Power conversion device

Abstract

Provided is a power conversion device in which it is possible to achieve both miniaturization and cost reduction. The power conversion device comprises a plurality of circuit components (20), a wiring board (30), a heat transport member (40), and a cooler (50). The heat transport member has a heat-receiving part (40A) and a heat-radiating part (40B) arranged side by side in a first direction (DR1) and is provided so as to transport heat from the heat-receiving part to the heat-radiating part. The plurality of circuit components are thermally connected to the heat-receiving part via the wiring board. The cooler is thermally connected to the heat-radiating part of the heat transport member.

Description

Power conversion device

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

[0002] In recent years, in response to the increasing demand for miniaturization and higher output of power conversion devices, the heat generation density of electronic components (circuit components) mounted on power conversion devices has been increasing. In order to prevent the temperature of the electronic components from exceeding the allowable temperature due to heat generation, there is a strong demand for improving the heat dissipation performance of power conversion devices. That is, in order to realize miniaturization and higher output of power conversion devices, it is necessary to improve the heat dissipation performance of power conversion devices.

[0003] Generally, a power conversion device includes a heat transport member (cooler) for releasing the heat generated in the electronic components to the outside in order to suppress the temperature rise of the electronic components.

[0004] The power conversion device described in Japanese Patent No. 6158051 (Patent Document 1) includes a heat dissipation base having a base portion with one surface facing the flow path of the cooling refrigerant and a standing portion formed on the other surface of the base portion on the opposite side of the one surface, and a power supply circuit mounted on the standing portion of the heat dissipation base.

[0005] Japanese Patent No. 6158051

[0006] However, in the power conversion device described in Patent Document 1, it is necessary to mount electronic components with a large amount of heat generation, such as switching elements and transformers, near the region of the standing portion that is connected to the base portion. In the heat dissipation base described in Patent Document 1, the heat dissipation performance for the electronic components deteriorates as the position on the standing portion where the electronic components are mounted is farther from the base portion.

[0007] Therefore, in the power conversion device described in Patent Document 1, it is necessary to provide a long connection region of the standing portion that is connected to the base portion in order to mount a large number of electronic components with a large amount of heat generation near the base portion, and it is difficult to miniaturize the power conversion device.

[0008] Furthermore, in the power conversion device described in Patent Document 1, the arrangement of electronic components that generate a lot of heat is restricted as described above, which increases the length of the wiring path through which the current flows, increasing parasitic inductance, and generating surge voltage and noise current during the switching operation of the switching element. For this reason, the above power conversion device requires high-voltage semiconductor elements and a structure to reduce noise current, making it difficult to miniaturize and reduce the cost of the power conversion device.

[0009] The primary objective of this disclosure is to provide a power conversion device that can achieve both miniaturization and cost reduction.

[0010] The power conversion device according to this disclosure comprises a plurality of circuit components, at least one wiring board, at least one heat transport member, and at least one cooler. The at least one heat transport member has a heat receiving section and a heat dissipation section arranged side by side in a first direction, and is configured to transport heat from the heat receiving section to the heat dissipation section. The plurality of circuit components are thermally connected to the heat receiving section via at least one wiring board. The at least one cooler is thermally connected to the heat dissipation section of the at least one heat transport member.

[0011] According to this disclosure, it is possible to provide a power conversion device that can achieve both miniaturization and cost reduction.

[0012] This is a circuit diagram of the power converter according to this embodiment. This is a perspective view of the power converter according to Embodiment 1. This is a cross-sectional view of the power converter according to Embodiment 1. This is a cross-sectional view of a first modified example of the power converter according to Embodiment 1. This is a cross-sectional view of a second modified example of the power converter according to Embodiment 1. This is a cross-sectional view taken from arrow VI-VI in Figure 5. This is a cross-sectional view of a third modified example of the power converter according to Embodiment 1. This is a cross-sectional view taken from arrow VIII-VIII in Figure 7. This is a cross-sectional view of the power converter according to Embodiment 2. Figure 10A is a cross-sectional view taken from arrow XA-XA in Figure 9. Figure 10B is a cross-sectional view showing an example of the state before the heat pipe condenser and cooling base shown in Figure 10A are assembled. This is a cross-sectional view of the power converter according to Embodiment 3. This is a cross-sectional view taken from arrow XII-XII in Figure 11. This is a cross-sectional view of a modified example of the power converter according to Embodiment 3. This is a cross-sectional view of the power converter according to Embodiment 4. This is a cross-sectional view of the power converter 1I according to Embodiment 5. This is a cross-sectional view taken from arrow XVI-XVI in Figure 15. This is a cross-sectional view of a first modified example of the power converter according to Embodiment 5. This is a cross-sectional view taken from arrow XVIII-XVIII in Figure 17. This is a cross-sectional view of a power converter 1K, which is a second modified example of the power converter 1I according to Embodiment 5. This is a cross-sectional view of the heat dissipation section and cooler shown in Figure 19.

[0013] Embodiments of the present disclosure will be described below with reference to the drawings. In the following, the same or corresponding parts will be denoted by the same reference numerals, and redundant descriptions will not be repeated.

[0014] <Configuration of Power Converter and Power Supply Circuit> The applications of the power converter according to the embodiments of this disclosure are not particularly limited, but for example, electric vehicles. The power converter according to the embodiments of this disclosure can also be applied to railway equipment and power transmission and distribution equipment.

[0015] The power conversion device according to the embodiment of this disclosure is, for example, a DC-DC converter. Figure 1 shows an example of a circuit diagram of a DC-DC converter. The DC-DC converter has the function of charging a lead-acid battery by converting the input voltage of a lithium-ion battery, for example, 100V to 300V, to a voltage of 12V to 15V, and outputting the converted voltage.

[0016] As shown in Figure 1, the power converter 1 comprises an inverter circuit section 2, a transformer section 3, a rectifier circuit section 4, an input terminal 6, an input capacitor 8, a control circuit section 10, and an output terminal 7. The power converter 1 comprises multiple circuit components that constitute each of the inverter circuit section 2, the transformer section 3, the rectifier circuit section 4, the input terminal 6, the input capacitor 8, the control circuit section 10, and the output terminal 7. Circuit components are a general term for the components mounted on the power converter 1. Circuit components include electronic components such as semiconductor elements, transformers, resistors, and capacitors, as well as wiring components and terminal components for electrically connecting each electronic component to other electronic components or external devices.

[0017] The inverter circuit section 2 is composed of, for example, four switching elements 9a, 9b, 9c, and 9d. The switching operation of the four switching elements 9 is controlled by the control circuit section 10. Each of the switching elements 9a, 9b, 9c, and 9d is a power semiconductor element such as a MOS transistor (MOSFET: Metal Oxide Semiconductor Field Effect Transistor) or an insulated gate bipolar transistor (IGBT: Insulated Gate Bipolar Transistor). The semiconductor material constituting each of the switching elements 9a, 9b, 9c, and 9d is not particularly limited, but includes, for example, silicon carbide (SiC).

[0018] The transformer section 3 is composed of a transformer 11 having a primary winding section 11a and a secondary winding section 11b. The rectifier circuit section 4 is composed of rectifier elements 12. Here, the rectifier circuit section 4 is composed of four rectifier elements 12a, 12b, 12c, and 12d. As the rectifier elements 12, power semiconductor elements such as diodes, MOS transistors, or thyristors are used. The smoothing circuit section 5 is composed of a smoothing reactor 13 and a smoothing capacitor 14.

[0019] In the power converter 1, the DC voltage input from the input terminal 6 is converted to an AC voltage by controlling the switching operation of each of the four switching elements 9a, 9B, 9C, and 9d in the inverter circuit section 2 using the control circuit section 10.

[0020] In the transformer section 3, the AC voltage converted in the inverter circuit section 2 is converted to an arbitrary voltage by the transformer 11. The converted voltage is determined by the winding ratio of the primary winding section 11a and the secondary winding section 11b in the transformer 11. The transformer 11 electrically insulates the input terminal 6 and the output terminal 7.

[0021] In the rectifier circuit section 4, the AC voltage supplied from the transformer section 3 is converted back into a DC voltage by the rectifier element 12. In the smoothing circuit section 5, the DC voltage converted by the rectifier circuit section 4 is smoothed by the smoothing reactor 13 and the smoothing capacitor 14. This stabilizes the output voltage output from the output terminal 7.

[0022] Among the multiple circuit components included in the power converter 1, the heat generated by the switching elements 9a, 9B, 9C, 9d, the rectifier elements 12a, 12b, 12c, 12d, the transformer 11, and the smoothing reactor 13 is higher than that generated by the other circuit components. The power converter 1 further includes a heat dissipation section to dissipate the heat generated by the switching elements 9a, 9B, 9C, 9d, the rectifier elements 12a, 12b, 12c, 12d, the transformer 11, and the smoothing reactor 13, and to keep their temperatures below their allowable temperature. The allowable temperature of each of the above-mentioned circuit components is, for example, 100°C to 120°C.

[0023] In the embodiments 1 to 4 shown below, the heat dissipation section of the power converter according to the embodiments of this disclosure will be described in detail. For the sake of convenience in the following explanation, a first direction DR1, a second direction DR2, and a third direction DR3 that are orthogonal to each other are introduced.

[0024] Embodiment 1. Figure 2 is a perspective view of a power converter 1A according to Embodiment 1. Figure 3 is a cross-sectional view of the power converter 1A. As shown in Figures 2 and 3, the power converter 1A comprises, for example, a plurality of power units 60. Each power unit 60 includes a plurality of circuit components 20, a wiring board 30, a heat transport member 40, and a cooler 50. Note that the power converter 1A only needs to have at least one power unit 60.

[0025] The multiple circuit components 20 include switching elements 9a, 9B, 9C, 9d, rectifier elements 12a, 12b, 12c, 12d, a transformer 11, and a smoothing reactor 13. The multiple circuit components 20 are mounted on a wiring board 30.

[0026] The wiring board 30 is, for example, a metal base substrate and has a metal layer 31, an insulating layer 32, and a conductor pattern 33. The metal layer 31, the insulating layer 32, and the conductor pattern 33 are stacked in order in the second direction DR2. The wiring board 30 has a first main surface 30A and a second main surface 30B located on the opposite side of the first main surface 30A. The first main surface 30A and the second main surface 30B are both end faces of the wiring board 30 in the second direction DR2. The first main surface 30A is one end face of the metal layer 31 in the second direction DR2. The second main surface 30B is one end face of the conductor pattern 33 in the second direction DR2. The first main surface 30A is connected to the heat receiving portion 40A of the heat transport member 40. The second main surface 30B is connected to a plurality of circuit components 20.

[0027] The metal layer 31 is a plate-shaped member made of a metallic material. Specific examples of the constituent materials of the metal layer 31 include copper, copper alloys, aluminum, aluminum alloys, iron, iron alloys, etc. The thermal conductivity of the constituent material of the metal layer 31 is, for example, 1.0 W / (m·K) or higher. Preferably, the thermal conductivity of the constituent material of the metal layer 31 is 10 W / (m·K) or higher. More preferably, the thermal conductivity of the constituent material of the metal layer 31 is 100 W / (m·K) or higher.

[0028] The insulating layer 32 is disposed on the metal layer 31. The insulating layer 32 is made of an electrically insulating material. Specific examples of constituent materials for the insulating layer 32 include epoxy resin, glass fiber reinforced epoxy resin, and polyimide resin. The resin material included in the constituent material of the insulating layer 32 may contain a thermal conductive filler to improve the thermal conductivity of the insulating layer 32. The thickness of the insulating layer 32 is preferably as thin as possible, as long as it does not affect electrical insulation or manufacturing. Preferably, the thickness of the insulating layer 32 is 1 μm or more and 2000 μm or less. More preferably, the thickness of the insulating layer 32 is 1 μm or more and 150 μm or less.

[0029] The conductor pattern 33 is arranged on the insulating layer 32. The conductor pattern 33 is formed of a conductor. Specific examples of the constituent materials of the conductor pattern 33 include metal materials such as copper, copper alloys, nickel, nickel alloys, gold, gold alloys, aluminum, aluminum alloys, silver, silver alloys, tin, and tin alloys. The thickness of the conductor pattern 33 is, for example, 1 μm to 2000 μm. Multiple circuit components 20 are electrically connected to the conductor pattern 33. In this embodiment, the wiring board 30 is preferably a metal-based substrate, but is not limited to a metal-based substrate; a general multilayer printed wiring board without a metal base (metal layer 31) may also be used.

[0030] The heat transport member 40 has a heat receiving section 40A and a heat dissipation section 40B. The heat receiving section 40A and the heat dissipation section 40B are arranged side by side in a first direction DR1. The heat receiving section 40A is thermally connected to the wiring board 30. In this specification, "thermally connected to one part" means that the two parts are connected directly or via a heat transfer member without other members in between. In the following, the term "thermally" may be omitted. The heat receiving section 40A is connected, for example, to the metal layer 31 of the wiring board 30. The heat dissipation section 40B is thermally connected to the cooler 50. The heat transport member 40 is provided to transport heat from the heat receiving section 40A to the heat dissipation section 40B. If the wiring board 30 is a multilayer printed circuit board, the heat receiving section 40A only needs to be thermally connected to one main surface of the multilayer printed circuit board. Multiple circuit components 20 may be thermally connected to the heat receiving section 40A via the conductor pattern 33 (surface electrode pattern) and insulating layer of the multilayer printed circuit board. Multiple circuit components 20 may be thermally connected to the heat receiving section 40A via the conductor pattern 33 (surface electrode pattern), insulating layer, and back electrode pattern of the multilayer printed circuit board.

[0031] The heat transport member 40 includes, for example, a heat pipe 41 and a heat transfer base 42. The heat pipe 41 is a device that transfers heat using a working fluid sealed inside it. The heat pipe 41 has an evaporation section 41A and a condensation section 41B. The evaporation section 41A is included in the heat receiving section 40A. The condensation section 41B is included in the heat dissipation section 40B. In the evaporation section 41A, the working fluid, such as water, absorbs heat transmitted from the metal layer 31, evaporates into a gas, and moves to the condensation section 41B, which is at a lower temperature than the evaporation section 41A. In the condensation section 41B, the working fluid dissipates heat to the cooler 50, condenses back into a liquid, passes through the wick section inside the heat pipe 41, and returns to the evaporation section 41A. Therefore, in order to use the heat pipe 41 efficiently, it is preferable that the evaporation section 41A is connected to a plurality of circuit components 20, which are heat-generating parts, via the widest possible surface area. Similarly, it is preferable that the condensation section 41B is connected to the cooler 50, which is a cooling section, via the widest possible surface area. Each of the evaporation section 41A and the condensing section 41B extends, for example, along the first direction DR1.

[0032] The heat transport member 40 may have any structure for transporting heat from the heat receiving section 40A to the heat dissipation section 40B, either in place of or in addition to the heat pipe 41. The heat transport member 40 may have a graphene sheet. The in-plane direction of the graphene sheet is, for example, along the first main surface 30A.

[0033] The heat transfer base 42 has, for example, a first heat transfer section 42A and a second heat transfer section 42B. The first heat transfer section 42A connects the metal layer 31 and the evaporation section 41A of the heat pipe 41. The first heat transfer section 42A has a main surface that is in contact with the main surface 30A of the metal layer 31. The second heat transfer section 42B connects the condensation section 41B of the heat pipe 41 and the cooler 50. The first heat transfer section 42A and the second heat transfer section 42B are arranged side by side in a first direction DR1. The first heat transfer section 42A and the second heat transfer section 42B are connected, for example, in a first direction DR1.

[0034] The thermal conductivity of the constituent material of the heat transfer base 42 is equal to or greater than that of the constituent material of the metal layer 31. Specific examples of constituent materials for the heat transfer base 42 include copper, copper alloys, aluminum, aluminum alloys, iron, iron alloys, etc. The thermal conductivity of the constituent material of the heat transfer base 42 is, for example, 1.0 W / (m·K) or higher. Preferably, the thermal conductivity of the constituent material of the heat transfer base 42 is 10 W / (m·K) or higher. More preferably, the thermal conductivity of the constituent material of the heat transfer base 42 is 100 W / (m·K) or higher. The heat capacity of the heat transfer base 42 is, for example, greater than or equal to the heat capacity of the metal layer 31.

[0035] The cooler 50 includes, for example, a cooling base 51 and a first refrigerant pipe 52. The cooling base 51 is connected to the heat dissipation section 40B of the heat transport member 40. The cooling base 51 is connected to, for example, the condensation section 41B of the heat pipe 41 via the second heat transfer section 42B of the heat transfer base 42. The first refrigerant pipe 52 is connected to the heat dissipation section 40B of the heat transport member 40 via the cooling base 51. The first refrigerant pipe 52 constitutes part of a refrigerant circuit (not shown) through which the refrigerant circulates. In the cooler 50, the cooling base 51 is cooled by heat exchange with the refrigerant flowing inside the first refrigerant pipe 52. For example, the entire first refrigerant pipe 52 is arranged to overlap with the heat dissipation section 40B of the heat transport member 40 in the second direction DR2. For example, the entire first refrigerant pipe 52 is arranged to overlap with the condensation section 41B of the heat pipe 41 in the second direction DR2. The first refrigerant pipe 52 is, for example, a straight pipe extending along the third direction DR3. The first refrigerant pipe 52 is located, for example, in the central part of the cooling base 51 in each of the first direction DR1 and the second direction DR2.

[0036] Specific examples of constituent materials for the cooling base 51 include copper, copper alloys, aluminum, aluminum alloys, iron, iron alloys, etc. The thermal conductivity of the constituent material of the cooling base 51 is, for example, 1.0 W / (m·K) or higher. Preferably, the thermal conductivity of the constituent material of the cooling base 51 is 10 W / (m·K) or higher. More preferably, the thermal conductivity of the constituent material of the cooling base 51 is 100 W / (m·K) or higher.

[0037] The first refrigerant pipe 52 is, for example, a copper pipe. The method of connecting the cooling base 51 and the first refrigerant pipe 52 is not particularly limited, but may include, for example, brazing, bonding using adhesive or thermal conductive grease, press-fitting, or crimping. The cooling base 51 is provided with a through hole through which the first refrigerant pipe 52 passes. The method of forming this through hole is not particularly limited, but may include, for example, extrusion molding or cutting using a drill. The cooling base 51 may be a joint of two or more base bodies. In this case, grooves may be provided on the joint surfaces of each base body, and the through hole may be formed by connecting the grooves of each base body.

[0038] The cooler 50 has a portion that is positioned to overlap with a plurality of circuit components 20 and the wiring board 30 in a first direction DR1. The dimension of the cooler 50 in the first direction DR1 is, for example, larger than the dimension of the cooler 50 in a second direction DR2.

[0039] Furthermore, the cooler 50 may be provided with an air passage through which air flows, either in place of the first refrigerant pipe 52 or in addition to the first refrigerant pipe 52.

[0040] Each of the multiple power units 60 is a single structure. In each of the multiple power units 60, the multiple circuit components 20, the wiring board 30, the heat transport member 40, and the cooler 50 are integrated with each other.

[0041] Multiple power units 60 are arranged side by side in the second direction DR2. Each wiring board 30 of the multiple power units 60 is arranged to overlap each other in the second direction DR2. Each heat transport member 40 of the multiple power units 60 is arranged to overlap each other in the second direction DR2. Each cooler 50 of the multiple power units 60 is arranged to overlap each other in the second direction DR2. The heat receiving portion 40A of each heat transport member 40 of the multiple power units 60 is arranged with a gap between it and, for example, the multiple circuit components 20 of other adjacent power units 60. The heat dissipation portion 40B of each heat transport member 40 of the multiple power units 60 is also connected to, for example, the cooler 50 of other adjacent power units 60.

[0042] The power converter 1A further includes, for example, a connection board 70. The connection board 70 is located on the opposite side of the cooler 50 in the first direction DR1. Each of the wiring boards 30 of the multiple power units 60 is fixed to the connection board 70.

[0043] In the power conversion device 1A, the heat generated in each of the plurality of circuit components 20 is quickly transmitted to the heat radiating part 40B through the wiring board 30 and the heat receiving part 40A of the heat transport member 40, and can be released from the heat radiating part 40B to the outside of the power conversion device 1A by the cooler 50. The heat generated in the circuit component 20 separated from the cooler 50 is aggregated in the heat transport member 40 together with the heat generated in the circuit component 20 close to the cooler 50, and can be released to the outside of the power conversion device 1A through the cooler 50. Therefore, in the power conversion device 1A, each of the plurality of circuit components 20 can be efficiently cooled. As a result, in the power conversion device 1A, after the cooler 50 is provided long in the third direction DR3, it is not necessary to arrange a plurality of circuit components 20 having a relatively large amount of heat generation side by side in the third direction DR3 near the cooler 50. Further, in the power conversion device 1A, it is not necessary to increase the size of the circuit component 20 in order to reduce the heat generation density, or to increase the size of the cooler 50 in order to improve the cooling performance. Therefore, the power conversion device 1A can be miniaturized as compared with the conventional power conversion device described above.

[0044] Furthermore, in the power conversion device 1A, since the restriction on the arrangement of the circuit component 20 having a large amount of heat generation is relaxed, an increase in parasitic inductance and thus the generation of noise current can be suppressed. Therefore, in the power conversion device 1A, a structure for reducing the noise current can be made unnecessary, and it is possible to achieve both low noise, miniaturization, and low cost.

[0045] Also, in the power conversion device 1A, since the dimension of the cooler 50 in the first direction DR1 is larger than the dimension of the cooler 50 in the second direction DR2, compared with the case where the dimension of the cooler 50 in the first direction DR1 is smaller than the dimension of the cooler 50 in the second direction DR2, the cooler 50 can be miniaturized in the second direction DR2, and the area of the contact surface between the heat radiating part 40B of the heat transport member 40 and the cooler 50 can be increased. Therefore, in the power conversion device 1A, while suppressing an increase in the thermal resistance between the heat radiating part 40B of the heat transport member 40 and the cooler 50, miniaturization of the cooler 50 and thus miniaturization of the power conversion device 1A are possible.

[0046] In the power conversion device 1A, the heat radiating part 40B of the heat transport member 40 of one of the two power units 60 adjacent to each other in the second direction DR2 is connected to the cooler 50 of the other power unit 60. Therefore, in the power conversion device 1A, compared with the case where the heat radiating part 40B of the heat transport member 40 of one of the two adjacent power units 60 is not connected to the cooler 50 of the other power unit 60, it is possible to more efficiently cool the plurality of circuit components 20 of each power unit 60.

[0047] In the power conversion device 1A, each of the plurality of power units 60 is an integral structure having a heat transport member 40 and a cooler 50. The plurality of power units 60 can be easily assembled. Also, each power unit 60 can be individually replaced. Therefore, the power conversion device 1A is excellent in terms of assembly and maintainability.

[0048] <Power conversion device 1A modification example> Figure 4 is a cross-sectional view of a power conversion device  1B, which is a first modification example of the power conversion device 1A. As shown in Figure 4, in the power conversion device 1B, the first refrigerant pipe 52 of the cooler 50 is connected to the surface 51A of the cooling base 51. The surface 51A is the surface that appears outside in the cooling base 51. Preferably, the surface 51A faces the side opposite to the wiring board 30 in the first direction DR1. More preferably, a groove is provided on the surface 51A. A part of the outer peripheral surface of the first refrigerant pipe 52 is connected to the inner peripheral surface of the groove. Between the inner peripheral surface of the groove of the cooling base 51 and the outer peripheral surface of the first refrigerant pipe 52, a heat conductive material such as TIM (Thermal Interface Material) is filled, for example.

[0049] In the power conversion device 1B, the first refrigerant pipe 52 of each power unit 60 can be easily connected to the cooling base 51 after other components of the power conversion device 1B are assembled. Also, during maintenance of the power conversion device 1B, the first refrigerant pipe 52 of each power unit 60 can be easily removed from the cooling base 51. Therefore, the power conversion device 1B is excellent in terms of assembly and maintainability.

[0050] Figure 5 is a cross-sectional view of power converter 1C, which is a second modified example of power converter 1A. Figure 6 is a cross-sectional view taken from arrow VI-VI in Figure 5. In Figure 6, components other than the cooler 50 are omitted from the illustration. As shown in Figures 5 and 6, in power converter 1C, the cooler 50 has a first refrigerant pipe 52 and a second refrigerant pipe 53. The second refrigerant pipe 53 is spaced apart from the first refrigerant pipe 52 in the first direction DR1. The second refrigerant pipe 53 is connected to the heat dissipation section 40B of the heat transport member 40 via a cooling base 51. The second refrigerant pipe 53 has a portion that is arranged to overlap with the heat dissipation section 40B in the second direction DR2.

[0051] Each of the first refrigerant pipe 52 and the second refrigerant pipe 53 extends along the third direction DR3. The second refrigerant pipe 53 extends, for example, parallel to the first refrigerant pipe 52. In the first direction DR1, the second refrigerant pipe 53 is positioned, for example, closer to the wiring board 30 than the first refrigerant pipe 52. The distance in the second direction DR2 between the second refrigerant pipe 53 and the heat dissipation portion 40B of the heat transport member 40 is equal to, for example, the distance in the second direction DR2 between the first refrigerant pipe 52 and the heat dissipation portion 40B of the heat transport member 40. In the first direction DR1, the second refrigerant pipe 53 may be positioned further away from the wiring board 30 than the first refrigerant pipe 52.

[0052] As shown in Figure 6, the second refrigerant pipe 53 is connected in series with the first refrigerant pipe 52 such that the direction of refrigerant flow in the second refrigerant pipe 53 is opposite to the direction of refrigerant flow in the first refrigerant pipe 52. The first refrigerant pipe 52 and the second refrigerant pipe 53 form a single refrigerant flow path. In Figure 5, symbols indicating the direction of refrigerant flow are shown inside each of the first refrigerant pipe 52 and the second refrigerant pipe 53. In Figure 5, the refrigerant flowing through the first refrigerant pipe 52 flows from the front to the back of the paper. The refrigerant flowing through the second refrigerant pipe 53 flows from the back to the front of the paper.

[0053] The first refrigerant pipe 52 has an inlet 54 through which the refrigerant flows in. The second refrigerant pipe 53 has an outlet 55 through which the refrigerant flows out. The cooling base 51 has a surface 51B facing one side of the third direction DR3. The inlet 54 and the outlet 55 are located on the surface 51B of the cooling base 51.

[0054] The first refrigerant pipe 52 and the second refrigerant pipe 53 are configured, for example, as part of a U-shaped pipe. The cooler 50 has a curved pipe section 56 that connects one end each of the first refrigerant pipe 52 and the second refrigerant pipe 53 in the third direction DR3. The curved pipe section 56 protrudes outward from the surface of the cooling base 51, for example, facing away from the surface 51B in the third direction DR3.

[0055] The refrigerant that flows into the first refrigerant pipe 52 from the inlet 54 exchanges heat with the cooling base 51 via the first refrigerant pipe 52, and then flows into the second refrigerant pipe 53 via the curved pipe section 56. The refrigerant that flows into the second refrigerant pipe 53 exchanges heat with the cooling base 51 via the second refrigerant pipe 53, and then flows out to the outside from the outlet 55.

[0056] In the power converter 1C, the cooler 50 may have three or more refrigerant pipes. From a different perspective, in the power converter 1C, three or more refrigerant flow paths may be connected in series with each other in each cooler 50.

[0057] In the power converter 1C, the cooler 50 has a first refrigerant pipe 52 and a second refrigerant pipe 53, and each of the first refrigerant pipe 52 and the second refrigerant pipe 53 is connected to the heat dissipation section 40B of the heat transport member 40 via a cooling base 51. Therefore, in the power converter 1C, compared to a case where the cooler 50 does not have a second refrigerant pipe 53, the area of ​​the heat transfer surface between the cooling base 51 and the first refrigerant pipe 52 and the second refrigerant pipe 53 can be increased, and the thermal resistance between the heat dissipation section 40B of the heat transport member 40 and the first refrigerant pipe 52 and the second refrigerant pipe 53 of the cooler 50 can be reduced.

[0058] Furthermore, the refrigerant flowing through the first refrigerant pipe 52 and the second refrigerant pipe 53 is heated by heat exchange with the cooling base 51. If the first refrigerant pipe 52 and the second refrigerant pipe 53 were connected in a straight line, heat exchange with the refrigerant flowing through the first and second refrigerant pipes 52 and 53 would cause a temperature distribution in the third direction DR3 on the cooling base 51, and the cooling capacity of the cooler 50 would locally decrease in the high-temperature portion of the cooling base 51. To compensate for this decrease in cooling capacity, the cooling base 51 would need to be enlarged. In contrast, in the power converter 1C, the second refrigerant pipe 53 is connected in series with the first refrigerant pipe 52 such that the direction of refrigerant flow in the second refrigerant pipe 53 is opposite to the direction of refrigerant flow in the first refrigerant pipe 52. As a result, the temperature distribution of the third direction DR3 formed on the cooling base 51 by heat exchange with the refrigerant flowing through the second refrigerant pipe 53 is formed to reduce the temperature distribution of the third direction DR3 formed on the cooling base 51 by heat exchange with the refrigerant flowing through the first refrigerant pipe 52. Therefore, with the power converter 1C, a localized decrease in the cooling capacity of the cooler 50 can be suppressed without increasing the size of the cooling base 51.

[0059] In the power converter 1C, since the inlet 54 and outlet 55 are located on the same surface 51B of the cooling base 51, installation work for connecting the inlet 54 and outlet 55 to the remaining part of the refrigerant circuit (not shown) and maintenance work on the connection part are easy.

[0060] Figure 7 is a cross-sectional view of a power converter 1D, which is a third modified example of power converter 1A. Figure 8 is a cross-sectional view taken from arrow VIII-VIII in Figure 7. In Figure 8, all parts of each power unit 60 except the heat transport member 40 and the cooler 50 are omitted from the illustration. As shown in Figures 7 and 8, in the power converter 1D, the cooler 50 of each power unit 60 has a first refrigerant pipe 52 and a second refrigerant pipe 53. The second refrigerant pipe 53 is spaced apart from the first refrigerant pipe 52 in the first direction DR1. The second refrigerant pipe 53 is connected to the heat dissipation section 40B of the heat transport member 40 via a cooling base 51. The second refrigerant pipe 53 has a portion that is arranged to overlap with the heat dissipation section 40B in the second direction DR2.

[0061] Each of the first refrigerant pipe 52 and the second refrigerant pipe 53 extends along the third direction DR3. The second refrigerant pipe 53 extends, for example, parallel to the first refrigerant pipe 52. In the first direction DR1, the second refrigerant pipe 53 is positioned, for example, closer to the wiring board 30 than the first refrigerant pipe 52. The distance in the second direction DR2 between the second refrigerant pipe 53 and the heat dissipation portion 40B of the heat transport member 40 is equal to, for example, the distance in the second direction DR2 between the first refrigerant pipe 52 and the heat dissipation portion 40B of the heat transport member 40. In the first direction DR1, the second refrigerant pipe 53 may be positioned further away from the wiring board 30 than the first refrigerant pipe 52.

[0062] As shown in Figures 7 and 8, the first refrigerant pipes 52 of the cooler 50 of each power unit 60 are connected in series to form a first refrigerant flow path F1. The first refrigerant pipes 52 of the cooler 50 of each power unit 60 are connected in series to form a second refrigerant flow path F2 via a bent pipe section 57. The second refrigerant pipes 53 of the cooler 50 of each power unit 60 are connected in series to form a second refrigerant flow path F2. The second refrigerant flow path F2 is connected in series to the first refrigerant flow path F1 via a bent pipe section 58.

[0063] The second refrigerant pipe 53 of the cooler 50 of each power unit 60, the curved pipe section 57 connecting the second refrigerant pipes 53 together, and the second refrigerant flow path F2 are arranged in the first direction DR1 so as to overlap with the first refrigerant pipe 52 of the cooler 50 of each power unit 60, the curved pipe section 57 connecting the first refrigerant pipes 52 together, and the first refrigerant flow path F1. Therefore, in Figure 8, the second refrigerant pipe 53 of the cooler 50 of each power unit 60, the curved pipe section 57 connecting the second refrigerant pipes 53 together, and the second refrigerant flow path F2 are not shown.

[0064] The first refrigerant pipe 52 of one of the multiple power units 60, power unit 60A, has an inlet 54 through which refrigerant flows in. The second refrigerant pipe 53 of power unit 60A has an outlet 55 through which refrigerant flows out. The first refrigerant pipe 52 of another of the multiple power units 60, power unit 60B, is connected in series to the second refrigerant pipe 53 of power unit 60B via a curved section 58.

[0065] The cooling base 51 of the cooler 50 of each power unit 60 has a surface 51B facing one side of the third direction DR3 and a surface 51C facing the other side. The surfaces 51B of the cooler 50 of each power unit 60 are connected via the heat dissipation portion 40B of the heat transport member 40. The surfaces 51C of the cooler 50 of each power unit 60 are connected via the heat dissipation portion 40B of the heat transport member 40.

[0066] The inlet 54 and outlet 55 are located on the surface 51B of the cooling base 51 of the power unit 60A. Each curved pipe section 57 protrudes outward from the surface 51B or surface 51C of the cooling base 51 of two adjacent power units 60 in the second direction DR2. Each curved pipe section 57 has a heat dissipation section 40B sandwiched between two adjacent cooling bases 51 in the second direction DR2, and a portion that is positioned opposite in the third direction DR3. The curved pipe section 58 protrudes outward from the surface 51B of the cooling base 51 of the power unit 60A, for example. If the number of power units 60 is odd, the curved pipe section 58 may protrude outward from the surface 51C.

[0067] The refrigerant that flows from the inlet 54 into the first refrigerant pipe 52 of power unit 60A exchanges heat with the cooling base 51 via the first refrigerant pipe 52 in the cooler 50 of each power unit 60, and then flows through the curved pipe section 58 into the second refrigerant pipe 53 of power unit 60B. The refrigerant that flows into the second refrigerant pipe 53 of power unit 60B exchanges heat with the cooling base 51 via the second refrigerant pipe 53 in the cooler 50 of each power unit 60, and then flows out to the outside from the outlet 55.

[0068] In the power converter 1D, each cooler 50 may have three or more refrigerant pipes. From a different perspective, in the power converter 1D, three or more refrigerant flow paths may be connected in series with respect to each other in multiple coolers 50.

[0069] In the power converter 1D, the first refrigerant flow path F1 and the second refrigerant flow path F2, which are formed across the coolers 50 of each of the multiple power units 60, function to suppress temperature variations in each of the coolers 50 of the multiple power units 60. Therefore, in the power converter 1D, when each power unit 60 is operated in parallel, the temperature difference between each power unit 60 can be suppressed without the need for a parallel control circuit to adjust the output of each power unit 60. Since a complex parallel control circuit is not required in the power converter 1D, it is possible to miniaturize and reduce the cost of the power converter 1D.

[0070] In the power converter 1D, as in the power converter 1C, the inlet 54 and outlet 55 are located on the same surface 51B of the cooling base 51 of a single power unit 60A. Therefore, installation work to connect the inlet 54 and outlet 55 to the remaining part of the refrigerant circuit (not shown) and maintenance work on the connection part are easy.

[0071] Embodiment 2. Figure 9 is a cross-sectional view of the power converter 1E according to Embodiment 2. Figure 10A is a cross-sectional view taken from arrow XA-XA in Figure 9. Figure 10B is a cross-sectional view showing an example of the state before the condensation section 41B and cooling base 51 of the heat pipe 41 shown in Figure 10A are assembled. In Figures 10A and 10B, parts other than the condensation section 41B and cooling base 51 of the heat pipe 41 of each power unit 60 are omitted from the illustration.

[0072] As shown in Figures 9, 10A, and 10B, the power converter 1E according to Embodiment 2 has the same configuration and effects as Embodiment 1 unless otherwise specified. Therefore, the same reference numerals are used for components identical to those in Embodiment 1, and their descriptions are not repeated.

[0073] In the power converter 1E, the condensing section 41B of the heat pipe 41 is directly connected to the cooler 50. The condensing section 41B is connected to the cooling base 51 of the cooler 50 without going through the second heat transfer section 42B of the heat transfer base 42.

[0074] In the power converter 1E, in the second direction DR2, one of the two adjacent coolers 50 has a first cooling base 511, and the other cooler 50 has a second cooling base 512.

[0075] Each of the first cooling base 511 and the second cooling base 512 has a coupling surface 51D to which they are joined together. A groove 51E is provided in each coupling surface 51D of the first cooling base 511 and the second cooling base 512. The dimension (depth) of the groove 51E in the second direction DR2 is smaller than, for example, the dimension (width) of the groove 51E in the third direction DR3. The grooves 51E of the first cooling base 511 and the second cooling base 512 form holes facing each other. In a cross-section perpendicular to the first direction DR1, the shape of these holes is, for example, flat. The condensation portion 41B of the heat pipe 41 is fitted into the holes. In a cross-section perpendicular to the first direction DR1, the outer shape of the condensation portion 41B of the heat pipe 41 is, for example, flat. A thermally conductive material such as TIM (Thermal Interface Material) may be filled between the condensation portion 41B of the heat pipe 41 and the inner circumferential surface of the groove 51E of the cooling base 51.

[0076] The coupling structure between the condensing portion 41B of the heat pipe 41 shown in Figure 10A and the first cooling base 511 and the second cooling base 512 can be formed by coupling the respective coupling surfaces 51D of the first cooling base 511 and the second cooling base 512, as shown in Figure 10B. The respective coupling surfaces 51D of the first cooling base 511 and the second cooling base 512 are coupled, for example, when two adjacent power units 60 are coupled to each other.

[0077] As shown in Figure 10B, in a cross-section perpendicular to the first direction DR1, the outer shape of the condensed portion 41B of the heat pipe 41 before coupling is, for example, circular. The dimension (depth) of the groove 51E in the second direction DR2 may be smaller than the outer diameter of the condensed portion 41B of the heat pipe 41 before coupling. The condensed portion 41B of the heat pipe 41 may be crushed in the second direction DR2 by the first cooling base 511 and the second cooling base 512.

[0078] In the power converter 1E, the condensing portion 41B of the heat pipe 41 is connected to the cooler 50 without going through the heat transfer base 42. Therefore, compared to the power converter 1A, where the condensing portion 41B of the heat pipe 41 is connected to the cooler 50 via the heat transfer base 42, the thermal resistance between the condensing portion 41B (heat dissipation portion 40B) and the cooler 50 can be reduced. Consequently, in the power converter 1E, it is possible to miniaturize the cooler 50 and, consequently, the power converter 1E, while suppressing the increase in thermal resistance between the heat dissipation portion 40B of the heat transport member 40 and the cooler 50.

[0079] Each cooler 50 may have a first cooling base 511 and a second cooling base 512. In each power unit 60, the condensation portion 41B of the heat pipe 41 may be connected to the cooler 50 without going through the heat transfer base 42.

[0080] Embodiment 3. Figure 11 is a cross-sectional view of the power converter 1F according to Embodiment 3. Figure 12 is a cross-sectional view taken from arrow XII-XII in Figure 11. In Figure 12, parts other than the condensation section 41B of the heat pipe 41 and the cooler 50 of each power unit 60 are omitted from the illustration.

[0081] As shown in Figures 11 and 12, the power converter 1F according to Embodiment 3 has the same configuration and effects as Embodiment 1 unless otherwise specified. Therefore, the same reference numerals are used for components identical to those in Embodiment 1, and their descriptions are not repeated.

[0082] The power converter 1F comprises a first wiring board 301 and a second wiring board 302. Each of the first wiring board 301 and the second wiring board 302 has a structure similar to that of the wiring board 30 of the power converter 1A. Each of the first wiring board 301 and the second wiring board 302 has a metal layer 31, an insulating layer 32, and a conductor pattern 33. Multiple circuit components 20 are mounted on the conductor pattern 33 of each of the first wiring board 301 and the second wiring board 302.

[0083] The first wiring board 301 and the second wiring board 302 are arranged so as to sandwich a heat receiving portion 40A of a single heat transport member 40. The heat receiving portion 40A is connected to the respective metal layers 31 of the first wiring board 301 and the second wiring board 302.

[0084] The power converter 1F comprises a first cooler 501 and a second cooler 502. Each of the first cooler 501 and the second cooler 502 has the same structure as the cooler 50 of the power converter 1A. Each of the first cooler 501 and the second cooler 502 has a cooling base 51 and a first refrigerant pipe 52.

[0085] The first cooler 501 and the second cooler 502 are arranged so as to sandwich a heat dissipation section 40B of a single heat transport member 40. The heat dissipation section 40B is connected to the first cooler 501 and the second cooler 502, respectively.

[0086] In the power converter 1F, the first wiring board 301 and the multiple circuit components 20 mounted thereon, and the second wiring board 302 and the multiple circuit components 20 mounted thereon are arranged to operate in parallel with each other, for example. From a different perspective, in the power converter 1F, two power units 60C and 60D, which are adjacent in the second direction DR2 among the multiple power units 60 that operate in parallel with each other, share one heat transport member 40.

[0087] As shown in Figure 12, the first refrigerant pipe 52 of the second cooler 502 is connected in series with the first refrigerant pipe 52 of the first cooler 501, for example, such that the direction of refrigerant flow is opposite to the direction of refrigerant flow in the first refrigerant pipe 52 of the first cooler 501. The first refrigerant pipes 52 of the first cooler 501 and the second cooler 502 each form a single refrigerant flow path. In Figure 11, as in Figure 5, symbols indicating the direction of refrigerant flow are shown inside each first refrigerant pipe 52.

[0088] In two adjacent power units 60C and 60D, the cooling base 51 of the second cooler 502 of one power unit 60C is connected to the cooling base 51 of the first cooler 501 of the other power unit 60D.

[0089] In two adjacent power units 60C and 60D, the multiple circuit components 20 mounted on the second wiring board 302 of one power unit 60C are arranged with a gap between them and the multiple circuit components 20 mounted on the first wiring board 301 of the other power unit 60D in the second direction DR2.

[0090] In the power converter 1F, multiple circuit components 20 mounted on the first wiring board 301 and the second wiring board 302 can be cooled using a single heat transport member 40. Therefore, the power converter 1F can be made even smaller than the power converter 1A.

[0091] In the power converter 1F, the heat dissipation portion 40B of one heat transport member 40 can be cooled by the first cooler 501 and the second cooler 502. Therefore, the thermal resistance between the heat dissipation portion 40B of the heat transport member 40 and each of the first cooler 501 and the second cooler 502 can be reduced. As a result, the power converter 1F can be miniaturized.

[0092] <Modified Example of Power Conversion Device 1F> Figure 13 is a cross-sectional view of a power conversion device 1G, which is a modified example of power conversion device 1F. As shown in Figure 13, power conversion device 1G comprises a first wiring board 301, a second wiring board 302, a third wiring board 303, a plurality of circuit components 20 mounted on each of the first wiring board 301, the second wiring board 302, and the third wiring board 303, a first heat transport member 401, a second heat transport member 402, and a cooler 50. The third wiring board 303 has a structure similar to the wiring board 30 of power conversion device 1A. Each of the first heat transport member 401 and the second heat transport member 402 has a structure similar to, for example, the heat transport member 40 of power conversion device 1A. Each of the first heat transport member 401 and the second heat transport member 402 has a heat receiving section 40A and a heat dissipation section 40B.

[0093] The first wiring board 301 and the second wiring board 302 are arranged so as to sandwich the heat receiving portion 40A of the first heat transport member 401. The heat receiving portion 40A of the first heat transport member 401 is connected to the respective metal layers 31 of the first wiring board 301 and the second wiring board 302. The heat receiving portion 40A of the second heat transport member 402 is connected to the metal layer 31 of the third wiring board 303. The cooler 50 is connected to the respective heat dissipation portions 40B of the first heat transport member 401 and the second heat transport member 402.

[0094] In the power converter 1G, the first wiring board 301 and the multiple circuit components 20 mounted thereon, the second wiring board 302 and the multiple circuit components 20 mounted thereon, and the third wiring board 303 and the multiple circuit components 20 mounted thereon are arranged to operate in parallel with each other, for example. From a different perspective, in the power converter 1G, three power units 60F, 60G, and 60H that are adjacent in the second direction DR2 among the multiple power units 60 that operate in parallel with each other share one cooler 50.

[0095] In the power converter 1G, multiple circuit components 20 mounted on the first wiring board 301, the second wiring board 302, and the third wiring board 303 can be cooled using a single cooler 50. Therefore, the power converter 1G can be made even smaller than the power converter 1F.

[0096] The power converter 1G may further include a fourth wiring board 304. The third wiring board 303 and the fourth wiring board 304 may be arranged so as to sandwich the heat receiving portion 40A of the second heat transport member 402. The heat receiving portion 40A of the second heat transport member 402 may be connected to the respective metal layers 31 of the third wiring board 303 and the fourth wiring board 304.

[0097] Furthermore, in each of the first heat transport member 401 and the second heat transport member 402, the condensation portion 41B of the heat pipe 41 may be connected to the cooling base 51 of the cooler 50 without going through the heat transfer base 42.

[0098] Embodiment 4. Figure 14 is a cross-sectional view of the power converter 1H according to Embodiment 4. As shown in Figure 14, the power converter 1H according to Embodiment 4 has the same configuration and effects as Embodiment 1 unless otherwise specified. Therefore, the same reference numerals are used for components identical to those in Embodiment 1, and the descriptions are not repeated.

[0099] The power converter 1H comprises a fifth wiring board 305, a sixth wiring board 306, a third heat transport member 403, and a fourth heat transport member 404.

[0100] Each of the fifth wiring board 305 and the sixth wiring board 306 has a structure similar to that of the wiring board 30 of the power converter 1A. Each of the fifth wiring board 305 and the sixth wiring board 306 has a metal layer 31, an insulating layer 32, and a conductor pattern 33. Multiple circuit components 20 are mounted on the conductor pattern 33 of each of the fifth wiring board 305 and the sixth wiring board 306.

[0101] Each of the third heat transport member 403 and the fourth heat transport member 404 has a structure similar to that of the heat transport member 40 of the power converter 1A. Each of the third heat transport member 403 and the fourth heat transport member 404 has a heat receiving section 40A and a heat dissipation section 40B.

[0102] The third heat transport member 403 and the fourth heat transport member 404 are arranged so as to sandwich the fifth wiring board 305 and the sixth wiring board 306. The heat receiving portion 40A of the third heat transport member 403 is connected to each of the metal layers 31 of the fifth wiring board 305. The heat receiving portion 40A of the fourth heat transport member 404 is connected to the metal layer 31 of the sixth wiring board 306.

[0103] The power converter 1H further comprises, for example, a third cooler 503 and a fourth cooler 504. Each of the third cooler 503 and the fourth cooler 504 has a structure similar to that of the cooler 50 of the power converter 1A. Each of the third cooler 503 and the fourth cooler 504 has a cooling base 51 and a first refrigerant pipe 52.

[0104] The third cooler 503 and the fourth cooler 504 are positioned between the heat dissipation section 40B of the third heat transport member 403 and the heat dissipation section 40B of the fourth heat transport member 404. The heat dissipation section 40B of the third heat transport member 403 is connected to the third cooler 503. The heat dissipation section 40B of the fourth heat transport member 404 is connected to the fourth cooler 504.

[0105] In the power converter 1H, the third heat transport member 403, the fourth heat transport member 404, the third cooler 503, and the fourth cooler 504 constitute at least a part of the housing of the power converter 1H. Preferably, the constituent materials of the third heat transport member 403, the fourth heat transport member 404, the third cooler 503, and the fourth cooler 504 are metal materials that have high durability in the environment in which the power converter 1H is installed.

[0106] In the power converter 1H, for example, the third heat transport member 403, the fourth heat transport member 404, the third cooler 503, and the fourth cooler 504 constitute the housing of the power converter 1H.

[0107] In the power converter 1H, the third heat transport member 403, the fourth heat transport member 404, the third cooler 503, and the fourth cooler 504 all serve as at least a part of the housing of the power converter 1H, thus simplifying the housing of the power converter 1H. As a result, the power converter 1H can be made smaller and less expensive.

[0108] Embodiment 5. Figure 15 is a cross-sectional view of the power converter 1I according to Embodiment 5. Figure 16 is a cross-sectional view taken from arrow XVI-XVI in Figure 15. In Figure 16, parts other than the condensation section 41B of the heat pipe 41, the heat transfer base 42, and the metal layer 31 are omitted from the illustration.

[0109] As shown in Figures 15 and 16, the power converter 1I according to Embodiment 5 has the same configuration and effects as Embodiment 1 unless otherwise specified. Therefore, the same reference numerals are used for components identical to those in Embodiment 1, and their descriptions are not repeated.

[0110] As shown in Figure 15, in the heat transport member 40, the heat dissipation section 40B is bent relative to the heat receiving section 40A. The heat dissipation section 40B is inclined toward the wiring board 30 side relative to the heat receiving section 40A when viewed from the third direction DR3. When viewed from the third direction DR3, the angle formed by the extending direction of the heat dissipation section 40B and the extending direction of the heat receiving section 40A (the angle formed by the respective central axes of the condensing section 41B and the evaporation section 41A) is, for example, 90 degrees. Note that when viewed from the third direction DR3, the angle formed by the extending direction of the heat dissipation section 40B and the extending direction of the heat receiving section 40A (the angle formed by the respective central axes of the condensing section 41B and the evaporation section 41A) may be any angle other than 180 degrees, and may be, for example, an obtuse angle.

[0111] The heat dissipation section 40B does not include, for example, the second heat transfer section 42B of the heat transfer base 42. The heat dissipation section 40B is composed solely of, for example, the condensation section 41B of the heat pipe 41.

[0112] As shown in Figure 16, when viewed from the first direction DR1, the heat dissipation section 40B has a bent portion that is bent at an acute angle with respect to the main surface 30A of the metal layer 31. The central axis C of the condensation section 41B of the heat pipe 41 included in the inclined portion of the heat dissipation section 40B is inclined at an acute angle with respect to the main surface 30A of the metal layer 31. For example, the entire heat dissipation section 40B is inclined at an acute angle with respect to the main surface 30A of the metal layer 31. The inclined portion of the heat dissipation section 40B is inclined at an acute angle with respect to the main surface of the first heat transfer section 42A that is in contact with the main surface 30A of the metal layer 31.

[0113] As shown in Figure 16, the heat transport member 40 has a plurality of heat pipes 41 that are spaced apart from each other in the third direction DR3. Viewed from the first direction DR1, the condensation portions 41B of each of the plurality of heat pipes 41 extend parallel to each other.

[0114] The heat dissipation section 40B shown in Figures 15 and 16 is bent relative to the heat receiving section 40A when viewed from the first direction DR1, the second direction DR2, and the third direction DR3, respectively.

[0115] In the power converter 1I, the heat dissipation section 40B has a bent portion that bends at an acute angle with respect to the main surface 30A of the metal layer 31 when viewed from the first direction DR1. Therefore, the length of the heat dissipation section 40B in the extending direction can be increased without increasing the dimension of the heat dissipation section 40B in the second direction DR2. As a result, the contact area between the heat dissipation section 40B and the cooler 50 can be increased without increasing the dimension of the heat dissipation section 40B in the second direction DR2. Consequently, in the power converter 1I, it is possible to miniaturize the cooler 50 and, consequently, the power converter 1I, while suppressing the increase in thermal resistance between the heat dissipation section 40B of the heat transport member 40 and the cooler 50.

[0116] <Modification> Figure 17 is a cross-sectional view of a power converter 1J, which is a first modification of the power converter 1I according to Embodiment 5. Figure 18 is a cross-sectional view taken from arrow XVIII-XVIII in Figure 17. In Figure 18, parts other than the condensation section 41B of the heat pipe 41 and the heat transfer base 42 are omitted from the illustration.

[0117] As shown in Figure 17, in the power converter 1J, the heat dissipation section 40B is bent relative to the heat receiving section 40A. The heat dissipation section 40B is inclined toward the wiring board 30 side relative to the heat receiving section 40A when viewed from the third direction DR3. When viewed from the third direction DR3, the angle formed by the extending direction of the heat dissipation section 40B and the extending direction of the heat receiving section 40A (the angle formed by the respective central axes of the condensing section 41B and the evaporation section 41A) is, for example, 90 degrees. Note that when viewed from the third direction DR3, the angle formed by the extending direction of the heat dissipation section 40B and the extending direction of the heat receiving section 40A (the angle formed by the respective central axes of the condensing section 41B and the evaporation section 41A) may be any angle other than 180 degrees, and may be, for example, an obtuse angle.

[0118] The heat dissipation section 40B does not include, for example, the second heat transfer section 42B of the heat transfer base 42. The heat dissipation section 40B is composed solely of, for example, the condensation section 41B of the heat pipe 41.

[0119] As shown in Figure 18, when viewed from the first direction DR1, the heat dissipation section 40B has a first section 42B1 and a second section 42B2. The second section 42B2 is connected to the heat receiving section 40A via the first section 42B1. The first section 42B1 and the second section 42B2 are, for example, part of the condensation section 41B of the heat pipe 41. The evaporation section 41A, the first section 42B1, and the second section 41B2 are connected in order. One end of the first section 41B1 is connected to one end of the evaporation section 41A. The other end of the first section 41B1 is connected to one end of the second section 41B2.

[0120] Viewed from the first direction DR1, the second portion 42B2 is bent relative to the first portion 42B1. Viewed from the first direction DR1, the central axis of the second portion 42B2 is inclined relative to the central axis of the first portion 42B1. The angle formed by the respective central axes of the first portion 42B1 and the second portion 42B2, as viewed from the first direction DR1, can be any angle, but for example, it is 90 degrees or greater.

[0121] The first portion 41B1 extends in a direction intersecting the main surface of the first heat transfer portion 42A, which is in contact with the main surface 30A of the metal layer 31, for example. The first portion 41B1 extends along the second direction DR2, for example. When viewed from the first direction, the angle that the central axis of the first portion 42B1 makes with the main surface of the first heat transfer portion 42A is, for example, 90 degrees. The angle that the central axis of the first portion 42B1 makes with the main surface of the first heat transfer portion 42A may be an acute angle.

[0122] The second portion 42B2 extends, for example, parallel to the main surface of the first heat transfer section 42A. The second portion 42B2 extends, for example, along the third direction DR3. When viewed from the first direction, the angle that the central axis of the second portion 42B2 makes with the main surface of the first heat transfer section 42A is, for example, 0 degrees. The angle that the central axis of the first portion 42B1 makes with the main surface of the first heat transfer section 42A may be acute.

[0123] In the power converter 1J, at least one of the first portion 42B1 and the second portion 42B2 may have a bent portion that is bent at an acute angle with respect to the main surface 30A of the metal layer 31. The entirety of each of the first portion 42B1 and the second portion 42B2 may be inclined at an acute angle with respect to the main surface 30A of the metal layer 31.

[0124] In the power converter 1J, when viewed from the first direction DR1, the second portion 42B2 is bent relative to the first portion 42B1. Therefore, compared to the case where the second portion 42B2 is not bent relative to the first portion 42B1, the length of the heat dissipation portion 40B in the extending direction can be increased without increasing the dimension of the heat dissipation portion 40B in the second direction DR2. As a result, the contact area between the heat dissipation portion 40B and the cooler 50 can be increased without increasing the dimension of the heat dissipation portion 40B in the second direction DR2. Consequently, even in the power converter 1J, it is possible to miniaturize the cooler 50 and, consequently, the power converter 1J, while suppressing the increase in thermal resistance between the heat dissipation portion 40B of the heat transport member 40 and the cooler 50.

[0125] Furthermore, the heat dissipation section 40B may also have a bent portion (not shown) that is connected to the first portion 42A via the second portion 42B and bent relative to the second portion 42B when viewed from the first direction DR1, and a third portion (not shown) that is connected to the second portion 42B via the bent portion. The third portion may extend along the second direction DR2. When viewed from the first direction DR1, the heat dissipation section 40B may have a U-shape. In this case, the heat dissipation section 40B can be extended in its extending direction without increasing the dimensions of the heat dissipation section 40B in each of the first direction DR1 and the second direction DR2, and the contact area between the heat dissipation section 40B and the cooler 50 can be increased. Even in such a power conversion device 1J, it is possible to further miniaturize the cooler 50 and, consequently, the power conversion device 1J, while suppressing the increase in thermal resistance between the heat dissipation section 40B of the heat transport member 40 and the cooler 50.

[0126] Figure 19 is a cross-sectional view of a power converter 1K, which is a second modified example of the power converter 1I according to Embodiment 5. Figure 20 is a cross-sectional view of the heat dissipation section 40B and the cooler 50 shown in Figure 19. In Figure 20, components other than the heat dissipation section 40B and the cooler 50 are omitted from the illustration.

[0127] In the power converter 1K, the heat dissipation section 40B has a first surface portion 41B3 facing the wiring board 30 side in the first direction DR1, and a second surface portion 41B4 located on the opposite side from the first surface portion 41B3. Each of the first surface portion 41B3 and the second surface portion 41B4 is, for example, a part of the surface of the condensation portion 41B of the heat pipe 41.

[0128] The cooler 50 is connected to the first surface portion 41B3 and the second surface portion 41B4, respectively. The cooler 50 includes, for example, a cooling base 51, a first heat dissipation spacer 59A, and a second heat dissipation spacer 59B. The first surface portion 41B3 is connected to the second heat dissipation spacer 59B. The second surface portion 41B4 is connected to the cooling base 51 and the first heat dissipation spacer 59A.

[0129] The first heat dissipation spacer 59A has surfaces that contact the surface portion of the second surface portion 41B4 of the heat dissipation section 40B that is not connected to the cooling base 51, and the surface portion of the cooling base 51 facing the wiring board 30 that is not connected to the second surface portion 41B4 of the heat dissipation section 40B, and is provided to connect the two surface portions. The first heat dissipation spacer 59A forms a heat path from the surface portion of the second surface portion 41B4 of the heat dissipation section 40B that is not connected to the cooling base 51, to the surface portion of the cooling base 51 facing the wiring board 30 that is not connected to the second surface portion 41B4 of the heat dissipation section 40B.

[0130] The second heat dissipation spacer 59B has surfaces that contact the first surface 41B3 of the heat dissipation section 40B and the surface portion of the cooling base 51 facing the wiring board 30 that is not connected to the second surface 41B4 of the heat dissipation section 40B, and is provided to connect the two surface portions. The second heat dissipation spacer 59B forms a heat path from the first surface 41B3 of the heat dissipation section 40B to the surface portion of the cooling base 51 facing the wiring board 30 that is not connected to the second surface 41B4 of the heat dissipation section 40B.

[0131] Specific examples of constituent materials for the first heat dissipation spacer 59A and the second heat dissipation spacer 59B include copper, copper alloys, aluminum, aluminum alloys, etc. The thermal conductivity of the constituent materials for the first heat dissipation spacer 59A and the second heat dissipation spacer 59B is, for example, 1.0 W / (m·K) or higher. Preferably, the thermal conductivity of the constituent materials for the first heat dissipation spacer 59A and the second heat dissipation spacer 59B is 10 W / (m·K) or higher. More preferably, the thermal conductivity of the constituent materials for the first heat dissipation spacer 59A and the second heat dissipation spacer 59B is 100 W / (m·K) or higher. Each of the first heat dissipation spacer 59A and the second heat dissipation spacer 59B may be formed from, for example, aluminum die casting. Each of the first heat dissipation spacer 59A and the second heat dissipation spacer 59B may be fixed to the cooling base 51 by any fixing means such as screws.

[0132] Preferably, the second heat dissipation spacer 59B is connected to the side surface 30C of the wiring board 30. The side surface 30C includes the side surface of the metal layer 31. Such a second heat dissipation spacer 59B forms a heat path from the side surface 30C of the wiring board 30 to the surface portion of the cooling base 51 facing the wiring board 30 that is not connected to the second surface portion 41B4 of the heat dissipation section 40B.

[0133] In the power converter 1K, the cooler 50 is connected to the first surface 41B3 and the second surface 41B4 of the heat dissipation section 40B, respectively, making it possible to efficiently cool each of the multiple circuit components 20.

[0134] In the embodiments and modified examples described above, the combinable configurations may be combined with each other.

[0135] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this application is indicated by the claims and not by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

[0136] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, 1K Power converter, 2 Inverter circuit section, 3 Transformer section, 4 Rectifier circuit section, 5 Smoothing circuit section, 6 Input terminal, 7 Output terminal, 8 Input capacitor, 9, 9a, 9b, 9c, 9d Switching element, 10 Control circuit section, 11 Transformer, 11a Primary winding section, 11b Secondary winding section, 12, 12a, 12b, 12c, 12d Rectifier element, 13, 14 Smoothing reactor, 20 Circuit components, 30 Wiring board, 30A First main surface, 30B Second main surface, 30C Side surface, 31 Metal layer, 32 Insulating layer, 33 Conductor pattern, 40 Heat transport member, 40A Heat receiving section, 40B Heat dissipation section, 41 Heat pipe, 41A Evaporation section, 41B Condensation section, 41B1 First part, 41B2 Second part, 41B3 First surface, 41B4 Second surface, 42 Heat transfer base, 42A First heat transfer section, 42B Second heat transfer section, 42B1 First part, 42B2 Second part, 50 Cooler, 51 Cooling base, 51A, 51B, 51C Surface, 51D Bonding surface, 51E Groove, 52 First refrigerant pipe, 53 Second refrigerant pipe, 54 Inlet, 55 Outlet, 56, 57 Curved pipe section, 58 Curved pipe section, 59A First heat dissipation spacer, 59B Second heat dissipation spacer, 60, 60A, 60B, 60C, 60D, 60F, 60G, 60H Power unit, 70 Connection board, 301 First wiring board, 302 Second wiring board, 303 Third wiring board, 304 Fourth wiring board, 305 Fifth wiring board, 306 Sixth wiring board, 401 First heat transport member, 402 Second heat transport member, 403 Third heat transport member, 404 Fourth heat transport member, 501 First cooler, 502 Second cooler, 503 Third cooler, 504 Fourth cooler, 511 First cooling base, 512 Second cooling base.

Claims

1. A power conversion device comprising: a plurality of circuit components; at least one wiring board; at least one heat transport member; and at least one cooler, wherein the at least one heat transport member has a heat receiving section and a heat dissipation section arranged side by side in a first direction, and is provided to transport heat from the heat receiving section to the heat dissipation section; the plurality of circuit components are thermally connected to the heat receiving section via the at least one wiring board; and the at least one cooler is thermally connected to the heat dissipation section of the at least one heat transport member.

2. The power conversion device according to claim 1, wherein the heat receiving portion of the at least one heat transport member, the at least one wiring board, and the plurality of circuit components are stacked in order in a second direction perpendicular to the first direction, and the at least one cooler has a portion that is arranged to overlap with the plurality of circuit components and the at least one wiring board in the first direction.

3. The power conversion device according to claim 1, wherein the at least one cooler comprises a cooling base and a first refrigerant pipe connected via the cooling base to the heat dissipation portion of the at least one heat transport member, and the first refrigerant pipe has a portion that is arranged to overlap with the heat dissipation portion in a second direction perpendicular to the first direction.

4. The power conversion device according to claim 3, wherein the cooling base has a surface exposed to the outside, and the first refrigerant pipe is connected to the surface.

5. The power conversion device according to claim 3, wherein the at least one cooler further comprises a second refrigerant pipe spaced apart from the first refrigerant pipe in the first direction, the second refrigerant pipe being thermally connected to the heat dissipation portion of the heat transport member via the cooling base, and the second refrigerant pipe being connected in series with the first refrigerant pipe such that the direction of flow of the refrigerant in the second refrigerant pipe is opposite to the direction of flow of the refrigerant in the first refrigerant pipe.

6. The power conversion device according to claim 5, wherein the first refrigerant pipe has an inlet for refrigerant to flow in, the second refrigerant pipe has an outlet for refrigerant to flow out, and the inlet and the outlet are arranged on the same plane.

7. The power conversion device according to any one of claims 3 to 6, wherein the at least one cooler comprises a plurality of coolers, the first refrigerant pipes of each of the plurality of coolers are connected in series with each other to form a first refrigerant flow path, each of the plurality of coolers further comprises a second refrigerant pipe spaced apart from the first refrigerant pipe in the first direction, the second refrigerant pipes of each of the plurality of coolers are connected in series with each other to form a second refrigerant flow path, and the second refrigerant flow path is connected in series with the first refrigerant flow path.

8. The power conversion device according to any one of claims 1 to 7, wherein the at least one heat transport member comprises a heat pipe and a heat transfer base, the heat pipe comprises an evaporation section included in the heat receiving section and a condensation section included in the heat dissipation section, the heat transfer base thermally connects the at least one wiring board and the evaporation section, and the condensation section is thermally connected to the at least one cooler without the heat transfer base.

9. The power conversion device according to claim 8, wherein the at least one cooler comprises a first cooling base and a second cooling base, the first cooling base and the second cooling base have coupling surfaces that are coupled to each other, grooves are provided on the coupling surfaces of the first cooling base and the second cooling base, the grooves of the first cooling base and the second cooling base form holes facing each other, and the condensing portion is fitted into the holes.

10. The power conversion device according to any one of claims 1 to 9, wherein the at least one wiring board comprises a first wiring board and a second wiring board, the first wiring board and the second wiring board are arranged to sandwich the heat receiving portion, and the heat receiving portion is thermally connected to each of the first wiring board and the second wiring board.

11. The power conversion device according to claim 10, wherein the at least one cooler comprises a first cooler and a second cooler, the first cooler and the second cooler are arranged so as to sandwich the heat dissipation section, and the heat dissipation section is thermally connected to each of the first cooler and the second cooler.

12. The power conversion device according to claim 10 or 11, wherein the at least one wiring board further comprises a third wiring board, the at least one heat transport member comprises a first heat transport member and a second heat transport member, the heat receiving portion of the first heat transport member is thermally connected to the first wiring board and the second wiring board, the heat receiving portion of the second heat transport member is thermally connected to the third wiring board, and the at least one cooler is thermally connected to the heat dissipation portion of the first heat transport member and the second heat transport member.

13. The power conversion device according to any one of claims 10 to 12, wherein the at least one heat transport member comprises a third heat transport member and a fourth heat transport member, the third heat transport member and the fourth heat transport member are arranged to sandwich the at least one wiring board, and the third heat transport member, the fourth heat transport member and the at least one cooler constitute at least a part of the housing of the power conversion device.

14. The power conversion device according to any one of claims 1 to 13, wherein the at least one wiring board has a main surface, the heat receiving portion is connected to the main surface, and the heat dissipation portion has a bent portion that, when viewed from the first direction, is bent at an acute angle with respect to the main surface.

15. The power conversion device according to any one of claims 1 to 13, wherein the heat dissipation portion is bent relative to the heat receiving portion, the heat dissipation portion has a first portion and a second portion that is thermally connected to the heat receiving portion via the first portion, and when viewed from the first direction, the second portion is bent relative to the first portion.

16. The power conversion device according to claim 14 or 15, wherein the heat dissipation portion has a first surface portion facing the at least one wiring board side in the first direction and a second surface portion located on the opposite side from the first surface portion, and the at least one cooler is thermally connected to each of the first surface portion and the second surface portion.

17. The power conversion device according to claim 15, wherein the heat dissipation portion has a first surface portion facing the at least one wiring board side in the first direction and a second surface portion located on the opposite side from the first surface portion, and the at least one cooler is thermally connected to each of the first surface portion and the second surface portion.

18. The power conversion device according to any one of claims 1 to 17, wherein the at least one wiring board has a metal layer in contact with the heat receiving portion, an insulating layer disposed on the metal layer, and a conductor pattern disposed on the insulating layer and connected to the plurality of circuit components.

Images