Cooling system

Abstract

To provide a cooling system for more appropriately cooling an electric device.SOLUTION: The cooling system includes a cooling device that circulates and supplies cooling water to a cooling target including an electric device, and a control device that controls the cooling device. The control device sets a temperature threshold based on a season or an outside air temperature, estimates a temperature of the electric device based on a heat generation amount of the cooling target, and increases a flow rate of the cooling water when the temperature of the electric device is higher than the temperature threshold compared to when the temperature of the electric device is equal to or lower than the temperature threshold.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to cooling systems. [Background technology]

[0002] A fuel cell system has been proposed that includes a fuel cell stack, a voltage converter that uses a switching element circuit to step down the output voltage of the fuel cell stack and supplies power to multiple electrical devices, a cooler that includes a refrigerant that cools the voltage converter, and a controller that controls the voltage converter (see, for example, Patent Document 1). In this fuel cell system, the controller determines the upper limit of the output of the voltage converter depending on the temperature of the switching element and the temperature of the refrigerant. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2024-71120 Summary of the Invention [Problem to be solved by the invention]

[0004] In a cooling system equipped with a cooling device that circulates and supplies cooling water to cooling targets including electrical devices, the temperature of the electrical devices is affected by the season (outdoor temperature), and therefore more appropriate cooling of the electrical devices is required. The cooling system of the present disclosure has a primary purpose of more appropriately cooling the electrical devices. [Means for solving the problem]

[0005] The cooling system of the present disclosure employs the following measures to achieve the above-mentioned primary object: The cooling system of the present disclosure includes a cooling device that circulates and supplies cooling water to a cooling target including an electric device, and a control device that controls the cooling device, wherein the control device sets a temperature threshold based on the season or outside air temperature, estimates the temperature of the electric device based on the heat generation amount of the cooling target, and increases the flow rate of the cooling water when the temperature of the electric device is higher than the temperature threshold compared to when the temperature of the electric device is equal to or lower than the temperature threshold.

[0006] In the cooling system of the present disclosure, a temperature threshold is set based on the season or the outside temperature, the temperature of the electrical device is estimated based on the heat generation amount of the cooling target, and when the temperature of the electrical device is higher than the temperature threshold, the flow rate of cooling water is increased compared to when the temperature of the electrical device is equal to or lower than the temperature threshold. This allows the electrical device to be cooled more appropriately based on the season and the outside temperature. For example, by lowering the temperature threshold in winter compared to summer, or by lowering the temperature threshold the lower the outside temperature, the temperature of the electrical device can be lowered in winter or when the outside temperature is low, thereby extending the life of the electrical device. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of a fuel cell vehicle equipped with a cooling system according to an embodiment; [Figure 2] FIG. 2 is a schematic diagram of an electronic control unit provided in a fuel cell vehicle. [Figure 3] 10 is a flowchart illustrating an example of a processing routine. DETAILED DESCRIPTION OF THE INVENTION

[0008] A mode (embodiment) for carrying out the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram of a fuel cell vehicle 10 equipped with a cooling system according to an embodiment of the present disclosure. As shown in the figure, the fuel cell vehicle 10 includes a motor MG, an inverter 14, a fuel cell stack (FC stack) 21, a hydrogen pump (HP) 22, an inverter 23, an air compressor (ACP) 24, an inverter 25, and a DC / DC converter 26. The fuel cell vehicle 10 also includes a DC / DC converter 30, a high-voltage battery 32, a DC / DC converter 34, an auxiliary battery 36, a cooling device 50, and an electronic control unit (ECU) 60. The fuel cell stack 21 and the DC / DC converter 26 are housed in the same case or arranged adjacent to each other, forming a power supply module 20. The inverter 14, the inverter 25, the DC / DC converter 30, the DC / DC converter 34, and the electronic control unit 60 are housed in the same case or arranged adjacent to each other, forming a power control unit (PCU) 12. The inverter 23 and / or the inverter 54 of the cooling device 50 may also be part of the power control unit 12. The cooling system of the embodiment mainly includes the cooling device 50 and the electronic control unit 60.

[0009] The rotor of the motor MG is connected to the drive wheels. The inverter 14 is connected to the power line L1. The inverter 14 is controlled by the electronic control unit 60 and drives the motor MG. The fuel cell stack 21 generates electricity through an electrochemical reaction between hydrogen supplied to the anode electrode and oxygen supplied to the cathode electrode. The hydrogen pump 22 supplies hydrogen from a hydrogen tank to the anode electrode. The inverter 23 is connected to the power line L2. The inverter 23 is controlled by the electronic control unit 60 and drives the hydrogen pump 22. The air compressor 24 supplies oxygen from the air to the cathode electrode. The inverter 25 is connected to the power line L1. The inverter 25 is controlled by the electronic control unit 60 and drives the air compressor 24. The DC / DC converter 26 is connected to the power line L0 and the power line L1. The DC / DC converter 26 is controlled by the electronic control unit 60 and boosts the power on the power line L0 and supplies it to the power line L1.

[0010] The DC / DC converter 30 is connected to the power line L1 and the power line L2. The DC / DC converter 30 is controlled by the electronic control unit 60, and boosts the power on the power line L2 and supplies it to the power line L1, or lowers the power on the power line L1 and supplies it to the power line L2. The high-voltage battery 32 is a battery with a rated voltage of several hundred volts and is connected to the power line L2. The DC / DC converter 34 is connected to the power line L2 and the power line L3. The DC / DC converter 34 is controlled by the electronic control unit 60, and lowers the power on the power line L2 and supplies it to the power line L3. The auxiliary battery 36 is a battery with a rated voltage of approximately 12 volts and is connected to the power line L3.

[0011] The cooling device 50 includes a circulation flow path 51, a reserve tank 52, a water pump 53, an inverter 54, an oil cooler 55, and a radiator 56. The circulation flow path 51 is configured as a flow path for circulating cooling water through the power supply module 20, the power control unit 12, the reserve tank 52, the water pump 53, the air compressor 24, the oil cooler 55, and the radiator 56 in this order. The water pump 53 circulates the cooling water through the circulation flow path 51. The inverter 54 is connected to the power line L2. The inverter 54 is controlled by the electronic control unit 60 and drives the water pump 53.

[0012] As shown in FIGS. 1 and 2 , the electronic control unit 60 includes a microcomputer having a CPU 62 and other components, a power supply circuit 64, various drive circuits, and various logic ICs. The power supply circuit 64 is connected to the power line 16 and converts the power from the power line 16 into a first voltage V1, a second voltage V2, and a third voltage V3, which are output to power lines 65, 67, and 69, respectively. The first, second, and third voltages may be, for example, 5.0 V, 2.5 V, and 1.5 V, respectively. Capacitors 66, 68, and 70 are connected to the power lines 65, 67, and 69, respectively. The voltages on the power lines 65, 67, and 69 are required to operate the CPU 62, the switching elements of the inverters 14, 23, 25, and 54, the DC / DC converters 26, 30, and 34, and various sensors. Signals from the various sensors are input to the electronic control unit 60. For example, the electronic control unit 60 receives inputs such as the voltages VL0, VL1, VL2, and VL3 of the power lines L0, L1, L2, and L3 from the voltage sensors, the output voltage Vfc and output current Ifc of the fuel cell stack 21 from the voltage sensor and current sensor, the rotation speed Nw of the water pump 53 from the rotation speed sensor, the outside air temperature To from the outside air temperature sensor, and a switch signal from the power switch. The electronic control unit 60 calculates the generated power (output power) Pfc of the fuel cell stack 21 based on the output voltage Vfc and output current Ifc of the fuel cell stack 21. Various control signals are output from the electronic control unit 60. For example, control signals are output to the inverters 14, 23, 25, and 54 and the DC / DC converters 26, 30, and 34. Note that at least a portion of the inverters 23 and 54 and the DC / DC converter 26 may be controlled by an electronic control unit other than the electronic control unit 60.

[0013] Next, a description will be given of the operation of the cooling system provided in the fuel cell vehicle 10 of this embodiment. Fig. 3 is a flowchart showing an example of a processing routine repeatedly executed by the CPU 62 of the electronic control unit 60 every predetermined time Δt (for example, several seconds to several tens of seconds).

[0014] When this routine is executed, the CPU 62 determines whether this is the first execution of this routine since the power switch was turned on and the system was started (step S100). If it is determined that this is the first execution of this routine, the CPU 62 sets the threshold value Taref based on the initial temperature Ta0, which is the temperature Ta around the capacitors 66, 68, and 70 when the system was started (step S110), and sets the value of counter C to 0 (step S120), and proceeds to step S140. The initial temperature Ta0 can be, for example, the initial outside air temperature To0, which is the outside air temperature To when the system was started. The threshold value Taref can be set, for example, by applying the initial temperature Ta0 to a threshold map that is predetermined by experiment, analysis, or the like as a relationship between the initial temperature Ta0 and the threshold value Taref, and deriving the corresponding threshold value Taref. In this embodiment, the threshold value Taref is set to be lower as the initial temperature Ta0 is lower. The reason for this will be described later. If it is determined in step S100 that this is the second or subsequent execution of this routine, the CPU 62 increments the value of counter C by 1 (step S130), and proceeds to step S140.

[0015] Next, the heat generation amount Qfcm of the power supply module 20 is estimated based on the power generation amount Pfc of the fuel cell stack 21 (step S140), the inlet water temperature Twi of the power control unit 12 is estimated based on the estimated heat generation amount Qfcm (step S150), and the outlet water temperature Two of the power control unit 12 is estimated based on the estimated inlet water temperature Twi (step S160). The heat generation amount Qfcm can be estimated, for example, by applying the power generation amount Pfc to a heat generation amount map that has been determined in advance through experiments, analysis, etc. as the relationship between the power generation amount Pfc and the heat generation amount Qfcm, and deriving the corresponding heat generation amount Qfc. The inlet water temperature Twi can be estimated, for example, by applying the heat generation amount Qfcm to an inlet water temperature map that has been determined in advance through experiments, analysis, etc. as the relationship between the heat generation amount Qfcm and the inlet water temperature Twi, and deriving the corresponding inlet water temperature Twi. The outlet water temperature Two can be estimated, for example, by applying the inlet water temperature Twi to an outlet water temperature map that is predetermined by experiment, analysis, etc. as the relationship between the inlet water temperature Twi and the outlet water temperature Two, and deriving the corresponding outlet water temperature Two.

[0016] Then, a base temperature Tatmp, which is a base value of the temperature Ta around the capacitors 66, 68, and 70, is estimated based on the inlet water temperature Twi and the outlet water temperature Two (step S170), and the estimated base temperature Tatmp is added to the product of a counter C and a coefficient kt to estimate the temperature Ta (step S180). The base temperature Tatmp can be estimated, for example, by applying the inlet water temperature Twi and the outlet water temperature Two to a base temperature map that is predetermined by experiment, analysis, or the like as a relationship between the inlet water temperature Twi, the outlet water temperature Two, and the base temperature Tatmp, and deriving the corresponding base temperature Tatmp. The coefficient kt is predetermined by experiment, analysis, or the like as the amount of increase in temperature Ta over a predetermined time Δt.

[0017] After estimating temperature Ta in this manner, it is determined whether the estimated temperature Ta is equal to or less than the threshold value Taref (step S190). If it is determined that temperature Ta is equal to or less than threshold value Taref, target rotation speed Nf* of water pump 53 is set to normal value Nw1 (step S200), and target voltage VL3* of power line L3 is set to normal value VL31 (step S210), and this routine ends. After setting target rotation speed Nw* and target voltage VL3*, inverter 54 is controlled so that water pump 53 rotates at target rotation speed Nw*, and DC / DC converter 34 is controlled so that voltage VL3 of power line L3 becomes target voltage VL3*.

[0018] When temperature Ta is higher than threshold value Taref in step S190, target rotation speed Nf* of water pump 53 is set to value Nw2, which is higher than value Nw1 (step S220), and target voltage VL3* of power line L3 is set to value VL32, which is lower than value VL31 (step S230), and this routine ends. When temperature Ta is higher than threshold value Taref, rotation speed Nw of water pump 53 is increased to increase the flow rate of coolant through circulation flow path 51 compared to when temperature Ta is equal to or lower than threshold value Taref, thereby improving the cooling performance of power control unit 12 by the coolant and suppressing an increase in temperature Ta. Furthermore, when temperature Ta is higher than threshold value Taref, voltage VL3 of power line L3 is lowered compared to when temperature Ta is equal to or lower than threshold value Taref, thereby reducing the voltage difference before and after step-down of power supply circuit 64, suppressing the amount of heat generated by power supply circuit 64, and suppressing an increase in temperature Ta.

[0019] In this embodiment, the threshold value Taref is set based on the initial temperature Ta0 (initial outside air temperature To0) around the capacitors 66, 68, 70, so that the capacitors 66, 68, 70 can be more appropriately cooled based on the initial temperature Ta0. Specifically, the threshold value Taref is set to be lower as the initial temperature Ta0 decreases, so that the temperature rise of the capacitors 66, 68, 70 when the initial temperature Ta0 is low can be more effectively suppressed, thereby extending the life of the capacitors 66, 68, 70. When the initial temperature Ta0 is high, the power consumption of the water pump 53 can be prevented from increasing.

[0020] In the cooling system of the embodiment described above, the threshold value Taref is set to decrease as the initial temperature Ta0 (initial outside air temperature To0) decreases, and thereafter, when the temperature Ta is higher than the threshold value Taref, the rotation speed Nw of the water pump 53 is increased to increase the flow rate of the coolant compared to when the temperature Ta is equal to or lower than the threshold value Taref. As a result, when the initial temperature Ta0 is low, the temperature rise of the condensers 66, 68, 70 (objects to be cooled) is further suppressed, thereby extending the life of the condensers 66, 68, 70. When the initial temperature Ta0 is high, the power consumption of the water pump 53 can be suppressed from increasing.

[0021] In the above-described embodiment, the threshold value Taref is set to be lower as the initial temperature Ta0 (initial outside air temperature To0) is lower, but this is not limiting. For example, a year may be divided into two, and the threshold value Taref may be set lower in winter (e.g., November to April) than in summer (May to October). Alternatively, a year may be divided into four, and the threshold value Taref may be set in winter, spring, autumn, and summer from the lowest to the highest.

[0022] In the above-described embodiment, the inlet water temperature Twi of the power control unit 12 is estimated based on the heat generation amount Qfcm of the power supply module 20, and the outlet water temperature Two of the power control unit 12 is estimated based on the estimated inlet water temperature Twi, but this is not limiting. For example, a temperature sensor may be attached near the inlet of the power control unit 12 in the circulation flow path 51, and the inlet water temperature Twi may be detected by this temperature sensor. Alternatively, a temperature sensor may be attached near the outlet of the power control unit 12 in the circulation flow path 51, and the outlet water temperature Two may be detected by this temperature sensor.

[0023] In the above-described embodiment, when the temperature Ta is higher than the threshold value Taref, the rotation speed Nw of the water pump 53 is increased to increase the flow rate of the coolant and the voltage VL3 of the power line L3 is decreased compared to when the temperature Ta is equal to or lower than the threshold value Taref. However, this is not limiting. For example, it is also possible to simply increase the rotation speed Nw of the water pump 53 to increase the flow rate of the coolant.

[0024] In the above-described embodiment, the cooling system is mounted on a fuel cell vehicle 10 including a motor MG, a fuel cell stack 21, a hydrogen pump 22, an air compressor 24, a DC / DC converter 26, etc., and a high-voltage battery 32, but is not limited to this. For example, the cooling system may be mounted on an electric vehicle including a motor and a high-voltage battery, or on a hybrid vehicle including an engine in addition to a motor and a high-voltage battery. Other than these, the cooling system may be one including a cooling device that circulates and supplies coolant to objects to be cooled, including electric devices, and a control device that controls the cooling device.

[0025] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be explained below. In the embodiment, capacitors 66, 68, 70, etc. correspond to the "object to be cooled," cooling device 50 corresponds to the "cooling device," and electronic control unit 60 corresponds to the "control device."

[0026] The above describes the forms for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0027] The present disclosure is applicable to the cooling system manufacturing industry and the like. [Explanation of symbols]

[0028] 10 fuel cell vehicle, 12 power control unit, 14, 23, 25, 54 inverter, 16 power line, 20 power module, 21 fuel cell stack, 22 hydrogen pump, 24 air compressor, 26, 30, 34 DC / DC converter, 32 high-voltage battery, 36 auxiliary battery, 50 cooling device, 51 circulation flow path, 52 reserve tank, 53 water pump, 54 inverter, 55 oil cooler, 56 radiator, 60 electronic control unit, 62 CPU, 64 power circuit, 65, 67, 69, L0 to L3 power lines, 66, 68, 70 capacitor, 72 power control unit.

Claims

[Claim 1] A cooling system including a cooling device that circulates and supplies cooling water to an object to be cooled, including an electric device, and a control device that controls the cooling device, the control device sets a temperature threshold based on the season or an outside air temperature, estimates the temperature of the electric device based on the heat generation amount of the cooling target, and when the temperature of the electric device is higher than the temperature threshold, increases the flow rate of the cooling water compared to when the temperature of the electric device is equal to or lower than the temperature threshold. Cooling system.

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