMC bus 22 even without splitting the core. In addition, by making the inner diameter of core 21 wider than the EMC bus 22 in the cross section, the width of EMC bus 22 can also be widened, which can suppress heat generation. Furthermore, the degree of freedom of core 21 in mounting to EMC bus 22 is increased.

[0033] By forming the core 21 into a flat structure with different lengths in the length and width directions, the height of the EMC busbar 22 in the stacking direction can be suppressed. Furthermore, by making the inner diameter of the through hole in the core 21 larger than the positioning rib 33 used for mounting on the rib 23 and the housing 18, installation can be easily performed. Simultaneously, by making the cross-sectional dimension of the EMC busbar 22 shorter than the inner diameter 28 in the direction along the inner diameter 28 and shorter than the inner diameter 29 in the direction along the inner diameter 29, the EMC busbar 22 can be inserted during the assembly of the core 21.

[0034] The GND bus 25, which is connected to the Y capacitor 14, is separate from the EMC bus 22. The GND bus 25 is connected to the EMC bus 22 after the EMC bus 22 is inserted into the through hole of the core 21. In this way, the GND bus 25 will not become an obstacle when the core 21 is inserted into the EMC bus 22, so the size of the core 21 can be suppressed.

[0035] Furthermore, in the core 21, the outer peripheral surface of the through hole in the longitudinal direction becomes a plane along the long inner diameter 28, namely a plane portion 26, which suppresses the height of the EMC busbar 22 in the stacking direction and increases the area that can contact the housing 18 or other components. Thus, by placing the filter section 20 directly on the housing 18, or placing it on the housing 18 via a thermally conductive member, the housing 18 can function as a heat dissipation member for the filter section 20.

[0036] Furthermore, by adopting this shape to suppress heat generation of the EMC bus 22 and reduce residual heat to surrounding components, the range of usable environments can be expanded. Additionally, improved cooling performance can increase the usable temperature range. Moreover, suppression in the stacking (height) direction allows for mounting on the housing 18. Ultimately, miniaturization of the power conversion device 1 is facilitated by improved cooling performance due to the increased cooling area, suppression in the height direction associated with the shape change, and heat generation suppression, all of which contribute to increased output.

[0037] (Modified Example) Figure 4 Is Figure 3The image shows a perspective view of the filter section of the resin part. Figure 4 (a) is a perspective view of the filter section with a resin section. Figure 4 (b) is a cross-sectional view of the filter section with a resin section.

[0038] By providing a resin portion 27 of the resin sealing member that integrally seals and fixes the laminated EMC busbar 22A, and by placing this resin portion 27 together with the EMC busbar 22A within the through hole of the core 21A, the core 21A can be easily positioned relative to the EMC busbar 22A. Furthermore, since the purpose is positioning, the resin portion 27 is only used for temporary fixation. Therefore, when the resin portion 27 is inserted into the through hole of the core 21A, a gap may exist between the resin portion 27 and the inner wall of the core 21A. Of course, the resin portion 27 can also be used for permanent fixation.

[0039] Figure 5 This is a side view of the filter section according to one embodiment of the present invention.

[0040] Even though the filter section 20 has a filter capacitor element (Y capacitor 14), the inner diameter 28 of the through hole in the length direction of the core 21 is larger than the distance 31 between its positive and negative terminals (the distance between the terminals of the rib 23 and the GND bus 25). Therefore, the core 21 can be easily assembled in any position in the filter section 20.

[0041] Figure 6 and 7 The assembly process of the filter section according to one embodiment of the present invention is shown. Figure 6 express Figure 3 The assembly process of the filter section 20 shown is as follows: Figure 7 express Figure 4 The assembly process of the filter section 20A shown.

[0042] like Figure 6 , Figure 7 As shown, during the assembly of cores 21 and 21A in filter sections 20 and 20A, EMC busbars 22 and 22A can be inserted into the through holes of cores 21 and 21A respectively in the insertion direction 32 without splitting the cores. Figure 7 Before the core 21A is assembled and inserted, a resin portion 27 is molded around the EMC bus 22A, and then the resin portion 27 is fitted into the through hole of the core 21A. That is, the resin portion 27 serves to fit the EMC bus 22A into the through hole of the core 21A and to hold the core 21A in place. This ensures the stability of the filter section 20A.

[0043] In addition, compared with the circular cores used in the prior art, the portion with the planar portion 26 of cores 21 and 21A is larger, but since they can be assembled as in the present invention, it helps to miniaturize the inverter as a whole.

[0044] According to the above-described embodiment of the present invention, the following effects are achieved.

[0045] (1) The power conversion device 1 includes: a DC bus 22 that transmits DC current; a filter capacitor element 14 connected to the DC bus 22; and a magnetic core 21 having a through hole for the DC bus 22 to pass through and formed from a single component. The through hole is formed in the magnetic core 21 such that the inner diameter 28 along the width direction of the DC bus 22 is longer than the inner diameter 29 orthogonal to the inner diameter 28. Thus, a power conversion device 1 that achieves both improved noise removal performance and miniaturization can be provided.

[0046] (2) The magnetic core 21 of the power conversion device 1 has a flat portion 26 along the inner diameter 28 on its outer peripheral surface, and is mounted on the housing 18, which serves as a heat dissipation member, through the flat portion 26. In this way, the complexity of the mounting position caused by the conventional circular core mounting is eliminated, and assembly is easy.

[0047] (3) The inner diameter 28 of the magnetic core 21 is made larger than the distance 31 between the positive and negative terminals of the capacitor element 14 for the filter. This makes it easy to assemble the core 21.

[0048] (4) The power conversion device 1 includes a resin sealing member 27 that integrally seals a DC bus 22A with a stacked structure. This resin sealing member 27 is disposed together with the DC bus 22A within a through hole of the magnetic core 21A. This improves the stability of the core 21A and the bus 22A, thereby improving the reliability of the filter section 20A.

[0049] (5) The cross-sectional dimensions of the DC bus 22 of the power conversion device 1 are shorter than the short inner diameter 29 and the long inner diameter 28. This allows for easy assembly of the core 21.

[0050] (6) The resin sealing member 27 of the power conversion device 1 is a core holding part that fits the DC bus 22A into the through hole of the magnetic core 21A and retains the magnetic core 21A. In this way, the fixation of the core 21A and the bus 22A is improved, and the reliability of the filter part 20A is improved.

[0051] Furthermore, in the embodiments of the present invention described above, the magnetic cores 21 and 21A are described to have respectively as follows: Figure 3 , Figure 4The example shown is an ellipse (a rounded rectangle with two opposite sides that are arc-shaped), but other shapes are also possible. For example, it could be a shape where both opposite sides are straight lines and the apex is a rounded rectangle with arc-shaped corners, or an ellipse without straight lines. In addition, as long as the through hole is formed with one of the two orthogonal inner diameters becoming longer, the magnetic core 21, 21A can be formed in any shape.

[0052] The above description clarifies that, without departing from the inventive concept, deletions, substitutions, or additions of other components are possible and are also included within the scope of this invention. Furthermore, it can also be a combination of the above-described embodiments and multiple variations. Symbol Explanation

[0053] 1 Power conversion device 11 Power Conversion Module 12 DC bus 13 X capacitors 14 Y capacitor 15. Filter Circuit 18. Frame housing 19 DC power input section 20 EMC Filter Section 21 EMC core 22 EMC bus 23 Welding Beads 24 waterways 25 GND bus 26. Planar section 27 Resin Section 28. Inner diameter along the length of the through hole 29. Inner diameter in the width direction of the through hole Width of the cross-section along the length of the 30 DC bus 31. Distance between the positive and negative terminals of the capacitor element used in the filter Insertion direction of 32 EMC core 33 Positioning reinforcement bars

Claims

1. A power conversion device, comprising: DC bus, which transmits DC current; Filter capacitor elements connected to the DC bus; and The magnetic core, having a through hole for the DC bus to pass through, is formed from a single component. The power conversion device is characterized in that... The through hole is formed in the magnetic core with a first inner diameter length that is orthogonal to the first inner diameter, along the width direction of the DC bus. The magnetic core has a first planar portion formed along the first inner diameter on its outer peripheral surface, which faces one side of the DC bus and the other side of the DC bus. The magnetic core is mounted on the heat dissipation component via the first planar portion or the second planar portion.

2. The power conversion device according to claim 1, characterized in that, The first inner diameter is formed to be larger than the distance between the positive and negative terminals of the capacitor element used in the filter.

3. The power conversion device according to claim 1 or 2, characterized in that, It includes a resin sealing component that integrally seals the DC bus having a laminated structure. The resin sealing component is disposed together with the DC bus in the through hole.

4. The power conversion device according to claim 1, characterized in that, The cross-sectional dimension of the DC bus is smaller than the first inner diameter in the direction along the first inner diameter and smaller than the second inner diameter in the direction along the second inner diameter.

5. The power conversion device according to claim 3, characterized in that, The resin sealing component is a core retaining part that fits the DC bus into the through hole and holds the magnetic core.

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