Electric machinery

Abstract

This system aims to suppress cost increases and size increases for liquid-cooled power equipment while promptly detecting leaks and preventing malfunctions in such equipment. [Solution] The power equipment of the present disclosure includes a power module, a cooling plate supporting the power module, a housing to which the cooling plate is fixed, a heat transfer medium passage formed in the housing and supplied with a liquid heat transfer medium to exchange heat with the power module via the cooling plate, a sealing member disposed between the cooling plate and the housing to seal the heat transfer medium passage, a leak receiving recess formed in the housing extending along at least a portion of the sealing member and covered by the cooling plate, a leak detection device having a plurality of fiber Bragg gratings and including optical fibers disposed within the leak receiving recess, and a control device that stops the operation of the power equipment and the supply of liquid heat transfer medium to the heat transfer medium passage in response to a leak being detected by the leak detection device.

Description

Technical Field

[0003] , ,

[0001] The present disclosure relates to electrical equipment including a power module.

Background Art

[0002] Conventionally, a method for identifying a water leakage location in an underground excavation hole without directly detecting moisture has been known (see, for example, Patent Document 1). In this method, a water-curable substance layer (for example, cement powder) that exhibits a heat generation phenomenon during reaction with water is provided under the water leakage prevention surface of a location where water leakage prevention is required in an underground excavation hole used for waste treatment or the like, and an optical fiber connected to an OTDR is laid on the lower surface of the water-curable substance layer. Then, this method identifies the water leakage location by detecting, with an OTDR on the incident end side, the backscattered light generated with respect to the incident light on the optical fiber due to the heat generated by the curing reaction between the water-curable substance layer and the water leakage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, when applying the water leakage detection technology using an optical fiber as described above to a liquid-cooled electrical equipment including a power module, since it is necessary to install a water-curable substance layer near the optical fiber, it leads to an increase in the cost and size of the electrical equipment. Further, in order to detect a liquid leakage, it is necessary to cure the water-curable substance layer by reaction with the liquid leakage, and there is a risk that the liquid refrigerant continuously supplied to the electrical equipment may flow out of the electrical equipment before the water-curable substance layer is cured after the occurrence of the liquid leakage.

[0005] Therefore, the primary objective of this disclosure is to suppress the increase in cost and size of liquid-cooled power equipment while promptly detecting liquid leakage and preventing malfunctions in said power equipment. [Means for solving the problem]

[0006] The power equipment of this disclosure includes a power module, a cooling plate supporting the power module, and a housing to which the cooling plate is fixed, the power equipment including a heat transfer medium passage formed in the housing and supplied with a liquid heat transfer medium to exchange heat with the power module via the cooling plate, a sealing member disposed between the cooling plate and the housing to seal the heat transfer medium passage, a leak receiving recess formed in the housing extending along at least a portion of the sealing member and covered by the cooling plate, a leak detection device including a plurality of fiber Bragg gratings and optical fibers disposed within the leak receiving recess, and a control device that stops the operation of the power equipment and the supply of the liquid heat transfer medium to the heat transfer medium passage in response to the detection of a leak by the leak detection device.

[0007] In the power equipment of this disclosure, if the liquid heat transfer fluid leaks from the heat transfer fluid passage due to faulty assembly or deterioration of the sealing member, the leaked liquid heat transfer fluid flows into the leak-receiving recess and comes into contact with the optical fiber. The fiber Bragg grating that comes into contact with the liquid heat transfer fluid expands or contracts in response to the temperature change caused by contact with the liquid heat transfer fluid, thereby changing the Bragg wavelength of the light reflected by the fiber Bragg grating. Therefore, by monitoring the Bragg wavelength of the light reflected from the optical fiber using a control device and a leak detection device, leakage of the liquid heat transfer fluid from the heat transfer fluid passage can be quickly detected without providing a water-curable material layer in the power equipment. As a result, it is possible to quickly detect leaks and suppress the occurrence of malfunctions in the power equipment while suppressing cost increases and the enlargement of the housing of liquid-cooled power equipment. [Brief explanation of the drawing]

[0008] [Figure 1]This is a schematic diagram showing the power equipment disclosed herein. [Figure 2] This is a cross-sectional view showing the power equipment of this disclosure. [Figure 3] This flowchart illustrates routines executed by the control device of the power equipment described herein. [Modes for carrying out the invention]

[0009] Next, with reference to the drawings, embodiments for carrying out the invention of this disclosure will be described.

[0010] Figure 1 is a schematic diagram showing the power equipment 1 of this disclosure, and Figure 2 is a cross-sectional view showing the power equipment 1. The power equipment 1 shown in these drawings is, for example, a power converter or voltage converter, etc., mounted on a vehicle (electric vehicle) not shown, and includes a power module 2, a cooling plate 4 that supports the power module 2 via a heat transfer member 3 (see Figure 2), and a housing 5 to which the cooling plate 4 is fixed. The power module 2 includes a plurality of packaged power semiconductors (not shown) and is fixed to the cooling plate 4 by being pressed against the cooling plate 4 via a fixing device (not shown). The heat transfer member 3 is a heat dissipation sheet or thermal conductive grease, etc., which has high thermal conductivity. The cooling plate 4 is made of a metal such as an aluminum alloy which has high thermal conductivity, and as shown in Figure 2, has a plurality of heat transfer fins 4f that protrude from the back side of the power module 2 and the heat transfer member 3 toward the side opposite to the power module 2.

[0011] The housing 5 is made of metal or the like, and a relatively shallow cooling plate housing recess 50 is formed on its surface (the top surface in Figure 1) where the cooling plate 4 is placed. In addition, a heat transfer medium passage 51 is formed in the housing 5, as shown in Figure 2. The heat transfer medium passage 51 is a recess deeper than the cooling plate housing recess 50, located below the power module 2 and heat transfer member 3 supported by the cooling plate 4 in Figure 2, and recessing downward in the figure from the bottom surface of the cooling plate housing recess 50. The cooling plate 4 is positioned in the cooling plate housing recess 50 such that each of its multiple heat transfer fins 4f protrudes into the heat transfer medium passage 51, and is fixed (fastened) to the housing 5 via multiple bolts B.

[0012] As shown in Figure 2, the housing 5 has a heat transfer medium supply hole 51i and a heat transfer medium outlet hole 51o, which communicate with the heat transfer medium passage 51. A heat transfer medium circulation device 6, including a pump, heater, cooler, and tank (not shown), is connected to the heat transfer medium supply hole 51i via piping, and a liquid heat transfer medium, mainly composed of ethylene glycol, is supplied from the heat transfer medium circulation device 6. The liquid heat transfer medium supplied into the heat transfer medium passage 51 from the heat transfer medium supply hole 51i exchanges heat with the power module 2 via the multiple heat transfer fins 4f and heat transfer members 3 of the cooling plate 4, and is returned to the heat transfer medium circulation device 6 via the heat transfer medium outlet hole 51o and piping. The liquid heat transfer medium that flows out from the heat transfer medium outlet hole 51o is conditioned by the heater or cooler and supplied again to the heat transfer medium supply hole 51i by the heat transfer medium circulation device 6. This makes it possible to circulate the liquid heat transfer medium in the heat transfer medium passage 51 and adjust the temperature of the power module 2 via the cooling plate 4. Furthermore, due to heat exchange with power module 2, the temperature of the liquid heat transfer medium fluctuates within a range of approximately -40°C to 70°C.

[0013] Furthermore, the housing 5 has a seal-receiving recess 52 and a leak-receiving recess 53. The seal-receiving recess 52 is an endless recess that surrounds the heat transfer medium passage 51 at a distance from it and is recessed downward in the figure from the bottom surface of the cooling plate-receiving recess 50. A seal member 7 having a height greater than the depth of the seal-receiving recess 52 is placed inside the seal-receiving recess 52. In this embodiment, the seal member 7 is an endless (frame-shaped in this embodiment) double-lip gasket, for example. When the cooling plate 4 is fixed to the housing 5 via a plurality of bolts B, the seal member 7 is compressed between the cooling plate 4 and the housing 5 to such an extent that the back surface of the cooling plate 4 (bottom surface in Figure 2) does not come into contact with the bottom surface of the cooling plate-receiving recess 50 of the housing 5. As a result, the heat transfer medium passage 51 is sealed by the seal member 7.

[0014] The leak-receiving recess 53 is an endless recess that surrounds the seal-receiving recess 52 at a distance from it, and is recessed downward in the figure from the bottom surface of the cooling plate-receiving recess 50. In this embodiment, as shown in Figure 2, the leak-receiving recess 53 is a V-groove having a pair of sloped surfaces that approach each other as they move away from the bottom surface of the cooling plate-receiving recess 50. In addition, an endless gap 54 is defined between the outer circumferential surface of the cooling plate 4 and the wall portion of the housing 5 that defines the cooling plate-receiving recess 50. As shown in Figure 2, the gap 54 communicates with the leak-receiving recess 53 through a low-profile space between the back surface of the cooling plate 4 and the bottom surface of the cooling plate-receiving recess 50 when the cooling plate 4 is fixed to the housing 5 via a plurality of bolts B.

[0015] Then, the power module 2 is exposed on the surface of the housing 5 and the surface of the cooling plate 4 (the upper surface in Figure 2), and a covering member 8 such as waterproof tape is attached to cover the multiple bolts B and the gap 54. As a result, the upper opening of the gap 54 in Figure 2 is closed, and an endless closed space is formed around the cooling plate 4 by the gap 54 and the covering member 8. In addition, as shown in Figures 1 and 2, a communication passage 55 is formed in the housing 5 that communicates with the gap 54. The communication passage 55 opens on one side of the housing 5 and is liquid-tightly connected to a branch pipe 56. The branch pipe 56 is connected via a hose 57 to a foldable bag 58 located outside the housing 5. The bag 58 is made of an insulating material and is capable of storing a liquid heat transfer medium inside.

[0016] Furthermore, the power equipment 1 includes a leak detection device 9 and an electronic control unit (hereinafter referred to as "ECU") 10. In this embodiment, the leak detection device 9 is an FBG sensor unit including two optical fibers 90 and an interrogator 95 to which the optical fibers 90 are connected. Each optical fiber 90 has a plurality of fiber Bragg gratings (diffraction gratings, hereinafter referred to as "FBG") 91 of a predetermined length (for example, about 10 mm) formed on the core at intervals (for example, about 10 mm) in the direction of extension of the optical fiber 90 by laser processing or the like. The two optical fibers 90 are laid in the leak receiving recess 53 so as to extend over almost the entire circumference of the leak receiving recess 53 and surround the seal receiving recess 52 and the seal member 7.

[0017] In this embodiment, as shown in Figure 2, a heat insulating material 59 is arranged around the entire circumference of the bottom of the leak-receiving recess 53. Two optical fibers 90 are laid on the heat insulating material 59 in the leak-receiving recess 53, generally parallel to each other, and the FBG91 of one optical fiber 90 is adjacent to the portion of the other optical fiber 90 where the FBG91 is not formed (dead zone). One end of each optical fiber 90 is fixed to a predetermined location in the leak-receiving recess 53, and the other end of each optical fiber 90 is led out to the outside of the housing 5 via the low-profile space between the back surface of the cooling plate 4 and the bottom surface of the cooling plate housing recess 50, the connecting passage 55 and the branch pipe 56, and connected to the interrogator 95. The interrogator 95 incidents light of a predetermined wavelength onto each optical fiber 90 and acquires the Bragg wavelength of the reflected light from each optical fiber 90 (FBG91).

[0018] The ECU 10 includes a microcomputer (not shown) with a CPU, ROM, RAM, input / output interface, etc. The ECU 10 controls the power module 2 of the power device 1 based on requests from the vehicle on which the power device 1 is installed and signals from various sensors (not shown). The ECU 10 also controls the heat transfer medium circulation device 6 based on the temperature of the liquid heat transfer medium or the measured or estimated temperature of the power module 2.

[0019] In this case, the seal member 7, which may have been twisted during the manufacturing process, is assembled into the seal housing recess 52, and the cooling plate 4 is fastened to the housing 5 with a portion of the lip of the seal member 7 protruding from the seal housing recess 52. In such a case, although the sealing performance of the seal member 7 is ensured, a crack (break) initiation point is formed in the portion of the seal member 7 that protrudes from the seal housing recess 52. As a result, cracks may occur in the thin-walled portion of the seal member 7 due to deterioration over time, and liquid heat transfer fluid may leak from the heat transfer fluid passage 51 to the leak-receiving recess 53 through these cracks. Furthermore, even if the seal member 7 is properly installed in the seal housing recess 52, a gap may be formed between the cooling plate 4 and the seal member 7 due to deterioration of the seal member 7 over time or loosening of the bolts B.

[0020] Therefore, in the power equipment 1, in order to suppress problems caused by the leaked liquid heat medium coming into contact with the power module 2 and the increase in repair costs, the routine shown in FIG. 2 is repeatedly executed by the ECU 10 at short time intervals during the operation of the power equipment 1. When the execution timing of the routine shown in FIG. 2 arrives, the ECU 10 acquires the Bragg wavelength of the reflected light from each optical fiber 90 from the interrogator 95 of the liquid leakage detection device 9 (step S100). Next, the ECU 10 determines the presence or absence of leakage of the liquid heat medium based on the Bragg wavelength acquired in step S100 (step S110). In step S110, the ECU 10 calculates the difference between the previous value and the current value of the Bragg wavelength of the reflected light for each optical fiber 90, and compares the calculated difference with a predetermined threshold value. The threshold value may be a constant value or a variable value that varies according to the temperature of the liquid heat medium or the temperature of the power module 2.

[0021] When the liquid heat medium has not leaked from the heat medium passage 51 to the liquid leakage receiving recess 53 side, since the heat insulating material 59 is disposed between the housing 5 and each optical fiber 90, the temperature change of each optical fiber 90 according to the operation of the power equipment 1 is relatively small, and the difference between the previous value and the current value of the Bragg wavelength calculated in step S110 is below the threshold value. On the other hand, when the liquid heat medium leaked from the heat medium passage 51 flows into the liquid leakage receiving recess 53, the FBG 91 in contact with the liquid heat medium expands or contracts according to the temperature change, and thereby the Bragg wavelength of the light reflected by the FBG 91 changes. Therefore, when the liquid heat medium has leaked from the heat medium passage 51 to the liquid leakage receiving recess 53 side, the difference between the previous value and the current value of the Bragg wavelength calculated in step S110 exceeds the threshold value.

[0022] If the difference between the previous and current Bragg wavelengths calculated for each optical fiber 90 is below the threshold, the ECU 10 determines that no leakage of the liquid heat transfer medium has occurred (step S120: NO) and terminates the routine shown in Figure 2. If at least one of the differences between the previous and current Bragg wavelengths calculated for each optical fiber 90 exceeds the threshold, the ECU 10 determines that leakage of the liquid heat transfer medium has occurred and that the liquid heat transfer medium has flowed into the leakage receiving recess 53 (step S120: YES). In step S120, it is also possible to determine that leakage of the liquid heat transfer medium has occurred when the difference between the previous and current Bragg wavelengths has exceeded the threshold multiple times in a row. When the ECU 10 determines that leakage of the liquid heat transfer medium has occurred, it stops the operation of the power equipment 1 and the supply of the liquid heat transfer medium from the heat transfer medium circulation device 6 to the heat transfer medium passage 51 (step S130). Furthermore, the ECU 10 transitions the operating mode of the power equipment 1 to fail-safe mode (step S140), and terminates the routine shown in Figure 2. Note that in step S130, the power equipment 1 and the heat transfer medium circulation device 6 may be stopped approximately simultaneously, the power equipment 1 may be stopped after the heat transfer medium circulation device 6 has been stopped, or the heat transfer medium circulation device 6 may be stopped after the power equipment 1 has been stopped.

[0023] Furthermore, in the power equipment 1, the leak-receiving recess 53 is connected to the bag 58 via the low-profile space between the back surface of the cooling plate 4 and the bottom surface of the cooling plate housing recess 50, the gap 54 around the cooling plate 4, the connecting passage 55, the branch pipe 56, and the hose 57. This allows the liquid heat transfer medium that leaks from the heat transfer medium passage 51 and flows into the leak-receiving recess 53 to be guided into the bag 58 and stored in the unfolded bag 58. As a result, even if liquid heat transfer medium leaks from the heat transfer medium passage 51 in the power equipment 1, it is possible to suppress contact between the leaked liquid heat transfer medium and the power module 2 very effectively. Moreover, if liquid heat transfer medium leakage occurs in the power equipment 1, the power equipment 1 can be used continuously by replacing the sealing member 7, the covering material 8, and the bag 58, and, if necessary, the bolt B and the optical fiber 90. As a result, it is possible to suppress the increase in repair costs caused by liquid heat transfer medium leakage very effectively.

[0024] As described above, the power device 1 of the present disclosure includes a power module 2, a cooling plate 4 that supports the power module 2, a housing 5 to which the cooling plate 4 is fixed, a heat medium circulation device 6, a liquid leakage detection device 9, and an ECU 10 as a control device. Further, a heat medium passage 51, a seal accommodation recess 52, and a liquid leakage reception recess 53 are formed in the housing 5. A liquid heat medium is supplied from the heat medium circulation device 6 to the heat medium passage 51 so as to exchange heat with the power module 2 via the cooling plate 4, and a seal member 7 is disposed in the seal accommodation recess 52 so as to seal the heat medium passage 51 between the cooling plate 4 and the housing 5. The liquid leakage reception recess 53 is formed in the housing 5 so as to extend along the seal accommodation recess 52 and the seal member 7 and surround both of them over the entire circumference, and is covered by the cooling plate 4. Further, the liquid leakage detection device 9 includes two optical fibers 90 having a plurality of FBGs 91 and disposed in the liquid leakage reception recess 53, and the ECU 10 stops the operation of the power device 1 and the supply of the liquid heat medium to the heat medium passage 51 in response to the detection of liquid leakage by the liquid leakage detection device 9 (steps S 100 - S 130).

[0025] In such a power device 1, when the liquid heat medium leaks from the heat medium passage 51 due to improper assembly or deterioration of the seal member 7, etc., the leaked heat medium flows into the liquid leakage reception recess 53 and contacts the optical fiber 90. Then, the FBG 91 that has come into contact with the heat medium expands or contracts according to the temperature change due to the contact with the liquid heat medium, and thereby the Bragg wavelength of the light reflected by the FBG 91 changes. Therefore, by monitoring the Bragg wavelength of the reflected light from each optical fiber 90 by the ECU 10 and the liquid leakage detection device 9, it is possible to quickly detect the leakage of the liquid heat medium from the heat medium passage 51 without providing a water-curable material layer on the power device 1. As a result, it is possible to suppress an increase in the cost of the liquid-cooled power device 1 and an increase in the size of the housing 5, and to quickly detect the leakage of the liquid heat medium and suppress the occurrence of problems in the power device 1.

[0026] Furthermore, in the power equipment 1, a leak-receiving recess 53 is formed in the housing 5 so as to surround the seal-receiving recess 52 and the seal member 7, and the optical fiber 90 of the leak detection device 9 is laid around almost the entire circumference of the leak-receiving recess 53. This makes it possible to properly detect whether or not there is a leak of the liquid heat transfer medium even when the vehicle equipped with the power equipment 1 is located on an inclined surface such as a ramp. However, depending on the application of the power equipment 1 (for example, when the power equipment 1 is included in stationary equipment, etc.), the configuration of the heat transfer medium passage 51, and the arrangement of the seal member 7, it is not always necessary for the leak-receiving recess 53 to be formed in the housing 5 so as to surround the seal-receiving recess 52 and the seal member 7, and the leak-receiving recess 53 may be formed in the housing 5 so as to extend along at least a part of the seal member 7.

[0027] Furthermore, in the power equipment 1, the leak-receiving recess 53 has a pair of slopes that move closer to each other as they move away from the bottom surface of the cooling plate housing recess 50. This allows the liquid heat transfer medium leaking from the heat transfer medium passage 51 to quickly flow down into the leak-receiving recess 53 and come into contact with the optical fiber 90. In addition, each optical fiber 90 of the leak detection device 9 is laid on a heat insulating material 59 placed inside the leak-receiving recess 53. This suppresses the transfer of heat from the liquid heat transfer medium to the optical fiber 90 through the housing 5, and ensures that a sufficient temperature difference is maintained between the optical fiber 90 and the liquid heat transfer medium. However, in the power equipment 1, the heat insulating material 59 inside the leak-receiving recess 53 may be omitted. Furthermore, in the power equipment 1, two optical fibers 90 are laid inside the leak-receiving recess 53 such that the FBG91 of one optical fiber 90 is adjacent to the portion of the other optical fiber 90 where the FBG91 is not formed (dead zone). This effectively eliminates the dead zone of the leak detection device 9, making it possible to quickly and accurately detect the presence or absence of liquid heat transfer fluid leakage. However, to effectively eliminate the dead zone of the leak detection device 9, three or more optical fibers 90 may be laid in the leak receiving recess 53, or a single optical fiber 90 having multiple FBGs 91 formed at a fine pitch may be laid in the leak receiving recess 53.

[0028] Furthermore, the invention disclosed herein is not limited in any way to the embodiments described above, and it goes without saying that various modifications can be made within the scope of this disclosure. Moreover, the embodiments described above are merely one specific form of the invention described in the summary of the invention, and do not limit the elements of the invention described in the summary of the invention. [Industrial applicability]

[0029] The invention disclosed herein can be used in industries such as the manufacturing of power equipment, including power modules. [Explanation of symbols]

[0030] 1 Power equipment, 2 Power module, 3 Heat transfer component, 4 Cooling plate, 4f Heat transfer fin, 5 Housing, 50 Cooling plate housing recess, 51 Heat transfer medium passage, 51i Heat transfer medium supply hole, 51o Heat transfer medium outlet hole, 52 Seal housing recess, 53 Leakage receiving recess, 54 Gap, 55 Connecting passage, 56 Branch pipe, 57 Hose, 58 Bag, 59 Insulation material, 6 Heat transfer medium circulation device, 7 Seal component, 8 Covering component, 9 Leakage detection device, 90 Optical fiber, 91 Fiber Bragg grating (FBG), 95 Interrogator, 10 Electronic control unit (ECU).

Claims

[Claim 1] A power device comprising a power module, a cooling plate supporting the power module, and a housing to which the cooling plate is fixed, A heat transfer medium passage is formed in the housing, through which a liquid heat transfer medium is supplied to exchange heat with the power module via the cooling plate, A sealing member is disposed between the cooling plate and the housing to seal the heat transfer medium passage, A leak-receiving recess is formed in the housing so as to extend along at least a portion of the sealing member and be covered by the cooling plate, A leak detection device having multiple fiber Bragg gratings and including optical fibers disposed within the leak receiving recess, A control device that stops the operation of the power equipment and the supply of the liquid heat transfer medium to the heat transfer medium passage in response to the detection of a leak by the leak detection device, Power equipment equipped with the following features.

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