Power conversion device

Abstract

To provide a power conversion device capable of preventing semiconductor elements on a leeward side from being affected by heat of semiconductor elements on a windward side, increasing cooling efficiency, preventing the occurrence of a temperature difference between the semiconductor elements on the windward side and the leeward side, and suppressing performance degradation of surrounding elements.SOLUTION: A power conversion device comprises a semiconductor element and a heat sink for cooling the semiconductor element. The heat sink includes a heat receiving plate on which the semiconductor element is disposed, and a first fin group and a second fin group erected on one surface of the heat receiving plate where the semiconductor element is disposed. A height of fins in the first fin group is lower than a height of fins in the second fin group.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a power conversion device using a forced air cooling system. [Background technology]

[0002] Generally, a power converter for an elevator is composed of semiconductor elements, a cooler for cooling the semiconductor elements, and other electrical equipment. Here, the semiconductor elements of the power converter are provided with a heat sink for cooling, and it is important to efficiently dissipate the heat from the semiconductor elements to this heat sink and release it into the outside air using a cooling fan.

[0003] Coolers can be broadly divided into forced circulation liquid cooling using pumps, forced air cooling using cooling fans and blowers, and natural air cooling using only a heat sink. When selecting a cooling method, various factors are considered, including cooling performance, low cost, low noise, energy saving, and maintenance-free operation. However, natural air cooling is no longer sufficient when the load on the semiconductor elements becomes too great. Therefore, forced air cooling is often chosen for power conversion equipment for elevators. In particular, forced air cooling in power conversion equipment that uses multiple semiconductor elements involves arranging multiple semiconductor elements, transferring their heat to a heat sink, and then dissipating the heat with the air generated by a cooling fan. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-190268 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a power conversion device with a large number of semiconductor elements, the semiconductor elements on the downwind side are affected by the heat of the semiconductor elements on the upwind side. Therefore, when the load on the semiconductor elements is the same, the temperature rise of the semiconductor elements increases the further downwind they are. In addition, a temperature difference occurs between the semiconductor elements on the upwind and downwind sides, making the semiconductor elements with a large temperature rise more susceptible to damage (reducing reliability), which is a problem.

[0006] The present invention has been made in view of the above circumstances, and has as its object to provide a power conversion device that can reduce the thermal influence that semiconductor elements on the downwind side receive from the heat of semiconductor elements on the upwind side, increase cooling efficiency, make it less likely that a temperature difference will occur between the semiconductor elements on the upwind and downwind sides, and prevent damage to the semiconductor elements due to temperature rise. [Means for solving the problem]

[0007] To solve the above problems, one embodiment of the power conversion device includes a semiconductor device and a heat sink for cooling the semiconductor device. The heat sink includes a heat receiving plate that contacts the semiconductor device, and a first group of fins and a second group of fins that are erected on one surface of the heat receiving plate that contacts the semiconductor device. Here, the height of the fins of the first group of fins is shorter than the height of the fins of the second group of fins. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 10 is a schematic perspective view of a cooling section (heat sink) of a power conversion device as a comparative example. [Figure 2] 1 is a perspective view of the entire power conversion device according to a first embodiment. [Figure 3] FIG. 10 is a perspective view of the entire power conversion device according to a second embodiment. [Figure 4] FIG. 10 is a perspective view of the entire power conversion device according to a modified example of the second embodiment. [Figure 5] FIG. 10 is a perspective view of the entire power conversion device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, each embodiment will be described with reference to the drawings. In each embodiment, the same components are denoted by the same reference numerals and the description thereof will be omitted.

[0010] (Specific issues assumed in each embodiment) First, a cooling section (heat sink) of a power conversion device as a comparative example, which is a premise of the present embodiment, will be described. Fig. 1 is a schematic perspective view of the cooling section (heat sink) of a power conversion device as a comparative example.

[0011] In FIG. 1, the power conversion device includes a semiconductor element 200 that rectifies input AC power into DC power and converts the rectified DC power back into AC power, a heat sink 100 that cools the heat generated by the semiconductor element 200, a heat receiving plate (base plate) 600 that contacts the semiconductor element 200, a duct structure 500 that is provided on one side of the heat sink 100 and that connects the heat sink 100 and the cooling fan 300, and the cooling fan 300 that is arranged on the downwind side.

[0012] Here, the heat sink 100 has a plurality of fins, each of which is made of a material with a high heat dissipation effect, such as aluminum. Regarding cooling, cooling air for cooling the heat sink 100 is discharged from an end of the heat sink 100 by a cooling fan 300 provided at one end of the heat sink, and the semiconductor element 200 is cooled by discharging heat passing between the plurality of fins provided on the heat sink 100 to the outside. In other words, heat generated by the plurality of semiconductor elements 200 is transferred to the heat sink 100, and is exhausted as heat 400 by the air blown by the cooling fan 300.

[0013] In recent years, advances in the semiconductor elements 100 have led to the miniaturization of packages in power conversion devices. However, the amount of heat generated by the semiconductor elements 100 has not been significantly reduced. Therefore, the miniaturization of the package has resulted in further concentration of heat, and the temperature rise caused by the concentrated heat has been a major cause of damage to the semiconductor elements 100.

[0014] The following embodiments provide techniques that can address these problems. This technique allows the semiconductor elements on the downwind side to reduce the thermal impact of the semiconductor elements on the upwind side, thereby increasing cooling efficiency. This reduces the temperature difference between the semiconductor elements on the upwind and downwind sides. This prevents heat from concentrating, making it possible to prevent damage to the semiconductor elements 100 due to temperature rise caused by concentrated heat.

[0015] [First embodiment] FIG. 2 shows the first embodiment, and the power conversion device of the first embodiment will be described based on this drawing.

[0016] Fig. 2 is a perspective view of the entire power converter according to the first embodiment. The power converter in Fig. 2 has a structure in which a plurality of semiconductor elements 13 are arranged in the direction of airflow, and these semiconductor elements 13 are cooled using a fan 8 and a heat sink 15 equipped with first and second comb-shaped fins 6 and 7.

[0017] In this specification, "upwind" means the side of the heat sink 15 that is farther from the fan 8 in the longitudinal direction, and "downwind" means the side of the heat sink 15 that is closer to the fan 8 in the longitudinal direction. In other words, referring to the drawings, the airflow from the fan 8 flows from the left to the right in the longitudinal direction of the heat sink 15.

[0018] 2, the power conversion device includes a semiconductor element 13 that rectifies input AC power to DC power and converts the rectified DC power back into AC power, a heat sink 15 that cools the heat generated by the semiconductor element 13, a heat receiving plate (base plate) 12 having a first surface that contacts the semiconductor element 13, a leakage prevention duct structure 10 that is provided on the heat sink 15 and prevents air that has entered the heat sink 15 from leaking outside the outlet of the heat sink 15, and a cooling fan 8 that is provided at one end of the heat sink 15. The heat sink 15 also includes the heat receiving plate 12 that contacts the semiconductor element 13, first comb-shaped fins (first fin group) 6, and second comb-shaped fins (second fin group) 7, and the fin height of the first comb-shaped fins 6 is shorter than the fin height of the second comb-shaped fins 7. Here, the first and second comb-shaped fins 6, 7 are first and second fin groups each made up of a plurality of fins erected on one surface of the heat receiving plate 12 that contacts the semiconductor elements 13. Furthermore, a flow dividing plate 9 is provided at the end of the first comb-shaped fin 6, which is lower in height on the windward side, to separate the air that has entered the first comb-shaped fin 6 from the air that has not passed through the first comb-shaped fin 6. Here, the cooling fan 8 cools the semiconductor elements 13 by discharging to the outside the heat that passes through the fins provided on the heat sink 15. That is, the heat generated by the semiconductor elements 13 is transferred to the heat sink 15, and the heat 11 is dissipated by the airflow of the cooling fan 8.

[0019] The heat sink 15 has a comb-shaped structure with multiple plate-shaped heat dissipation fins on a second surface (hereinafter sometimes referred to as the "base surface"), which is the back surface opposite to the first surface that contacts the semiconductor element 13 on the heat receiving plate 12, and the main surface of each fin is arranged approximately perpendicular to the base surface. Here, each fin is plate-shaped. As shown in FIG. 2, the first (low-profile) and second (high-profile) comb-shaped fins (first and second fin groups) 6, 7 are each composed of multiple plate-shaped fins, and the fins are arranged approximately parallel to each other at a predetermined interval. That is, the first and second comb-shaped fins 6, 7 are arranged approximately parallel to each other at a predetermined interval in a direction that is approximately perpendicular to the first base, which is the heat receiving plate 12, and the second base, which is the heat receiving plate 12. Furthermore, the first and second bases that serve as the bases for the first and second comb-shaped fins (first and second fin groups) 6, 7 have the same or approximately the same thickness. However, the present invention is not limited to this. The first base and the second base may be configured to have different thicknesses.

[0020] 2, in the forced air cooling method of this embodiment, a plurality of semiconductor elements 13 are arranged in the direction of airflow, and these semiconductor elements 13 are cooled using a fan 8, first comb-shaped fins 6 with short fin heights arranged on the upwind side, and second comb-shaped fins 7 with taller fin heights arranged on the downwind side. Heat generated by the semiconductor elements 13 is transferred to the first comb-shaped fins 6 and second comb-shaped fins 7 through the heat receiving plate 12, and is dissipated via the first comb-shaped fins 6 and second comb-shaped fins 7. Here, the heat sink 15 according to this embodiment is characterized in that the height of the fins of the heat sink 15 differs between the upwind and downwind sides, with the height of the fins on the downwind side being higher than the height of the fins on the upwind side. Furthermore, a flow dividing plate 9 is installed at the end of the shorter upwind fin to separate the air that enters the fin from the air that does not pass through the fin, thereby reducing the temperature difference between the elements on the upwind and downwind sides. Furthermore, a duct structure 10, which is a leakage prevention plate, is installed to prevent the air that enters the heat sink 15 from leaking outside the outlet of the heat sink 15, allowing the air that enters the heat sink 15 to be efficiently exhausted as heat 11.

[0021] The heat receiving plate 12 is a base for the first and second comb-shaped fins 6 and 7. There are no particular limitations on the planar shape, but it may be a rounded shape such as a circle or an oval, or a polygonal shape such as a quadrangle (rectangle, square), hexagon, or octagon.

[0022] [Operation of the first embodiment] Next, the operation of the forced air cooling system in the power conversion device according to the first embodiment will be described.

[0023] In a structure in which multiple semiconductor elements 13 are arranged in the direction of airflow, the semiconductor elements 13 on the downwind side are affected by the heat of the semiconductor elements 13 on the upwind side. As a result, for the same load on the semiconductor elements 13, the temperature rise of the semiconductor elements 13 increases toward the downwind side, resulting in a temperature difference between the semiconductor elements 13 on the downwind side and the upwind side. In contrast, by adopting the configuration of the heat sink 15 of the power conversion device in this embodiment, first (low-profile) comb-shaped fins 6 with a low fin height are arranged on the upwind side, and second (high-profile) comb-shaped fins 7 with a high fin height are arranged on the downwind side, thereby improving the fin cooling performance on the downwind side compared to the upwind side. Fresh air unaffected by the heat from the first comb-shaped fins 6 on the upwind side can be supplied to the second comb-shaped fins 7 on the downwind side. This reduces the temperature of the semiconductor elements on the downwind side. Furthermore, a duct structure 10, which functions as a leak prevention plate, is installed to prevent the air entering the heat sink 15 from leaking outside the outlet of the heat sink 15. This allows the air entering the heat sink 15 to be efficiently exhausted.

[0024] [Effects of the first embodiment] In the power conversion device according to the present embodiment, the fins on the downwind side are taller than the fins on the upwind side, providing high cooling performance and allowing fresh air to be supplied to the downwind side. This reduces the temperature difference between the semiconductor elements on the upwind and downwind sides, and lowering the fin height on the upwind side reduces ventilation resistance. This reduces the temperature difference between the semiconductor elements on the upwind and downwind sides when multiple semiconductor elements are arranged in the direction of airflow. This prevents heat from concentrating, preventing damage to the semiconductor elements due to temperature rises caused by concentrated heat, and improving the reliability of the semiconductor elements.

[0025] Although the present embodiment describes a comb-shaped heat dissipation fin, the present invention is not limited thereto. For example, the heat dissipation fins may have a pin fin structure, in which each fin is pin-shaped, or may have a structure with other shapes. In other words, any fin structure is acceptable as long as the fan's air can pass from the windward side to the leeward side of the heat sink. When the multiple fins have a pin fin structure, each of the multiple pin fins extends in a direction perpendicular to the base surface. The multiple pin fins are arranged at intervals in a first direction along the surface of the base surface and a second direction perpendicular to the first direction. The multiple pin fins may be arranged in a staggered pattern, alternately offset in the first direction, or the pin fins may be arranged in a predetermined regular pattern. Even with this configuration, the same effects as those of the present embodiment can be obtained.

[0026] [Second embodiment] FIG. 3 is a perspective view of the entire power converter according to the second embodiment. This embodiment differs from the first embodiment in that it includes two heat sinks, which are arranged opposite each other with respect to the airflow direction. Specifically, in this embodiment, the fin heights of the heat sink 15 differ between the upwind and downwind sides of FIG. 2 , and the fin height on the downwind side is higher than that on the upwind side. This configuration increases the area of the heat receiving portion of the heat sink 15, thereby increasing the number of semiconductor devices 15 to be cooled. Furthermore, in this embodiment, a turbulence promotion plate 6 is installed in a portion of the step between the first comb-shaped fins 6 (which are shorter on the upwind side) and the second comb-shaped fins 7 (which are taller on the downwind side) to promote turbulence in the airflow.

[0027] In the forced air-cooling system of the power conversion device according to this embodiment, similar to the first embodiment, multiple semiconductor elements 13 are arranged in the direction of airflow, and these semiconductor elements 13 are cooled using a fan 8, first comb-shaped fins 6 with short fin heights arranged facing each other on the upwind side, and second comb-shaped fins 7 with tall fin heights arranged facing each other on the downwind side. Heat generated by the semiconductor elements 13 is transferred to the first comb-shaped fins 6 and the second comb-shaped fins 7 through the heat-receiving plate 12, and is dissipated through the first comb-shaped fins 6 and the second comb-shaped fins 7. Here, a flow dividing plate 9 is installed at the end of the first comb-shaped fins 6 to separate the air that has entered the first comb-shaped fins 6 from the air that has not passed through the first comb-shaped fins 6, and a duct structure 10 is installed to prevent the air that has entered the heat sink 15 from leaking outside the outlet of the heat sink 15.

[0028] [Operation of the second embodiment] Next, the operation of the forced air cooling system in the power conversion device according to the second embodiment will be described.

[0029] In the power converter according to this embodiment, the first comb fins 6 and the second comb fins 7 are arranged facing each other, doubling the heat-receiving area. Furthermore, by arranging the first comb fins 6 with a low fin height on the upwind side and the second comb fins 7 with a high fin height on the downwind side, the fin cooling performance can be improved on the downwind side compared to the upwind side. Furthermore, the airflow dividing plates 9 are installed at the ends of the first comb fins 6 to separate the air that has entered the first comb fins 6 from the air that has not passed through the first comb fins 6. This allows fresh air that is not affected by the heat from the first comb fins 6 on the upwind side to be supplied to the second comb fins 7 on the downwind side, thereby reducing the temperature of the semiconductor elements 13 on the downwind side.

[0030] [Effects of the second embodiment] The power converter according to the present embodiment, as described above, has the same advantages as the power converter according to the first embodiment. Furthermore, compared to the power converter according to the first embodiment, the power converter according to the present embodiment has a larger heat-receiving portion of the heat sink 15, allowing for a larger number of semiconductor elements 13 to be cooled. Therefore, when cooling the same number of semiconductor elements 13, the planar installation area for the semiconductor elements 13 can be halved. Furthermore, compared to the power converter according to the first embodiment, the turbulence promoting plate 14 that promotes turbulence in the airflow is installed in a portion of the step between the first comb-shaped fin 6 on the upwind side and the second comb-shaped fin 7 on the downwind side. This turbulence promoting plate 14 turbulently promotes turbulence in the airflow entering the second comb-shaped fin 7 on the downwind side, thereby improving the cooling efficiency of the fins. This solves the problem of temperature differences between the upwind and downwind semiconductor elements when multiple semiconductor elements 13 are arranged in the airflow direction. This prevents damage to the semiconductor elements 13 due to heat rise, thereby improving the reliability of the semiconductor elements.

[0031] In this embodiment, the heat dissipation fins have been described as having a comb-shaped structure, but the present invention is not limited to this. In other words, any fin structure is acceptable as long as the fan's air can pass from the windward side to the leeward side of the heat sink. For example, as shown in FIG. 4, the heat dissipation fins may have a pin fin structure or other shapes. When the multiple fins have a pin fin structure, each of the multiple pin fins extends in a direction perpendicular to the base surface. The multiple pin fins are arranged at intervals in a first direction along the surface of the base surface and a second direction perpendicular to the first direction. The multiple pin fins may be arranged in a staggered pattern, alternately offset in the first direction, or the pin fins may be arranged in a predetermined regular pattern. Even with this configuration, the same effects as those of this embodiment can be obtained.

[0032] [Third embodiment] Fig. 5 is a perspective view of the entire power converter according to the third embodiment. The power converter according to this embodiment in Fig. 5 differs from the power converter in Fig. 3 in that a heat pipe 17 is installed on the heat receiving plate 12 of the heat sink 15. In this case, the heat pipe 17 is installed so that the direction of the air flowing through the heat sink 15 is the longitudinal direction of the heat pipe 17.

[0033] In the forced-air cooling system of the power converter according to this embodiment, similar to the power converters according to the above-described embodiments, a plurality of semiconductor elements 13 are arranged in the direction of airflow, and the semiconductor elements 13 are cooled using a fan 8, first comb-shaped fins 6 with short fin heights arranged on the upwind side facing each other, second comb-shaped fins 7 with tall fin heights arranged on the downwind side facing each other, and a heat pipe 17 installed on a heat receiving plate 12. Heat generated by the semiconductor elements 13 is transferred to the first comb-shaped fins 6 and the second comb-shaped fins 7 through the heat receiving plate 12 and the heat pipe 17 installed thereon, and is then dissipated through the first comb-shaped fins 6 and the second comb-shaped fins 7. A flow dividing plate 9 is installed at the end of the first comb-shaped fins 6 to separate the air that has entered the first comb-shaped fins 6 from the air that has not passed through the first comb-shaped fins 6. A turbulence promoting plate 14 is installed in a part of the step between the first comb-shaped fins 6 on the upwind side and the second comb-shaped fins 7 on the downwind side to promote turbulence in the airflow. In addition, a duct structure 10 is installed so that the airflow entering the heat sink 15 does not leak out anywhere other than the outlet of the heat sink 15. The heat pipe 17 is embedded in the heat receiving plate 12 so that the direction of the airflow flowing through the heat sink 15 is the longitudinal direction of the heat pipe 17.

[0034] [Operation of the third embodiment] Next, the operation of the forced air cooling system in the power conversion device according to the third embodiment will be described.

[0035] In the power converter according to this embodiment, the first comb fins 6 and the second comb fins 7 are arranged facing each other, doubling the heat-receiving area. Furthermore, by arranging the first comb fins 6 with a low fin height on the upwind side and the second comb fins 7 with a high fin height on the downwind side, the fin cooling performance can be improved on the downwind side compared to the upwind side. Furthermore, a flow dividing plate 9 is installed at the end of the first comb fins 6 to separate the air that enters the first comb fins 6 from the air that does not pass through the first comb fins 6. This allows fresh air that is not affected by the heat from the first comb fins 6 on the upwind side to be supplied to the downwind side second comb fins 7, thereby reducing the temperature of the semiconductor devices on the downwind side. Furthermore, a turbulence promoting plate 14 is installed at a portion of the step between the first comb fins 6 and the second comb fins 7 to promote turbulence in the air flow. This turbulence increases the air flow entering the downwind side second comb fins 7, improving the fin cooling efficiency. Furthermore, since the heat pipe 17 is installed on the heat receiving plate 12 so that the direction of the air flowing through the heat sink 15 coincides with the longitudinal direction of the heat pipe 17, the heat receiving plate 12 can be uniformly heated.

[0036] [Effects of the third embodiment] The power converter according to the present embodiment as described above can achieve the same effects as the power converter according to the second embodiment. Furthermore, compared to the second embodiment, by embedding the heat pipes 17 in the heat receiving plate 12 in the longitudinal direction of the airflow through the heat sink 15, the heat receiving plate 12 can be uniformly heated, thereby reducing the temperature difference between the semiconductor elements 13 on the upwind and downwind sides. This solves the problem of temperature differences occurring between the semiconductor elements 13 on the upwind and downwind sides when multiple semiconductor elements 13 are arranged side by side in the airflow direction, thereby preventing damage to the semiconductor elements due to heat temperature rise and improving the reliability of the semiconductor elements 13.

[0037] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as set forth in the claims. [Explanation of symbols]

[0038] 6. First (low profile) comb fin 7 Second (high) comb fin 8 Cooling Fan 9 Stream plate 10 Duct structure 11. Heat Dissipation 12 Heat receiving plate (Base plate) 13 Semiconductor elements 14 Turbulence promoter 15 Heatsink 17 Heat pipe

Claims

1. A power conversion device having a semiconductor element and a heat sink for cooling the semiconductor element, the heat sink includes a heat receiving plate in contact with the semiconductor element, and a first fin group and a second fin group provided upright on one surface of the heat receiving plate in contact with the semiconductor element, The height of the fins in the first fin group is lower than the height of the fins in the second fin group. Power conversion device.

2. The first fin group is arranged upwind of the second fin group. The power conversion device according to claim 1 .

3. A flow dividing plate is further installed at an end of the first fin group to separate the air that has entered the fins of the first fin group from the air that has not passed through the fins of the first fin group. The power conversion device according to claim 1 .

4. A duct structure has been added to prevent the air entering the heat sink from leaking outside the heat sink outlet. The power conversion device according to claim 1 .

5. The first and second fin groups extend in a direction substantially perpendicular to the first base and the second base on which the fins are erected, and a plurality of fins are arranged substantially parallel to each other at predetermined intervals. The power conversion device according to claim 1 .

6. The power converter according to claim 5 , wherein the first base and the second base have substantially the same thickness.

7. The power converter according to claim 5 , wherein each of the fins has a plate shape or a pin shape.

8. The power conversion device according to claim 1 , wherein the cooling fan is disposed on the downwind side.

9. a heat pipe is provided on the heat receiving plate of the heat sink; The heat pipe is installed so that the direction of the air flowing through the heat sink is the longitudinal direction of the heat pipe. The power conversion device according to claim 1 .

10. The two heat sinks are provided, and the two heat sinks are arranged opposite each other with the air flow direction as the center. The power conversion device according to claim 1 .

11. A turbulence promoting plate for promoting turbulence of the airflow is further provided at a part of the step portion between the first fin group and the second fin group. The power converter according to claim 10.

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