GB2523625A

GB2523625A - Power conversion device and railway vehicle equipped with the same

Info

Publication number: GB2523625A
Application number: GB1421746.7A
Authority: GB
Inventors: Sunao Funakoshi; Takeshi Tanaka; Hiroshi Okawara; Noriyoshi Urushiwara; Shuichi Terakado; Yosuke Yasuda
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2014-02-20
Filing date: 2014-12-08
Publication date: 2015-09-02
Anticipated expiration: 2034-12-08
Also published as: GB2523625B; JP2015156411A; DE102015202487A1; GB201421746D0; CN104867915A

Abstract

A power conversion device for a railway vehicle has a heat receiving member 5, power semiconductor elements 70-73, 80-83 and 90-93 emitting different amounts of heat, heat pipes 1-4, and fins 6 attached to the heat pipes. The power semiconductor elements are disposed on one surface of the heat receiving member, whilst the heat pipes are disposed on the other surface. The heat pipes have heat radiation portions and heat receiving portions. There are two kinds of heat pipes having different lengths of heat receiving portions, the heat receiving portions being arranged so that their longitudinal direction is substantially perpendicular to a flow direction of a cooling air flowing in the heat radiation members. The heat pipes having shorter heat receiving portions are located inside of a projection region of the power semiconductor elements emitting more heat, and the heat pipes having longer heat receiving portions are arranged across the inside and the outside of a projection region of the power semiconductor elements emitting less heat. This provides more efficient cooling.

Description

POWER CONVERSION DEVICE AND RAILWAY VEHICLE EQUIPPED WITH THE SAllE

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a power conversion device and a railway vehicle equipped with the power conversion device.

2. Description of the Related Art

The power conversion device is configured to control an electric motor that drives a vehicle such as an electric railway vehicle, and installed under a floor of the vehicle. Because a space under the floor of the vehicle is limited, it is desirable to downsize the power conversion device. In a related art power conversion device, a structure has been known in which in a structure where a heat receiving portion of a heat pipe is arranged to come in thermal contact with a heat receiving metter, a fin is arranged in a heat radiation portion of the heat pipe, and a cooling air is applied to the fin to cool a power semiconductor element as disclosed in JP-A-2011-259536, a direction of the heat receiving portion of the heat pipe in a longitudinal direction thereof is arranged in both directions parallel and perpendicular to the cooling air.

In particular, in the power conversion device such as a high speed vehicle, since the heat generating elements such as the power semiconductors of high heat generating density tend to be arranged densely, it is important how high heat generation is cooled to suppress a temperature rise of the semiconductor element. Also, in an inverter or a converter of a three-level circuit, semiconductor elements larger in the amount of heat generation, and semiconductor elements smaller in the amount of heat generation are mixed together, and in particular, it is required to more cool the semiconductor elements larger itt the amount of heat generation.

In the related art structure disclosed in JP-A-2011-259536, because the number of heat pipes arranged in the direction perpendicular to a flow of the coding air is small, heat cannot be sufficiently distributed in the flow direction of the cooling air when the amount of heat generation of the power semiconductor element has a large distribution, resulting in such a problem that the cooling effect is not sufficiently obtained.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a power conversion device that can effectively cool a power semiconductor element large in an amount of heat generation even if the heat generation of the power semiconductor element in the power conversion device is distributed.

In order to achieve the above object, according to the present invention, there is provided a power conversion device, including: a heat receiving member; a plurality of power semiconductor elements; a plurality of heat pipes; and a plurality of heat radiation members fitted to the heat pipes, in which the plurality of power semiconductor elements are disposed on one surface of the heat receiving member, the plurality of heat pipes are disposed on the other surface of the heat receiving member, and at least a part of the plurality of heat pipes includes heat radiation portions erected outside of the heat receiving member, the plurality of power semiconductor elements include at least two kinds of power semiconductor elements different in the amount of heat generation, the plurality of heat pipes include at least two kinds of heat pipes different in a length of heat receiving portions which are portions embedded in the heat receiving member, the heat receiving portions are arranged so that a longitudinal direction of the heat receiving portions is substantially perpendicular to a flow direction of a cooling air flowing in the heat radiation members, the heat pipes shorter in a length of the heat receiving portions are arranged inside of a projection region of the power semiconductor elements larger in the amount of heat generation to the heat receiving member, and the heat pipes longer in the length of the heat receiving portions are arranged across the inside and the outside of a projection region of the power semiconductor elements smaller in the amount of heat generation to the heat receiving member.

According to the present invention, even if the heat generation in the power semiconductor elements is distributed, the heat generation is concentrated to be radiated on the fin side from the heat pipe shorter in the heat receiving portion for the element high in the amount of heat generation, and the heat pipe longer in the heat receiving portion is provided in the element relatively lower in the amount of heat generation or the heat receiving member at a position where nc element is present, as a result of which since heat can be migrated from the element larger in the amount of heat generation to a region of the heat receiving member having the element smaller in the amount of heat generation or a region having no element, the heat generation of the power semiconductor elements is efficiently dispersed to improve a cooling performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional view of a power conversion device when viewed from a direction parallel to a flow direction of a cooling air according to an embodiment of the present invention; FIG. 2 is a vertical cross-sectional view of the power conversion device when viewed from a direction perpendicular to the flow direction of the cooling air according to the embodiment of the present invention; FIG. 3 is a diagram illustrating a layout of a heat pipe and a semiconductor element in the power conversion device according to the erithodixaent of the present invention; FIG. 4 is a diagram illustrating a layout of a power semiconductor element in the power conversion device according to the embodiment of the present invention; FIG. 5 is a diagram illustrating a layout of a heat pipe and a semiconductor element in an example of a related art power conversion device; FIG. 6 is a diagram illustrating numerical simulation results of a cooling performance in the power conversion devices with a structure of FIG. 5 and a structure (FIG. 3) of the embodiment of the present invention; and FIG. 7 is a diagram illustrating a configuration in which the power conversion device of the present invention is mounted on a railway vehicle.

DETAILED DESCRIPTICN OF THE INVENTION

Embodiments of the present invention will be described with reference to the drawings below. FIG. 7 is a diagram illustrating a configuration in which a power conversion device according to the embodiment of the present invention is mounted on a railway vehicle. The power conversion device according to the present invention is installed under a floor of the railway vehicle, converts an AC power supply of overhead lines into DC by a converter, and also controls a frequency of an electric power to be supplied to an electric motor which drives the vehicle by an inverter to control a rotating speed of the electric motor. Referring to FIG. 7, a power conversion device 1000 is fixed to a vehicle body 1002. An arrow 30 indicates a flow of cooling air. The cooling air is sucked from a grill 41 by a blower 40, and supplied to a cooling device 1001 of the power conversion device 1000.

FIG. 1 is a vertical cross-sectional view of the power conversion device when viewed from a direction parallel to a flow direction of a cooling air in the power conversion device according to this embodiment (first embodiment), FIG. 2 is a vertical cross-sectional view of the power conversion device when viewed from a direction perpendicular to the flow direction of the cooling air. Referring to FIGS. 1 and 2, so-called power semiconductor modules (hereinafter, the module called "power semiconductor element") 70, 71, 72, and 73 including power semiconductor elements such as plural IGBT (integrated gate bipolar transistor) are installed on one side of a heat receiving member S made of metal such as aluminum alloy. Referring to FIG. 1, reference numeral 1000 denotes an overall power conversion device, and 1001 denotes the cooling device of the power conversion device. The cooling device includes the heat receiving member 5, heat pipes 1, 2, 3, 4, and a heat radiation fin 6. The power semiconductor elements 70, 71, 72, and 73 are fixed to the heat receiving member 5 through a member (not shown) such as grease by a screw (not shown). An electronic component 10 such as an IGBT driver circuit or a filter capacitor is installed on a power semiconductor element side of the heat receiving member 5.

Also, surroundings of the power semiconductor elements installed on the heat receiving member 5 are sealed by cases 11, 12, and 13. A heat receiving portion 101 of the U-shaped heat pipe 3. is embedded on a side of the heat receiving member opposite to a power semiconductor element installation surface, and the heat receiving portion 101 is thermally connected to the heat receiving member 5 by soldering. Heat radiation portions 102 erect from both sides of the heat receiving portion 101 of the U-shaped heat pipe 1. The heat radiation portions 102 are connected with plural fins 6 made of metal such as aluminum or copper by press-fitting. The U-shaped heat pipes are used with the combination of pipes having a shape different in the length of the heat receiving portion or the length of the heat radiation portions.

A layout of the heat receiving member 5, the heat pipes, and the power semiconductor elements is illustrated in FIG. 3. Also, a layout of the power semiconductor elements on the heat receiving member 5 is illustrated in FIG. 4. Referring *1 to FIGS. 3 and 4, reference numerals 70, 71, 72, 73, 80, 81, 82, 83, 90, 91, 92, and 93 denote power semiconductor elements.

The power semiconductor elements are installed on a surface opposite to the heat pipes, and indicated by dashed lines in FIG. 3. The heat receiving portions of the heat pipes are also embedded within a heat block. However, for clarity of the drawing, the heat receiving portions of the heat pipes are indicated by solid lines. The layout of those elements will be described with a converter of a three-level circuit as an example. The power semiconductor elements 70, 71, 72, and 73 are configured by IGBT modules including plural IGBT (insulated gate bipolar transistor) elements, and free-wheeling diodes, the power semiconductor elements 80, 81, 82, and 83 are configured by cramp diode modules, and the power semiconductor elements 90, 91, 92, and 93 are configured by IGBT modules. The amount of heat generation of the power semiconductor elements 70, 71, 72, and 73 may be large, and the amount of heat generation of the power semiconductor elements 90, 91, 92, and 93 may be large depending on operating conditions (power running operation, regenerative operation, etc.), and the amount of heat generation of the power semiconductor elements 80, 81, 82, and 83 is relativey small.

As illustrated in FIGS. 1 to 3, the heat receiving portions 101 and 301 of the heat pipes 1 and 3 are set to be shorter in length than heat receiving portions 201 and 401 of the heat pipes 2 and 4. Also, the heat radiation portions 102 and 202 of the heat pipes 1 arid 2 are set to be longer in length than heat radiation portions 302 and 402 of the heat pipes 3 and 4. The heat receiving portions 101 and 301 of the heat pipes 1 and 3 are each set to a length entering the inside of a portion where the power semiconductor element 90 is proj ected to the heat receiving member 5. The heat pipes 2 and 4 longer in the heat receiving portion are arranged in the intermediate of the respective heat pipes 1 and 3 group shorter in the heat receiving portion.

A duct 14 is disposed around the cooling device 1001, and as illustrated in FIG. 7, the cooling air is fed into the duct 14 by the blower 40. In this embodiment, a structure in which the cooling air is forcedly blown by the cooling fan will be described. However, the present invention can be also applied to a structure in which the power conversion device is cooled by a traveling wind generated when the vehicle travels, and a structure in which the power conversion device is cooled with the use of a natural convection that the heated air rises.

In the structure using the traveling wind, because the cooling wind has substantially the same direction as that of the traveling direction, a longitudinal direction of the heat receiving portions of the heat pipes 1 and 2 is arranged in a direction perpendicular to the traveling direction of the vehicle. Also, in the structure using the natural convection, the longitudinal direction of the heat receiving portions of the heat pipes 1 and 2 is arranged in a direction perpendicular to the vertical direction (direction of gravitational force) of the railway vehicle, that is, substantially in the horizontal direction.

Subsequently, the operation of cooling the respective power semiconductor elements will be described with the power semiconductor element 90 as an example. Referring to FIG. 2, the heat generated by operating the power semiconductor disposed within the power semiconductor element 90 is transmitted to the heat receiving member 5 by heat conduction, and reaches the heat receiving portion 101 of the heat pipe 1. A refrigerant (pure water, etc.) is enclosed in the heat pipe 1. The refrigerant heated in the heat receiving portion 101 is evaporated into gas, and migrates to the heat radiation portions 102. The refrigerant cooled by air in the heat radiation portions 102 is condensed back to liquid. The refrigerant condensed by the heat radiation portions 102 returns to the heat receiving portion 101 by gravity. In this way, evaporation and condensation are repeated, and the refrigerant migrates with the result that the heat of the heat receiving member 5 is radiated to the outside of the power conversion device such as atmosphere. The refrigerant is also enclosed in the heat pipes 2, 3, and 4, and likewise, evaporation and condensation are repeated, and the refrigerant migrates with the result that the heat of the heat receiving member 5 is radiated to the outside of the power conversion device such as atmosphere.

If the amount of heat generation in the power semiconductor elements 80, 81, 82, and 83 are smaller than that of the power semiconductor elements 70, 71, 72, and 73, and the power semiconductor elements 90, 91, 92, and 93, the number of heat radiation portions 102 and 302 increases in the heat pipes 1 and 3 shorter in the heat receiving portion to radiate heat to the fin side. Also, the heat in the vicinity of the elements larger in the amount of heat generation of the heat receiving member 5 is transferred to an area in which the elements smaller in the amount of heat generation are present, or an area in which the elements are not present by the heat pipes 2 and 4 longer in the heat receiving portion, thereby being capable of effectively cooling the elements larger in the amount of heat generation.

The heat pipes 3 and 4 shorter in the heat radiation portion are relatively difficult to freeze even when the outside air temperature is a low temperature below the freezing point. Under the circumstances, the heat pipe 3 shorter in both of the heat receiving pcrtion and the heat radiation portions, and the heat pipe 4 longer in the heat receiving portion and shorter in the heat radiation portion are provided in addition to the heat pipes 1 and 2, as a result of which even when the outside air is at a low temperature, the heat radiation from the power semiconductor element larger in the amount of heat generation to the fin side is ensured by the heat pipe 3 shorter in both of the heat receiving portion and the heat radiation portions. Also, the heat in the vicinity of the elements larger in the amount of heat generation of the heat receiving member S is transferred to an area in which the elements smaller in the amount of heat generation are present, or an area in which the elements are not present by the heat pipe 4 longer in the heat receiving portion and shorter in the heat radiation portions, thereby being capable of effectively cooling the elements larger in the amount of heat generation.

Also, at least one heat pipe (for example, heat pipes 3 and 4 in this embodiment) shorter in the heat radiation portions is arranged in the region of the heat receiving member to which one power semiconductor element is projected, to thereby prevent the temperature of the semiconductor chip from rising without operating the heat pipe of a specific element at all. In particular, in order to balance the cooling performances when the outside air is at the high temperature and at the low temperature with each other, it is desirable that a rate of the heat pipes shorter in the heat radiation portions to all the heat pipes is 20% to 60% in the region of the heat receiving member to which one element is projected.

As described above, the heat pipes different in the length of the heat receiving portion are arranged in combination on the basis of the amount of heat generation of the element to be cooled and the layout of the elements, and the elements, whereby even if the amount of heat generation of the elements is distributed, the elements can be efficiently cooled. Further, in the heat pipes having the heat receiving portions different in the length, the heat radiation portions are set to different lengths, to thereby further obtain the effect of ensuring the cooling performance during cold. Also, because the temperature of the cooling air in a downstream area increases due to heat exchange with the heat radiation portion in an upstream area, as illustrated in FIG. 1, the number of heat radiation fins 6 which are heat radiation members increases in the downstream area in which the cooling air flows, thereby being capable of more keeping the cooling performance of the power semiconductor elements in the downstream area.

As illustrated in FIG. 5, in a case where three heat pipes substantially equal in the length of the heat receiving portion are arranged, and in a case where the heat pipes are arranged according to this embodiment of FIG. 2, the results of numeric simulation comparing a temperature distribution on the element attaching surfaces of the heat receiving members are illustrated in FIGS. 6A and 6W.

In FIGS. 6A and 6B, a temperature difference between the highest temperature of the heat receiving member and an inlet air temperature in the layout of FIG. 5 is set as 100, and the temperature difference is relatively indicated. As is understood from FIGS. 6A and 6B, the configuration of the heat pipe according to this embodiment in FIG. 2 can reduce the temperature difference between the heat receiving member and the inlet air by 7% as compared with the configuration of FIG. 5. FIG. 5 illustrates a case in which the lengths of the heat receiving members in the heat pipes 1, 3, and the heat pipes 2, 4 in FIG. 3 are equal to each other, which obtains the effects obtained by provision of the heat pipes 2 and 4 different in the length of the heat radiation portion as described below, and is not excluded from the present invention.

Pillars 16 in FIG. 3 are connected to beams 15 in FIG. 1 to hold the duct 14. The beams 15 function to fix the pillars 16, and also suppress the passage of the cooling air that bypasses an upper portion of the heat radiation fits 6 that is the heat radiation members. If a length of the heat pipe which enters a certain portion of the pillars 16 is too short, the length of the heat receiving portion in a heat pipe 17 of the portion of the pillars may be made longer as illustrated in FIG. 3.

If the length of the heat pipe 17 between the pillar and the pillar, or between the pillar and an end of the heat receiving member is adjusted to a length corresponding to a position of the pillar, the cooling performance is improved.

On the other hand, if the heat pipe 17 is configured by any one of the heat pipes 1 to 4, because the heat pipes can be manufactured without increasing the kind of heat pipes, there is advantageous in that the manufacturing costs become low.

As described above, according to this embodiment, the longitudinal direction of the heat receiving portion of the heat pipes is arranged in the direction substantially perpendicular to the flow direction of the cooling air, the heat pipes shorter in the heat receiving portions entering the projection regions in the heat receiving member of the power semiconductor elements larger in the amount of heat generation in the portion of the heat receiving portion embedded in the heat receiving member, and the heat pipes longer in the heat receiving portions arranged across the projection region in the heat receiving member of the power semiconductor elements having a relatively small amount of heat generation in the heat receiving portion, and the portion in which the power semiconductor is not present, are arranged so that even if the heat generation in the power semiconductor elements is distributed, the heat generation is concentrated to be radiated on the fin side from the heat pipe shorter in the heat receiving portion for the element high in the amount of heat generation, and the heat pipe relatively longer in the heat receiving portion is provided in the element having a relatively small amount of heat generation or the heat receiving member at a position where no element is present, as a result of which since heat can be migrated from the element larger in the amount of heat generation to the portion smaller in the amount of heat generation, the heat generation of the power semiconductor elements is efficiently dispersed to improve a cooling performance.

Claims

What is claimed is: 1. A power conversion device comprising: a heat receiving member; a plurality of power semiconductor elements; a plurality of heat pipes; and a plurality of heat radiation members fitted to the heat pipes, wherein the plurality of power semiconductor elements are disposed on one surface of the heat receiving member, the plurality of heat pipes are disposed on the other surface of the heat receiving member, and at least a part of the plurality of heat pipes includes heat radiation portions erected outside of the heat receiving member, the plurality of power semiconductor elements include at least two kinds of power semiconductor elements different in the amount of heat generation, the plurality of heat pipes include at least two kinds of heat pipes different in a length of heat receiving portions which are portions embedded in the heat receiving member, the heat receiving portions are arranged so that a longitudinal direction of the heat receiving portions is substantially perpendicular to a flow direction of a cooling air flowing in the heat radiation members, the heat pipes shorter in a length of the heat receiving portions are arranged inside of a projection region of the power semiconductor elements larger in the amount of heat generation to the heat receiving member, and the heat pipes longer in the length of the heat receiving portions are arranged across the inside and the outside of a projection region of the power semiconductor elements smaller in the amount of heat generation to the heat receiving member.
2. The power conversion device according to claim 1, wherein the plurality of heat pipes include heat pipes different in the length of the heat radiation portions.
3. The power conversion device according to claim 2, wherein at least one of the heat pipes shorter in the heat radiation portions is arranged in each of projection regions of the plurality of power semiconductor elements to the respective heat receiving members.
4. The power conversion device according to any one of claims 1 to 3, wherein the nunber of the heat radiation members disposed on a downstream side of the flow of the cooling air is larger than that on an upstream side.
5. The power conversion device according to any one of claims 1 to 4, further comprising: a duct that covers a space in which the cooling air flows, and is disposed outside of the heat pipes; a plurality of pillars that are disposed between the duct and the heat receiving member to hold the duct; and a heat pipe having the heat receiving portions based on a length between the respective pillars or between the pillars and an end of the heat receiving member.
6. A railway vehicle equipped with the power conversion device according to any one of claims 1 to 5.