cooling system

Abstract

The present specification provides a cooling system that grasps the temperature of a heat medium flowing into each unit by a simple structure. The cooling system includes: a cooling path that causes the heat medium to flow through in the order of a first unit and a second unit; a temperature sensor that detects the temperature of the heat medium flowing into the first unit; and a control device that controls each operation of the first unit and the second unit. The control device performs temperature estimation processing that estimates the temperature of the heat medium flowing into the second unit. The temperature estimation processing includes: processing that acquires a detected temperature detected by the temperature sensor; processing that calculates a temperature rise amount of the heat medium in the first unit; and processing that decides an estimated value of the temperature of the heat medium flowing into the second unit by adding the calculated temperature rise amount to the detected temperature detected by the temperature sensor.

Description

Technical Field

[0001] The technology disclosed in this specification relates to cooling systems. Background Technology

[0002] Japanese Patent Application Publication No. 2009-284597 discloses a cooling system for cooling multiple units. This cooling system includes a cooling path through which a heat transfer medium flows to multiple units, and a temperature sensor that detects the temperature of the heat transfer medium flowing in the cooling path. It is configured to adjust the flow rate of the heat transfer medium based on its temperature.

[0003] In the aforementioned cooling system, the heat transfer medium flows sequentially through multiple units. Therefore, the temperature of the heat transfer medium rises each time it passes through a unit, with the temperature increasing as the medium flows into the downstream unit. Consequently, to control the operation of each unit based on the temperature of the heat transfer medium, it is necessary to know the temperature of the heat transfer medium flowing into each unit individually. In this case, it is possible to install a temperature sensor in each unit, but this would complicate the structure. Summary of the Invention

[0004] The problem that the invention aims to solve

[0005] In view of the above-mentioned actual situation, this specification provides a technique for controlling the temperature of the heat medium flowing into each unit through a simple structure.

[0006] One aspect of this disclosure provides a cooling system for cooling a first unit and a second unit. The cooling system includes: a cooling path through which a heat transfer medium flows in the order of the first unit and the second unit; a temperature sensor configured to detect the temperature of the heat transfer medium flowing into the first unit; and a control device connected to the temperature sensor and configured to control the operation of each of the first and second units based on the detected temperature detected by the temperature sensor. The control device is configured to perform a temperature estimation process that estimates the temperature of the heat transfer medium flowing into the second unit based on the detected temperature detected by the temperature sensor. The temperature estimation process includes: obtaining the detected temperature detected by the temperature sensor; calculating a temperature rise in the heat transfer medium in the first unit; and determining an estimated value of the temperature of the heat transfer medium flowing into the second unit by adding the calculated temperature rise to the detected temperature detected by the temperature sensor.

[0007] In the above structure, the temperature of the heat medium flowing into the first unit is detected by a temperature sensor. The temperature of the heat medium flowing into the second unit is estimated through a temperature estimation process. Specifically, the estimated temperature of the heat medium flowing into the second unit is determined by adding the detected temperature (i.e., the temperature of the heat medium flowing into the first unit) to the temperature rise of the heat medium in the first unit. With this structure, the temperature of the heat medium flowing into each unit can be determined using a simple method without the need for temperature sensors in both the first and second units. Attached Figure Description

[0008] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and in the drawings:

[0009] Figure 1 This is a diagram showing the main structure of a vehicle 100 equipped with the cooling system 10 of the embodiment.

[0010] Figure 2 This is a diagram illustrating the structure of the cooling system 10 in the embodiment. Also shown are the first PCU 112, the second PCU 114, and the control device 116 of the vehicle 100.

[0011] Figure 3 This diagram illustrates the temperature of the heat transfer medium flowing within the cooling path 12. Here, the first temperature T1 is the temperature of the heat transfer medium shortly after passing through the heat sink 14. The second temperature T2 is the temperature of the heat transfer medium flowing out of the first PCU 112. The third temperature T3 is the temperature of the heat transfer medium flowing out of the second PCU 114. Here, the first temperature T1 is the same as the temperature of the heat transfer medium flowing into the first PCU 112, and the second temperature T2 is the same as the temperature of the heat transfer medium flowing into the second PCU 114.

[0012] Figure 4 This is a flowchart illustrating an example of temperature estimation processing performed by the cooling control device 20.

[0013] Figure 5 This is a flowchart illustrating a modified example of the temperature estimation process performed by the cooling control device 20.

[0014] Figure 6 This is a flowchart illustrating a modified example of the temperature estimation process performed by the cooling control device 20. Detailed Implementation

[0015] In the cooling system described above, the temperature rise can also be calculated based on at least one heating index representing the operating state of the first unit and at least one cooling index representing the cooling state of the first unit based on the heat medium during the temperature rise calculation process. With this structure, the temperature of the heat medium flowing into the second unit can be estimated based on the actual operating and cooling states of the first unit.

[0016] In the cooling system described above, at least one heat generation indicator may include an action command value for the first unit. With this structure, compared to calculating the temperature rise based on a detection value indicating the operating state of the first unit, it is not necessary to remove detection noise, thus allowing for a simpler calculation of the temperature rise. However, in other embodiments, at least one heat generation indicator may also include a detection value indicating the operating state of the first unit.

[0017] In the cooling system described above, the first unit may be a power conversion device that controls the power supplied to the motor. In this case, the action command value may also be the target torque value that the motor should output. In the aforementioned power conversion device, it is considered that the target torque value that the motor should output has a significant impact on the heat generation in the power conversion device compared to other action command values. Therefore, without considering other action command values, the temperature rise of the heat transfer medium in the power conversion device is calculated based on the target torque value that the motor should output, thereby reducing the computational load on the control device. However, in other embodiments, the temperature rise of the heat transfer medium in the power conversion device may also be calculated based on other action command values ​​in addition to the target torque value that the motor should output.

[0018] In the cooling system described above, at least one heat generation indicator may include operating parameters related to the power loss in the first unit. Based on this structure, the temperature of the heat transfer medium flowing into the second unit can be estimated based on the power loss in the first unit.

[0019] In the cooling system described above, the first unit could be a power conversion device that controls the power supplied to the motor. In this case, the operating parameters could include at least one of the following: the input voltage to the power conversion device, the output current of the power conversion device, the carrier frequency of the power conversion device, and the control mode of the power conversion device. In the aforementioned power conversion device, it is considered that at least one of the following—the input voltage to the power conversion device, the output current of the power conversion device, the carrier frequency of the power conversion device, and the control mode of the power conversion device—significantly affects the temperature rise of the heat transfer medium. Therefore, by relatively reducing the operating parameters that need to be considered when calculating the temperature rise of the heat transfer medium in the power conversion device, the computational load on the control device can be reduced.

[0020] In the cooling system described above, at least one heat generation indicator may include the actual temperature detected within the first unit. Based on this structure, the temperature of the heat transfer medium flowing into the second unit can be estimated based on the actual temperature detected within the first unit.

[0021] In the cooling system described above, the first unit could be a power conversion device that controls the power supplied to the motor. In this case, the actual temperature could be the actual temperature detected by a component temperature sensor embedded in a semiconductor element installed in the power conversion device. When the power conversion device operates, it is assumed that the heat generated from the semiconductor element significantly affects the temperature rise of the heat transfer medium. Therefore, by determining the components to be considered when calculating the temperature rise of the heat transfer medium in the power conversion device, the computational load on the control device can be reduced. Furthermore, the number of semiconductor elements installed in the power conversion device is not particularly limited, as long as there is at least one.

[0022] Referring to the accompanying drawings, the cooling system 10 of the embodiment and the vehicle 100 equipped with the cooling system 10 will be described. The vehicle 100 referred to here is a so-called automobile, a vehicle that travels on a road. Figure 1 As shown, the vehicle 100 includes a body 102 and a plurality of wheels 104f and 104r. The plurality of wheels 104f and 104r are rotatably mounted on the body 102. The plurality of wheels 104f and 104r includes a pair of front wheels 104f located at the front of the body 102 and a pair of rear wheels 104r located at the rear of the body 102. The pair of front wheels 104f are coaxially arranged with each other, and the pair of rear wheels 104r are also coaxially arranged with each other. Furthermore, the number of wheels 104f and 104r is not limited to four. Additionally, although not specifically limited, the body 102 is constructed of a metal such as steel or aluminum alloy.

[0023] like Figure 1 As shown, the vehicle 100 also includes a front electric motor 106 and a rear electric motor 108. The front electric motor 106 is connected to a pair of front wheels 104f and is capable of driving the pair of front wheels 104f. The rear electric motor 108 is connected to a pair of rear wheels 104r and is capable of driving the pair of rear wheels 104r. That is, the vehicle 100 is capable of four-wheel drive. Although not particularly limited, in this embodiment, the front electric motor 106 and the rear electric motor 108 are each a three-phase electric generator with a U-phase, a V-phase, and a W-phase.

[0024] like Figure 1 As shown, the vehicle 100 also includes a battery 110. The battery 110 contains multiple rechargeable battery cells, configured to be repeatedly charged by external power. Furthermore, although not specifically limited, the battery 110 is a lithium-ion battery, nickel-metal hydride battery, or the like.

[0025] like Figure 1 As shown, the vehicle 100 also includes two power control units (hereinafter referred to as "PCUs") 112 and 114. The two PCUs 112 and 114 are capable of controlling the power supplied to the corresponding electric motors 106 and 108. The two PCUs 112 and 114 include a first PCU 112 and a second PCU 114. The first PCU 112 is disposed between the battery 110 and the front electric motor 106. The first PCU 112 is an inverter with multiple semiconductor elements 118 (see reference). Figure 2 The first PCU112 can convert DC power from battery 110 into AC power and supply it to the front motor 106. Additionally, the first PCU112 can convert AC power generated by the front motor 106 into DC power and supply it to the battery 110. That is, the vehicle 100 can charge the battery 110 by supplying regenerative power generated by the front motor 106 to the battery 110 during braking. In addition to the inverter, the first PCU112 may also include a DC-DC converter. Furthermore, as... Figure 2 As shown, a component temperature sensor 118a for detecting its own temperature is built into the semiconductor element 118 of the first PCU112.

[0026] The second PCU114 is disposed between the battery 110 and the rear motor 108. The second PCU114 is an inverter with multiple semiconductor elements 120 (see reference). Figure 2 The second PCU114 can convert DC power from battery 110 into AC power and supply it to the rear motor 108. Additionally, the second PCU114 can convert AC power generated by the rear motor 108 into DC power and supply it to battery 110. That is, vehicle 100 can charge battery 110 by supplying regenerative power generated by the rear motor 108 to battery 110 during braking. In addition to the inverter, the second PCU114 may also include a DC-DC converter.

[0027] like Figure 1As shown, the vehicle 100 also includes a control device 116. The control device 116 is a computer device with a processor, memory, etc. The control device 116 can be a single computer device or a combination of multiple computer devices. The control device 116 can communicatively connect to the front motor 106, the rear motor 108, the battery 110, the first PCU 112, and the second PCU 114, and can monitor and control their operation. Operation information describing user actions and vehicle information indicating the state of the vehicle 100 are input to the control device 116. The control device 116 controls the operation of each part of the vehicle 100 based on the input operation information and vehicle information. For example, the control device 116 can determine the target torque values ​​for the front motor 106 and the rear motor 108 based on the input operation information and vehicle information. Furthermore, the control device 116 can provide feedback control to the operation of the first PCU 112 and the second PCU 114 in a manner that makes the actual torque output by these motors 106 and 108 equal to the target torque value.

[0028] Next, the cooling system 10 of this embodiment will be described. The cooling system 10 of this embodiment cools the first PCU 112 and the second PCU 114. For example... Figure 2 As shown, the cooling system 10 includes a cooling path 12, a radiator 14, and a pump 16. The cooling path 12 is the path through which the heat transfer medium flows. The heat transfer medium can be, for example, cooling water. The radiator 14 is capable of exchanging heat between the heat transfer medium and the outside air, and releasing heat from the heat transfer medium. The pump 16 is located in the cooling path 12 and is capable of adjusting the flow rate of the heat transfer medium flowing within the cooling path 12. The cooling path 12 is connected to the radiator 14, the first PCU 112, and the second PCU 114. The heat transfer medium flows through the first PCU 112 and the second PCU 114 in that order, thereby recovering heat from the first PCU 112 and the second PCU 114 respectively. Therefore, the temperature of the heat transfer medium rises each time it passes through each of the first PCU 112 and the second PCU 114. Furthermore, the temperature of the heat transfer medium decreases by releasing heat from the heat transfer medium using the radiator 14.

[0029] Regarding the above aspects, refer to Figure 3The temperature change of the heat medium as it flows through the cooling path 12 will be explained. Shortly after passing through the radiator 14, the heat medium has a first temperature T1. Here, the first temperature T1 is the same as the outside air temperature. Then, the heat medium flows into the first PCU 112 while maintaining the first temperature T1. As the heat medium flows through the first PCU 112, it recovers heat from the first PCU 112. As a result, the temperature of the heat medium rises to a second temperature T2. Then, as the heat medium flows through the second PCU 114, it recovers heat from the second PCU 114. As a result, the temperature of the heat medium rises to a third temperature T3. Then, when the heat medium reaches the radiator 14, it releases heat through heat exchange with the radiator 14. As a result, the temperature of the heat medium decreases back to the first temperature T1. As described above, the cooling system 10 manages the temperature of the first PCU112 and the second PCU114 by recovering heat from the first PCU112 and the second PCU114 and releasing that heat from the heat sink 14 to the outside.

[0030] like Figure 2 As shown, the cooling system 10 also includes a temperature sensor 18. The temperature sensor 18 detects the temperature of the heat transfer medium flowing into the first PCU 112. As an example, the temperature sensor 18 is disposed within the first PCU 112. Furthermore, as in other embodiments, the temperature sensor 18 may also be disposed at a location representing a temperature substantially equal to the temperature of the heat transfer medium flowing into the first PCU 112. For example, as in this embodiment, if the temperature of the heat transfer medium is considered to remain unchanged from shortly after passing through the heat sink 14 until it flows into the first PCU 112, the temperature sensor 18 may also be disposed at any location between the heat sink 14 and the first PCU 112.

[0031] like Figure 2As shown, the cooling system 10 also includes a cooling control device 20. The cooling control device 20 is a computer device with a processor, memory, etc., which controls and monitors the operation of the cooling system 10. The cooling control device 20 can be a single computer device or a combination of multiple computer devices. The cooling control device 20 is communicatively connected to the temperature sensor 18 and can obtain the temperature detected by the temperature sensor 18. Furthermore, the cooling control device 20 is also communicatively connected to the control device 116 of the vehicle 100 and can obtain operation information and vehicle information input to the control device 116. The cooling control device 20 is configured to perform temperature estimation processing, which estimates the temperature of the heat medium flowing into the second PCU 114 based on the detected temperature detected by the temperature sensor 18 and the information obtained from the control device 116, as detailed later. The control device 116 obtains the detected temperature detected by the temperature sensor 18 and the estimated value from the temperature estimation processing from the cooling control device 20, and controls the operations of the first PCU 112 and the second PCU 114 based on these values.

[0032] Furthermore, the two cooling targets of the cooling system 10 do not necessarily have to be the first PCU 112 and the second PCU 114. As another embodiment, the cooling system 10 may also cool either PCU 112 or 114 and other heat sources (e.g., the engine). As yet another embodiment, two other heat sources may also be cooled.

[0033] Next, refer to Figure 4 The temperature estimation process performed by the cooling control device 20 will be explained. In step S10, the cooling control device 20 obtains the detected temperature by the temperature sensor 18. As described above, the temperature sensor 18 detects the temperature of the heat medium flowing into the first PCU 112, therefore, the temperature obtained by the cooling control device 20 in step S10 is the temperature of the heat medium flowing into the first PCU 112.

[0034] In step S12, the cooling control device 20 communicates with the control device 116 of the vehicle 100 to detect the target torque value that the front motor 106 should output. Here, the target torque value that the front motor 106 should output is an example of the operation command value for the first PCU 112, and also an example of a heat index indicating the operating state of the first PCU 112. As another embodiment, the cooling control device 20 may replace the target torque value that the front motor 106 should output with a sensor or the like to detect the actual torque output by the front motor 106.

[0035] In step S14, the cooling control device 20 calculates the reference temperature rise of the heat medium in the first PCU 112 based on the torque target value detected in step S12. The reference temperature rise refers to the temperature rise of the heat medium that the first PCU 112 may generate when the flow rate of the heat medium is assumed to be a predetermined reference flow rate. The cooling control device 20 stores a maximum value of the reference temperature rise for calculating the reference temperature rise. The maximum value of the reference temperature rise refers to the temperature rise of the heat medium that the first PCU 112 may generate when the flow rate of the heat medium is a predetermined reference flow rate and the torque target value of the front motor 106 is set to its maximum value. The maximum value of the reference temperature rise is an indicator determined based on the specific structure of the vehicle 100 including the cooling system 10, and can be predetermined through experimentation or simulation. The cooling control device 20 can calculate the reference temperature rise using the formula: "Reference Temperature Rise" = "Maximum Value of Reference Temperature Rise" × ("Torque Target Value Detected in Step S12" / "Maximum Value of Torque Target Value").

[0036] In step S16, the cooling control device 20 acquires a cooling index representing the cooling state of the first PCU 112 based on the heat medium. The cooling index representing the cooling state of the first PCU 112 based on the heat medium includes, for example, the flow rate of the heat medium. While not particularly limited, in this embodiment, the pump 16 is configured to adjust the flow rate of the heat medium according to an operation command sent from the cooling control device 20. Therefore, the cooling control device 20 can determine the flow rate of the heat medium based on its own set operation command value for the pump 16. However, as another embodiment, the cooling control device 20 may also use a sensor or the like to acquire the actual flow rate of the heat medium.

[0037] In step S18, the cooling control device 20 calculates the temperature rise of the heat medium in the first PCU112. As an example, the temperature rise of the heat medium in the first PCU112 can be calculated using the reference temperature rise calculated in step S14 and the flow rate of the heat medium obtained in step S16, through the relationship "temperature rise of heat medium" = "reference temperature rise" × ("reference flow rate" / "flow rate of heat medium").

[0038] In step S20, the cooling control device 20 determines an estimated value for the temperature of the heat medium flowing into the second PCU114. Specifically, the estimated value for the temperature of the heat medium flowing into the second PCU114 is determined by adding the detected temperature from step S10, which is obtained by the temperature sensor 18, to the temperature rise of the heat medium from step S18.

[0039] In the above structure, the temperature of the heat medium flowing into the first PCU112 (equivalent to...) Figure 3The first temperature T1 in the first PCU112 is detected by temperature sensor 18. The temperature of the heat medium flowing into the second PCU114 is estimated by temperature estimation processing. Specifically, the estimated temperature of the heat medium flowing into the second PCU114 is determined by adding the detected temperature (i.e., the temperature of the heat medium flowing into the first PCU112) to the temperature rise of the heat medium in the first PCU112. Figure 3 The second temperature T2 in the middle). According to this structure, the temperature of the heat medium flowing into each PCU112, 114 can be determined by a simple structure without the need to set temperature sensors 18 in both the first PCU112 and the second PCU114.

[0040] In the above structure, it is believed that the target torque value that the front motor 106 should output when the first PCU112 is activated has a significant impact on the heat generation in the first PCU112 compared to other operation command values. Therefore, in Figure 4 In the series of temperature estimation processes shown, the temperature rise of the heat medium in the first PCU112 is calculated based on the target torque value that the front motor 106 should output. According to this structure, the temperature rise of the heat medium in the first PCU112 is calculated based on the target torque value that the front motor 106 should output, without considering other action command values, thereby reducing the computational load of the cooling control device 20.

[0041] Although not specifically limited, in the above temperature estimation process, the cooling control device 20 may consider other heat generation indicators in addition to the target torque value that the front motor 106 should output. Besides the torque output by the front motor 106, heat generation indicators that affect the heat generation of the first PCU 112 may include the input voltage to the first PCU 112, the current flowing through the first PCU 112, the carrier frequency of the first PCU 112, and the control mode of the first PCU 112. The cooling control device 20 may also further determine one or more of these heat generation indicators when calculating the reference temperature rise in step S14, and correct the reference temperature rise based on the determined heat generation indicators.

[0042] Furthermore, the cooling control device 20 does not necessarily need to calculate the temperature rise of the heat transfer medium in the first PCU112 based on the target torque value that the front motor 106 should output. That is, the cooling control device 20 only needs to calculate the temperature rise of the heat transfer medium in the first PCU112 based on at least one heat generation indicator representing the operating state of the first PCU112. Here, the at least one heat generation indicator representing the operating state of the first PCU112 includes not only the aforementioned operating command value for the first PCU112, but also operating parameters related to power loss in the first PCU112 and the actual temperature detected within the first PCU112. Hereinafter, as... Figure 4 The variation of the presumed treatment shown is referred to Figure 5 , 6 The temperature estimation process for calculating the temperature rise of the heat medium in the first PCU112 based on the operating parameters related to the power loss in the first PCU112 or the actual temperature detected in the first PCU112 is explained.

[0043] exist Figure 5 In the temperature estimation process shown, the temperature rise of the heat medium in the first PCU112 is calculated based on the operating parameters related to the power loss in the first PCU112. Figure 5 The temperature estimation process has been changed. Figure 4 The temperature estimation process shown is part of a process that modifies the process of calculating the temperature rise of the heat medium in the first PCU112 (i.e., the processes in steps S12-S18). Therefore, the following will describe... Figure 5 Steps S32-S38 will be explained. Furthermore, Figure 5 Steps S30 and S40 are respectively with Figure 4 Steps S10 and S20 are the same.

[0044] In step S32, the cooling control device 20 communicates with the control device 116 of the vehicle 100 to detect operating parameters related to power loss in the first PCU 112. These operating parameters include at least one of the following: the input voltage to the first PCU 112, the output current of the first PCU 112, the carrier frequency of the first PCU 112, and the control mode of the first PCU 112. These operating parameters can be operating command values ​​or detection values ​​indicating the actual operating state. Furthermore, as mentioned above, the first PCU 112 in this embodiment is an inverter; therefore, the power loss in the first PCU 112 in step S32 refers to the power loss in the inverter.

[0045] In step S34, the cooling control device 20 calculates the power loss in the first PCU112. For example, the cooling control device 20 can pre-store a formula or mapping describing the relationship between the operating parameters related to the power loss in the first PCU112 and the power loss in the first PCU112. Therefore, the cooling control device 20 can calculate the power loss in the first PCU112 based on the operating parameters detected in step S32 and the aforementioned formula or mapping.

[0046] In step S36, the cooling control device 20 acquires a cooling index representing the cooling state of the first PCU112 based on the heat medium. The cooling index representing the cooling state of the first PCU112 based on the heat medium includes, for example, the flow rate of the heat medium. Furthermore, step S36 is related to... Figure 4 The same applies to step S16.

[0047] In step S38, the cooling control device 20 calculates the temperature rise of the heat transfer medium in the first PCU112. For example, the temperature rise of the heat transfer medium in the first PCU112 can be obtained by dividing the power loss in the first PCU112 calculated in step S34 by the heat capacity of the heat transfer medium passing through the first PCU112. That is, the temperature rise of the heat transfer medium can be calculated according to the relationship: "Temperature rise of heat transfer medium" = "Power loss in the first PCU112" / ("Density of heat transfer medium" × "Specific heat of heat transfer medium" × "Flow rate of heat transfer medium obtained in step S36").

[0048] In the above structure, it is assumed that when the first PCU112 operates, the operating parameters related to the power loss in the first PCU112 significantly affect the temperature rise of the heat transfer medium. Here, the operating parameters related to the power loss in the first PCU112 include at least one of the following: the input voltage input to the first PCU112, the output current of the first PCU112, the carrier frequency of the first PCU112, and the control mode of the first PCU112. Figure 5 In the series of temperature estimation processes shown, the temperature rise of the heat transfer medium in the first PCU112 is calculated based on operating parameters related to the power loss in the first PCU112. According to this structure, by relatively reducing the operating parameters to be considered when calculating the temperature rise of the heat transfer medium in the first PCU112, the computational load of the cooling control device 20 can be reduced.

[0049] exist Figure 6 In the temperature estimation process shown, the temperature rise of the heat medium in the first PCU112 is calculated based on the actual temperature detected in the first PCU112. Figure 6 The temperature estimation process has been changed. Figure 4The temperature estimation process shown is part of a process that modifies the process for calculating the reference temperature rise in the first PCU112 (i.e., the processes in steps S12 and S14). Therefore, the following mainly focuses on... Figure 6 Steps S52-S58 will be explained. Furthermore, Figure 6 Steps S50 and S60-S64 are respectively with Figure 4 Steps S10 and S16-S20 are the same.

[0050] In step S52, the cooling control device 20 obtains the actual temperature detected by the component temperature sensor 118a. As described above, the component temperature sensor 118a is built into the semiconductor element 118 disposed in the first PCU 112 and detects the temperature of the semiconductor element 118. In this embodiment, since component temperature sensors 118a are respectively disposed in multiple semiconductor elements 118, each component temperature sensor 118a detects the temperature of the corresponding semiconductor element 118. The detected temperature detected by each component temperature sensor 118a is obtained by the cooling control device 20. Furthermore, the temperature of the semiconductor element 118 does not necessarily have to be the detected value detected by the component temperature sensor 118a, but can also be an estimated value estimated based on the operating state of the first PCU 112 with the built-in semiconductor element 118.

[0051] In step S54, the cooling control device 20 calculates the difference between the temperature of the semiconductor element 118 and the temperature of the heat medium flowing into the first PCU 112 (hereinafter referred to as "difference"). Specifically, the difference is calculated by subtracting the detected temperature obtained in step S50 from the detected temperature obtained in step S52 by the element temperature sensor 118a.

[0052] In step S56, the cooling control device 20 calculates the total heat dissipation of the semiconductor elements 118. For each of the plurality of semiconductor elements 118, the heat dissipation in each semiconductor element 118 is obtained by multiplying the area of ​​the semiconductor element 118 by the difference calculated in step S54. Then, for all semiconductor elements 118, the total heat dissipation of each semiconductor element 118 is obtained by summing the heat dissipation in each semiconductor element 118.

[0053] In step S58, the cooling control device 20 calculates the reference temperature rise. The reference temperature rise is calculated by multiplying the total heat dissipated by the semiconductor element 118 by a predetermined conversion factor. Furthermore, the predetermined conversion factor can be a value determined experimentally or through predetermined steps and calculations. While not particularly limited, the cooling control device 20 in this embodiment stores the predetermined conversion factor in advance.

[0054] Next, the cooling control device 20 acquires cooling indicators representing the cooling state of the first PCU112 based on the heat medium, such as the flow rate of the heat medium (step S60), and calculates the temperature rise of the heat medium in the first PCU112 (step S62). After that, the cooling control device 20 determines an estimated value for the temperature of the heat medium flowing into the second PCU114 (step S64).

[0055] In the above structure, it is assumed that when the first PCU112 operates, the heat generated from the semiconductor element 118 significantly affects the temperature rise of the heat transfer medium. Figure 6 In the series of temperature estimation processes shown, the temperature rise of the heat transfer medium in the first PCU112 is calculated based on the actual temperature detected by the element temperature sensor 118a, which is built into the semiconductor element 118 disposed in the first PCU112. According to this structure, by determining the components to be considered when calculating the temperature rise of the heat transfer medium in the first PCU112, the computational load of the cooling control device 20 can be reduced.

[0056] The above provides detailed examples, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes techniques obtained by various modifications and alterations to the above-described examples. The technical elements described in this specification or the accompanying drawings are useful individually or in combination.

Claims

1. A cooling system for cooling a first unit and a second unit, characterized in that, include: A cooling path that allows the heat medium to flow in the order of the first unit and the second unit; A temperature sensor configured to detect the temperature of the heat medium flowing into the first unit; as well as A control device is connected to the temperature sensor and configured to control the actions of the first unit and the second unit based on the detected temperature detected by the temperature sensor. The control device is configured to perform a temperature estimation process, which estimates the temperature of the heat medium flowing into the second unit based on the detected temperature detected by the temperature sensor. The temperature estimation process includes: Processing to obtain the detected temperature from the temperature sensor; The process of calculating the temperature rise of the heat medium in the first unit; and The process of determining the estimated temperature of the heat medium flowing into the second unit by adding the detected temperature detected by the temperature sensor to the calculated temperature rise is used. The first unit is a power conversion device that controls the power supplied to the electric motor. The control device stores the maximum value of a reference temperature rise, which is the temperature rise of the heat medium generated by the first unit when the flow rate of the heat medium is a predetermined reference flow rate and the target torque value of the motor is set to its maximum value. The process of calculating the temperature rise includes: The steps of obtaining the target torque value that the motor should output and the flow rate of the heat medium flowing in the cooling path; The step of calculating the reference temperature rise by multiplying the maximum value of the reference temperature rise by the ratio of the target torque value to be output by the motor to the maximum value of the target torque value of the motor; and The step of calculating the temperature rise by multiplying the calculated reference temperature rise by the ratio of the reference flow rate to the flow rate of the heat medium.

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