Cooling system of power conversion device

Abstract

To realize cooling of a power conversion device by saving power.SOLUTION: A system for cooling a power conversion device comprises: a first flow channel; a second flow channel; a heat exchanger; a turbine power generation device; and a cooling device. A first heat medium flows to the first flow channel. A second heat medium at a boiling point lower than that of the first heat medium flows to the second flow channel. The heat exchanger vaporizes the second heat medium at a liquid state by heat exchange between the first heat medium discharged from the power conversion device and the second heat medium. The turbine power generation device converts heat energy held by the second heat medium in a gas state discharged from the heat exchanger into rotation energy. The cooling device liquefies the second heat medium in the gas state discharged from the turbine power generation device to be transmitted to the heat exchanger.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a system for cooling a power conversion device.

Background Art

[0002] Patent Document 1 discloses an underfloor air conditioning system using a residential photovoltaic power generation system. This conventional underfloor air conditioning system includes a storage room in which a power conversion device for performing photovoltaic power generation is stored, and a circulation passage that circulates between this storage room and the underfloor space of a house. In the circulation passage, air heated by the heat generated as the power conversion device operates circulates, thereby heating the underfloor of the house. That is, according to the conventional underfloor air conditioning system, the underfloor is heated using the heat generated as the power conversion device operates.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The amount of heat generated from an IGBT (Insulated Gate Bipolar Transistor) module incorporated in the heart of a power conversion device increases as the amount of energization increases. Therefore, cooling the power conversion device to suppress an increase in the temperature of the power conversion device is important from the viewpoint of maintaining the operating state of the IGBT module appropriately and maintaining the conversion efficiency. To cool the power conversion device, usually, a fan attached to the power conversion device or an air conditioner that controls the temperature of the power conversion device is driven. However, power is required to drive these auxiliary machines. Therefore, an improvement for performing the cooling of the power conversion device with low power consumption is desired.

[0005] One object of the present invention is to provide a system capable of realizing cooling of a power conversion device with low power consumption.

Means for Solving the Problem

[0006] The present invention is a system for cooling a power conversion device and has the following features. The system includes a first flow path, a second flow path, a heat exchanger, a turbine power generation device, and a cooling device. A first heat medium for cooling the power conversion device flows through the first flow path. A second heat medium having a boiling point lower than that of the first heat medium flows through the second flow path. The heat exchanger is provided in the middle of the first flow path and also in the middle of the second flow path. The heat exchanger vaporizes the second heat medium in a liquid state by heat exchange between the first heat medium discharged from the power conversion device and the second heat medium. The turbine power generation device is provided in the middle of the second flow path. The turbine power generation device also converts the thermal energy of the second heat medium in a gaseous state discharged from the heat exchanger into rotational energy. The cooling device is provided between the turbine power generation device and the heat exchanger in the second flow path. The cooling device also liquefies the second heat medium in a gaseous state discharged from the turbine power generation device and sends it to the heat exchanger.

Advantages of the Invention

[0007] In the present invention, a first heat medium for cooling a power conversion device exchanges heat with a second heat medium having a boiling point lower than that of the first heat medium in a heat exchanger. The second heat medium vaporizes by heat exchange with the first heat medium and is sent to the turbine power generation device. In the turbine power generation device, the thermal energy of the second heat medium in a gaseous state is converted into rotational energy to generate electricity. The second heat medium discharged from the turbine power generation device is liquefied in the cooling device and sent to the heat exchanger.

[0008] Thus, according to the present invention, the power conversion device can be cooled by utilizing the heat exchange between the first heat medium and the second heat medium. Therefore, it is possible to appropriately maintain the operating state of the IGBT module and maintain the conversion efficiency without installing the above-described fan or air conditioner. In addition, according to the present invention, power generation can be performed by utilizing the heat exchange between the first heat medium and the second heat medium. Therefore, for example, by supplying the generated electric power to the power conversion device main body or the components of the system that cools the power conversion device, it is possible to realize power saving in cooling the power conversion device.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals are given to common elements, and redundant descriptions are omitted. In addition, the present invention is not limited by the following embodiments.

[0011] 1. First Configuration Example FIG. 1 is a diagram for explaining a first configuration example of a cooling system according to an embodiment. The cooling system 100 shown in FIG. 1 is a system including a PCS (Power conditioning System) that connects a DC power source generated by a secondary battery such as a lithium-ion battery to an AC system, a system including a PCS that converts a DC voltage generated by a solar panel into an AC voltage, or a battery system including a PCS and a storage battery. The cooling system 100 may be applied to a large-scale PCS (frequency converter). The PCS is an example of the "power conversion device" of the present invention.

[0012] The cooling system 100 includes a housing 1 that houses the PCS. The housing 1 has an outlet 11 for discharging the first heat medium M1 to the outside and an inlet 12 for sucking the first heat medium M1 from the outside. For example, the outlet 11 is formed on the upper surface or the upper part of the side surface of the housing 1, and the inlet 12 is formed on the lower part of the side surface of the housing 1. Inside the housing 1, the outlet 11 and the inlet 12 are connected by an internal flow path (not shown). The internal flow path may utilize the inner space of the housing 1 as it is, or may utilize a flow path member separately provided in the internal space of the housing 1. In the former case, since the inner space of the housing 1 can serve as the flow path of the first heat medium M1, the outlet 11 and the inlet 12 are provided at a distance. In the latter case, the internal flow path is provided around the PCS. For example, the internal flow path is provided so as to surround the PCS.

[0013] The first heat medium M1 is a refrigerant for cooling the PCS (IGBT module). The first heat medium M1 is, for example, a hydrofluorocarbon-based refrigerant. The hydrofluorocarbon-based refrigerant cools the PCS by a state change between gas and liquid. The first heat medium M1 may be an appropriate combination of hydrocarbon gases such as methane, ethane, and butane, noble gases such as helium, neon, and argon, and inert gases such as nitrogen and carbon dioxide. The first heat medium M1 may be air. That is, the first heat medium M1 is not particularly limited as long as it is a medium that can receive heat directly or indirectly from the PCS.

[0014] The discharge port 11 is connected to the first inlet 21 of the heat exchanger 2 via the external flow path 4. Inside the heat exchanger 2, a first internal flow path (not shown) connected to the first inlet 21 is formed. Inside the heat exchanger 2, a second internal flow path (not shown) through which the second heat medium M2 flows is also formed. Inside the heat exchanger 2, heat exchange is performed between the first heat medium M1 flowing through the first internal flow path and the second heat medium M2 flowing through the second internal flow path. The second heat medium M2 and the second internal flow path of the heat exchanger 2 will be described later.

[0015] The first internal flow path of the heat exchanger 2 is connected to the first outlet 22 of the heat exchanger 2. The pump device 3 is connected to the first outlet 22 via the external flow path 4. The pump device 3 sends out the first heat medium M1 sucked here to the external flow path 4. The suction port 12 is connected to the delivery side of the pump device 3 via the external flow path 4. That is, in the configuration example shown in FIG. 1, the internal flow path of the housing 1, the external flow path 4, and the first internal flow path of the heat exchanger 2 form one circulation flow path, and the first heat medium M1 flows along this circulation flow path. This circulation flow path is an example of the "first flow path" of the present invention.

[0016] The second heat medium M2 is a refrigerant that exchanges heat with the first heat medium M1. Examples of the refrigerant that can be used for the second heat medium M2 include hydrofluorocarbon-based refrigerants that can also be used for the first heat medium M1. However, for the second heat medium M2, a refrigerant with a lower boiling point than the refrigerant used as the first heat medium M1 is used. By using such a low-boiling-point refrigerant, part or all of the liquid second heat medium M2 can be vaporized by heat exchange with the first heat medium M1 while the second heat medium M2 flows through the second internal flow path of the heat exchanger 2.

[0017] The second internal flow path of the heat exchanger 2 is formed between the second inlet 23 and the second outlet 24 of the heat exchanger 2. From this second outlet 24, the gaseous second heat medium M2 is discharged. The second heat medium M2 in a gaseous state or a gas-liquid mixed state flows through the external flow path 7 and flows into the turbine power generation device 5. The turbine power generation device 5 converts the thermal energy possessed by the gaseous second heat medium M2 into rotational energy to generate electricity. For example, the turbine power generation device 5 rotates the turbine 51 with the gaseous second heat medium M2 to generate electricity.

[0018] In another example, a separator (not shown) provided upstream of the turbine 51 is used to separate the liquid-state second heat medium M2 from the gas-liquid mixed-state second heat medium M2. Further, the liquid-state second heat medium M2 is introduced into a decompressor (not shown) to extract the second heat medium M2 in a low-pressure gaseous state. Then, the turbine 51 is rotated with the second heat medium M2 in the low-pressure gaseous state and the second heat medium M2 in the high-pressure gaseous state separated by the separator to generate electricity.

[0019] The gaseous second heat medium M2 that has passed through the turbine is discharged from the turbine power generation device 5 and flows into the cooling device 6. The cooling device 6 includes, for example, a condenser and a cooler. The condenser cools the gaseous second heat medium M2 to a gas-liquid mixed state. The gas-liquid mixed-state second heat medium M2 is sent from the condenser to the cooler and further cooled to return to a liquid state. The liquid-state second heat medium M2 is discharged from the cooling device 6, flows through the external flow path 7, and flows into the second inlet 23. That is, in the configuration example shown in FIG. 1, the second internal flow path of the heat exchanger 2, the external flow path 7, the internal flow path of the turbine power generation device 5, and the internal flow path of the cooling device 6 form one circulation flow path, and the second heat medium M2 flows along this circulation flow path. This circulation flow path is an example of the "second flow path" of the present invention.

[0020] In the example shown in FIG. 1, the electric power generated by the turbine power generation device 5 is charged into the storage battery. This secondary battery is a battery different from the storage battery connected to the PCS. Part or all of the electric power charged into this different storage battery is used, for example, to drive the pump device 3. In another example, part or all of this different storage battery is used to drive peripheral devices such as the control of the PCS and the data logger of the storage battery connected to the PCS. As shown by the dashed arrow in FIG. 1, the electric power generated by the turbine power generation device 5 may be supplied to the pump device 3, the PCS, and the peripheral devices of the PCS without passing through another storage battery.

[0021] As described above, according to the example shown in FIG. 1, the PCS (IGBT module) can be cooled by utilizing the heat exchange between the first heat medium M1 and the second heat medium M2. In addition, power generation can also be performed by utilizing the heat exchange between the first heat medium M1 and the second heat medium M2. Therefore, by supplying electric power to the pump device 3 and the PCS, it becomes possible to realize the cooling of the PCS with power saving. Also, by supplying electric power to the peripheral devices of the PCS, it becomes possible to cover part or all of the electric power required for the operation of the PCS system and the storage battery system.

[0022] 2. Second Configuration Example FIG. 2 is a diagram for explaining a second configuration example of the cooling system according to the embodiment. The cooling system 200 shown in FIG. 2 includes a cooling device 8. The configuration other than the cooling device 8 is common to the cooling system 100 shown in FIG. 1.

[0023] The cooling device 8 cools the first heat medium M1 discharged from the heat exchanger 2 and sends it to the pump device 3. When the first heat medium M1 is a hydrofluorocarbon-based refrigerant, the cooling device 8 may be composed of a combination of a condenser and a cooler. This combination is as described in the explanation of the cooling device 6, and according to this combination, the gaseous first heat medium M1 can be returned to the liquid state through a plurality of cooling steps.

[0024] In the example shown in FIG. 2, the internal flow path of the housing 1, the external flow path 4, the first internal flow path of the heat exchanger 2, and the internal flow path of the cooling device 8 form one circulation flow path, and the first heat medium M1 flows along this circulation flow path. This circulation flow path is an example of the "first flow path" of the present invention.

[0025] Similar to the example shown in FIG. 1, in the example shown in FIG. 2, the electric power generated by the turbine power generation device 5 is charged into another battery. Also, part or all of the electric power charged into this other battery is used to drive peripheral devices such as the pump device 3, control the PCS, and drive the data logger of the battery connected to the PCS. In the example shown in FIG. 2, part or all of the electric power charged into this other battery is used to drive the cooling device 8. As shown by the dashed arrow in FIG. 2, the electric power generated by the turbine power generation device 5 may be supplied to the pump device 3, the PCS, the peripheral devices of the PCS, and the cooling device 8 without passing through another battery.

[0026] As described above, according to the example shown in FIG. 2, it is possible to obtain the same effects as those of the example shown in FIG. 1. Also, since the first heat medium M1 can be cooled in the cooling device 8, it is possible to improve the efficiency of cooling the PCS (IGBT module) by the first heat medium M1 as compared with the example shown in FIG. 1.

[0027] 3. Third Configuration Example FIG. 3 is a diagram for explaining a third configuration example of the cooling system according to the embodiment. The cooling system 300 shown in FIG. 3 is a system that uses outside air (air) as the first heat medium M1. The cooling system 300 includes a CO2 absorption device 9 that absorbs CO2 gas from the outside air. In the cooling system 300, the external flow path 4 branches in the middle. Other configurations are common to the cooling system 100 shown in FIG. 1.

[0028] The CO2 absorber 9 contains a CO2 absorbent. The CO2 absorber 9 also includes a pump device 91 that sends outside air into the inner space of the CO2 absorber 9. When air (the first heat medium M1) is sent into the inner space of the CO2 absorber 9 by the pump device 91, the CO2 gas in the air (the first heat medium M1) is separated and recovered by the CO2 absorbent. The air (the first heat medium M1) from which the CO2 gas has been removed flows into the pump device 3 via the external flow path 41.

[0029] The air (the first heat medium M1) that has flowed into the pump device 3 reaches the discharge port 11 via the suction port 12 and the internal flow path of the housing 1. The air (the first heat medium M1) discharged from the discharge port 11 flows through the external flow path 42. The external flow path 42 is connected to the external flow path 43 and the external flow path 44. The external flow path 43 is a branch flow path leading to the heat exchanger 2, and the external flow path 44 is a branch flow path leading to the CO2 absorber 9.

[0030] The air (the first heat medium M1) that has flowed into the external flow path 43 further flows into the first internal flow path of the heat exchanger 2 from the first inlet 21 and exchanges heat with the second heat medium M2 flowing through the second internal flow path of the heat exchanger 2. By this heat exchange, part or all of the second heat medium M2 in the liquid state vaporizes. The air (the first heat medium M1) that has flowed through the first internal flow path is discharged to the outside from the first outlet 22. The second heat medium M2 that has flowed through the second internal flow path is used for power generation in the turbine power generation device 5.

[0031] The air (the first heat medium M1) that has flowed into the external flow path 44 further flows into the CO2 absorber 9. In the example shown in FIG. 3, the inner space of the CO2 absorber 9 is divided into a first space (for example, the upper space) 92 and a second space (for example, the lower space) 93. The first space 92 is filled with a CO2 absorbent. Also, outside air sent from the pump device 91 flows through the first space 92. The air (the first heat medium M1) that has flowed into the external flow path 44 flows through the second space 93. When the air (the first heat medium M1) flows through the second space 93, the CO2 absorbent filled in the first space 92 is heated. Thereby, the separation and recovery of CO2 gas by the CO2 absorbent is promoted. The air (the first heat medium M1) that has flowed through the second space 93 is discharged to the outside.

[0032] In the example shown in FIG. 3, the first heat medium M1 flows through the first space 92, the external flow path 41, the internal flow path of the housing 1, the external flow path 42, the external flow path 43, and the first internal flow path of the heat exchanger 2. This flow path is an example of the "first flow path" of the present invention. The first heat medium M1 also flows through the first space 92, the external flow path 41, the internal flow path of the housing 1, the external flow path 42, the external flow path 44, and the second space 93. This flow path is also an example of the "first flow path" of the present invention, but can also be considered as a sub-flow path when the flow path including the external flow path 43 is taken as the main flow path.

[0033] Similar to the example shown in FIG. 1, in the example shown in FIG. 3, the electric power generated by the turbine power generation device 5 is charged to another storage battery. Also, part or all of the electric power charged to this other storage battery is used to drive peripheral devices such as the pump device 3, the control of the PCS, and the data logger of the storage battery connected to the PCS. In the example shown in FIG. 3, part or all of the electric power charged to this other storage battery is used to drive the pump device 91. As shown by the dashed arrow in FIG. 3, the electric power generated by the turbine power generation device 5 may be supplied to the pump device 3, the PCS, the peripheral devices of the PCS, and the pump device 91 without passing through another storage battery.

[0034] As described above, according to the example shown in FIG. 3, the same effects as those of the example shown in FIG. 1 can be obtained. In addition, the heat discharged from the PCS can be utilized for applications other than power generation that utilize the heat exchange between the first heat medium and the second heat medium.

[0035] 4. Fourth Configuration Example FIG. 4 is a diagram for explaining a fourth configuration example of the cooling system according to the embodiment. The cooling system 400 shown in FIG. 4 includes housings 1a and 1b. In the cooling system 400, the external flow path 4 branches in the middle. In the cooling system 400, the heat exchanger 2 also includes first inlets 21a and 21b. Other configurations are common to the cooling system 100 shown in FIG. 1.

[0036] In the example shown in FIG. 4, the PCSs are respectively housed in the housings 1a and 1b. To cool these PCSs, the housing 1a has an outlet 11a and an inlet 12a, and the housing 1b has an outlet 11b and an inlet 12b. An external flow path 45 is connected to the outlet 11a and the inlet 12a, and an external flow path 46 is connected to the outlet 11b and the inlet 12b. Further, the external flow path 45 and the external flow path 46 merge in the heat exchanger 2. The first heat medium M1 discharged from the heat exchanger 2 flows into the pump device 3 via the external flow path 47 and flows into the external flow paths 45 and 46 respectively upstream of the inlets 12a and 12b.

[0037] In the example shown in FIG. 4, the first heat medium M1 flows through the internal flow path of the housing 1a, the external flow path 45, the first internal flow path of the heat exchanger 2, and the external flow path 47. This flow path is an example of the "first flow path" of the present invention. The first heat medium M1 also flows through the internal flow path of the housing 1b, the external flow path 46, the first internal flow path of the heat exchanger 2, and the external flow path 47. This flow path is also an example of the "first flow path" of the present invention. The external flow path 47 and the first internal flow path of the heat exchanger 2 are an example of the "main flow path" of the present invention. The combination of the internal flow path of the housing 1a and the external flow path 45, and the combination of the internal flow path of the housing 1b and the external flow path 46 are an example of the "sub flow path" of the present invention.

[0038] As described above, according to the example shown in FIG. 4, the effects according to the example shown in FIG. 1 can be obtained in a PCS system or a storage battery system including a plurality of PCSs.

Description of Signs

[0039] 1, 1a, 1b... housing, 2... heat exchanger, 3, 91... pump device, 4, 7, 41, 42, 43, 44, 45, 46, 47... external flow path, 5... turbine power generation device, 6, 8... cooling device, 9... CO2 absorption device, 92... first space, 93... second space, 100, 200, 300, 400... cooling system, M1... first heat medium, M2... second heat medium

Claims

1. A system for cooling a power conversion device, comprising: a first flow path through which a first heat medium for cooling the power conversion device flows; a second flow path through which a second heat medium having a boiling point lower than that of the first heat medium flows; a heat exchanger provided in the middle of the first flow path and in the middle of the second flow path, for vaporizing the second heat medium in a liquid state by heat exchange between the first heat medium discharged from the power conversion device and the second heat medium; a turbine power generation device provided in the middle of the second flow path, for converting the thermal energy of the second heat medium in a gaseous state discharged from the heat exchanger into rotational energy to generate electricity; a cooling device provided between the turbine power generation device and the heat exchanger in the second flow path, for liquefying the second heat medium in a gaseous state discharged from the turbine power generation device and sending it to the heat exchanger; A cooling system for a power conversion device, characterized by comprising the above.

2. The cooling system for a power conversion device according to claim 1, further comprising a pump device provided in the middle of the first flow path for sending the first heat medium discharged from the heat exchanger to the power conversion device, wherein the generated electric power of the turbine power generation device is supplied to the pump device.

3. The cooling system for a power conversion device according to claim 1, characterized in that the generated electric power of the turbine power generation device is supplied to the power conversion device.

4. The cooling system for a power conversion device according to claim 1, further comprising a cooling device provided between the heat exchanger and the power conversion device in the first flow path for cooling the first heat medium discharged from the heat exchanger and sending it to the power conversion device.

5. The cooling system for a power conversion device according to claim 1, further comprising a pump device provided in the middle of the first flow path for sending outside air as the first heat medium to the power conversion device. a pump device in the first flow path, the pump device being disposed upstream of the pump device ... ２ CO absorbing gas ２ Further comprising an absorber.

6. the CO ２ The inner space of the absorption device is partitioned into a first space where the absorbent is accommodated and outside air as the first heat medium flowing to the power conversion device flows, and a second space where the outside air as the first heat medium discharged from the power conversion device flows, with respect to CO ２ absorbent is accommodated, and is divided into a first space through which outside air, which is the first heat medium, flows and is sent to the power conversion device, and a second space through which the outside air, which is the first heat medium, discharged from the power conversion device flows

7. The cooling system for a power conversion device according to claim 5, characterized in that the generated electric power of the turbine power generation device is supplied to the pump device.

8. The power conversion device includes a plurality of power conversion devices, and the first flow path includes a main flow path through which the first heat medium flows, and a plurality of sub-flow paths branched from the main flow path for cooling the plurality of power conversion devices respectively. A pump device for sending the first heat medium to the main flow path is further provided between the heat exchanger and the power conversion device in the main flow path. The cooling system for a power conversion device according to claim 1, characterized in that.

9. The generated power of the turbine power generation device is supplied to the pump device. The cooling system for a power conversion device according to claim 8, characterized in that.

10. The power conversion device is included in the battery system. The cooling system for a power conversion device according to any one of claims 1 to 9, characterized in that.

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