Power conversion device

Abstract

To provide a power conversion device capable of reducing pump power of a cooling system and achieving cost reduction.SOLUTION: In a power conversion device 1, a heat transfer block of a heat receiving unit 12 has a semi-conductor module 11 mounted on one main surface and a plurality of fins 31b formed on the other main surface. A porous body 32 is provided in the heat transfer block. A liquid-phase working refrigerant 100 flows through a first flow path 35. A second flow path 36 has a plurality of vapor discharge units 36a formed between a plurality of fins of the heat transfer block, and a gas-phase working refrigerant 101 flows therethrough. A reservoir tank stores the working refrigerant. A heat exchange unit is connected to the second flow path and the reservoir tank. A check valve is disposed between the heat exchange unit and the reservoir tank and regulates movement of the working refrigerant from a reservoir tank side to a heat exchange unit side. A pump is connected to the first flow path and the reservoir tank, and delivers the working refrigerant in the reservoir tank to the first flow path.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] FIELD An embodiment of the present invention relates to a power conversion device. [Background technology]

[0002] There is known a technology for using a power conversion device in a railway vehicle or the like. Such a power conversion device applies a circulating water cooling system, which is a circulation type, to the cooling method of a system including a semiconductor module. The circulating water cooling system of this power conversion device has a circulating water cooling system including, for example, a heat receiving part, a heat exchanger, a reservoir tank, and a pump. The heat receiving part has a heat sink block that mounts and cools the semiconductor module. The pump supplies the internal fluid from the reservoir tank to the heat receiving part and the heat exchanger, and returns the fluid from the heat exchanger to the reservoir tank.

[0003] Such circulating water cooling systems circulate the working refrigerant at a constant flow rate, so they can maintain stable cooling performance. However, in applications of power electronics equipment with large load fluctuations, circulating at a constant flow rate can lead to a state in which the semiconductor elements are overcooled, which can lead to large temperature changes in the semiconductor elements. In addition, the temperature fluctuations of the cooling water cooling system increase in response to load fluctuations in the power conversion equipment system. In addition, circulating water cooling systems are required to have a high heat flux. However, in order to increase the heat flux of a circulating water cooling system, a high flow rate is necessary, which poses the issue of increased pump power due to pressure loss.

[0004] For example, a cooling system that can handle high heat fluxes is known to use the boiling cooling method, which utilizes the latent heat of evaporation caused by the phase change of the working refrigerant. However, the cooling system that uses the boiling cooling method has an issue with its cooling responsiveness (stability) to sudden loads. In particular, it is difficult to configure multiple modules in parallel and increase the capacity. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6407542 [Patent Document 2] Patent No. 6693476 [Patent Document 3] Patent No. 6760214 [Patent Document 4] Patent No. 6461361 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a power conversion device that can reduce the pump power of a cooling system and can also reduce costs. [Means for solving the problem]

[0007] The power conversion device of the embodiment includes a semiconductor module, a heat transfer block, a porous body, a first flow path, a second flow path, a reservoir tank, a heat exchanger, a check valve, and a pump. The heat transfer block has a semiconductor module attached to one main surface and a plurality of fins formed on the other main surface. The porous body is provided on the heat transfer block. A liquid-phase working refrigerant flows through the first flow path. A gas-phase working refrigerant flows through the second flow path, the second flow path having a plurality of vapor exhaust portions formed between the plurality of fins of the heat transfer block. The reservoir tank stores the working refrigerant. The heat exchanger is connected to the second flow path and the reservoir tank. The check valve is disposed between the heat exchanger and the reservoir tank, and regulates the movement of the working refrigerant from the reservoir tank side to the heat exchanger side. The pump is connected to the first flow path and the reservoir tank, and sends the working refrigerant from the reservoir tank to the first flow path. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram illustrating a schematic configuration of a power conversion device according to a first embodiment. [Diagram 2]FIG. 1 is an explanatory diagram illustrating a schematic configuration of a cooling system for a power conversion device according to a first embodiment. [Diagram 3] FIG. 1 is an explanatory diagram illustrating a schematic configuration of a cooling system for a power conversion device according to a first embodiment. [Figure 4] FIG. 2 is an explanatory diagram illustrating a schematic configuration of a heat receiving portion of the power conversion device according to the first embodiment. [Diagram 5] FIG. 2 is an exploded perspective view showing the configuration of a heat receiving portion according to the first embodiment. [Figure 6] FIG. 2 is a cross-sectional view showing the configuration of a heat receiving part according to the first embodiment. [Figure 7] FIG. 2 is an enlarged cross-sectional view showing the configuration of a heat receiving portion according to the first embodiment. [Figure 8] FIG. 2 is a cross-sectional view showing a partial configuration of a heat receiving part according to the first embodiment. [Figure 9] FIG. 4 is an explanatory diagram of gas-liquid separation conditions of the heat receiving portion according to the first embodiment. [Figure 10] FIG. 11 is a cross-sectional view showing the configuration of a heat receiving portion of a power conversion device according to a second embodiment. [Figure 11] FIG. 11 is an enlarged cross-sectional view showing the configuration of a heat receiving portion according to a second embodiment. [Figure 12] FIG. 11 is a cross-sectional view showing the configuration of a heat receiving portion of a power conversion device according to a third embodiment. [Figure 13] FIG. 11 is an enlarged cross-sectional view showing the configuration of a heat receiving portion according to a third embodiment. [Figure 14] FIG. 13 is a cross-sectional view showing the configuration of a heat receiving portion of a power conversion device according to a fourth embodiment. [Figure 15] FIG. 13 is a cross-sectional view showing the configuration of a heat receiving portion of a power conversion device according to a fourth embodiment. [Figure 16] FIG. 13 is a cross-sectional view showing the configuration of a heat receiving portion of a power conversion device according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a power conversion device 1 according to an embodiment will be described with reference to Fig. 1 to Fig. 9. In each drawing, for the sake of convenience, the scale of each component will be appropriately changed and some components will be omitted or simplified.

[0010] Fig. 1 is an explanatory diagram showing a schematic configuration of a power converter 1 according to an embodiment. Fig. 2 is an explanatory diagram showing a schematic configuration of a cooling system 2 of the power converter 1, and a flow of the working refrigerant when the working refrigerant boils, and Fig. 3 is an explanatory diagram showing a schematic configuration of the cooling system 2 of the power converter 1, and a flow of the working refrigerant when the working refrigerant is not boiling.

[0011] Fig. 4 to Fig. 7 are schematic diagrams showing the configuration of the heat receiving section 12 of the power converter 1, Fig. 4 is an explanatory diagram of the heat receiving section 12, Fig. 5 is an exploded perspective view of the heat receiving section 12, and Figs. 6 and 7 are cross-sectional views of the heat receiving section 12. Fig. 8 is a cross-sectional view showing the configuration of a first flow path 35 formed in the porous body 32 of the heat receiving section 12, and a heat receiving section inlet 37 and a heat receiving section outlet 38 provided in the first flow path 35. Fig. 9 is an explanatory diagram of the gas-liquid separation conditions of the heat receiving section 12.

[0012] The power conversion device 1 is provided, for example, in a railway vehicle such as an electric locomotive, etc. The power conversion device 1 converts, for example, DC power supplied from an overhead line via a pantograph into AC power.

[0013] 1, the power conversion device 1 includes a semiconductor module 11, a heat receiving unit 12, a heat exchange unit 13, a reservoir tank 14, a pump 15, a blower 16, a check valve 17, piping 18, a temperature sensor 19, a pressure sensor 20, and a control unit 21. As shown in Fig. 2 and Fig. 3, the heat receiving unit 12, the heat exchange unit 13, the reservoir tank 14, the pump 15, and the check valve 17 of the power conversion device 1 are connected by piping 18 to configure a cooling system 2.

[0014] In such a power conversion device 1, the heat receiving unit 12, the heat exchange unit 13, the reservoir tank 14, and the pump 15 are fluidly connected by piping 18. As a specific example, the heat receiving unit 12 is fluidly connected to the heat exchange unit 13, the reservoir tank 14, and the pump 15 via the piping 18. The heat exchange unit 13 is fluidly connected to the reservoir tank 14 via a check valve 17. The reservoir tank 14 is fluidly connected to the pump 15 via the piping 18. The pump 15 is fluidly connected to the heat receiving unit 12.

[0015] As shown in Figs. 2 and 3, the liquid-phase working refrigerant stored in the reservoir tank 14 is pumped out by the pump 15 and circulates through the heat receiving section 12, the heat exchange section 13, and the reservoir tank 14. As shown in Fig. 2, the working refrigerant that has changed from the liquid phase to the gas phase due to the temperature of the heat receiving section 12 is separated into gas and liquid from the liquid-phase working refrigerant in the heat receiving section 12, moves to the heat exchange section 13, and is condensed in the heat exchange section 13, changing from the gas phase to the liquid phase, and is sent to the reservoir tank 14. The working refrigerant is preferably one that has high latent heat of vaporization, surface tension, density, and low viscosity coefficient, assuming that the working refrigerant is within the saturation temperature operating range applied to the power conversion device. In addition, the working refrigerant is preferably one that is environmentally friendly, with small ozone depletion coefficient and global temperature coefficient. When applied to this cooling system, the working refrigerant can be appropriately set.

[0016] For example, one or more semiconductor modules 11 are attached to one heat receiving section 12. The semiconductor module 11 may be, for example, a module in which a plurality of semiconductor elements are housed in one package, or a module including a control circuit, a drive circuit, and a protection circuit in addition to the semiconductor elements. The semiconductor module 11 may be configured such that the semiconductor elements are directly attached to the heat receiving section 12, or may be configured such that the semiconductor elements are attached to the heat receiving section 12 via another member. In other words, as long as the semiconductor module 11 is configured such that it can be cooled by the heat receiving section 12 when it generates heat by being attached to the heat receiving section 12, the arrangement and attachment method of the components can be set as appropriate.

[0017] The heat receiving section 12 passes the liquid phase working refrigerant 100. The heat receiving section 12 separates the liquid phase working refrigerant 100 from the gas phase working refrigerant 101, which is a part of the liquid phase working refrigerant 100 that has undergone a phase change due to the heat of the attached semiconductor module 11. The heat receiving section 12 sends the liquid phase working refrigerant 100 to the reservoir tank 14, and sends the gas phase working refrigerant 101 to the heat exchange section 13. For example, as shown in FIG. 1, a plurality of heat receiving sections 12 are provided.

[0018] 4 to 7, the heat receiving section 12 includes, for example, a pair of heat transfer blocks 31, a porous body 32, and a header member 33. The heat receiving section 12 also includes a first flow path 35 provided in the porous body 32, through which a liquid-phase working refrigerant 100 flows as a single-phase flow, and a second flow path 36 through which a gas-phase working refrigerant 101 flows as a single-phase flow through a gap between the pair of heat transfer blocks 31 and the porous body 32 within the header member 33. The heat receiving section 12 also includes a heat receiving section inlet 37 and a heat receiving section outlet 38 that connect the first flow path 35 to the piping 18.

[0019] The heat transfer block 31 is formed in a flat plate shape with one main surface formed in a flat shape and the other main surface formed in a comb-shaped fin shape. The heat transfer block 31 has a plurality of grooves 31a extending in one direction formed in a surface (the other main surface) facing the porous body 32. Also, for example, the heat transfer block 31 has a porous layer 31c formed on each surface of the plurality of grooves 31a. The heat transfer block 31 is formed of a material having a high thermal conductivity such as aluminum. The porous body 32 is provided between the opposing main surfaces of the pair of heat transfer blocks 31. Also, the pair of heat transfer blocks 31 have the semiconductor module 11 attached to the outer surface, which is the main surface opposite to the opposing main surfaces. As a specific example, the pair of heat transfer blocks 31 have the semiconductor module 11 attached to one of the main surfaces (outer surface) of each of the pair of heat transfer blocks 31.

[0020] The grooves 31a extend in one direction. The grooves 31a are formed so that the cross-sectional shape perpendicular to the longitudinal direction of the grooves 31a is rectangular. The grooves 31a are arranged at equal intervals in a direction perpendicular to the extension direction of the grooves 31a. The grooves 31a extend in the vertical direction, for example, in the posture in which the heat receiving portion 12 is attached. By forming such grooves 31a on one surface side, the heat transfer block 31 is formed into a fin shape in which a plurality of rectangular fins 31b extending in one direction are formed on the surface facing the porous body 32.

[0021] The porous layer 31c is bonded to the surface of the groove 31a. In other words, the porous layer 31c is formed around the fin 31b. The porous layer 31c formed on the surface of the groove 31a does not fill the groove 31a, but forms a space inside it. That is, the porous layer 31c formed in the groove 31a forms a vapor discharge part 36a, which is a vapor flow path (gas phase region) that discharges vapor and constitutes a part of the second flow path 36 covered with the porous body 32, inside the porous layer 31c. The porous layer 31c has a plurality of holes that allow the working refrigerant 100 of the liquid tank that has passed through from the heat transfer block 31 to pass through. The porous layer 31c is a sintered body, a foam body, a lotus type, or the like, of resin or metal fibers / particles, and has an appropriate thermal conductivity and an appropriate porosity.

[0022] The porous body 32 is formed in a flat plate shape and is provided between a pair of heat transfer blocks 31. The porous body 32 has a first flow path 35 formed therein through which the liquid-phase working refrigerant 100 flows. The porous body 32 covers the grooves 31a of the heat transfer blocks 31 to form a plurality of vapor discharge sections 36a between the pair of heat transfer blocks 31. The porous body 32 also passes a portion of the liquid-phase working refrigerant 100 flowing through the first flow path 35, and has a plurality of holes formed therein such that the pressure difference level between the liquid phase of the first flow path 35 and the vapor phase of the vapor discharge section 36a across the porous body 32 is below the maximum capillary force inside the porous body 32. As a result, as shown in FIG. 6, the porous body 32 passes the liquid-phase working refrigerant 100 through the first flow path 35, and passes a portion of the liquid-phase working refrigerant 100 from the first flow path 35 through the inside to the outer surface side through the plurality of holes formed therein. The porous body 32 prevents the liquid phase working refrigerant 100 from moving to the vapor discharge portion 36a, and moves the working refrigerant 100 in the liquid tank to the porous layer 31c. The porous layer 31c and the porous body 32 separate the working refrigerant 100 into gas and liquid at the interface between the porous body 32 and the heat transfer block 31 and the joint portion of the porous layer 31c and the groove 31a of the heat transfer block 31, and allow the gas phase working refrigerant 101 to pass through the multiple vapor discharge portions 36a, which are the second flow path 36.

[0023] The conditions for achieving gas-liquid separation in the porous layer 31c and the porous body 32 are as follows. The pressure (atmospheric pressure) on the gas phase side is Pv, the pressure on the liquid phase side is Pl, the surface tension of the working medium is σ [N / m], and the average pore radius of the porous body 32 is r [m]. Here, the pressure on the gas phase side Pv is the vapor pressure in the vapor discharge portion 36a, and the pressure on the liquid phase side Pl is the pressure of the working refrigerant 100 flowing in the first flow path 35 formed in the porous body 32. In this case, the conditions for achieving gas-liquid separation are as follows: Pv-Pl<2σ / r In order to satisfy the gas-liquid separation establishment condition, the cooling system is set based on, for example, the amount of heat generated by the semiconductor module 11, the flow rate from the pump 15, the type of working medium, and the like in addition to the porosity and pore shape of the porous body 32. In addition, the control unit 21 controls the driving of the pump 15 in order to satisfy the gas-liquid separation establishment condition.

[0024] The porous body 32 is, for example, a sintered body of resin or metal fibers / particles, a foam body, a lotus type body, or the like, and has an appropriate thermal conductivity and an appropriate porosity.

[0025] In addition, the porous body 32 is molded integrally with the pair of heat transfer blocks 31, or is formed separately from the pair of heat transfer blocks 31, and a portion of it is in contact with the pair of heat transfer blocks 31 and assembled integrally or joined thereto.

[0026] The header member 33 is disposed on the upper part of the heat receiving part 12 in a posture in which the heat receiving part 12 is disposed on a railway vehicle or the like. The header member 33 covers the upper ends of the multiple steam discharge parts 36a, and constitutes a second flow path 36 together with the multiple steam discharge parts 36a. The header member 33 has an opening 33a to which the pipe 18 is connected.

[0027] The first flow passage 35 is disposed, for example, inside the porous body 32. The first flow passage 35 is a flow passage through which the liquid-phase working refrigerant 100 flows in a single phase. As shown in FIG. 8, one end of the first flow passage 35 is connected to a heat receiving section inlet 37, and the other end is connected to a heat receiving section outlet 38. The first flow passage 35 is set to a predetermined flow passage width, for example, in order to obtain a predetermined flow passage length, and has a flow passage shape that is bent at multiple points. Note that the first flow passage 35 may be a chamber that is fluidly continuous with the heat receiving section inlet 37 and the heat receiving section outlet 38 without being bent at multiple points.

[0028] The second flow path 36 is a flow path through which the gas-phase refrigerant flows in a single phase. The second flow path 36 is composed of a porous layer 31c provided in a plurality of grooves 31a of the heat transfer block 31 and a plurality of vapor discharge parts 36a formed by the internal space of the porous body 32. The second flow path 36 is a flow path through which the gas-phase working refrigerant 101 separated from the porous layer 31c provided in the plurality of grooves 31a and the porous body 32 contacting the plurality of fins 31b flows from the plurality of vapor discharge parts 36a to the internal space of the header member 33 above. In the second flow path 36, each side surface of the porous body 32 other than the surface facing the heat transfer block 31 and the header member 33 and the lower end of the vapor discharge part 36a are closed by a cover or the like so that the gas-phase working refrigerant 101 does not flow from the vapor discharge part 36a to any other place than the internal space of the header member 33.

[0029] The heat exchange section 13 condenses the gas-phase working refrigerant by passing through the inside and exchanging heat with the gas-phase working refrigerant, thereby changing the phase of the working refrigerant into a liquid-phase working refrigerant.

[0030] The reservoir tank 14 stores the liquid phase working refrigerant. The reservoir tank 14 sends the liquid phase working refrigerant to the heat receiving section 12, and collects the liquid phase working refrigerant that has passed through the heat receiving section 12 and the liquid phase working refrigerant that has condensed in the heat exchange section 13.

[0031] The pump 15 increases the pressure of the liquid-phase working refrigerant in the reservoir tank 14 to a predetermined pressure, and pumps it to the heat receiving section 12. The pump 15 can also adjust the flow rate (pressure) of the working refrigerant that is discharged.

[0032] The blower 16 blows air external to the power conversion device 1 to the heat exchanger 13. For example, the blower 16 takes in outside air from an air duct 16a. The blower 16 blows air to the heat exchanger 13, thereby performing heat exchange between the outside air and the gas-phase working refrigerant flowing through the heat exchanger 13.

[0033] The check valve 17 prevents the working refrigerant from flowing back from the reservoir tank 14 to the heat exchange unit 13. That is, the check valve 17 allows the working refrigerant to flow from the heat exchange unit 13 side to the reservoir tank 14 side, and regulates the flow of the working refrigerant from the reservoir tank 14 side to the heat exchange unit 13 side.

[0034] The piping 18 connects each component of the cooling system and constitutes a flow path of the working refrigerant. As a specific example, as shown in Figures 1 to 3, the piping 18 includes a heat receiving section inlet pipe 18a, a heat receiving section outlet pipe 18b, a steam circulation pipe 18c, and a liquid return pipe 18d.

[0035] The heat receiving section inlet pipe 18a connects the reservoir tank 14 and the primary sides of the first flow paths 35 of the multiple heat receiving sections 12 via the pump 15. Specifically, the heat receiving section inlet pipe 18a connects the reservoir tank 14 and the pump 15, as well as the pump 15 and the heat receiving section inlets 37 of the multiple heat receiving sections 12. For example, the heat receiving section inlet pipe 18a is a branch pipe connected to the multiple heat receiving section inlets 37 on the secondary side of the pump 15.

[0036] The heat receiving section outlet pipe 18b connects the secondary sides of the first flow paths 35 of the multiple heat receiving sections 12 and the reservoir tank 14. Specifically, the heat receiving section outlet pipe 18b connects the heat receiving section outlets 38 of the multiple heat receiving sections 12 and the reservoir tank 14. The heat receiving section outlet pipe 18b is a junction pipe that joins the multiple heat receiving section outlets 38 on the secondary sides.

[0037] The steam circulation pipe 18c connects the second flow paths 36 of the heat receiving sections 12 and the heat exchange section 13. For example, the number of steam circulation pipes 18c is the same as the number of heat receiving sections 12. The multiple steam circulation pipes 18c are connected to the openings 33a of the header members 33 of the heat receiving sections 12, respectively, and form a flow path for the gas phase working refrigerant into the heat exchange section 13. Note that instead of providing multiple steam circulation pipes 18c, one junction pipe may be used. In this case, the steam circulation pipe 18c is configured to be able to prevent the movement from the second flow path 36 of one heat receiving section 12 to the second flow path 36 of another heat receiving section 12.

[0038] The liquid return pipe 18d connects the heat exchange unit 13 and the reservoir tank 14. A check valve 17 is disposed midway through the liquid return pipe 18d.

[0039] The temperature sensor 19 detects, for example, the temperature of the heat receiving portion 12. For example, the temperature sensor 19 outputs an output signal, which is a voltage value corresponding to the detected temperature, to the control portion 21. The temperature sensor 19 may be provided in each of the heat receiving portions 12, or may be provided in any one of the heat receiving portions 12.

[0040] The pressure sensor 20 detects the pressure of the flow path through which the gas-phase working medium flows. The pressure sensor 20 is provided, for example, in the vapor flow pipe 18c. The pressure sensor 20 may be provided in the second flow path 36. The pressure sensor 20 may be provided in each vapor flow pipe 18c, or in any one of the vapor flow pipes 18c.

[0041] The control unit 21 controls the pump 15 to satisfy the conditions for gas-liquid separation in the porous body 32, for example, based on the temperature detected by the temperature sensor 19 and / or the pressure of the gas-phase working medium detected by the pressure sensor 20.

[0042] For example, the control unit 21 includes an input unit 41, a display unit 42, a communication unit 43, an interface 44, a storage unit 45, and a processor 46. For example, the control unit 21 is a control panel, a processing terminal, or the like.

[0043] The input unit 41 is a device that accepts user input, such as an operation panel including buttons, a touch panel, a keyboard, a mouse, etc. The display unit 42 is a display device such as a liquid crystal display or an organic EL display, etc. The communication unit 43 is an arbitrary communication interface that is controlled by the processor 46 and can communicate with an external terminal such as a personal computer or a management system using wired communication technology or wireless communication technology.

[0044] The interface 44 is a terminal or a circuit that can be connected to an external device. For example, the interface 44 is connected to the temperature sensor 19 and the pressure sensor 20.

[0045] The memory unit 45 includes a memory and a storage. The memory unit 45 stores various data. For example, the memory unit 45 stores a control program and control data for the pump 15. The memory unit 45 stores, for example, information on temperature and pressure detected by the temperature sensor 19 and the pressure sensor 20. The memory unit 45 may store the temperature and pressure information in association with the date and time, and the identification number of the heat receiving unit 12.

[0046] Such a storage unit 45 includes, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory) (registered trademark), a ROM (Read Only Memory), a RAM (Random Access Memory), a NAND type flash memory, an SSD (Solid State Drive), and the like.

[0047] The processor 46 includes a processing circuit. The processor 46 includes, for example, a CPU (Central Processing Unit). The processor 46 may be a microcomputer, an FPGA (Field Programmable Gate Array), a DSP (Digital Signal Processor), a GPU (Graphics Processing Unit), or other general-purpose or dedicated processors. The processor 46 may be singular or plural, and may be mounted on a circuit board such as a motherboard.

[0048] The processor 46 controls the pump 15 based on, for example, a control program and control data stored in the memory unit 45 and information on the temperature and pressure detected by the temperature sensor 19 and the pressure sensor 20. The processor 46 controls the pump 15 to drive and control the pump 15 so as to satisfy the conditions for gas-liquid separation in the porous layer 31c and the porous body 32.

[0049] Next, the operation of the power conversion device 1 configured as above will be described. In the following description, an example in which the power conversion device 1 is provided in a railway vehicle will be described. For example, when power is supplied from a pantograph to enable a railway vehicle to run, the processor 46 of the control unit 21 drives the pump 15. The liquid-phase working refrigerant stored in the reservoir tank 14 passes through the first flow path 35 of the heat receiving unit 12 sent out from the pump 15 and is recovered in the reservoir tank 14. In addition, a part of the liquid-phase working refrigerant 100 flowing through the first flow path 35 permeates into the porous body 32 due to capillary force. In addition, the semiconductor module 11 attached to the heat receiving unit 12 generates heat due to the operation of the power conversion device.

[0050] At this time, when the railroad vehicle is running, the temperature of the semiconductor module 11 rises to a temperature at which the liquid-phase working refrigerant 100 boils inside the heat receiving section 12. Therefore, the heat of the semiconductor module 11 is transferred from the pair of heat transfer blocks 31 of the heat receiving section 12 to the porous body 32. Then, in the porous layer 31c and the porous body 32, the liquid-phase working refrigerant 100 in the vicinity of the plurality of vapor discharge sections 36a, specifically, in the vicinity of the joints between the plurality of grooves 31a and the porous layer 31c and the vicinity of the joints between the tip surfaces of the plurality of fins 31b and the porous body 32, as shown in FIG. 7, becomes vapor. That is, the liquid-phase working refrigerant 100 changes phase to the gas-phase working refrigerant 101. As a result, vapor is induced in the vapor discharge section 36a.

[0051] At this time, if the pressure difference between the pressure Pv of the gas phase working refrigerant 101 in the vapor discharge portion 36a and the pressure Pl of the liquid phase working refrigerant 100 flowing in the first flow path 35 of the porous body 32 is equal to or less than the maximum capillary head (2σ / r) in the porous body 32, a pressure balance between the supply of the working refrigerant to the joint between the heat transfer block 31 and the porous body 32 and the evaporation is maintained. This causes the gas and liquid of the working refrigerant to be separated by the porous body 32. For example, the control unit 21 controls the drive of the pump 15 based on the temperature detected by the temperature sensor 19 and the pressure detected by the pressure sensor 20 so that a pressure balance between the supply of the working refrigerant and the evaporation is maintained.

[0052] 2, the vapor (gas-phase working refrigerant) generated in the vapor discharge section (gas-phase region) 36a is sent to the header member 33 at the top of the heat receiving section 12, and is sent to the heat exchange section 13 via the vapor circulation pipe 18c. The outside air is sent by the blower 16 installed in the heat exchange section 13, and the gas-phase working refrigerant is heat-exchanged in the heat exchange section 13, whereby the gas-phase working refrigerant inside the heat exchange section 13 is condensed and dissipates heat. The condensed working refrigerant changes phase from gas to liquid, and is sent to the reservoir tank 14 via the liquid return pipe 18d.

[0053] At this time, the check valve 17 prevents the liquid-phase working refrigerant in the reservoir tank 14 from flowing back into the heat exchange unit 13 due to pressure fluctuations in the heat exchange unit 13 and the reservoir tank 14. The liquid-phase working refrigerant separated into gas and liquid through the porous body 32 is sent into the reservoir tank 14 via the heat receiving unit outflow pipe 18b.

[0054] The liquid-phase working refrigerant flowing through the heat receiving section outflow pipe 18b may be in a low subcooling state because heat is transported by receiving and transferring heat loss due to sensible heat other than the latent heat of evaporation in the porous layer 31c and the porous body 32. Note that, in order to maintain the heat balance of the cooling system 2, piping for this heat loss and the heat capacity of the reservoir tank 14 are required.

[0055] In this way, when the semiconductor module 11 is subjected to a high heat load, such as when the railway vehicle is traveling, the working refrigerant is separated into a liquid phase and a gas phase in the heat receiving section 12 as shown in FIG. 2, and each phase is circulated to circulate the working refrigerant, thereby maintaining the cooling system functioning normally.

[0056] Furthermore, when the railroad vehicle is stopped, the temperature of the semiconductor module 11 rises to a temperature at which the liquid-phase working refrigerant does not boil in the heat receiving section 12. Therefore, the liquid-phase working refrigerant does not change phase to gas phase in the heat receiving section 12. Therefore, the liquid-phase working refrigerant is sent into the reservoir tank 14 via the heat receiving section outflow pipe 18b of the porous body 32. In this way, when the semiconductor module 11 is under a low thermal load, such as when the railroad vehicle is stopped, the liquid-phase working refrigerant that has passed through the heat receiving section 12 is refluxed to circulate the working refrigerant, thereby allowing the cooling system to function normally, as shown in FIG. 3.

[0057] As described above, the power converter 1 of this embodiment circulates the liquid-phase working refrigerant through the heat receiving section 12 by the pump 15, but does not need to circulate the liquid-phase working refrigerant through the heat exchange section 13. The power converter 1 can reduce the pump power because there is no pressure loss in the heat exchange section 13. Therefore, the power converter 1 can contribute to miniaturization and energy saving of the pump 15. In addition, since the temperature difference can be reduced by liquefying the working refrigerant from a gas phase state rather than dissipating heat through a single-phase liquid flow, when compared under the same heat dissipation conditions, the power converter 1 of this embodiment can make the volume of the heat exchange section 13 smaller than the volume of a heat exchange section of a conventional circulating water cooling system. Therefore, the power converter 1 can be made smaller, which improves the freedom of installation of the heat exchange section 13 and reduces the weight of the cooling system.

[0058] In addition, in normal operation where the liquid-phase working refrigerant boils, the power conversion device 1 utilizes the latent heat of evaporation due to boiling cooling, so a high heat flux can be expected, and even when the liquid-phase working refrigerant does not boil at a low flow rate, heat transport and dissipation are possible with low pump power. Therefore, the cooling system of the power conversion device 1 can reduce fluctuations in heat load caused by overcooling caused by conventional circulating water cooling systems and overshooting caused by conventional boiling cooling systems. Therefore, the power conversion device 1 can suppress and level temperature fluctuations, thereby extending the life of the semiconductor elements used in the semiconductor module 11.

[0059] Also, the vapor discharge section 36a through which the gas-phase working refrigerant passes is formed by a space surrounded by the multiple grooves 31a of the heat transfer block 31 and the porous layers 31c formed in the grooves 31a. Therefore, as shown in Fig. 5, by forming the porous body 32 arranged inside the heat receiving section 12 in a simple plate shape and forming the heat transfer block 31 in a fin shape, it is possible to suppress the liquid supply pressure loss and reduce the manufacturing cost of the porous body 32, which results in a reduction in the cost of the heat receiving section 12. Also, by providing the porous layer 31c around the fins 31b of the heat transfer block 31 (on the surface of the grooves 31a), it is possible to capture the supplied liquid by capillary force and suppress drying out of the heat transfer surface.

[0060] As described above, the power converter 1 of this embodiment enables gas-liquid separation of the working refrigerant in the heat receiving section 12, and circulates the liquid and gas phase working refrigerant when the working refrigerant boils, and circulates the liquid phase working refrigerant when the working refrigerant does not boil. In addition, a porous layer 31c is provided in the groove 31a of the heat transfer block 31, and the porous body 32 is formed in a plate shape. Therefore, the power converter 1 can reduce the pumping power of the pump 15 of the cooling system and reduce costs.

[0061] The embodiment is not limited to the above-mentioned example. For example, the material, optimal porosity, pore size, etc. of the porous layer 31c and the porous body 32 vary depending on the applied working refrigerant and the heat load condition of the semiconductor module 11. Therefore, as in the heat receiving section 12A according to the second embodiment shown in Figs. 10 and 11, the heat transfer block 31 and the porous body 32 may be alternately interlocked as fins, thereby optimizing the manufacturing and molding costs of the heat transfer block 31 and the porous body 32. Hereinafter, the heat receiving section 12A used in the power conversion device 1 according to the second embodiment will be described with reference to Figs. 10 and 11. Among the configurations of the heat receiving section 12A according to the second embodiment, the same configurations as those of the heat receiving section 12 according to the first embodiment described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0062] The heat receiving section 12A includes a pair of heat transfer blocks 31, a porous body 32A, and a header member 33. The heat receiving section 12A also includes a first flow path 35 provided in the porous body 32A, through which a liquid-phase working refrigerant flows as a single-phase flow, and a second flow path 36 through which a gas-phase working refrigerant flows as a single-phase flow through a gap between the pair of heat transfer blocks 31 and the porous body 32A within the header member 33. The heat receiving section 12A also includes a heat receiving section inlet 37 and a heat receiving section outlet 38 that connect the first flow path 35 to the piping 18.

[0063] Heat transfer block 31 is formed in a flat plate shape. Heat transfer block 31 has a plurality of grooves 31a extending in one direction formed on a surface facing porous body 32A. For example, heat transfer block 31 does not have porous layer 31c.

[0064] The groove 31a extends in one direction. The groove 31a has a rectangular cross section perpendicular to the longitudinal direction of the groove 31a. The grooves 31a are arranged at equal intervals in a direction perpendicular to the extension direction of the groove 31a. The grooves 31a extend in the vertical direction, for example, in the posture in which the heat receiving portion 12 is attached. By forming such a plurality of grooves 31a on one surface side, the surface of the heat transfer block 31 facing the porous body 32 is formed into a fin shape in which a plurality of rectangular fins 31b extending in one direction are formed. Note that the width of the groove 31a in the direction perpendicular to the longitudinal direction, in other words, the interval between adjacent fins 31b, is set to a width that allows two steam exhaust portions 36a of the second flow path 36 to be arranged and allows fins 32a of the porous body 32A to be arranged.

[0065] The porous body 32A is provided between a pair of heat transfer blocks 31. The porous body 32A is formed in a flat plate shape, and is provided between a pair of heat transfer blocks 31 whose main surfaces facing the pair of heat transfer blocks 31 are porous fins formed in a fin shape. The porous body 32A has a first flow path 35 formed therein through which a liquid-phase working refrigerant flows. The porous body 32A has a plurality of rectangular fins 32a extending in one direction on each of the pair of main surfaces facing the heat transfer blocks 31.

[0066] Each fin 32a is disposed at the center in the width direction of each groove 31a of the heat transfer block 31 and joined to the inner surface of the groove 31a, whereby the multiple fins 31b of the heat transfer block 31 and the multiple fins 32a of the porous body 32A are arranged alternately and a steam exhaust portion 36a is formed between adjacent fins 31b and fins 32a. The multiple fins 31b of the heat transfer block 31 are joined to the main surface of the porous body 32A (the grooves between the adjacent fins 32a), and the multiple fins 32a of the porous body 32A are joined to the bottom surface on the center side in the width direction of the multiple grooves 31a of the heat transfer block 31.

[0067] In the heat receiving section 12A, the heat transfer block 31 and the porous body 32A are shaped so that the multiple fins 31b, 32a of both are alternately interlocked (arranged), thereby forming a vapor discharge section 36a between the adjacent fins 31b, 32a. Then, gas-liquid separation of the working refrigerant 100 is performed at the interface where the heat transfer block 31 and the porous body 32A contact each other, that is, the interface between the fin 31b of the heat transfer block 31 and the porous body 32A, and the joint between the fin 32a of the porous body 32A and the heat transfer block 31. Then, the gas phase working refrigerant 101 passes through the multiple vapor discharge sections 36a, which are the second flow paths 36. As a result, the heat receiving section 12A has the same effect as the heat receiving section 12A according to the first embodiment described above.

[0068] The heat receiving section 12A has a porous body 32A on a plate with multiple fins 32a on the main surface, but the pitch (spacing) of the multiple fins 32a may be such that the multiple fins 32a are arranged between the multiple fins 31b of the heat transfer block 31 to form the steam exhaust section 36a together with the multiple fins 31b of the heat transfer block 31. This allows the number and spacing of the multiple fins 32a to be reduced compared to a configuration in which multiple fins of the porous body are arranged side by side to form the steam exhaust section 36a. Thus, the power conversion device 1 can reduce the pump power of the pump 15 of the cooling system and reduce costs.

[0069] In addition, the embodiment is not limited to the above-mentioned example. For example, as shown in a heat receiving section 12B according to a third embodiment shown in Fig. 12 and Fig. 13, a porous layer 31c provided in the heat transfer block 31 of the heat receiving section 12 according to the first embodiment may be provided in a plurality of grooves 31a of the heat transfer block 31 of the heat receiving section 12A according to the second embodiment. The heat receiving section 12B may be configured to provide a porous body 32A between a pair of heat transfer blocks 31 having such a porous layer 31c.

[0070] Furthermore, for example, as shown in the heat receiving portion 12 according to the fourth embodiment shown in Figs. 14 to 16, in the porous body 32 according to the first to third embodiments, the porosity of the porous body 32 may be increased near the contact interface between the porous body 32 and the heat transfer block 31. Since steam generation due to boiling becomes significant near the contact interface between the porous body 32 and the heat transfer block 31, if the steam is not properly discharged, it will lead to rapid deterioration of heat transfer due to dryout. Therefore, as shown in each example shown in Figs. 14 to 16, by providing a porous layer 32b having a porosity higher than that of the porous body 32 near the contact interface between the porous body 32 and the heat transfer block 31, the pressure loss due to the escape of steam can be reduced and the discharge of steam can be promoted.

[0071] Any of the power conversion devices configured as described above can reduce the pump power of the pump 15 of the cooling system and can reduce costs.

[0072] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0073] 1...power conversion device, 2...cooling system, 11...semiconductor module, 12, 12A, 12B...heat receiving section, 13...heat exchange section, 14...reservoir tank, 15...pump, 16...blower, 16a...wind tunnel duct, 17...check valve, 18...piping, 18a...heat receiving section inlet pipe, 18b...heat receiving section outlet pipe, 18c...steam flow pipe, 18d...liquid return pipe, 19...temperature sensor, 20...pressure sensor, 21...control section, 31...heat transfer block, 31a... Groove, 31b...fin, 31c...porous layer, 32, 32A...porous body, 32b...porous layer, 32a...fin, 33...header member, 33a...opening, 35...flow path, 36...flow path, 36a...steam exhaust section, 37...heat receiving section inlet, 38...heat receiving section outlet, 41...input section, 42...display section, 43...communication section, 44...interface, 45...memory section, 46...processor, 100...working refrigerant (liquid phase), 101...working refrigerant (gas phase).

Claims

1. a semiconductor module; a heat receiving section including a heat transfer block having a semiconductor module attached to one main surface and a plurality of fins formed on the other main surface, a porous body provided in the heat transfer block, a first flow path through which a liquid-phase working refrigerant flows, and a second flow path through which a gas-phase working refrigerant flows, the second flow path having a plurality of vapor outlets formed between the plurality of fins of the heat transfer block; a reservoir tank for storing the working refrigerant; a heat exchange unit connected to the second flow path and the reservoir tank; a pump connected to the first flow path and the reservoir tank, for delivering the working refrigerant from the reservoir tank to the first flow path; A power conversion device comprising:

2. The power conversion device according to claim 1 , wherein the heat transfer block has a porous layer provided on the surface of a plurality of grooves formed between the plurality of fins.

3. The heat transfer blocks are provided in pairs, The power conversion device according to claim 1 , wherein the semiconductor module is provided on each of the main surfaces of the pair of heat transfer blocks.

4. the porous body is provided between the pair of heat transfer blocks and defines the first flow path therein; The power conversion device according to claim 2 , wherein the plurality of steam exhaust portions are formed between the plurality of fins.

5. The porous body has a plurality of fins, 3. The power conversion device according to claim 1, wherein the plurality of fins formed on the heat transfer block and the plurality of fins formed on the porous body are arranged alternately with the steam discharge portion formed therebetween.

6. a temperature sensor for detecting the temperature of the heat receiving portion; a pressure sensor that detects a pressure in the second flow path or a flow path that connects the second flow path and the heat exchange unit; The power conversion device according to claim 1 , further comprising a control unit that controls the flow rate of the working refrigerant based on temperature information detected by the temperature sensor and pressure information detected by the pressure sensor.

7. The power conversion device according to claim 1 , further comprising a blower that blows air to the heat exchange section.

8. A power conversion device as described in claim 1, comprising a check valve arranged between the heat exchange unit and the reservoir tank, which regulates the movement of the working refrigerant from the reservoir tank side to the heat exchange unit side.

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