Battery Cooling System

Abstract

To appropriately perform suppression of a sub-cool abnormality and suppression of a surging phenomenon in a battery cooling system.SOLUTION: A battery cooling system comprises a refrigeration cycle for forming a circuit, in which a coolant is circulated, and a control device. The refrigeration cycle includes: a compressor of which the compression system is a speed type; a condenser; a fan which cools the condenser; a plurality of evaporators each disposed correspondingly to each of a plurality of batteries; a plurality of branch channels each connected to each of one-side ends of the plurality of evaporators; and a plurality of decompressors each disposed in each of the plurality of branch channels. The control device adjusts at least one of a rotation speed of the fan and a rotation speed of the compressor so as to suppress a surging phenomenon in a case where it is determined that the surging phenomenon may occur and adjusts at least one of the rotation speed of the fan and the rotation speed of the compressor so as to suppress a sub-cool abnormality in a case where it is determined that the surging phenomenon may not occur but the sub-cool abnormality may occur.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a battery cooling system for cooling multiple batteries. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 2020-184427 (Patent Document 1) discloses a battery cooling system that cools multiple battery modules. The refrigeration cycle installed in this battery cooling system is configured to branch a refrigerant supplied from a condenser into multiple branch flow paths to cool each of the multiple battery modules, with an expansion valve and an evaporator disposed in each of the multiple branch flow paths, and each evaporator cooling each battery module. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-184427 Summary of the Invention [Problem to be solved by the invention]

[0004] In a refrigeration cycle configuration in which an expansion valve (pressure reducer) and an evaporator are provided in each of multiple branch flow paths, such as the battery cooling system disclosed in JP 2020-184427 A, it is desirable to distribute the same amount of refrigerant to each of the multiple branch flow paths in order to evenly cool the multiple battery modules. To achieve this, it is desirable to maintain the refrigerant in a liquid state (subcooled state) in the multiple branch flow paths. However, depending on the temperature of each battery module and the ambient air temperature around the condenser, a subcooling anomaly may occur, in which the refrigerant in the multiple branch flow paths does not reach a liquid state. Furthermore, if the rotational speed of the compressor or the fan cooling the condenser is set to an excessively high value as a countermeasure, the power consumption of the compressor and fan may unnecessarily increase, potentially reducing the range of the vehicle equipped with the battery modules. Furthermore, if the compressor uses a speed-type compression method, depending on the operating conditions of the compressor, surging may occur, preventing the compressor from operating normally. Furthermore, because surging is more likely to cause system failure, surging is more likely to cause serious system problems than subcooling anomalies.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to effectively suppress subcooling abnormalities and surging phenomena in a battery cooling system equipped with a refrigeration cycle in which a pressure reducer and an evaporator are arranged in each of multiple branch flow paths. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided a battery cooling system as follows. (Item 1) The battery cooling system includes a refrigeration cycle that forms a circuit through which a refrigerant circulates, and a control device. The refrigeration cycle includes a compressor, a condenser, a fan that cools the condenser, multiple evaporators arranged corresponding to multiple batteries, a first flow path connected to a discharge port of the compressor and one end of the condenser, a second flow path connecting the other end of the condenser and one end of each of the multiple evaporators, and a third flow path connecting the other ends of the multiple evaporators and a suction port of the compressor. The compressor is a velocity-type compressor. The second flow path includes multiple branch flow paths that are respectively connected to one end of each of the multiple evaporators. The battery cooling system further includes multiple pressure reducers arranged in the multiple branch flow paths, a first detection means that detects the state of the refrigerant upstream of the pressure reducer in the second flow path, and a second detection means that detects the state of the compressor. The control device is configured to determine, based on the detection result of the first detection means, whether a subcooling abnormality will occur in which the refrigerant will no longer be in a liquid state upstream of the pressure reducer in the second flow path; determine, based on the detection result of the second detection means, whether a surging phenomenon will occur in the compressor; and, if it is determined that a surging phenomenon will occur, adjust at least one of the rotation speed of the fan and the rotation speed of the compressor so as to suppress the surging phenomenon; and, if it is determined that a surging phenomenon will not occur but a subcooling abnormality will occur, adjust at least one of the rotation speed of the fan and the rotation speed of the compressor so as to suppress the subcooling abnormality.

[0007] In the above configuration, when it is determined that surging will not occur (i.e., the compressor can operate normally) and when it is determined that subcooling abnormality will occur (i.e., the refrigerant will no longer be in a liquid state upstream of the pressure reducer in the second flow path), at least one of the fan rotation speed and the compressor rotation speed is adjusted to suppress the subcooling abnormality. This makes it less likely that the subcooling abnormality will occur. On the other hand, when it is determined that surging will occur, at least one of the fan rotation speed and the compressor rotation speed is adjusted to at least suppress the surging abnormality, regardless of the determination result of the subcooling abnormality. This makes it possible to more reliably avoid the surging phenomenon.

[0008] The battery cooling system described in the above item 1 may have the configuration described in any one of items 2 to 5 below.

[0009] (Item 2) The battery cooling system described in item 1 further has the following feature. The control device is configured to, in determining a subcooling abnormality, determine whether the state of the refrigerant corresponds to a first state in which a subcooling abnormality occurs, a second state in which a subcooling abnormality is unlikely to occur, or a third state that is neither the first state nor the second state. The control device is configured to accelerate at least one of the rotation speed of the fan and the rotation speed of the compressor when it is determined that no surging phenomenon occurs and the refrigerant state is in the first state, to slow down at least one of the rotation speed of the fan and the rotation speed of the compressor when it is determined that no surging phenomenon occurs and the refrigerant state is in the second state, and to keep both the rotation speed of the fan and the rotation speed of the compressor unchanged when it is determined that no surging phenomenon occurs and the refrigerant state is in the third state.

[0010] According to the above configuration, when a subcooling abnormality occurs, at least one of the rotation speed of the fan and the rotation speed of the compressor is accelerated, which makes it easier to accurately avoid the subcooling abnormality. Also, when a subcooling abnormality is unlikely to occur, at least one of the rotation speed of the fan and the rotation speed of the compressor is decelerated, which makes it possible to reduce energy consumption while maintaining the refrigerant in a liquid state upstream of the pressure reducer in the second flow path.

[0011] (Item 3) The battery cooling system described in item 2 further has the following feature. The control device is configured to determine whether the rotation speed of the fan is less than an upper limit value and to determine whether the rotation speed of the compressor is greater than a lower limit value. The control device is configured to accelerate the rotation speed of the fan when it is determined that no surging phenomenon is occurring, the state of the refrigerant is in a first state, and the rotation speed of the fan is less than the upper limit value; to accelerate the rotation speed of the compressor when it is determined that no surging phenomenon is occurring, the state of the refrigerant is in the first state, and the rotation speed of the fan is not less than the upper limit value; to decelerate the rotation speed of the compressor when it is determined that no surging phenomenon is occurring, the state of the refrigerant is in a second state, and the rotation speed of the compressor is greater than the lower limit value; and to decelerate the rotation speed of the fan when it is determined that no surging phenomenon is occurring, the state of the refrigerant is in the second state, and the rotation speed of the compressor is not greater than the lower limit value.

[0012] Typically, the energy consumed to drive the compressor that draws in and discharges the refrigerant is greater than the energy consumed to drive the fan that cools the condenser. With the above configuration, when a subcooling abnormality occurs, the fan is driven more frequently (the rotation speed is increased) than the compressor, making it easier to accurately avoid the subcooling abnormality while suppressing energy consumption. Furthermore, when a subcooling abnormality is unlikely to occur, the compressor is driven more frequently (the rotation speed is reduced) than the fan, making it possible to reduce energy consumption while maintaining the refrigerant in a liquid state upstream of the pressure reducer in the second flow path.

[0013] (Item 4) The battery cooling system according to any one of Items 1 to 3 further has the following feature: The control device is configured to determine whether the rotation speed of the fan is less than an upper limit of fan rotation, determine whether the rotation speed of the compressor is less than an upper limit, and determine whether the rotation speed of the compressor is greater than a lower limit. The control device is configured to accelerate the rotation speed of the fan when it is determined that surging will occur when the rotation speed of the fan is less than the upper limit of fan rotation, and to accelerate or decelerate the rotation speed of the compressor so as to suppress surging when it is determined that surging will occur when the rotation speed of the fan is not less than the upper limit of fan rotation and the rotation speed of the compressor is greater than the lower limit and less than the upper limit.

[0014] According to the above configuration, when a surging phenomenon occurs, the driving amount of the fan is increased (the rotation speed is increased) in preference to the compressor, which makes it easier to accurately avoid the surging phenomenon while suppressing energy consumption.

[0015] (Item 5) The battery cooling system described in any one of Items 1 to 4 further has the following features. The first detection means includes a pressure sensor that detects the pressure of the refrigerant upstream of the pressure reducer in the second flow path, and a temperature sensor that detects the temperature of the refrigerant upstream of the pressure reducer in the second flow path. The control device is configured to calculate a saturation temperature of the refrigerant upstream of the pressure reducer in the second flow path based on the refrigerant pressure detected by the pressure sensor, and to determine whether a subcooling abnormality will occur based on the saturation temperature and the refrigerant temperature detected by the temperature sensor. The second detection means includes a first pressure sensor that detects a suction pressure that is the pressure of the refrigerant on the suction side of the compressor, a second pressure sensor that detects a discharge pressure that is the pressure of the refrigerant on the discharge side of the compressor, and a flow rate sensor that detects a flow rate of the refrigerant flowing through the compressor. The control device is configured to identify an operating point of the compressor using the suction pressure, discharge pressure, and flow rate detected by the second detection means, and to determine whether a surging phenomenon will occur based on whether the identified operating point is within a predetermined surging region. In addition, the above-mentioned pressure sensor, temperature sensor, first pressure sensor, second pressure sensor, and flow rate sensor are concepts that not only directly detect the pressure, temperature, and flow rate of the refrigerant at the corresponding location, but also include configurations that estimate the pressure, temperature, and flow rate of the refrigerant at the corresponding location from other detection values ​​in the battery cooling system.

[0016] According to the above configuration, it becomes easier to appropriately determine whether or not a subcooling abnormality will occur and whether or not a surging phenomenon will occur. [Effects of the Invention]

[0017] According to the present disclosure, in a battery cooling system having a refrigeration cycle in which a pressure reducer and an evaporator are arranged in each of a plurality of branch flow paths, it is possible to effectively suppress subcooling abnormalities and surging phenomena. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a diagram showing the overall configuration of a battery cooling system according to an embodiment of the present disclosure. [Figure 2]2 is a diagram showing an example of the arrangement of a plurality of branch flow paths and a plurality of pressure reducers in the battery cooling system shown in FIG. 1. FIG. [Figure 3] 5 is a flowchart illustrating an example of a processing procedure of a control device according to an embodiment of the present disclosure. [Figure 4] 4 is a flowchart showing details of the process relating to the first determination shown in FIG. 3. [Figure 5] 4 is a flowchart showing details of the process relating to the second determination shown in FIG. 3. [Figure 6] 6 is a flowchart showing the details of the process for avoiding the surging phenomenon shown in FIG. 5. [Figure 7] FIG. 2 is a diagram for explaining a first example of vehicle control according to the present embodiment. [Figure 8] FIG. 6 is a diagram for explaining a second example of vehicle control according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and description thereof will not be repeated.

[0020] FIG. 1 is a diagram showing the overall configuration of a battery cooling system 1 according to the present embodiment. Referring to FIG. 1, the battery cooling system 1 is mounted on a vehicle. The vehicle is, for example, an xEV (electric vehicle) configured to be able to run using power from an on-board battery (battery module 2). Examples of xEVs include BEVs (electric vehicles), HEVs (hybrid vehicles), PHEVs (plug-in hybrid vehicles), FCEVs (fuel cell vehicles), and range extender EVs. The battery cooling system 1 includes multiple battery modules 2, a refrigeration cycle 10, and a control device 100. The battery cooling system 1 cools the multiple battery modules 2 using the refrigeration cycle 10. Each battery module 2 is formed by connecting multiple battery cells (not shown). The multiple battery modules 2 are packaged as a single battery pack, for example, by being housed in a housing (not shown).

[0021] The refrigeration cycle 10 forms a circuit through which a refrigerant circulates. The refrigeration cycle 10 includes a compressor 11, a condenser 12, a fan 13, a plurality of pressure reducers 14, a plurality of evaporators 15, flow paths 31, 32, and 35, a plurality of branch flow paths 33, and a plurality of branch flow paths 34.

[0022] The compressor 11 is a speed-type compressor that compresses refrigerant gas drawn in from a flow path 35 and discharges the compressed gas into a flow path 31. The flow path 31 connects the discharge port of the compressor 11 to the inlet of the condenser 12. The condenser 12 exchanges heat between the refrigerant supplied from the compressor 11 and flowing inside the condenser 12 and a fluid (e.g., outside air) present around the condenser 12. The fan 13 is disposed in a position where it can cool the condenser 12. The fan 13 functions as a cooling fan that air-cools the condenser 12. The fan 13 may cool the condenser 12 by sending air from outside the vehicle cabin to the condenser 12.

[0023] The flow path 32 connects the outlet of the condenser 12 with the connection point N1. The flow path 32 branches into a plurality of branch flow paths 33 at the connection point N1. The plurality of branch flow paths 33 connect the connection point N1 with the inlets of the plurality of evaporators 15, respectively. A plurality of pressure reducers 14 are provided on the plurality of branch flow paths 33, respectively. Each of the plurality of pressure reducers 14 is formed by, for example, an inexpensive fixed orifice. Each of the plurality of pressure reducers 14 may be an expansion valve (throttle valve).

[0024] 2 is a diagram showing an example of the arrangement of the plurality of branch flow paths 33 and the plurality of pressure reducers 14. As shown in Fig. 2, a main pipe 33m is arranged between the connection point N1 and each of the branch flow paths 33, connecting the connection point N1 and each of the branch flow paths 33. The refrigerant from the flow path 32 is supplied to the main pipe 33m at the connection point N1, and is distributed from the main pipe 33m to each of the branch flow paths 33. Note that the flow path 32, the main pipe 33m, and the plurality of branch flow paths 33 may correspond to the "second flow path" of the present disclosure.

[0025] In this embodiment, a pressure sensor 50 and a temperature sensor 60 are provided near a branch flow path (the rightmost branch flow path in FIG. 2) 33a in which a pressure reducer 14a (the rightmost pressure reducer in FIG. 2) having the longest flow path length from connection point N1 among the multiple pressure reducers 14 is arranged. The pressure sensor 50 detects a refrigerant pressure Pa near the branch flow path 33a in the multiple branch flow paths 33. The temperature sensor 60 detects a refrigerant temperature Ta near the branch flow path 33a in the multiple branch flow paths 33. Each of the pressure sensor 50 and the temperature sensor 60 outputs the detection results to the control device 100.

[0026] Referring again to FIG. 1 , the multiple evaporators 15 are arranged corresponding to the multiple battery modules 2, respectively, and perform heat exchange between the refrigerant flowing therethrough and the multiple battery modules 2. The multiple evaporators 15 have the same shape. Therefore, the multiple evaporators 15 have the same flow path cross-sectional area. The multiple branch flow paths 34 connect the outlets of the multiple evaporators 15 to a connection point N2, respectively. The multiple branch flow paths 34 merge into a flow path 35 at the connection point N2. The flow path 35 connects the connection point N2 to the suction port of the compressor 11.

[0027] A pressure sensor 71 (first pressure sensor) is provided on the suction side (e.g., near the suction port) of the compressor 11. The pressure sensor 71 detects the pressure Pb (suction pressure) of the refrigerant gas on the suction side of the compressor 11. A pressure sensor 72 (second pressure sensor) and a flow rate sensor 80 are provided on the discharge side (e.g., near the discharge port) of the compressor 11. The pressure sensor 72 detects the pressure Pc (discharge pressure) of the refrigerant gas on the discharge side of the compressor 11. The flow rate sensor 80 detects the flow rate Gc of the refrigerant gas flowing through the compressor 11 toward the condenser 12. Each of the pressure sensors 71, 72 and the flow rate sensor 80 outputs the detection results to the control device 100.

[0028] The control device 100 is configured to control the battery cooling system 1. As will be described in detail later, the control device 100 controls the rotation speeds of the compressor 11 and the fan 13 based on detection signals input from the pressure sensor 50, the temperature sensor 60, the pressure sensors 71 and 72, and the flow rate sensor 80. The control device 100 may also perform driving control of a vehicle equipped with the battery cooling system 1 (see, for example, FIGS. 7 and 8). The control device 100 includes a processor 110, a random access memory (RAM) 120, and a storage device 130. An example of the processor 110 is a central processing unit (CPU). The storage device 130 is configured to be able to save stored information. In this embodiment, the processor 110 executes programs stored in the storage device 130 to perform various controls (for example, controls shown in FIGS. 3 to 6, which will be described later). However, these processes may be performed solely by hardware (electronic circuits) without using software. The control device 100 may include any number of processors, and may include one or more.

[0029] In the operating state of the refrigeration cycle 10, high-temperature, high-pressure gas refrigerant compressed by the compressor 11 is sent to the condenser 12 and condensed by the condenser 12. This liquefies the refrigerant. The high-temperature, high-pressure liquid refrigerant condensed by the condenser 12 is supplied to the flow path 32 and distributed from the flow path 32 to each of the multiple branch flow paths 33. The refrigerant distributed to each of the multiple branch flow paths 33 is decompressed by each of the multiple pressure reducers 14 and then sent to each of the multiple evaporators 15.

[0030] The low-pressure refrigerant sent to the multiple evaporators 15 exchanges heat with the multiple battery modules 2 in the multiple evaporators 15 and evaporates (gasifies) to become low-pressure gas refrigerant, thereby cooling the multiple battery modules 2. The low-pressure gas refrigerants evaporated in the multiple evaporators 15 join together at the connection point N2, pass through the flow path 35, and are sucked into the compressor 11 again.

[0031] During the cooling operation as described above, in order to evenly cool the plurality of battery modules 2, it is desirable to distribute the same amount of refrigerant to each of the plurality of branch flow paths 33. To achieve this, it is desirable to maintain the refrigerant in a liquid state (subcooled state) in the main pipe 33m. In this embodiment, it is determined to be an abnormality (subcooled abnormality) when the refrigerant is no longer in a liquid state in the region downstream of the condenser 12 and upstream of the pressure reducer 14 of the refrigeration cycle 10 (i.e., the region upstream of the pressure reducer 14 in the second flow path).

[0032] However, depending on the temperature of each battery module 2 and the ambient air temperature around the condenser 12, the refrigerant in the main pipe 33m may not necessarily become liquid. If the rotation speed of the compressor 11 is increased excessively as a countermeasure, there is a concern that the power consumption of the compressor 11 may become unnecessarily large. Furthermore, depending on the operating state of the compressor 11, a surging phenomenon (i.e., the compressor 11 may not be able to operate normally) may occur. If the vehicle continues to run while a surging phenomenon is occurring, the NV (noise and vibration) performance of the vehicle will deteriorate. Furthermore, because surging is likely to cause system failure, surging is more likely to cause serious problems in the system than subcooling abnormalities.

[0033] Therefore, the control device 100 according to this embodiment is adapted to suitably suppress both the subcooling abnormality and the surging phenomenon by executing the control shown in Figures 3 to 6, which will be described below. Specifically, the control device 100 suppresses both the subcooling abnormality and the surging phenomenon when they can be suppressed simultaneously, but when only one of them can be suppressed, it preferentially suppresses the surging phenomenon.

[0034] Hereinafter, each step in the flowchart will be simply denoted as "S". The rotation speed command value from the control device 100 to the compressor 11 will be denoted as "Ncomp". Adjusting Ncomp to the acceleration side will be referred to as "Ncomp increase", and adjusting Ncomp to the deceleration side will be referred to as "Ncomp decrease". The rotation speed command value from the control device 100 to the fan 13 will be denoted as "Nfan". Adjusting Nfan to the acceleration side will be referred to as "Nfan increase", and adjusting Nfan to the deceleration side will be referred to as "Nfan decrease".

[0035] When the rotation speed of the compressor 11 is within a first operating range from an Ncomp lower limit (compressor rotation lower limit) to an Ncomp upper limit (compressor rotation upper limit), normal operation of the compressor 11 is guaranteed by the manufacturer. If the rotation speed of the compressor 11 deviates from the first operating range, the operation of the compressor 11 may become unstable or deterioration of the compressor 11 may be accelerated. The control device 100 basically controls the rotation speed of the compressor 11 within the first operating range. Furthermore, when the rotation speed of the fan 13 is within a second operating range below an Nfan upper limit (fan rotation upper limit), normal operation of the fan 13 is guaranteed by the manufacturer. If the rotation speed of the fan 13 deviates from the second operating range, the operation of the fan 13 may become unstable or deterioration of the fan 13 may be accelerated. The control device 100 basically controls the rotation speed of the fan 13 within the second operating range.

[0036] Fig. 3 is a flowchart showing an example of a processing procedure of the control device 100. The processing shown in this flowchart is repeatedly executed by the control device 100, for example, at a predetermined cycle. However, the present invention is not limited to this, and the control device 100 may execute the processing flow shown in Fig. 3 only when a predetermined start condition is met. The start condition may be set so as to be met only in a situation where at least one of a subcooling abnormality and a surging phenomenon may occur.

[0037] 3, in S1, the control device 100 determines whether the current value of Nfan is less than the Nfan upper limit value. Since the rotation speed of the fan 13 is controlled in accordance with Nfan (command value), the rotation speed of the fan 13 corresponds to Nfan. The current value of Nfan roughly coincides with the current rotation speed of the fan 13.

[0038] If the current value of Nfan is less than the Nfan upper limit (YES in S1), the control device 100 executes a first determination in S21. The first determination includes a subcooling determination and a surge determination. The subcooling determination is a determination as to whether or not the above-mentioned subcooling abnormality will occur. The control device 100 executes the subcooling determination based on the detection result of a first detection means that detects the state of the refrigerant upstream of the pressure reducer 14 in the second flow path. In this embodiment, the pressure sensor 50 and the temperature sensor 60 function as the first detection means. The surge determination is a determination as to whether or not a surging phenomenon will occur in the compressor 11. The control device 100 executes the surge determination based on the detection result of a second detection means that detects the state of the compressor 11. In this embodiment, the pressure sensors 71 and 72 and the flow rate sensor 80 function as the second detection means. FIG. 4 is a flowchart showing the details of the process (S21) related to the first determination.

[0039] Referring to FIG. 4, S111 to S113 and S121 to S129 are a process flow related to subcooling determination. In S111, control device 100 acquires refrigerant pressure Pa detected by pressure sensor 50. In the following S112, control device 100 calculates the saturation temperature of main pipe 33m near branch flow path 33a in multiple branch flow paths 33 based on refrigerant pressure Pa. For example, correspondence information (e.g., a map or a formula) defining the correspondence relationship between refrigerant pressure and saturation temperature may be stored in memory device 130 in advance. Control device 100 may calculate the saturation temperature corresponding to refrigerant pressure Pa by referring to the correspondence information. Next, in S113, control device 100 acquires refrigerant temperature Ta detected by temperature sensor 60. In the following S121, control device 100 determines which of the following first to third states the refrigerant state corresponds to based on a value (temperature difference) obtained by subtracting refrigerant temperature Ta from the saturation temperature.

[0040] The first state is a refrigerant state in which a subcooling abnormality occurs. The second state is a refrigerant state in which a subcooling abnormality is unlikely to occur. The third state is a refrigerant state that is neither the first state nor the second state. A determination that the refrigerant state corresponds to the second state or the third state means that a subcooling abnormality has been determined not to occur. In this embodiment, if the temperature difference (saturation temperature - Ta) is within the appropriate range, it is determined to be the third state (appropriate liquefaction state); if it is smaller than the appropriate range, it is determined to be the first state (insufficient liquefaction state); and if it is larger than the appropriate range, it is determined to be the second state (excessive liquefaction state). The closer the refrigerant temperature Ta is to the saturation temperature, the more likely a subcooling abnormality is to occur.

[0041] The appropriate range is, for example, a range between a first threshold value and a second threshold value. In this embodiment, if the temperature difference (saturation temperature - Ta) is less than the first threshold value, the control device 100 determines in S122 that the refrigerant state corresponds to the "first state," and then determines "A13" as the method for suppressing subcooling abnormalities in S123. The determination of A13 means that the adjustment made in response to the determination result of the subcooling abnormality is to increase Nfan. Increasing the rotation speed of the fan 13 without changing the rotation speed of the compressor 11 makes it less likely that a subcooling abnormality will occur. The degree of increase in Nfan (adjustment amount) made in accordance with the determination of A13 may be a predetermined fixed value or may be variable depending on a predetermined parameter (for example, the difference between the saturation temperature and the refrigerant temperature Ta, or the difference between the current Nfan value and the upper limit Nfan value).

[0042] If the temperature difference (saturation temperature - Ta) exceeds the second threshold, the control device 100 determines in S124 that the state of the refrigerant corresponds to the "second state," and the process proceeds to S125. In S125, the control device 100 determines whether the current value of Ncomp is greater than the Ncomp lower limit value. Since the rotation speed of the compressor 11 is controlled in accordance with Ncomp (command value), the rotation speed of the compressor 11 corresponds to Ncomp. The current value of Ncomp roughly matches the current rotation speed of the compressor 11.

[0043] If the current value of Ncomp is greater than the Ncomp lower limit value (YES in S125), the control device 100 subsequently determines "A12" in S126 regarding the method of suppressing subcooling abnormality. The determination of A12 means that the adjustment made in response to the determination result of subcooling abnormality is to reduce Ncomp. The lower the rotation speed of the compressor 11, the less energy is consumed by the compressor 11. The degree of Ncomp reduction (adjustment amount) made in response to the determination of A12 may be a predetermined fixed value, or may be variable depending on a predetermined parameter (for example, the difference between the saturation temperature and the refrigerant temperature Ta, or the difference between the current Ncomp value and the Ncomp lower limit value).

[0044] If the current value of Ncomp is equal to or less than the Ncomp lower limit value (NO in S125), the control device 100 subsequently determines "A11" in S127 regarding the method of suppressing subcooling abnormality. The determination of A11 means that the adjustment made in response to the determination result of subcooling abnormality is to reduce Nfan. The lower the rotation speed of the fan 13, the less energy is consumed by the fan 13. The degree of Nfan reduction (adjustment amount) made in accordance with the determination of A11 may be a predetermined fixed value, or may be variable depending on a predetermined parameter (for example, the difference between the saturation temperature and the refrigerant temperature Ta, or the difference between the current Nfan value and the Nfan lower limit value).

[0045] In this embodiment, the energy consumed to drive the compressor 11 that draws in and discharges the refrigerant is greater than the energy consumed to drive the fan 13 that cools the condenser 12. Therefore, the amount of energy consumption reduced by reducing Ncomp is greater than the amount of energy consumption reduced by reducing Nfan. The compressor 11 and the fan 13 may be driven by power supplied from the battery module 2, or by power supplied from another on-board battery (for example, an auxiliary battery).

[0046] If the temperature difference (saturation temperature - Ta) is equal to or greater than the first threshold and equal to or less than the second threshold, the control device 100 determines in S128 that the refrigerant state corresponds to the "third state," and then determines "A14" in relation to the method of suppressing subcooling abnormality in the subsequent S129. The determination of A14 means that the adjustment according to the determination result of subcooling abnormality is to leave both Nfan and Ncomp unchanged (no adjustment required). When any of the determinations A11 to A14 is made, the processing flow for subcooling determination ends.

[0047] S131 to S133 and S141 to S145 are processing flows related to surge determination. In S131, the control device 100 acquires the pressures Pb and Pc and the flow rate Gc detected by the pressure sensors 71 and 72 and the flow rate sensor 80, respectively. In the following S132, the control device 100 converts the flow rate Gc into a corrected flow rate (amount of suction refrigerant) indicating the operating point of the compressor 11. The control device 100 may convert the flow rate Gc into the corrected flow rate by multiplying the flow rate Gc by a predetermined correction coefficient. The control device 100 may also convert the flow rate Gc into the corrected flow rate based on the refrigerant temperature.

[0048] Next, in S133, the control device 100 identifies an operating point (Comp operating point) of the compressor 11 using the corrected flow rate corresponding to the flow rate Gc and the pressure ratio corresponding to the pressures Pb and Pc. Then, in S141, it determines whether the identified Comp operating point is included in a predetermined surging region. In this embodiment, the operating point of the compressor 11 is an operating state of the compressor 11 defined by the corrected flow rate (amount of suction refrigerant) of the compressor 11 and the pressure ratio (=Pc / Pb). The pressure ratio is the ratio of the pressure Pc (discharge pressure) to the pressure Pb (suction pressure). A map (see, for example, FIG. 6) showing the surge characteristics of the compressor 11 may be stored in advance in the storage device 130. A surge line indicating the surging region (i.e., an operating region where surging is likely to occur in the compressor 11) may be defined on the map. The surge line is a line indicating the boundary between the inside and outside of the surging region and may be defined taking into account a margin. Furthermore, if the flow rate Gc indicates the operating point of the compressor 11 with high accuracy, the conversion in S132 may be omitted.

[0049] If the operating point of the compressor 11 is within the surging region (YES in S141), the control device 100 determines in S142 that surging of the compressor 11 will occur (i.e., the compressor 11 is in a surge state), and subsequently determines "B11" as the method for suppressing the surging phenomenon in S143. The determination of B11 means that the adjustment based on the determination result of the surging phenomenon is to increase Nfan. Increasing the rotation speed of the fan 13 without changing the rotation speed of the compressor 11 makes it less likely that surging will occur. The degree of increase in Nfan (adjustment amount) based on the determination of B11 may be a predetermined fixed value or may be variable depending on a predetermined parameter (e.g., the Comp operating point, or the difference between the current Nfan value and the Nfan upper limit value).

[0050] If the operating point of the compressor 11 is not within the surging region (NO in S141), the control device 100 determines in S144 that the surging phenomenon of the compressor 11 is not occurring (i.e., the compressor 11 is in a non-surge state), and subsequently determines "B12" regarding the surging phenomenon suppression method in S145. The determination of B12 means that the adjustment according to the surging phenomenon determination result is to leave both Nfan and Ncomp unchanged (no adjustment required). When either the determination of B11 or B12 is made, the processing flow for surge determination ends.

[0051] After the processing flow for the first determination (subcooling determination and surge determination) shown in Fig. 4 has been executed, the processing returns to the processing flow of Fig. 3 and proceeds to S22. In S22, the control device 100 determines an adjustment amount for suppressing the occurrence of an abnormality based on the result of the first determination and the first determination matrix shown in Fig. 3, and then outputs the determined adjustment amount in S40. Then, the rotation speeds of the compressor 11 and the fan 13 are controlled by commands reflecting the determined adjustment amount (see Figs. 7 and 8, described later, for details).

[0052] Specifically, when the rotation speed of the fan 13 is less than the upper limit (YES in S1), the control device 100 determines the adjustment amount as described below, for example, using a first determination matrix stored in the storage device 130. If it is determined that the surging phenomenon will not occur (B12) but that a subcooling abnormality will occur (A13), the control device 100 adjusts the rotation speed of the fan 13 to suppress the subcooling abnormality (increase Nfan), and determines not to adjust the rotation speed of the compressor 11. More specifically, the control device 100 adjusts the rotation speed of the fan 13 to increase it by an adjustment amount according to the determination in A13. When the rotation speed of the compressor 11 is greater than the lower limit, if it is determined that the surging phenomenon will not occur (B12) and the refrigerant state is in the second state (A12), the control device 100 adjusts the rotation speed of the compressor 11 to decrease it by an adjustment amount according to the determination in A12 (decrease Ncomp), and determines not to adjust the rotation speed of the fan 13. When the rotation speed of the compressor 11 is not greater than the lower limit, if it is determined that surging is not occurring (B12) and the refrigerant state is in the second state (A11), the control device 100 adjusts the rotation speed of the fan 13 to decrease the speed (Nfan decrease) by an adjustment amount according to the A11 determination, and determines not to adjust the rotation speed of the compressor 11. If it is determined that surging is not occurring (B12) and the refrigerant state is in the third state (A14), the control device 100 determines not to change either the rotation speed of the fan 13 or the rotation speed of the compressor 11 (no adjustment). If it is determined that surging is occurring (B11), the control device 100 adjusts the rotation speed of the fan 13 to suppress surging, and does not adjust the rotation speed of the compressor 11. Specifically, the control device 100 adjusts the rotation speed of the fan 13 to increase the rotation speed by an adjustment amount according to the B11 determination.

[0053] If the current value of Nfan is equal to or greater than the Nfan upper limit (NO in S1), the control device 100 executes a second determination in S31. The second determination includes a subcooling determination and a surge determination. Fig. 5 is a flowchart showing the details of the process (S31) related to the second determination.

[0054] Referring to Fig. 5, S211 to S213 and S221 to S229 are a processing flow related to the sub-cooling determination. The processing of S211 to S213 and S221 to S229 in Fig. 5 is basically similar to the processing of S111 to S113 and S121 to S129 in Fig. 4 described above, respectively, and therefore redundant description will not be repeated. In the processing flow related to the sub-cooling determination shown in Fig. 5, S223 (A23 determination), S226 (A12 determination), S127 (A11 determination), and S129 (A14 determination) in Fig. 4 are replaced with S223 (A23 determination), S226 (A21 determination), S227 (A22 determination), and S229 (A24 determination), respectively.

[0055] In S223, the control device 100 determines "A23" regarding the method of suppressing subcooling abnormalities. The determination of A23 means that the adjustment made in response to the determination result of subcooling abnormalities is to increase Ncomp. By increasing the rotation speed of the compressor 11 without changing the rotation speed of the fan 13, subcooling abnormalities become less likely to occur. The degree of Ncomp increase (adjustment amount) made in accordance with the determination of A23 may be a predetermined fixed value, or may be variable depending on a predetermined parameter (for example, the difference between the saturation temperature and the refrigerant temperature Ta, or the difference between the current Ncomp value and the Ncomp upper limit value).

[0056] The A21 determination in S226 is the same as the A12 determination in S126 in Fig. 4. That is, the A21 determination indicates "Ncomp reduction." The A22 determination in S227 is the same as the A11 determination in S127 in Fig. 4. The A22 determination indicates "Nfan reduction." The A24 determination in S229 is the same as the A14 determination in S129 in Fig. 4. That is, the A24 determination indicates "no adjustment required." When any of the determinations A21 to A24 is made, the processing flow for subcooling determination ends.

[0057] S231 to S233 and S241 to S244 are processing flows relating to surge determination. The processes of S231 to S233 and S241 are basically the same as the processes of S131 to S133 and S141 in Fig. 4, respectively, and therefore overlapping descriptions will not be repeated.

[0058] If the operating point of the compressor 11 is included in the surging region (YES in S241), the control device 100 executes processing to avoid the surging phenomenon in S242. Fig. 6 is a flowchart showing the details of the processing to avoid the surging phenomenon (S242).

[0059] Referring to Figure 6, in S301, the control device 100 determines whether the adjustment direction of Ncomp to move the operating point (Comp operating point) of the compressor 11 out of the surging region is to increase or decrease, based on the map M1 (a map stored in the memory device 130) showing the surge characteristics of the compressor 11, the current value of Ncomp, the pressure Pb (suction pressure), the pressure Pc (discharge pressure), and the flow rate Gc.

[0060] If it is determined in S301 that the adjustment direction of Ncomp to avoid surging is to decrease (deceleration side), the control device 100 determines in S302 whether the current value of Ncomp is greater than the Ncomp lower limit. If the current value of Ncomp is greater than the Ncomp lower limit (YES in S302), the control device 100 determines "B21" as the surging suppression method in S303. The determination of B21 means that the adjustment in response to the surging determination result is to decrease Ncomp. The control device 100 calculates the degree of Ncomp decrease (adjustment amount to avoid surging) based on the map M1, the current value of Ncomp, pressures Pb and Pc, and flow rate Gc. On the other hand, if the current value of Ncomp is equal to or less than the Ncomp lower limit (NO in S302), the control device 100 generates a signal (load adjustment request signal) requesting adjustment of the battery load to avoid surging in S304. The load adjustment request signal is a signal that requests that a surge phenomenon be avoided by control outside the refrigeration cycle 10. The load adjustment request signal may request, for example, that at least one of charging and discharging of the battery module 2 be limited.

[0061] If it is determined in S301 that the adjustment direction of Ncomp to avoid surging is to increase (toward acceleration), the control device 100 determines in S305 whether the current value of Ncomp is less than the Ncomp upper limit. If the current value of Ncomp is less than the Ncomp upper limit (YES in S305), the control device 100 determines "B22" as the surging suppression method in S306. The determination of B22 means that the adjustment in response to the surging determination result is to increase Ncomp. The control device 100 calculates the degree of Ncomp increase (adjustment amount to avoid surging) based on the map M1, the current value of Ncomp, pressures Pb and Pc, and flow rate Gc. On the other hand, if the current value of Ncomp is equal to or greater than the Ncomp upper limit (NO in S305), the control device 100 generates a signal (load adjustment request signal) requesting adjustment of the battery load to avoid surging in S307.

[0062] Referring again to FIG. 5, if the operating point of the compressor 11 is not included in the surging region (NO in S241), the control device 100 determines in S243 that surging of the compressor 11 is not occurring, and subsequently determines "B23" regarding the surging suppression method in S244. The determination of B23 means that the adjustment according to the surging determination result is to leave both Nfan and Ncomp unchanged (no adjustment required). When any of the determinations B21 to B23 is made, the processing flow for surge determination ends. Also, when a load adjustment request signal (S304, S307 in FIG. 6) is generated, the processing flow for surge determination ends.

[0063] After the processing flow for the second determination (subcooling determination and surge determination) shown in Fig. 5 is executed, the processing returns to the processing flow in Fig. 3 and proceeds to S32. In S32, the control device 100 determines an adjustment amount for suppressing the occurrence of an abnormality based on the result of the second determination and the second determination matrix shown in Fig. 3, and then outputs the determined adjustment amount in S40.

[0064] Specifically, when the rotation speed of the fan 13 is equal to or greater than the upper limit (NO in S1), the control device 100 determines the adjustment amount as described below, for example, using a second determination matrix stored in the storage device 130. When it is determined that the surging phenomenon will not occur (B23) but that a subcooling abnormality will occur (A23), the control device 100 adjusts the rotation speed of the compressor 11 to suppress the subcooling abnormality (increase Ncomp), and determines not to adjust the rotation speed of the fan 13. More specifically, the control device 100 adjusts the rotation speed of the compressor 11 to accelerate by an adjustment amount according to the determination in A23. When the rotation speed of the compressor 11 is greater than the lower limit, when it is determined that the surging phenomenon will not occur (B23) and the refrigerant state is the second state (A21), the control device 100 adjusts the rotation speed of the compressor 11 to decelerate by an adjustment amount according to the determination in A21 (decrease Ncomp), and determines not to adjust the rotation speed of the fan 13. When the rotation speed of the compressor 11 is not greater than the lower limit, if surging does not occur (B23) and it is determined that the refrigerant state is in the second state (A22), the control device 100 adjusts the rotation speed of the fan 13 to decrease by an adjustment amount according to the determination in A22 (Nfan decrease), and determines not to adjust the rotation speed of the compressor 11. If surging does not occur (B23) and it is determined that the refrigerant state is in the third state (A24), the control device 100 determines not to change either the rotation speed of the fan 13 or the rotation speed of the compressor 11 (no adjustment). If it is determined that surging will occur when the rotation speed of the compressor 11 is greater than the lower limit and less than the upper limit, the control device 100 adjusts the rotation speed of the compressor 11 to decrease by an adjustment amount according to the determination in B21 (Ncomp decrease), or adjusts the rotation speed of the compressor 11 to increase by an adjustment amount according to the determination in B22. This suppresses the surging phenomenon.

[0065] Furthermore, if a load adjustment request signal (see FIG. 6) is generated in S31, the adjustment amount is determined to be "0 (no adjustment)" in S32, and then in S40, the control device 100 outputs the load adjustment request signal.

[0066] An example of vehicle control using the adjustment amount or load adjustment request signal obtained by the process shown in FIG. 3 will be described below with reference to FIGS. 7 and 8. As shown in FIGS. 7 and 8, the vehicle according to this example further includes a PCU (Power Control Unit) 3, an MG (Motor Generator) 4, and drive wheels W. The PCU 3 includes electronic circuits such as an inverter and a DC / DC converter, and is located between the battery module 2 and the MG 4. The PCU 3 drives the MG 4 using power supplied from the battery module 2 (e.g., a battery pack formed by a plurality of battery modules 2). The MG 4 functions as a traction motor for the vehicle. In a power running state, the MG 4 is driven by the PCU 3 to rotate the drive wheels W. The MG 4 also performs regenerative power generation, for example, when braking the vehicle. In a power generating state, the MG 4 outputs the generated power to the battery module 2. The number of motors and drive wheels is arbitrary, and may be one or more.

[0067] Fig. 7 is a diagram for explaining a first example of vehicle control according to the present embodiment. The control device 100A shown in Fig. 7 corresponds to the above-mentioned control device 100 (Fig. 1) and executes the processes shown in Figs. 3 to 6. Furthermore, the control device 100A includes adder circuits 141 and 142.

[0068] The control device 100A repeatedly executes the process shown in FIG. 3 at a predetermined interval. In this processing routine, Nfan and Ncomp (previous values) determined in the previous processing routine correspond to the current values ​​of Nfan and Ncomp, respectively. In S40 of FIG. 3, the determined adjustment amounts of Nfan and Ncomp are output to the adder circuits 141 and 142, respectively. The adder circuits 141 and 142 add the input adjustment amounts of Nfan and Ncomp to the previous values ​​of Nfan and Ncomp, respectively. The adjustment amount on the acceleration side is expressed as a positive value, the adjustment amount on the deceleration side is expressed as a negative value, and no adjustment is expressed as a value of "0." In this embodiment, the adjustment amount of at least one of Nfan and Ncomp is "0." The control device 100A determines the Nfan and Ncomp after addition output from the adder circuits 141 and 142 as Nfan and Ncomp (current values), respectively, and controls the fan 13 and the compressor 11 according to the determined Nfan and Ncomp.

[0069] 3 is output to the PCU 3 in S40. For example, the control device 100A limits the exchange of power between the battery module 2 and the MG 4 by sending the load adjustment request signal to the PCU 3. The load adjustment request signal may lower the upper limit of the power output from the battery module 2 to the MG 4. The load adjustment request signal may also lower the upper limit of the power input from the MG 4 to the battery module 2.

[0070] FIG. 8 is a diagram for explaining a second example of vehicle control according to the present embodiment. The control device 100B shown in FIG. 8 corresponds to the above-described control device 100 (FIG. 1) and executes the processes shown in FIGS. 3 to 6. Furthermore, the storage device of the control device 100B stores a map M2 (correspondence information) that defines the correspondence between the battery state and each of the target Nfan and target Ncomp. The battery state includes the temperatures of the multiple battery modules 2. The battery state may include current and voltage instead of or in addition to temperature.

[0071] The control device 100B refers to map M2 to obtain the target Nfan and target Ncomp corresponding to the current battery state. Subsequently, the control device 100B executes the process shown in FIG. 3 and adjusts the target Nfan and target Ncomp according to the adjustment amounts output in S40. The control device 100B determines the adjusted Nfan and Ncomp as Nfan and Ncomp (current values), respectively. If the adjustment amounts for both Nfan and Ncomp are "0 (no adjustment)," the target Nfan and target Ncomp are determined as Nfan and Ncomp (current values) as they are. The control device 100B then controls the fan 13 and the compressor 11 according to the determined Nfan and Ncomp. Furthermore, if a load adjustment request signal is generated in S31 of FIG. 3, the control device 100B, like the control device 100A described above, limits the exchange of power between the battery module 2 and MG4 by sending the load adjustment request signal to the PCU 3.

[0072] In the above, the PCU is shown as an example of the output destination of the load adjustment request signal, but the output destination of the load adjustment request signal is not limited to the PCU. For example, the driving load may be instructed to the PCU via a vehicle ECU or the like. Alternatively, output adjustment may be performed between the vehicle ECU and the charger during rapid charging, etc. The output destination of the load adjustment request signal can be set arbitrarily.

[0073] As described above, the control device (control devices 100, 100A, 100B) according to this embodiment determines whether or not a subcooling abnormality occurs in which the refrigerant does not become liquid on the upstream side of the pressure reducer 14 in the second flow path, based on the detection result of the first detection means (see FIGS. 3 to 5), determines whether or not a surging phenomenon occurs in the compressor 11, based on the detection result of the second detection means (see FIGS. 3 to 6), and, if it is determined that a surging phenomenon will occur, adjusts either the rotation speed of the fan 13 or the rotation speed of the compressor 11 so as to suppress the surging phenomenon. and, when it is determined that a surging phenomenon will not occur but a subcooling abnormality will occur, adjust either the rotation speed of the fan 13 or the rotation speed of the compressor 11 so as to suppress the subcooling abnormality (for example, adjustment corresponding to the A13 judgment and the B12 judgment in the first judgment matrix, and adjustment corresponding to the A23 judgment and the B23 judgment in the second judgment matrix).

[0074] In the above configuration, when it is determined that surging will not occur (i.e., the compressor 11 can operate normally) and when it is determined that a subcooling abnormality will occur (i.e., the refrigerant will no longer be in a liquid state upstream of the pressure reducer 14 in the second flow path), one of the rotation speed of the fan 13 and the rotation speed of the compressor 11 is adjusted to suppress the subcooling abnormality. This makes it less likely that the subcooling abnormality will occur. On the other hand, when it is determined that surging will occur, regardless of the determination result of the subcooling abnormality, one of the rotation speed of the fan 13 and the rotation speed of the compressor 11 is adjusted to suppress at least the surging abnormality. This makes it less likely that the surging abnormality will occur. According to the above configuration, control to suppress the surging abnormality is preferentially executed, thereby preventing the surging abnormality from being promoted by control to suppress the subcooling abnormality.

[0075] If both the rotation speed of the compressor 11 and the rotation speed of the fan 13 were changed simultaneously, these changes would affect each other, making it difficult to determine control parameters for suppressing abnormalities (subcooling abnormalities or surging). If the correct control parameters are not obtained, there is a possibility that abnormalities will not be avoided. Therefore, in the above configuration, either the rotation speed of the fan 13 or the rotation speed of the compressor 11 is adjusted. This makes it possible to determine the direction and amount of adjustment of the rotation speed of the compressor 11 to suppress abnormalities, assuming that the rotation speed of the fan 13 does not change. Furthermore, it makes it easier to accurately determine control parameters for suppressing abnormalities. This makes it possible to more reliably avoid abnormalities (especially surging). However, if changing only one of the rotation speeds of the compressor 11 and the fan 13 is insufficient, both may be changed.

[0076] The control device according to this embodiment calculates the saturation temperature of the refrigerant upstream of the pressure reducer 14 in the second flow path based on the refrigerant pressure detected by the pressure sensor 50 (first detection means) (S112 in FIG. 4 and S212 in FIG. 5), and determines whether a subcooling abnormality will occur based on the saturation temperature and the refrigerant temperature detected by the temperature sensor 60 (first detection means) (S113 and S121 in FIG. 4 and S213 and S221 in FIG. 5). This facilitates appropriate determination of whether a subcooling abnormality will occur. The control device according to this embodiment also identifies an operating point of the compressor 11 using the suction pressure, discharge pressure, and flow rate detected by the pressure sensors 71 and 72 and the flow rate sensor 80 (second detection means), and determines whether a surging phenomenon will occur based on whether the identified operating point is within a predetermined surging region (S131 to S133 and S141 in FIG. 4 and S231 to S233 and S241 in FIG. 5). This makes it easier to appropriately determine whether or not a surging phenomenon occurs.

[0077] The batteries cooled by the battery cooling system are not limited to those installed in xEVs, but may also be batteries used in vehicles other than automobiles (railroad vehicles, ships, airplanes, etc.), unmanned mobile objects (automated guided vehicles (AGVs), agricultural machinery, walking robots, drones, robot cleaners, space probes, etc.), or stationary energy storage systems.

[0078] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0079] 1 battery cooling system, 2 battery module, 3 PCU, 4 MG, 10 refrigeration cycle, 11 compressor, 12 condenser, 13 fan, 14 pressure reducer, 15 evaporator, 31, 32, 35 flow path, 33, 33a, 34 branch flow path, 50, 71, 72 pressure sensor, 60 temperature sensor, 80 flow rate sensor, 100, 100A, 100B control device.

Claims

1. A battery cooling system, comprising: The refrigeration cycle forms a circuit through which a refrigerant circulates, and a control device is provided. The refrigeration cycle includes: a compressor, a condenser, and a fan for cooling the condenser; a plurality of evaporators arranged corresponding to the plurality of batteries, respectively; a first flow path connected to a discharge port of the compressor and one end of the condenser; a second flow path connecting the other end of the condenser and one ends of the plurality of evaporators; a third flow path connecting the other ends of the plurality of evaporators and a suction port of the compressor; The compressor is a speed-type compressor, the second flow path includes a plurality of branch flow paths connected to one ends of the plurality of evaporators, The battery cooling system includes: a plurality of pressure reducers respectively disposed in the plurality of branch flow paths; a first detection means for detecting a state of the refrigerant upstream of the pressure reducer in the second flow path; and a second detection means for detecting a state of the compressor. The control device determining whether a subcooling abnormality occurs in which the refrigerant is not in a liquid state upstream of the pressure reducer in the second flow path based on a detection result of the first detection means; determining whether or not a surging phenomenon occurs in the compressor based on a detection result of the second detection means; When it is determined that the surging phenomenon will occur, adjusting at least one of the rotation speed of the fan and the rotation speed of the compressor so as to suppress the surging phenomenon; When it is determined that the surging phenomenon does not occur but the subcooling abnormality occurs, adjusting at least one of the rotation speed of the fan and the rotation speed of the compressor so as to suppress the subcooling abnormality; A battery cooling system configured to:

2. the control device is configured to determine, in determining the subcooling abnormality, whether the state of the refrigerant corresponds to a first state in which the subcooling abnormality occurs, a second state in which the subcooling abnormality is unlikely to occur, or a third state which is neither the first state nor the second state; The control device When the surging phenomenon does not occur and the state of the refrigerant is determined to be in the first state, at least one of the rotation speed of the fan and the rotation speed of the compressor is accelerated; When the surging phenomenon does not occur and the state of the refrigerant is determined to be in the second state, at least one of the rotation speed of the fan and the rotation speed of the compressor is reduced; The battery cooling system of claim 1, wherein when the surging phenomenon does not occur and the state of the refrigerant is determined to be in the third state, the rotational speed of the fan and the rotational speed of the compressor are not changed.

3. The control device determining whether the rotation speed of the fan is less than an upper limit value; determining whether the rotation speed of the compressor is greater than a lower limit value; configured to run The control device When it is determined that the surging phenomenon does not occur, the state of the refrigerant is the first state, and the rotation speed of the fan is less than the upper limit value, the rotation speed of the fan is accelerated; When it is determined that the surging phenomenon does not occur, the state of the refrigerant is the first state, and the rotation speed of the fan is not less than the upper limit value, the rotation speed of the compressor is accelerated; When it is determined that the surging phenomenon does not occur, the state of the refrigerant is the second state, and the rotation speed of the compressor is greater than the lower limit value, the rotation speed of the compressor is reduced; 3. The battery cooling system of claim 2, configured to reduce the rotational speed of the fan when it is determined that the surging phenomenon does not occur, the state of the refrigerant is in the second state, and the rotational speed of the compressor is not greater than the lower limit value.

4. The control device determining whether the rotation speed of the fan is less than an upper limit of fan rotation; determining whether the rotation speed of the compressor is less than an upper limit value; determining whether the rotation speed of the compressor is greater than a lower limit value; configured to run The control device If it is determined that the surging phenomenon occurs when the rotation speed of the fan is less than the upper limit of fan rotation, the rotation speed of the fan is accelerated; The battery cooling system of claim 1, wherein when it is determined that the surging phenomenon will occur when the rotation speed of the fan is not less than the fan rotation upper limit value and the rotation speed of the compressor is greater than the lower limit value and less than the upper limit value, the rotation speed of the compressor is accelerated or decelerated to suppress the surging phenomenon.

5. The first detection means a pressure sensor that detects a pressure of the refrigerant in the second flow path upstream of the pressure reducer; a temperature sensor that detects a temperature of the refrigerant upstream of the pressure reducer in the second flow path; Including, The control device calculating a saturation temperature of the refrigerant in the second flow path upstream of the pressure reducer based on the pressure of the refrigerant detected by the pressure sensor; determining whether or not the subcooling abnormality occurs based on the saturation temperature and the temperature of the refrigerant detected by the temperature sensor; configured to run The second detection means a first pressure sensor for detecting a suction pressure of the refrigerant on the suction side of the compressor; a second pressure sensor for detecting a discharge pressure of the refrigerant on the discharge side of the compressor; a flow rate sensor for detecting a flow rate of the refrigerant flowing through the compressor; Including, The battery cooling system of any one of claims 1 to 4, wherein the control device is configured to identify the operating point of the compressor using the suction pressure, the discharge pressure, and the flow rate detected by the second detection means, and to determine whether the surging phenomenon will occur based on whether the identified operating point is within a predetermined surging region.

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