Cooling System

Abstract

To provide a technology for grasping, with a simple configuration, the temperature of a heat medium flowing into each unit.SOLUTION: A cooling system for cooling a first unit and a second unit includes: a cooling path configured to allow a heat medium to circulated through, in the following order, the first unit and the second unit; a temperature sensor configured to detect a temperature of the heat medium flowing into the first unit; and a control device connected to the temperature sensor and configured to control each operation of the first unit and the second unit according to the temperature detected by the temperature sensor. The control device can execute a temperature estimation process of estimating a temperature of the heat medium flowing into the second unit, based on the temperature detected by the temperature sensor. The temperature estimation process includes a process of acquiring a temperature detected by the temperature sensor, a process of calculating an amount of temperature rise of the heat medium in the first unit; and a process of determining an estimated value of the temperature of the heat medium flowing into the second unit, by adding the calculated amount of temperature rise to the temperature detected by the temperature sensor.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a cooling system. [Background technology]

[0002] Patent Document 1 describes a cooling system for cooling multiple units. This cooling system includes a cooling path that circulates a heat medium through the multiple units, and a temperature sensor that detects the temperature of the heat medium circulating through the cooling path, and is configured to adjust the flow rate of the heat medium, etc., according to the temperature of the heat medium. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-284597 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above cooling system, the heat medium flows through the multiple units in sequence. Therefore, the temperature of the heat medium rises each time it passes through each unit, and the more downstream the unit, the higher the temperature of the heat medium that flows in. Therefore, in order to control the operation of each unit according to the temperature of the heat medium, it is necessary to know the temperature of the heat medium that flows into each unit. In this case, it is possible to provide a temperature sensor in each unit, but this would complicate the configuration.

[0005] In view of the above circumstances, this specification provides a technique for grasping the temperature of a heat medium flowing into each unit with a simple configuration. [Means for solving the problem]

[0006] The technology disclosed in this specification is embodied in a cooling system for cooling a first unit and a second unit. The cooling system includes a cooling path for circulating a heat medium through the first unit and the second unit in this order, a temperature sensor for detecting a temperature of the heat medium flowing into the first unit, and a control device connected to the temperature sensor for controlling the operation of each of the first unit and the second unit according to the temperature detected by the temperature sensor. The control device is capable of executing a temperature estimation process for estimating the temperature of the heat medium flowing into the second unit based on the temperature detected by the temperature sensor. The temperature estimation process includes a process for acquiring the temperature detected by the temperature sensor, a process for calculating an amount of temperature rise of the heat medium in the first unit, and a process for determining an estimated value of the temperature of the heat medium flowing into the second unit by adding the calculated amount of temperature rise to the temperature detected by the temperature sensor.

[0007] In the above-mentioned configuration, 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 by a temperature estimation process. In detail, an estimated value of the temperature of the heat medium flowing into the second unit is determined by adding the temperature rise of the heat medium in the first unit to the temperature detected by the temperature sensor (i.e., the temperature of the heat medium flowing into the first unit). With this configuration, it is possible to grasp the temperature of the heat medium flowing into each unit with a simple configuration without providing a temperature sensor in both the first unit and the second unit. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing a main configuration of a vehicle 100 on which a cooling system 10 of an embodiment is mounted. [Diagram 2] 1 is a diagram for explaining the configuration of a cooling system 10 according to an embodiment, which also shows a first PCU 112, a second PCU 114, and a control device 116 of a vehicle 100. [Diagram 3]1 is a diagram for explaining the temperature of the heat medium flowing through the cooling path 12. Here, the first temperature T1 is the temperature of the heat medium immediately after passing through the radiator 14. The second temperature T2 is the temperature of the heat medium flowing out from the first PCU 112. The third temperature T3 is the temperature of the heat medium flowing out from the second PCU 114. Here, the first temperature T1 matches the temperature of the heat medium flowing into the first PCU 112, and the second temperature T2 matches the temperature of the heat medium flowing into the second PCU 114. [Figure 4] 4 is a flow diagram showing an example of a temperature estimation process executed by the cooling control device 20. [Diagram 5] 6 is a flow diagram showing a modified example of the temperature estimation process executed by the cooling control device 20. FIG. [Figure 6] 6 is a flow diagram showing a modified example of the temperature estimation process executed by the cooling control device 20. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In one embodiment of the present technology, the process of calculating the temperature rise amount may calculate the temperature rise amount based on at least one heat generation index indicating the operating state of the first unit and at least one cooling index indicating the cooling state of the first unit by the heat medium. With this configuration, the temperature of the heat medium flowing into the second unit can be estimated based on the actual operating state and cooling state of the first unit.

[0010] In the above-described embodiment, at least one heat generation index may include an operation command value for the first unit. With this configuration, it is not necessary to remove detection noise compared to a case where the temperature rise amount is calculated based on a detection value that detects the operating state of the first unit, so the temperature rise amount can be calculated more easily. However, in other embodiments, at least one heat generation index may include a detection value that detects the operating state of the first unit.

[0011] In the above embodiment, the first unit may be a power conversion device that controls the power supply to the motor. In this case, the operation command value may be a torque target value to be output by the motor. In the above power conversion device, the torque target value to be output by the motor is considered to have a more significant effect on heat generation in the power conversion device than other operation command values. Therefore, the calculation load of the control device can be reduced by calculating the temperature rise amount of the heat medium in the power conversion device based on the torque target value to be output by the motor without considering other operation command values. However, in other embodiments, the temperature rise amount of the heat medium in the power conversion device may be calculated based on other operation command values ​​in addition to the torque target value to be output by the motor.

[0012] In some of the above-described embodiments, the at least one heat generation indicator may include an operating parameter that is correlated to a power loss in the first unit. In this configuration, the temperature of the heat medium flowing into the second unit can be estimated based on the power loss in the first unit.

[0013] In the above embodiment, the first unit may be a power converter that controls the power supply to the motor. In this case, the operating parameters may include at least one of an input voltage to the power converter, an output current of the power converter, a carrier frequency of the power converter, and a control mode of the power converter. In the above power converter, at least one of an input voltage to the power converter, an output current of the power converter, a carrier frequency of the power converter, and a control mode of the power converter is considered to have a significant effect on the temperature rise of the heat medium. Therefore, by relatively reducing the operating parameters to be considered when calculating the temperature rise of the heat medium in the power converter, the calculation load of the control device can be reduced.

[0014] In some of the above-described embodiments, the at least one heat generation indicator may include an actual temperature detected in the first unit, and in this configuration, the temperature of the heat medium flowing into the second unit can be estimated based on the actual temperature detected in the first unit.

[0015] In the above embodiment, the first unit may be a power conversion device that controls the power supply to the motor. In this case, the actual temperature may be an actual temperature detected by an element temperature sensor built into a semiconductor element provided in the power conversion device. When the above power conversion device is operating, it is considered that the heat generated from the semiconductor element significantly affects the temperature rise of the heat medium. Therefore, by specifying the components to be considered when calculating the temperature rise amount of the heat medium in the power conversion device, the calculation load of the control device can be reduced. The number of semiconductor elements provided in the power conversion device is not particularly limited, and may be at least one. EXAMPLES

[0016] A cooling system 10 according to an embodiment and a vehicle 100 on which the cooling system 10 is mounted will be described with reference to the drawings. The vehicle 100 referred to here is a so-called automobile, which runs on a road surface. As shown in FIG. 1, the vehicle 100 includes a body 102 and a plurality of wheels 104f, 104r. The plurality of wheels 104f, 104r are rotatably attached to the body 102. The plurality of wheels 104f, 104r include 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 arranged coaxially with each other, and the pair of rear wheels 104r are also arranged coaxially with each other. The number of wheels 104f, 104r is not limited to four. Although not particularly limited, the body 102 is made of a metal such as a steel material or an aluminum alloy.

[0017] As shown in FIG. 1, the vehicle 100 further includes a front motor 106 and a rear motor 108. The front motor 106 is connected to a pair of front wheels 104f and can drive the pair of front wheels 104f. The rear motor 108 is connected to a pair of rear wheels 104r and can drive the pair of rear wheels 104r. That is, the vehicle 100 is capable of four-wheel drive. Although not particularly limited, each of the front motor 106 and the rear motor 108 in this embodiment is a three-phase motor generator having a U phase, a V phase, and a W phase.

[0018] 1, the vehicle 100 further includes a battery 110. The battery 110 has a plurality of built-in secondary battery cells and is configured to be repeatedly rechargeable by external power. Although not limited thereto, the battery 110 may be a lithium ion battery, a nickel metal hydride battery, or the like.

[0019] As shown in FIG. 1, the vehicle 100 further includes two power conversion devices (Power Control Units: hereinafter, referred to as "PCUs") 112, 114. The two PCUs 112, 114 can control the power supplied to the corresponding motors 106, 108. The two PCUs 112, 114 include a first PCU 112 and a second PCU 114. The first PCU 112 is provided between the battery 110 and the front motor 106. The first PCU 112 is an inverter and has a plurality of semiconductor elements 118 (see FIG. 2). The first PCU 112 can convert DC power from the battery 110 into AC power and supply it to the front motor 106. The first PCU 112 can also convert AC power generated by the front motor 106 into DC power and supply it to the battery 110. That is, during braking, the vehicle 100 can charge the battery 110 by supplying regenerative power from the front motor 106 to the battery 110. The first PCU 112 may further include a DC-DC converter in addition to the inverter. As shown in FIG. 2, the semiconductor element 118 of the first PCU 112 includes an element temperature sensor 118a for detecting its own temperature.

[0020] The second PCU 114 is provided between the battery 110 and the rear motor 108. The second PCU 114 is an inverter and has a plurality of semiconductor elements 120 (see FIG. 2). The second PCU 114 can convert DC power from the battery 110 into AC power and supply it to the rear motor 108. The second PCU 114 can also convert AC power generated by the rear motor 108 into DC power and supply it to the battery 110. That is, the vehicle 100 can charge the battery 110 by supplying regenerative power by the rear motor 108 to the battery 110 during braking. The second PCU 114 may further have a DC-DC converter in addition to the inverter.

[0021] As shown in FIG. 1, the vehicle 100 further includes a control device 116. The control device 116 is a computer device having a processor, a memory, and the like. The control device 116 may be configured as a single computer device, or may be configured as a combination of multiple computer devices. The control device 116 is communicatively connected 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 operations. For example, operation information describing an operation by a user 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 described above according to the input operation information and vehicle information. For example, the control device 116 can determine torque target values ​​for the front motor 106 and the rear motor 108 according to the input operation information and vehicle information. The control device 116 can then feedback-control the operations of the first PCU 112 and the second PCU 114 so that the actual torques output by the motors 106, 108 become equal to the torque target values.

[0022] Next, a cooling system 10 of the embodiment will be described. The cooling system 10 of the embodiment cools the first PCU 112 and the second PCU 114. As shown in FIG. 2, the cooling system 10 includes a cooling path 12, a radiator 14, and a pump 16. The cooling path 12 is a path through which a heat medium flows. The heat medium may be, for example, cooling water. The radiator 14 exchanges heat between the heat medium and the outside air, and can release heat from the heat medium. The pump 16 is provided in the cooling path 12, and can adjust the flow rate of the heat medium flowing through 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 medium flows through the first PCU 112 and the second PCU 114 in this order, thereby recovering heat from each of the first PCU 112 and the second PCU 114. Therefore, the temperature of the heat medium increases each time it passes through each of the first PCU 112 and the second PCU 114. Then, the radiator 14 releases heat from the heat medium, causing the temperature of the heat medium to decrease.

[0023] Regarding the above point, referring to FIG. 3, a temperature change of the heat medium when the heat medium flows through the cooling path 12 will be described. The heat medium has a first temperature T1 immediately after passing through the radiator 14. Here, the first temperature T1 is a temperature approximately equal to the outside air temperature. Thereafter, the heat medium flows into the first PCU 112 while maintaining the first temperature T1. When the heat medium flows through the first PCU 112, the heat medium recovers heat from the first PCU 112. As a result, the temperature of the heat medium rises to a second temperature T2. When the heat medium flows through the second PCU 114, the heat medium 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, heat is released from the heat medium by heat exchange by the radiator 14. As a result, the temperature of the heat medium drops to the first temperature T1. As described above, the cooling system 10 can manage the temperatures of the first PCU 112 and the second PCU 114 by collecting heat from the first PCU 112 and the second PCU 114 and dissipating the heat from the radiator 14 to the outside.

[0024] As shown in FIG. 2, the cooling system 10 further includes a temperature sensor 18. The temperature sensor 18 detects the temperature of the heat medium flowing into the first PCU 112. As an example, the temperature sensor 18 is provided in the first PCU 112. Note that, as another embodiment, the temperature sensor 18 may be provided at a location that indicates a temperature substantially equal to the temperature of the heat medium flowing into the first PCU 112. For example, as in this embodiment, when it is considered that the temperature of the heat medium does not change from immediately after passing through the radiator 14 to flowing into the first PCU 112, the temperature sensor 18 may be provided at any location between the radiator 14 and the first PCU 112.

[0025] As shown in FIG. 2, the cooling system 10 further includes a cooling control device 20. The cooling control device 20 is a computer device having a processor, a memory, and the like, and controls and monitors the operation of the cooling system 10. The cooling control device 20 may be configured as a single computer device, or may be configured as a combination of multiple computer devices. The cooling control device 20 is communicatively connected to the temperature sensor 18 and can acquire the temperature detected by the temperature sensor 18. In addition, the cooling control device 20 is communicatively connected to the control device 116 of the vehicle 100 and can acquire operation information and vehicle information input to the control device 116. As will be described in detail later, the cooling control device 20 is configured to be able to execute a temperature estimation process for estimating the temperature of the heat medium flowing into the second PCU 114 based on the temperature detected by the temperature sensor 18 and the information acquired from the control device 116. The control device 116 acquires the temperature detected by the temperature sensor 18 and the estimated value by the temperature estimation process from the cooling control device 20, and controls the operations of the first PCU 112 and the second PCU 114 based on them.

[0026] The two cooling targets of the cooling system 10 do not necessarily have to be the first PCU 112 and the second PCU 114. In another embodiment, the cooling system 10 may cool either one of the PCUs 112, 114 and another heat source (e.g., an engine). In yet another embodiment, the cooling targets may be two other heat sources.

[0027] Next, the temperature estimation process executed by the cooling control device 20 will be described with reference to Fig. 4. In step S10, the cooling control device 20 acquires the temperature detected 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, and therefore the temperature acquired by the cooling control device 20 in step S10 is the temperature of the heat medium flowing into the first PCU 112.

[0028] In step S12, the cooling control device 20 communicates with the control device 116 of the vehicle 100 to detect a torque target value to be output by the front motor 106. Here, the torque target value to be output by the front motor 106 is an example of an operation command value for the first PCU 112, and is also an example of a heat generation index that indicates the operating state of the first PCU 112. As another embodiment, the cooling control device 20 may detect the actual torque output by the front motor 106 using a sensor or the like, instead of the torque target value to be output by the front motor 106.

[0029] In step S14, the cooling control device 20 calculates a reference temperature rise amount of the heat medium in the first PCU 112 based on the torque target value detected in step S12. The reference temperature rise amount here means a temperature rise amount of the heat medium that can occur in the first PCU 112 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 amount in order to calculate the reference temperature rise amount. The maximum value of the reference temperature rise amount means a temperature rise amount of the heat medium that can occur in the first PCU 112 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 a maximum value. The maximum value of the reference temperature rise amount is an index determined according to the specific configuration of the vehicle 100 including the cooling system 10, and can be specified in advance by an experiment or a simulation. The cooling control device 20 can calculate the reference temperature rise amount by the relational expression "reference temperature rise amount" = "maximum value of reference temperature rise amount" x ("torque target value detected in step S12" / "maximum value of torque target value").

[0030] In step S16, the cooling control device 20 acquires a cooling index indicating the cooling state of the first PCU 112 by the heat medium. The cooling index indicating the cooling state of the first PCU 112 by the heat medium includes, for example, the flow rate of the heat medium. Although not particularly limited, in this embodiment, the pump 16 is configured to adjust the flow rate of the heat medium in response to an operation command transmitted from the cooling control device 20. Therefore, the cooling control device 20 can specify the flow rate of the heat medium based on the operation command value for the pump 16 set by the cooling control device 20. However, in another embodiment, the cooling control device 20 may acquire the actual flow rate of the heat medium using a sensor or the like.

[0031] In step S18, the cooling control device 20 calculates the amount of temperature rise of the heat medium in the first PCU 112. As an example, the amount of temperature rise of the heat medium in the first PCU 112 can be calculated using the reference amount of temperature rise calculated in step S14 and the flow rate of the heat medium acquired in step S16, according to a relational expression: "amount of temperature rise of the heat medium" = "reference amount of temperature rise" x ("reference flow rate" / "flow rate of the heat medium").

[0032] In step S20, the cooling control device 20 determines an estimate of the temperature of the heat medium flowing into the second PCU 114. In detail, the estimate of the temperature of the heat medium flowing into the second PCU 114 is determined by adding the temperature rise of the heat medium in step S18 to the temperature detected by the temperature sensor 18 in step S10.

[0033] In the above-mentioned configuration, the temperature of the heat medium flowing into the first PCU 112 (corresponding to the first temperature T1 in FIG. 3) is detected by the temperature sensor 18. The temperature of the heat medium flowing into the second PCU 114 is estimated by a temperature estimation process. In detail, an estimated value of the temperature of the heat medium flowing into the second PCU 114 (corresponding to the second temperature T2 in FIG. 3) is determined by adding the temperature rise of the heat medium in the first PCU 112 to the temperature detected by the temperature sensor 18 (i.e., the temperature of the heat medium flowing into the first PCU 112). With this configuration, it is possible to grasp the temperature of the heat medium flowing into each of the PCUs 112 and 114 with a simple configuration without providing the temperature sensor 18 in both the first PCU 112 and the second PCU 114.

[0034] In the above-described configuration, it is considered that the torque target value to be output by the front motor 106 has a more significant effect on heat generation in the first PCU 112 than other operation command values ​​when the first PCU 112 is operating. Therefore, in the series of temperature estimation processes shown in Fig. 4, the temperature rise amount of the heat medium in the first PCU 112 is calculated based on the torque target value to be output by the front motor 106. With this configuration, the calculation load of the cooling control device 20 can be reduced by calculating the temperature rise amount of the heat medium in the first PCU 112 based on the torque target value to be output by the front motor 106 without taking other operation command values ​​into consideration.

[0035] Although not particularly limited, in the above-described temperature estimation process, the cooling control device 20 may take into account other heat generation indexes in addition to the torque target value to be output by the front motor 106. In addition to the torque output by the front motor 106, heat generation indexes that affect the amount of heat generated by the first PCU 112 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. When calculating the reference temperature rise amount in step S14, the cooling control device 20 may further specify one or more of these heat generation indexes and correct the reference temperature rise amount according to the specified heat generation index.

[0036] The cooling control device 20 does not necessarily need to calculate the temperature rise of the heat medium in the first PCU 112 based on the torque target value to be output by the front motor 106. That is, the cooling control device 20 may calculate the temperature rise of the heat medium in the first PCU 112 based on at least one heat generation index indicating the operation state of the first PCU 112. Here, the at least one heat generation index indicating the operation state of the first PCU 112 includes not only the operation command value for the first PCU 112 described above, but also an operation parameter correlated with the power loss in the first PCU 112 and an actual temperature detected in the first PCU 112. In the following, as a modified example of the estimation process shown in FIG. 4, a temperature estimation process for calculating the temperature rise of the heat medium in the first PCU 112 based on an operation parameter correlated with the power loss in the first PCU 112 or an actual temperature detected in the first PCU 112 will be described with reference to FIGS. 5 and 6.

[0037] In the temperature estimation process shown in Fig. 5, the temperature rise of the heat medium in the first PCU 112 is calculated based on an operating parameter correlated with the power loss in the first PCU 112. The temperature estimation process in Fig. 5 is a process in which part of the temperature estimation process shown in Fig. 4, specifically, the process of calculating the temperature rise of the heat medium in the first PCU 112 (i.e., the process of steps S12-S18) is modified. Therefore, steps S32-S38 in Fig. 5 will be described below. Note that steps S30 and S40 in Fig. 5 are similar to steps S10 and S20 in Fig. 4, respectively.

[0038] In step S32, the cooling control device 20 communicates with the control device 116 of the vehicle 100 to detect an operation parameter correlated with the power loss in the first PCU 112. The operation parameter here includes at least one of 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 operation parameters may be operation command values ​​or detection values ​​obtained by detecting an actual operating state. As described above, since the first PCU 112 in this embodiment is an inverter, the power loss in the first PCU 112 in step S32 means the power loss in the inverter.

[0039] In step S34, the cooling control device 20 calculates the power loss in the first PCU 112. As an example, the cooling control device 20 can store in advance a relational expression or a map describing the relationship between the operating parameters correlated with the power loss in the first PCU 112 and the power loss in the first PCU 112. Therefore, the cooling control device 20 can calculate the power loss in the first PCU 112 based on the operating parameters detected in step S32 and the above-mentioned relational expression or map.

[0040] In step S36, the cooling control device 20 acquires a cooling index indicating the cooling state of the first PCU 112 by the heat medium. The cooling index indicating the cooling state of the first PCU 112 by the heat medium includes, for example, the flow rate of the heat medium. Note that step S36 is similar to step S16 in FIG. 4.

[0041] In step S38, the cooling control device 20 calculates the amount of temperature rise of the heat medium in the first PCU 112. As an example, the amount of temperature rise of the heat medium in the first PCU 112 can be found by dividing the power loss in the first PCU 112 calculated in step S34 by the heat capacity of the heat medium passing through the first PCU 112. That is, the amount of temperature rise of the heat medium can be calculated from the relational expression "amount of temperature rise of the heat medium" = "power loss in the first PCU 112" / ("density of the heat medium" x "specific heat of the heat medium" x "flow rate of the heat medium acquired in step S36").

[0042] In the above-mentioned configuration, it is considered that the operation parameters correlated with the power loss in the first PCU 112 significantly affect the temperature rise of the heat medium during the operation of the first PCU 112. Here, the operation parameters correlated with the power loss in the first PCU 112 include at least one of 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. In a series of temperature estimation processes shown in FIG. 5, the temperature rise amount of the heat medium in the first PCU 112 is calculated based on the operation parameters correlated with the power loss in the first PCU 112. With such a configuration, the calculation load of the cooling control device 20 can be reduced by relatively reducing the number of operation parameters to be considered when calculating the temperature rise amount of the heat medium in the first PCU 112.

[0043] In the temperature estimation process shown in Fig. 6, the temperature rise of the heat medium in the first PCU 112 is calculated based on the actual temperature detected in the first PCU 112. The temperature estimation process in Fig. 6 is a process in which part of the temperature estimation process shown in Fig. 4, specifically, the process of calculating the reference temperature rise in the first PCU 112 (i.e., the processes of steps S12 and S14) is modified. Therefore, steps S52-S58 in Fig. 6 will be mainly described below. Note that steps S50 and S60-S64 in Fig. 6 are similar to steps S10 and S16-S20 in Fig. 4, respectively.

[0044] In step S52, the cooling control device 20 acquires the actual temperature detected by the element temperature sensor 118a. As described above, the element temperature sensor 118a is built into the semiconductor element 118 provided in the first PCU 112, and detects the temperature of the semiconductor element 118. In this embodiment, the element temperature sensor 118a is provided in each of the multiple semiconductor elements 118, and each element temperature sensor 118a detects the temperature of the corresponding semiconductor element 118. The detected temperature by each element temperature sensor 118a is acquired by the cooling control device 20. Note that the temperature of the semiconductor element 118 does not necessarily need to be a detected value by the element temperature sensor 118a, and may be an estimated value estimated from the operating state of the first PCU 112 in which the semiconductor element 118 is built.

[0045] In step S54, the cooling control device 20 calculates the difference (hereinafter simply referred to as "difference") between the temperature of the semiconductor element 118 and the temperature of the heat medium flowing into the first PCU 112. In detail, the difference is calculated by subtracting the temperature detected by the temperature sensor 18 obtained in step S50 from the temperature detected by the element temperature sensor 118a obtained in step S52.

[0046] In step S56, cooling control device 20 calculates the total amount of heat exhausted by semiconductor elements 118. For each of the multiple semiconductor elements 118, the area of ​​semiconductor element 118 is multiplied by the difference calculated in step S54 to obtain the amount of heat exhausted by each semiconductor element 118. Then, for all semiconductor elements 118, the amounts of heat exhausted by each semiconductor element 118 are added together to obtain the total amount of heat exhausted by semiconductor elements 118.

[0047] In step S58, the cooling control device 20 calculates a reference temperature rise amount. The reference temperature rise amount is calculated by multiplying the total value of the heat exhausted by the semiconductor elements 118 by a predetermined conversion coefficient. The predetermined conversion coefficient may be a value determined by an experiment, or may be a value determined by a predetermined procedure or formula. Although not particularly limited, the cooling control device 20 in this embodiment stores the predetermined conversion coefficient in advance.

[0048] Next, the cooling control device 20 acquires a cooling index indicating the cooling state of the first PCU 112 by the heat medium, for example, the flow rate of the heat medium (step S60), and calculates the temperature rise amount of the heat medium in the first PCU 112 (step S62). After that, the cooling control device 20 determines an estimate of the temperature of the heat medium flowing into the second PCU 114 (step S64).

[0049] In the above-mentioned configuration, when the first PCU 112 is operating, it is considered that the heat generated from the semiconductor element 118 significantly affects the temperature rise of the heat medium. In a series of temperature estimation processes shown in Fig. 6, the temperature rise amount of the heat medium in the first PCU 112 is calculated based on the actual temperature detected by the element temperature sensor 118a built in the semiconductor element 118 provided in the first PCU 112. With such a configuration, the calculation load of the cooling control device 20 can be reduced by specifying the components to be considered when calculating the temperature rise amount of the heat medium in the first PCU 112.

[0050] Although several specific examples have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical usefulness alone or in combination. [Explanation of symbols]

[0051] 10: Cooling system 12: Cooling path 14: Radiator 16: Pump 18: Temperature sensor 20: Cooling control device 100: Vehicle 102: Body 104f: Front wheel 104r: Rear wheel 106: Front motor 108: Rear motor 110: Battery 112: 1st PCU 114: 2nd PCU 116: Control device 118: Semiconductor elements 118a: Element temperature sensor 120: Semiconductor elements

Claims

[Claim 1] A cooling system for cooling a first unit and a second unit, comprising: a cooling path through which a heat medium flows in the order of the first unit and the second unit; a temperature sensor for detecting a temperature of the heat medium flowing into the first unit; a control device connected to the temperature sensor and controlling operations of the first unit and the second unit in response to a temperature detected by the temperature sensor; Equipped with the control device is capable of executing a temperature estimation process to estimate a temperature of the heat medium flowing into the second unit based on the detected temperature by the temperature sensor; The temperature estimation process includes: A process of acquiring the detected temperature by the temperature sensor; A process of calculating an amount of temperature rise of the heat medium in the first unit; determining an estimated value of a temperature of the heat medium flowing into the second unit by adding the calculated temperature increase amount to the temperature detected by the temperature sensor; the first unit is a power conversion device that controls power supplied to a motor, the control device stores a maximum value of a reference temperature rise amount, which is the temperature rise amount of the heat medium that can occur in the first unit when a flow rate of the heat medium is a predetermined reference flow rate and a torque target value of the motor is set to a maximum value; The process of calculating the temperature rise amount includes: acquiring a target torque value to be output by the motor and a flow rate of the heat medium flowing through the cooling path; calculating a reference temperature rise amount by multiplying the maximum value of the reference temperature rise amount by a ratio of the torque target value to be output by the motor to the maximum value of the torque target value of the motor; and multiplying the calculated reference temperature rise amount by a ratio of the reference flow rate to a flow rate of the heat medium to calculate the temperature rise amount. Cooling system.

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