Semiconductor cooling device, power control system and moving body

Abstract

Semiconductor cooling device (100, 200, 300, 500), comprising: - a refrigerant circulation path (1) through which a refrigerant (2) circulates; - a heat exchanger provided on the refrigerant circulation path (1) on which a semiconductor module (5) can be installed and is configured to exchange heat between the refrigerant (2) and the semiconductor module (5); - a microbubble generator (6) provided on the refrigerant circulation path (1) and configured to generate microbubbles in the refrigerant (2); - a controller (7) configured to control the microbubble generator (6); and - a refrigerant sensor (8; 10; 11; 12a; 12b) configured to measure a refrigerant temperature, refrigerant flow rate, refrigerant flow velocity or refrigerant pressure of the refrigerant (2) circulating in the refrigerant circulation path (1), wherein: - the controller (7) is configured to control the microbubble generator (6) based on a measurement result obtained from the refrigerant sensor (8; 10; 11; 12a; 12b) in order to control the amount of microbubbles produced, - the refrigerant sensor (8; 10; 11; 12a; 12b) has: - a refrigerant temperature sensor (8) configured to measure the refrigerant temperature, and - at least one of a - Sensor (10) for the refrigerant flow rate, configured to measure the refrigerant flow rate, - a sensor (11) for the refrigerant flow velocity, configured to measure the refrigerant flow velocity, and - Sensors (12a, 12b) for refrigerant pressure, configured to measure the refrigerant pressure at respective positions in the refrigerant circulation path (1), and - the controller (7) is configured to control the microbubble generator (6) based on the refrigerant temperature measured by the refrigerant temperature sensor (8) and on the basis of at least one parameter of the refrigerant flow rate measured by the refrigerant flow rate sensor (10), the refrigerant flow velocity measured by the refrigerant flow velocity sensor (11), and the refrigerant pressure measured by the refrigerant pressure sensors (12a, 12b) at appropriate locations.

Description

Technical field

[0001] The present invention relates to a semiconductor cooling device, a power control system and a moving body. General state of the art

[0002] To improve the reliability of a semiconductor module, the semiconductor module must be cooled efficiently. For example, the power conversion device described in patent document 1 employs a water-cooling method to cool a semiconductor module.

[0003] The temperature control device, which controls the temperature of an object whose temperature is to be controlled with a liquid refrigerant containing microbubbles, is proposed in patent document 2. State-of-the-art documents, patent documents [Patent document 1] Published Japanese patent application JP 2006-166604A [Patent document 2] Published Japanese patent application JP 2009-044100A

[0004] US 2005 / 0 279 491 A1 relates to a heat transfer arrangement for transferring heat from a heat generating device to a circulating fluid, wherein the heat transfer arrangement comprises an evaporator device with at least one microchannel formed therein in thermally conductive contact with the heat generating device, a condenser device, actuating means and distributor means for circulating the fluid between the evaporator device and the condenser device, wherein the heat transfer arrangement further comprises a bubble generator capable of generating bubbles in the at least one microchannel at a controlled frequency.

[0005] US Patent 2013 / 0025831A1 discloses a heat exchange system for exchanging heat with a heat source and a cold source. The system may include a circulation loop. The circulation loop may include a heat dissipation section configured to exchange heat with the cold source and a heat absorption section configured to exchange heat with the heat source, the heat absorption section comprising a channel.The embodiment may include a liquid pump configured to circulate a liquid through the circulation loop from an inlet of the channel to an outlet of the channel, and a bubble injector coupled to the circulation loop proximal to the inlet of the channel and configured to form a plurality of gas bubbles in the channel, each of the plurality of gas bubbles being monodisperse throughout the channel, with liquid segments separating successive gas bubbles of the plurality of gas bubbles.

[0006] DE 11 2017 004 529 T5 describes a device temperature controller in which a working fluid circulates. The controller has a heat absorber that causes the working fluid to absorb heat from a target device, thereby evaporating the working fluid, and a heat radiator located above the heat absorber that causes the working fluid to radiate heat, thereby condensing the working fluid. Furthermore, the device temperature controller has a forward flow section in which a forward flow passage is formed to cause the working fluid to flow from the heat radiator to the heat absorber, and a reverse flow section in which a reverse flow passage is formed to cause the working fluid to flow from the heat absorber to the heat radiator.Furthermore, the device temperature controller includes a bubble generator that creates a bubble in the working fluid, which collects in the heat absorber and has a liquid phase, and a control unit. If the circulation flow rate of the working fluid, circulating in a fluid circulation loop consisting of the heat radiator, the forward flow section, the heat absorber, and the reverse flow section, is a specified flow rate or less, the control unit causes the bubble generator to create the bubble. Summary Problem to be solved by the invention

[0007] The microbubbles mixed into the liquid refrigerant reduce the refrigerant's pressure drop. However, the liquid refrigerant containing microbubbles presents a problem in that the microbubble concentration decreases over time due to microbubble collapse or similar factors, thus diminishing the reduction in pressure drop and the improvement in heat dissipation. Conversely, if the microbubble concentration is too high, the microbubbles burst or disperse, creating air bubbles in the refrigerant flow path, and the heat dissipation effect is reduced. If a microbubble generator lacks the function to control the amount of microbubbles introduced into the refrigerant flow path, the reduction in pressure drop and the improvement in heat dissipation cannot be restored.

[0008] The present invention was made to solve the problems described above, and one object of the present invention is to provide a semiconductor cooling device that optimally maintains the amount of microbubbles mixed in the refrigerant and prevents the reduction of the cooling effect of the semiconductor module. Means to solve the problem

[0009] The problem underlying the invention is solved according to the invention in the case of a semiconductor cooling device by the features of claim 1, in the case of a power control system by the features of claim 5, and in the case of a moving body by the features of claim 6. Advantageous embodiments are the subject of the respective dependent claims.The semiconductor cooling device according to the present invention comprises a refrigerant circulation path through which a refrigerant circulates, a heat exchanger provided on the refrigerant circulation path on which a semiconductor module can be installed and is configured to exchange heat between the refrigerant and the semiconductor module, a microbubble generator provided on the refrigerant circulation path and configured to generate microbubbles in the refrigerant, a controller configured to control the microbubble generator, and a refrigerant sensor configured to measure a refrigerant temperature, a refrigerant volume flow rate or refrigerant flow rate, a refrigerant flow velocity, or a refrigerant pressure of the refrigerant circulating in the refrigerant circulation path.The controller is configured to control the microbubble generator based on a measurement result obtained from the refrigerant sensor, in order to control the amount of microbubbles produced.

[0010] According to the invention, the refrigerant sensor comprises a refrigerant temperature sensor configured to measure the refrigerant temperature, and at least one of a (i) refrigerant flow rate sensor configured to measure the refrigerant flow rate, (ii) refrigerant flow velocity sensor configured to measure the refrigerant flow velocity, and (iii) refrigerant pressure sensor configured to measure the refrigerant pressure at respective positions in the refrigerant circulation path.The controller configures the microbubble generator to control it based on the refrigerant temperature measured by the refrigerant temperature sensor and on the basis of at least one parameter of the refrigerant flow rate measured by the refrigerant flow velocity sensor, the refrigerant flow velocity measured by the refrigerant flow velocity sensor, and the refrigerant pressure measured by the refrigerant pressure sensors at appropriate locations. Effects of the invention

[0011] A semiconductor cooling device is created that optimally maintains the mixture of microbubbles in the refrigerant and prevents the reduction of the cooling effect of the semiconductor module.

[0012] These and other tasks, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when it is carried out in conjunction with the accompanying drawings. Brief description of the drawings [ Fig. 1] A diagram that schematically illustrates a configuration of a semiconductor cooling device according to an underlying technology. [ Fig. 2] A diagram schematically illustrating a configuration of a semiconductor cooling device according to embodiment 1. [ Fig. 3] A flowchart illustrating a control procedure for a mixture of microbubbles according to embodiment 1. [ Fig. 4] A graphical representation illustrating a relationship between a microbubble generation amount and ΔT3 according to embodiment 1. [ Fig. 5] A diagram schematically illustrating a configuration of a semiconductor cooling device according to embodiment 2. [ Fig. 6] A flowchart illustrating a control procedure for a mixture of microbubbles according to embodiment 2. [ Fig. 7] A graphical representation illustrating a correlation between refrigerant temperature and refrigerant flow rate in an optimal refrigerant condition. [ Fig. 8] A diagram schematically illustrating a configuration of a semiconductor cooling device according to embodiment 3. [ Fig. 9] A flowchart illustrating a control procedure for a mixture of microbubbles according to embodiment 3. [ Fig. 10] A graphical representation illustrating a correlation between refrigerant temperature and ΔP1 in an optimal refrigerant state. [ Fig. 11] A diagram schematically illustrating a configuration of a semiconductor cooling device according to embodiment 5. [ Fig. 12] A diagram schematically illustrating a configuration of a power control system and a moving body according to embodiment 6. Description of embodiments

[0013] Before describing embodiments of the semiconductor cooling device according to the present invention, the underlying technology of the present invention will be described.

[0014] Fig. Figure 1 is a diagram schematically illustrating a configuration of a semiconductor cooling device 900 according to an underlying technology of the present invention. The semiconductor cooling device 900 comprises a refrigerant circulation path 91 through which a refrigerant 92 containing microbubbles circulates, a circulator or recirculation device 93 that circulates or recirculates the refrigerant 92 through the refrigerant circulation path 91, and cooling fins 94. The cooling fins 94 exchange heat between the refrigerant 92 and the semiconductor module 95 installed on the cooling fins 94. The microbubbles reduce fluid friction of the refrigerant 92 and reduce pressure loss of the refrigerant 92.The semiconductor cooling device 900 makes it possible to increase the flow rate of the refrigerant 92, so that the thermal resistance Rth (j_w) between the semiconductor module 95 and the refrigerant 92 is reduced and as a result the heat radiation effect is improved.

[0015] In addition to the effects of the semiconductor cooling device 900 mentioned above, the semiconductor cooling device in each embodiment described below has the effect of maintaining the optimal mixing ratio of microbubbles in the refrigerant and preventing the reduction of the cooling effect on the semiconductor module. <Ausführungsform 1>

[0016] Fig. Figure 2 is a diagram that schematically illustrates a configuration of a semiconductor cooling device 100 according to embodiment 1.

[0017] The semiconductor cooling device 100 comprises a refrigerant circulation path 1 through which a refrigerant 2 circulates, a circulation device 3, a refrigerant sensor that measures the physical state of the refrigerant 2, i.e. a sensor 8 for the refrigerant temperature in embodiment 1, cooling fins 4 which are a heat exchanger, a sensor 9 for the module temperature, a microbubble generator 6 and a controller 7.

[0018] Refrigerant 2 is a refrigerant containing microbubbles, for example a mixture of an antifreeze liquid (LLC) and water with the microbubbles.

[0019] The circulation device 3 is arranged in the refrigerant circulation path 1 and allows the refrigerant 2 to circulate through the refrigerant circulation path 1.

[0020] The sensor 8 for the refrigerant temperature is provided at the inlet or outlet of the cooling fins 4 of the refrigerant circulation path 1 and measures the refrigerant temperature Tw. In embodiment 1, the sensor 8 for the refrigerant temperature is arranged at the inlet of the cooling fins 4.

[0021] The cooling fins 4, which constitute a heat exchanger, are arranged in the refrigerant circulation path 1 and exchange heat between the refrigerant 2 and the semiconductor module 5. For example, one side of the cooling fins 4 is in contact with the refrigerant 2 in the refrigerant circulation path 1, and the semiconductor module 5 is installed on the other side. It should be specifically noted that the cooling fins 4 are one example of a heat exchanger and the heat exchanger is not limited to the cooling fins 4.

[0022] Semiconductor module 5, for example, is a power semiconductor module and contains a semiconductor device whose main material is Si, SiC, or GaN. The semiconductor device contains, for example, a MOSFET or IGBT.

[0023] The module temperature sensor 9 measures the module temperature Tj of the semiconductor module 5 arranged on the cooling fins 4. The module temperature sensor 9 is, for example, arranged on one side of the cooling fins 4 on which the semiconductor module 5 is located. The module temperature Tj measured by the module temperature sensor 9 is preferably the temperature of the semiconductor device and more preferably the temperature of the junction of the semiconductor device.

[0024] The microbubble generator 6 generates microbubbles to be mixed into the refrigerant 2.

[0025] Although not shown, the controller 7 contains a processor that performs various arithmetic and determination operations, and a memory that stores various data. The controller 7 controls the microbubble generator 6 to regulate the amount of microbubbles produced. In embodiment 1, the controller 7 controls the output of the microbubble generator 6 based on the refrigerant temperature Tw measured by the refrigerant temperature sensor 8 and the module temperature Tj measured by the module temperature sensor 9.

[0026] Although not shown here, the controller 7 can be equipped with an input terminal for supplying a signal related to the module temperature Tj of the semiconductor module 5 instead of the module temperature sensor 9 described above. The input terminal receives, for example, a signal emitted by the module temperature sensor located on the semiconductor module 5. The signal can be a signal containing a value of the module temperature Tj, or it can be a signal indicating that the module temperature Tj is higher or lower than a predetermined value. The controller 7 controls the microbubble generator 6 based on the refrigerant temperature Tw measured by the refrigerant temperature sensor 8 and the signal supplied by the input terminal.

[0027] Next, the operation of the semiconductor cooling device 100 and a control method for the mixing amount of microbubbles are described. Fig. Figure 3 is a flowchart illustrating the control procedure for the amount of microbubbles mixed according to embodiment 1.

[0028] First, in step S10, a state is prepared in which the mixing ratio of microbubbles contained in refrigerant 2 is optimal. In the optimal state of refrigerant 2, the semiconductor module 5 is held in a given constant excitation state.

[0029] In step S11, the controller 7 receives the refrigerant temperature Tw1 measured by sensor 8 for the refrigerant temperature and the module temperature Tj1 measured by sensor 9 for the module temperature.

[0030] In step S12, the controller calculates ΔT1 = Tj1 - Tw1, which is the temperature difference between the refrigerant temperature Tw1 and the module temperature Tj1, and stores this temperature difference in memory as reference data. ΔT1 indicates the order of magnitude of the cooling effect in a state where the mixing ratio of the microbubbles is optimal.

[0031] In step S13, in a state where it is unclear whether the state of the refrigerant 2 is optimal or not, i.e., whether the state of the mixture of microbubbles is optimal or not, since the time from step S11 has elapsed, the semiconductor module 5 is controlled in the same state as the constant excitation state in which the reference data are acquired.

[0032] In step S14, the controller 7 receives the refrigerant temperature Tw2 measured by sensor 8 for the refrigerant temperature and the module temperature Tj2 measured by sensor 9 for the module temperature.

[0033] In step S15, the controller calculates 7 ΔT2 = Tj2 - Tw2, which is the temperature difference between the refrigerant temperature Tw2 and the module temperature Tj2.

[0034] In step S16, the controller 7 reads ΔT1 from memory, which was calculated in a state where the microbubbles contained in refrigerant 2 are in optimal condition. The controller 7 then calculates ΔT3 = ΔT1 - ΔT2, where ΔT2 was calculated in a state where it is unclear whether the state of refrigerant 2 is optimal or not, and ΔT1. If the microbubble mixture is not in its optimal state, a difference occurs between ΔT1 and ΔT2. For example, ΔT3 increases if the cooling effect of refrigerant 2 decreases.

[0035] In step S17, controller 7 determines whether the calculated ΔT3 falls within a predetermined permissible range. If ΔT3 falls within the permissible range, i.e., if step S17 is YES, the control procedure is terminated. If ΔT3 exceeds the permissible range, i.e., if step S17 is NO, the control procedure continues to step S18.

[0036] In step S18, the controller 7 controls the microbubble generator 6. Fig. Figure 4 is a graphical representation illustrating a correlation between ΔT3 and the amount of microbubble generation or the operating time of the microbubble generator 6, in order to bring the microbubbles to the optimal mixture level. Based on the correlation, the controller 7 controls the amount of microbubble generation according to ΔT3. Consequently, the mixture level of the microbubbles contained in the refrigerant 2 recovers to the optimal state. After controlling the microbubbles in step S18, the present control procedure can be terminated, or the procedure can proceed again to step S14 to confirm whether ΔT3 converges within the permissible range, as shown in Figure 4. Fig. 3 is illustrated.

[0037] In summary, the semiconductor cooling device 100 according to embodiment 1 comprises the refrigerant circulation path 1 through which the refrigerant 2 circulates, the cooling fins 4 arranged on the refrigerant circulation path 1 on which the semiconductor module 5 can be installed, and a heat exchanger that exchanges heat between the refrigerant 2 and the semiconductor module 5, the microbubble generator 6 arranged on the refrigerant circulation path 1 and generating microbubbles in the refrigerant 2, the controller 7 that controls the microbubble generator 6, and the refrigerant sensor that measures the state of the refrigerant 2 circulating in the refrigerant circulation path 1. In embodiment 1, the refrigerant sensor represents the refrigerant temperature sensor 8, which measures a refrigerant temperature Tw.

[0038] The semiconductor cooling device 100 further includes a module temperature sensor 9, which measures the module temperature Tj of the semiconductor module 5, which can be installed on the cooling fins 4 that form a heat exchanger. The controller 7 controls the microbubble generator 6 based on the refrigerant temperature Tw of the refrigerant 2 measured by the refrigerant temperature sensor 8 and the module temperature Tj of the semiconductor module 5 measured by the module temperature sensor 9.

[0039] Alternatively, the controller 7 also includes an input terminal for supplying a signal related to the module temperature Tj of the semiconductor module 5, which can be installed in the heat exchanger. The controller 7 controls the microbubble generator 6 based on the refrigerant temperature Tw measured by the refrigerant temperature sensor 8 and the signal supplied via the input terminal.

[0040] With the configuration described above, the semiconductor cooling device 100 maintains the mixture of microbubbles contained in the refrigerant 2 in an optimal state. This means that the semiconductor cooling device 100 reduces the pressure drop of the refrigerant 2 and ensures an increase in the flow velocity of the refrigerant 2. Consequently, the thermal resistance Rth (j_w) between the semiconductor module 5 and the refrigerant 2 is reduced, and the heat dissipation effect is improved. <Ausführungsform 2>

[0041] A semiconductor cooling device according to embodiment 2 is described. Descriptions of configurations and operations similar to those of embodiment 1 are omitted.

[0042] Fig. Figure 5 is a diagram schematically illustrating a configuration of a semiconductor cooling device 200 according to embodiment 2. The semiconductor cooling device 200 is provided at arbitrary positions along the refrigerant circulation path 1 with a refrigerant temperature sensor 8, which detects a refrigerant temperature Tw, and a refrigerant flow rate sensor 10, which measures the refrigerant flow rate L, or a refrigerant flow velocity sensor 11, which measures the refrigerant flow velocity V. The refrigerant temperature sensor 8 is preferably arranged in the immediate vicinity of the refrigerant flow rate sensor 10 or the refrigerant flow velocity sensor 11.The refrigerant temperature Tw and the refrigerant flow rate L or the refrigerant flow velocity V, measured in such an arrangement, reduce measurement errors due to the dispersion of the physical states of the refrigerant 2 with respect to the positions in the refrigerant circulation path 1.

[0043] The controller 7 controls the output of the microbubble generator 6 based on the refrigerant temperature Tw and the refrigerant flow rate L or the refrigerant flow velocity V.

[0044] Next, an operation of the semiconductor cooling device 200 and a control method for the mixing amount of microbubbles are described. Fig. Figure 6 is a flowchart illustrating the control procedure for the amount of microbubbles mixed according to embodiment 2.

[0045] First, in step S20, a state is prepared in which the mixing ratio of microbubbles contained in refrigerant 2 is optimal. In this optimal refrigerant 2 state, the semiconductor module 5 is held in a given constant excitation state.

[0046] In step S21, the controller 7 receives a refrigerant temperature Tw1 measured by sensor 8 and a refrigerant flow rate L1 measured by sensor 10, or a refrigerant flow velocity V1 measured by sensor 11. At this point, the controller 7 preferably receives a plurality of refrigerant flow rates L1 or a plurality of refrigerant flow velocities V1 for a plurality of refrigerant temperatures Tw1. Therefore, the correlation between the refrigerant temperature Tw1 and the refrigerant flow rate L1, or the correlation between the refrigerant temperature Tw1 and the refrigerant flow velocity V1, is obtained in the optimal refrigerant state.Controller 7 stores correlation data between the measured refrigerant temperature Tw1 and the refrigerant flow rate L1 or the refrigerant flow velocity V1 in memory as reference data. It should be particularly noted that... Fig. Figure 6 illustrates each step in the case of measuring the refrigerant flow rate L.

[0047] In step S22, in a state where it is unclear whether the state of the refrigerant 2 is optimal or not, i.e., whether the state of the mixture of microbubbles is optimal or not, since the time from step S21 has elapsed, the semiconductor module 5 is controlled in the same state as the constant excitation state in which the reference data are recorded.

[0048] In step S23, the controller 7 receives a refrigerant temperature Tw2 measured by the sensor 8 for refrigerant temperature and a refrigerant flow rate L2 measured by the sensor 10 for refrigerant flow rate or a refrigerant flow velocity V2 measured by the sensor 11 for refrigerant flow velocity.

[0049] In step S24, controller 7 reads the refrigerant flow rate L1 from memory, which was measured in a state where the microbubbles in refrigerant 2 are optimal. Controller 7 calculates ΔL3 = L1 - L2, where L2 is the refrigerant flow rate measured in a state where it is unclear whether the state of refrigerant 2 is optimal or not, and L1. The same applies to control based on the refrigerant flow velocity V. Controller 7 reads the refrigerant flow velocity V1 from memory, which was measured in a state where the microbubbles in refrigerant 2 are optimal. Controller 7 calculates ΔV3 = V1 - V2, where V2 is the refrigerant flow velocity measured in a state where it is unclear whether the state of refrigerant 2 is optimal or not, and V1.If the amount of microbubbles mixed is not in optimal condition, the effect of reducing the pressure loss through the microbubbles is reduced, so that ΔL3 or ΔV3 becomes large.

[0050] In step S25, the controller 7 determines whether the calculated ΔL3 or ΔV3 falls within a predetermined permissible range. If ΔL3 or ΔV3 falls within the permissible range, i.e., if step S25 is YES, the control procedure is terminated. If ΔL3 or ΔV3 exceeds the permissible range, i.e., if step S25 is NO, the control procedure continues to step S26.

[0051] In step S26, the controller 7 controls the microbubble generator 6. Fig. Figure 7 illustrates a correlation between the refrigerant temperature Tw1 and a refrigerant flow rate L1, which were recorded in step S21 under optimal refrigerant conditions. Fig. Figure 7 also illustrates the refrigerant temperature Tw2 and the refrigerant flow rate L2, which were recorded in step S23. Controller 7 controls the amount of microbubbles generated so that the values ​​of refrigerant temperature Tw2 and refrigerant flow rate L2 approach the target value shown in the graph illustrating the relationship between refrigerant temperature Tw1 and refrigerant flow rate L1. This control is repeated from step S23 to step S26 until the values ​​converge within the permissible range containing the target value. By performing such control, the amount of microbubbles in refrigerant 2 returns to its optimal state. The same control as described above is also performed when the amount of microbubbles generated is controlled by the refrigerant flow velocity V1 and the refrigerant flow velocity V2.

[0052] In summary, the refrigerant sensor included in the semiconductor cooling device 200 according to embodiment 2 comprises the refrigerant temperature sensor 8, which measures the refrigerant temperature Tw, and the refrigerant flow rate sensor 10, which measures the refrigerant flow rate L. The controller 7 controls the microbubble generator 6 based on the refrigerant temperature Tw measured by the refrigerant temperature sensor 8 and the refrigerant flow rate L measured by the refrigerant flow rate sensor 10.

[0053] Alternatively, the refrigerant sensor included in the semiconductor cooling device 200 comprises the refrigerant temperature sensor 8, which measures the refrigerant temperature Tw, and the refrigerant flow velocity sensor 11, which measures the refrigerant flow velocity V. The controller 7 controls the microbubble generator 6 based on the refrigerant temperature Tw measured by the refrigerant temperature sensor 8 and the refrigerant flow velocity V measured by the refrigerant flow velocity sensor 11.

[0054] With this configuration, the semiconductor cooling device 200 maintains the mixture of microbubbles contained in the refrigerant 2 in an optimal state. This means that the semiconductor cooling device 200 reduces the pressure drop of the refrigerant 2 and ensures an increase in the flow velocity of the refrigerant 2. Consequently, the thermal resistance Rth (j_w) between the semiconductor module 5 and the refrigerant 2 is reduced, and the heat dissipation effect is improved. <Ausführungsform 3>

[0055] A semiconductor cooling device according to embodiment 3 is described. Descriptions of configurations and operations similar to those of embodiment 1 are omitted.

[0056] Fig. Figure 8 is a diagram that schematically illustrates a configuration of a semiconductor cooling device 300 according to embodiment 3. The semiconductor cooling device 300 is provided with a refrigerant temperature sensor 8, which detects a refrigerant temperature Tw at any point in the refrigerant circulation path 1, a refrigerant pressure sensor 12a, which measures a refrigerant pressure Pa at a refrigerant inlet of the cooling fins 4, and a refrigerant pressure sensor 12b, which measures a refrigerant pressure Pb at a refrigerant outlet of the cooling fins 4.

[0057] The controller 7 controls the output of the microbubble generator 6 based on the refrigerant temperature Tw and a refrigerant pressure difference ΔP = Pb - Pa.

[0058] Next, an operation of the semiconductor cooling device 300 and a control method for the mixing amount of microbubbles are described. Fig. Figure 9 is a flowchart illustrating the control procedure for the amount of microbubbles mixed according to embodiment 3.

[0059] First, in step S30, a state is prepared in which the mixing ratio of microbubbles contained in refrigerant 2 is optimal. In this optimal refrigerant 2 state, the semiconductor module 5 is held in a given constant excitation state.

[0060] In step S31, the controller 7 receives a refrigerant temperature Tw1, measured by the refrigerant temperature sensor 8, a refrigerant pressure Pa1, measured by the refrigerant pressure sensor 12a, and a refrigerant pressure Pb1, measured by the refrigerant pressure sensor 12b. At this point, the controller 7 preferably receives a plurality of refrigerant pressures Pa1 and a plurality of refrigerant pressures Pb1 for a plurality of refrigerant temperatures Tw1.

[0061] In step S32, the controller 7 calculates ΔP1 = Pb1 - Pa1, which represents a pressure difference between the refrigerant pressure Pa1 and the refrigerant pressure Pb1. ΔP1 indicates the magnitude of the effect of a pressure drop reduction in a state where the microbubble mixing ratio is optimal. In step S31, a variety of refrigerant pressures Pa1 and Pb1 are obtained for a variety of refrigerant temperatures Tw1; therefore, the correlation between the refrigerant temperature Tw1 and ΔP1 is obtained. The controller 7 stores correlation data between the acquired refrigerant temperature Tw1 and ΔP1 in memory as reference data.

[0062] In step S33, in a state where it is unclear whether the state of the refrigerant 2 is optimal or not, i.e., whether the state of the mixture of microbubbles is optimal or not, since the time from step S31 has elapsed, the semiconductor module 5 is controlled in the same state as the constant excitation state in which the reference data are recorded.

[0063] In step S34, the controller 7 receives a refrigerant temperature Tw2 measured by sensor 8 for refrigerant temperature, a refrigerant pressure Pa2 measured by sensor 12a for refrigerant pressure and a refrigerant pressure Pb2 measured by sensor 12b for refrigerant pressure.

[0064] In step S35, the controller calculates 7 ΔP2 = Pb2 - Pa2, which represents a pressure difference between the refrigerant pressure Pa2 and the refrigerant pressure Pb2.

[0065] In step S36, the controller 7 determines whether the calculated ΔP2 falls within a predetermined permissible range or not. If ΔP2 falls within the permissible range, i.e., if step S36 is YES, the control procedure is terminated. If ΔP2 exceeds the permissible range, i.e., if step S36 is NO, the control procedure continues to step S37.

[0066] In step S37, the controller 7 controls the microbubble generator 6. Fig. Figure 10 illustrates a correlation between the refrigerant temperature Tw1 and ΔP1, which was recorded in step S32 under optimal refrigerant conditions. Fig. Figure 7 also illustrates the refrigerant temperature Tw2, which was recorded in step S34, and ΔP2, which was calculated in step S35. Controller 7 controls the amount of microbubbles generated so that the values ​​of the refrigerant temperature Tw2 and the refrigerant pressure difference ΔP2 approach the target value shown in the graphical representation, which illustrates the relationship between the refrigerant temperature Tw1 and the refrigerant pressure difference ΔP1. This control is repeated from step S34 to step S37 until the target values ​​converge within the permissible range containing the target value. Consequently, the amount of microbubbles in the refrigerant 2 returns to the optimal state.

[0067] In summary, the refrigerant sensor included in the semiconductor cooling device 300 comprises the refrigerant temperature sensor 8, which measures the refrigerant temperature Tw, and the refrigerant pressure sensors, which measure the refrigerant pressures at the respective positions in the refrigerant circulation path 1. In embodiment 3, the refrigerant pressure sensor 12a measures a refrigerant pressure Pa at a refrigerant inlet of the cooling fins 4, and the refrigerant pressure sensor 12b measures a refrigerant pressure Pb at a refrigerant outlet of the cooling fins 4. The controller 7 controls the microbubble generator 6 based on the refrigerant temperature Tw measured by the refrigerant temperature sensor 8 and the refrigerant pressure Pa and Pb measured by the refrigerant pressure sensor 12a and the refrigerant pressure sensor 12b, respectively.

[0068] With this configuration, the semiconductor cooling device 300 maintains the mixture of microbubbles contained in the refrigerant 2 in an optimal state. This means that the semiconductor cooling device 200 reduces the pressure drop of the refrigerant 2 and ensures an increase in the flow velocity of the refrigerant 2. Consequently, the thermal resistance Rth (j_w) between the semiconductor module 5 and the refrigerant 2 is reduced, and the heat dissipation effect is improved. <Ausführungsform 4>

[0069] A semiconductor cooling device according to embodiment 4 comprises a semiconductor cooling device in which any of the configurations of the semiconductor cooling device 100 in embodiment 1, the configuration of the semiconductor cooling device 200 in embodiment 2 and the configuration of the semiconductor cooling device 300 in embodiment 3 described above are combined, or a semiconductor cooling device comprising all the configurations.

[0070] The semiconductor cooling device in embodiment 4 restores the mixed concentration of microbubbles in the refrigerant circulation path 1 by controlling the microbubble generator 6 to control the reduction of the mixed concentration of microbubbles in the refrigerant 2, which was reduced due to a collapse or the like, with the configuration in which any of the two configurations of refrigerant sensors are combined, or the configuration in which all refrigerant sensors are combined. <Ausführungsform 5>

[0071] A semiconductor cooling device according to embodiment 5 is described. Fig. Figure 11 is a diagram illustrating a configuration of a semiconductor cooling device 500 according to embodiment 5.

[0072] In the same way as the semiconductor cooling device 300 described in embodiment 3, the semiconductor cooling device 500 comprises a sensor 8 for the refrigerant temperature, a sensor 12a for the refrigerant pressure, and a sensor 12b for the refrigerant pressure. However, the sensor 8 for the refrigerant temperature, the sensor 12a for the refrigerant pressure, and the sensor 12b for the refrigerant pressure are integrated into the cooling fins 4, which form a heat exchanger.

[0073] This configuration simplifies the construction of the piping for the cooling system, which forms the refrigerant circulation path 1. Furthermore, the refrigerant sensor measures the condition of the refrigerant 2 in the heat exchanger; therefore, the decrease in the pressure drop reduction effect and the decrease in the heat radiation effect of the refrigerant 2 are accurately detected.

[0074] The semiconductor cooling device in which the refrigerant temperature sensor 8, contained in the semiconductor cooling device 100 described in embodiment 1, is installed in the cooling fins 4, also exhibits the same effect described above. The semiconductor cooling device in which the refrigerant temperature sensor 8 and the refrigerant flow rate sensor 10 or the refrigerant flow velocity sensor 11, contained in the semiconductor cooling device 200 described in embodiment 2, are installed in the cooling fins 4, also exhibits the same effect described above. <Ausführungsform 6>

[0075] A power control system and a moving body according to embodiment 6 are described. Fig.Figure 12 is a diagram that schematically illustrates a configuration of a power control system 600 and a moving body 700 according to embodiment 6.

[0076] The power control system 600 includes the semiconductor cooling device 500 described in embodiment 5, the semiconductor module 5 installed in the cooling fins 4 of the semiconductor cooling device 500, a battery 15 to supply power to the semiconductor module 5 as a primary-side power source, and a motor 16 driven by power controlled by the semiconductor module 5.

[0077] The moving body 700 comprises the power control system 600 and a wheel 17, which is driven by the motor 16 contained in the power control system. The power control system 600 is controlled by a host controller of the moving body 700.

[0078] With such a configuration, the semiconductor cooling device 500 prevents the deterioration of the thermal resistance Rth (j_w) between the semiconductor device contained in the semiconductor module 5 and the refrigerant 2 circulating in the refrigerant circulation path 1, thus extending the service life of the semiconductor module 5. Consequently, the improved reliability and extended service life of the power control system 600 and the moving body 700 are ensured.

[0079] Furthermore, the power control system or the moving body which is provided with the semiconductor cooling device described in one of embodiments 1 to 4 instead of the semiconductor cooling device 500 also exhibits the same effect as described above. Explanation of reference symbols

[0080] 1 Refrigerant circulation path, 2 Refrigerant, 3 Circulation device, 4 Cooling fins, 5 Semiconductor module, 6 Microbubble generators, 7 Controller, 8 Refrigerant temperature sensor, 9 Module temperature sensor, 10 Refrigerant flow rate sensor, 11 Refrigerant flow velocity sensor, 12a Refrigerant pressure sensor, 12b Refrigerant pressure sensor, 15 Battery, 16 Motor, 17 Wheel, 100 Semiconductor cooling device, 500 Semiconductor cooling device, 600 Power control system, 700 Moving body, L Refrigerant flow rate, Pa Refrigerant pressure, Pb Refrigerant pressure, Tj Module temperature, Tw Refrigerant temperature, V Refrigerant flow velocity.

Claims

[1] Semiconductor cooling device (100, 200, 300, 500), comprising: - a refrigerant circulation path (1) through which a refrigerant (2) circulates; - a heat exchanger provided on the refrigerant circulation path (1) on which a semiconductor module (5) can be installed and is configured to exchange heat between the refrigerant (2) and the semiconductor module (5); - a microbubble generator (6) provided on the refrigerant circulation path (1) and configured to generate microbubbles in the refrigerant (2); - a controller (7) configured to control the microbubble generator (6); and - a refrigerant sensor (8; 10; 11; 12a; 12b) configured to measure a refrigerant temperature, refrigerant flow rate, refrigerant flow velocity or refrigerant pressure of the refrigerant (2) circulating in the refrigerant circulation path (1), wherein: - the controller (7) is configured to control the microbubble generator (6) based on a measurement result obtained from the refrigerant sensor (8; 10; 11; 12a; 12b) in order to control the amount of microbubbles produced, - the refrigerant sensor (8; 10; 11; 12a; 12b) has: - a refrigerant temperature sensor (8) configured to measure the refrigerant temperature, and - at least one of a - Sensor (10) for the refrigerant flow rate, configured to measure the refrigerant flow rate, - a sensor (11) for the refrigerant flow velocity, configured to measure the refrigerant flow velocity, and - Sensors (12a, 12b) for refrigerant pressure, configured to measure the refrigerant pressure at respective positions in the refrigerant circulation path (1), and - the controller (7) is configured to control the microbubble generator (6) based on the refrigerant temperature measured by the refrigerant temperature sensor (8) and on the basis of at least one parameter of the refrigerant flow rate measured by the refrigerant flow rate sensor (10), the refrigerant flow velocity measured by the refrigerant flow velocity sensor (11), and the refrigerant pressure measured by the refrigerant pressure sensors (12a, 12b) at appropriate locations. [2] Semiconductor cooling device (100, 200, 300, 500) according to claim 1, wherein the refrigerant sensor (8; 10; 11; 12a; 12b) is installed in the heat exchanger (4). [3] Semiconductor cooling device (100, 200, 300, 500) according to claim 1 or 2, - furthermore comprising a sensor (9) for the module temperature, which is configured to measure a module temperature of the semiconductor module (5) which can be installed on the heat exchanger (4), - wherein the controller (7) is configured to control the microbubble generator (6) also based on the module temperature measured by the sensor (9) for the module temperature. [4] Semiconductor cooling device (100, 200, 300, 500) according to claim 1 or 2, wherein - the controller (7) includes an input terminal for supplying a signal that is related to a module temperature of the semiconductor module (5) that can be installed on the heat exchanger (4), and - the controller (7) is configured to control the microbubble generator (6) also based on the signal fed in through the input terminal. [5] Power control system (600), comprising: - at least one semiconductor cooling device (100, 200, 300, 500) according to one of the preceding claims; - a semiconductor module (5) installed on the heat exchanger (4); - a battery (15) configured to supply power to the semiconductor module (5); and - a motor (16) which is driven by the power controlled by the semiconductor module (5). [6] Moving body (700), comprising: - a power control system (600) according to claim 5, and - a wheel (17) configured to be driven by the motor (16).

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