Method for controlling the cooling water temperature in a fuel cell system

Abstract

To efficiently control the heat management of an electrical component to ensure cooling performance and prevent the life of the electrical component from being shortened.SOLUTION: A control unit 320 determines the rotation speed of a cooling fan on the basis of the cooling water temperature at the inlet of a fuel cell stack and the first outside air temperature, and determines the target cooling performance for the electrical component on the basis of the power consumption of the plurality of electrical components, and sets to determine the rotation speed of a second pump on the basis of the target cooling performance of the electrical component, the rotation speed of the cooling fan, and the second outside air temperature.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The embodiments disclosed in this document relate to a technique for controlling the cooling water temperature in a fuel cell system.

Background Art

[0002] A fuel cell system can generate electrical energy using a fuel cell stack. For example, when hydrogen is used as the fuel of the fuel cell stack, it can be an alternative to solve global environmental problems, and thus continuous research and development on fuel cell systems are being carried out. A fuel cell system includes a fuel cell stack that generates electrical energy, a fuel supply device that supplies fuel (hydrogen) to the fuel cell stack, an air supply device that supplies oxygen in the air, which is an oxidant required for the electrochemical reaction, to the fuel cell stack, and a thermal management system (TMS) that removes the reaction heat of the fuel cell stack to the outside of the system, controls the operating temperature of the fuel cell stack, and performs a water management function.

[0003] The thermal management system is a type of cooling device that circulates an antifreeze liquid serving as cooling water through the fuel cell stack to maintain an appropriate temperature (for example, 60 to 70 °C). It can include a TMS line through which the cooling water circulates, a reservoir in which the cooling water is stored, a pump that circulates the cooling water, an ion filter that removes ions contained in the cooling water, and a radiator that releases the heat of the cooling water to the outside. Further, the thermal management system can include a heater that heats the cooling water, and an air conditioning unit (for example, a heater for heating) that cools and heats the interior of a device (e.g., a vehicle) in which the fuel cell system is included using the cooling water etc. The thermal management system can maintain the appropriate temperature not only of the fuel cell stack but also of the electrical components of the vehicle.

Summary of the Invention

Problems to be Solved by the Invention

[0004] While vehicles with fuel cell systems require high output from the fuel cell during operation, the fuel cell can be cooled by the airflow during driving. On the other hand, construction machinery performs tasks such as leveling and loading even when stationary, requiring high output from the fuel cell and electrical components, but the lack of airflow during driving can lead to insufficient overall cooling. Insufficient cooling can cause the coolant temperature to rise, which can negatively impact the safety and durability of the fuel cell and electrical components. [Means for solving the problem]

[0005] A fuel cell system according to one embodiment disclosed herein includes a fuel cell stack, a first cooling line through which first cooling water circulates via the fuel cell stack, a first pump located on the first cooling line and configured to pump the first cooling water, a first radiator located on the first cooling line and configured to cool the first cooling water, a plurality of electrical components, a second cooling line through which second cooling water circulates via the plurality of electrical components, a second pump located on the second cooling line and configured to pump the second cooling water, and a second cooling system located on the second cooling line and configured to cool the first cooling water. The system includes a second radiator configured to cool the cooling water, a cooling fan configured to blow outside air onto at least one of the first and second radiators, and a control unit connected to the first pump, the second pump, and the cooling fan. The control unit may be configured to determine the rotational speed of the cooling fan based on the cooling water temperature at the fuel cell stack inlet and a first ambient temperature, to determine the target cooling performance of the electrical components based on the power consumption of the electrical components, and to determine the rotational speed of the second pump based on the target cooling performance of the electrical components, the rotational speed of the cooling fan, and the second ambient temperature.

[0006] A method for operating a fuel cell system including a fuel cell stack according to one embodiment disclosed herein may include: determining the rotational speed of a cooling fan based on the cooling water temperature at the fuel cell stack inlet and a first ambient temperature; determining the target cooling performance of a plurality of electrical components based on the power consumption of the electrical components; and determining the rotational speed of a pump configured to pump the cooling water through the plurality of electrical components based on the target cooling performance of the electrical components, the rotational speed of the cooling fan, and a second ambient temperature. [Effects of the Invention]

[0007] According to the embodiments disclosed herein, the fuel cell system can ensure high output of the fuel cell while simultaneously ensuring safety and durability.

[0008] According to the embodiments disclosed herein, the fuel cell system can efficiently control the thermal management of electrical components to ensure cooling performance and prevent a reduction in the lifespan of the electrical components.

[0009] In addition, a variety of other effects may be conveyed, either directly or indirectly, through this document. [Brief explanation of the drawing]

[0010] [Figure 1] This document illustrates fuel cell systems in various embodiments. [Figure 2] This document illustrates fuel cell systems in various embodiments. [Figure 3] Block diagrams of fuel cell systems are shown using various embodiments. [Figure 4] This document illustrates the operational flow of a fuel cell system for controlling cooling water temperature through various embodiments. [Figure 5] This diagram shows the operation flow for determining the rotational speed of a pump using various embodiments. [Figure 6] This diagram shows the operation flow chart for determining the target cooling performance through various embodiments. [Figure 7]This diagram shows the operation flow for determining the rotation speed of the pump and the rotation speed of the cooling fan using various embodiments.

[0011] In relation to the description of the drawings, the same or similar reference numerals may be used for the same or similar components. [Modes for carrying out the invention]

[0012] Various embodiments of the present invention are described below with reference to the drawings. However, this should not be understood as limiting the present invention to any particular embodiment, but rather as including various modifications, equivalents, and / or alternatives to the embodiments of the present invention.

[0013] The various embodiments and terminology used herein are not intended to limit the technical features described herein to any particular embodiment, but should be understood to include various modifications, equivalents, or substitutes of such embodiments. In relation to the description of the drawings, similar or related reference numerals may be used for similar or related components. The singular form of a noun corresponding to an item may include one or more of such items unless otherwise indicated to be clearly different in the context. In this document, each phrase such as “A or B,” “at least one of A and B,” “at least one of A or B,” “A, B or C,” “at least one of A, B and C,” and “at least one of A, B or C” may include any one of the items listed together in the phrase, or any possible combination thereof. Terms such as “first,” “second,” or “first,” or “second” may be used merely to distinguish one component from other such components, and do not limit the component in any other respect (e.g., importance or order). When a component (e.g., the first) is referred to as "coupled" or "connected" with or without such terms, it means that the first component can be connected to the other component directly (e.g., by wire), wirelessly, or via the third component.

[0014] The term "module," as used in various embodiments of this document, may include units embodied in hardware, software, or firmware, and may be used interchangeably with terms such as logic, logic block, component, or circuit. A module can be a single component, or the smallest unit or part thereof of such component that performs one or more functions. For example, according to one embodiment, a module may be embodied in the form of an ASIC (application-specific integrated circuit).

[0015] Various embodiments of this document may be embodied in software (e.g., a program) containing one or more instruction words stored in a machine-readable storage medium (e.g., internal memory or external memory). For example, a machine may invoke and perform at least one instruction from the one or more instruction words stored in the storage medium. This enables the machine to be operated to perform at least one function by the invoked at least one instruction word. The one or more instruction words may include code generated by a compiler or code that can be performed by an interpreter. The machine-readable storage medium may be provided in the form of a non-transitory storage medium. Here, "non-transitory" simply means that the storage medium is a tangible device and does not contain signals (e.g., electromagnetic waves), and this term does not distinguish between cases where data is stored semi-permanently and cases where it is stored temporarily on the storage medium.

[0016] According to one embodiment, the methods according to the various embodiments disclosed herein may be provided as part of a computer program product. The computer program product may be traded as a commodity between a seller and a buyer. The computer program product may be distributed in the form of a device-readable storage medium (e.g., compact disc read-only memory (CD-ROM)) or online (e.g., download or upload) via an application store or directly between two user devices. In the case of online distribution, at least a portion of the computer program product may be temporarily stored or temporarily generated in a device-readable storage medium such as the memory of a manufacturer's server, an application store server, or an intermediary server.

[0017] According to various embodiments, each of the components (e.g., modules or programs) described above may include one or more entities, and some of the multiple entities may be separately arranged from other components. According to various embodiments, one or more of the aforementioned components or operations may be omitted, or one or more other components or operations may be added. Alternatively or additionally, multiple components (e.g., modules or programs) may be integrated into one component. In such a case, the integrated component can perform one or more functions of each of the multiple components in the same or similar manner as those performed by the corresponding component among the multiple components before the integration. According to various embodiments, the operations performed by a module, program, or other component may be executed sequentially, in parallel, repeatedly, or heuristically, or one or more of the operations may be executed in a different order, omitted, or one or more other operations may be added.

[0018] Figures 1 to 2 show a fuel cell system according to various embodiments.

[0019] Referring to FIG. 1, a vehicle fuel cell system may include a first cooling line 110 through which a first cooling water circulates via a fuel cell stack 10 of the vehicle, and a second cooling line 120 through which a second cooling water circulates via power electronic parts 200 of the vehicle. In an embodiment, the fuel cell system may further include a heat exchanger 300 for mutually heat-exchanging the first cooling water and the second cooling water, but it can be omitted.

[0020] The fuel cell system may form a heating loop (heating circulation path, or heating loop) with the first cooling line 110, or may include a first connecting line 130, a second connecting line 150, and a third connecting line 140 to form a cooling line with the first cooling line 110. The first coolant may be cooled or heated while circulating through the first connecting line 130, the second connecting line 150, or the third connecting line 140. For example, the first cooling line 110 may form a heating loop with the first connecting line 130 and the third connecting line 140 to ensure cold-start capability in the initial starting state of the vehicle, and during driving, it may form a cooling loop through which the first coolant passes the first radiator 60 so that the heat generated in the fuel cell stack 10 can be released to the outside. In another embodiment, if the outside air is as high as a specified temperature, the first cooling line 110 may not form a heating loop, and the fuel cell system may be able to ensure starting capability by the heat of the fuel cell stack 10. A fuel cell stack 10, a first valve 20, a first pump 30, a second valve 40, and a first radiator 60 may be arranged on the first cooling line 110 through which the first cooling water circulates.

[0021] A fuel cell stack 10 (or may be referred to as a "fuel cell") can be formed into a structure capable of producing electricity through a redox reaction between a fuel (e.g., hydrogen) and an oxidizer (e.g., air). As an example, the fuel cell stack 10 may include a membrane electrode assembly (MEA) with a central electrolyte membrane on which hydrogen ions move, and catalytic electrode layers attached to both sides of the membrane where electrochemical reactions occur; a gas diffusion layer (GDL) that uniformly distributes the reaction gas and transmits the generated electrical energy; gaskets and fasteners for maintaining airtightness and proper fastening pressure of the reaction gas and first coolant; and a bipolar plate for moving the reaction gas and first coolant.

[0022] In the fuel cell stack 10, hydrogen as fuel and air (oxygen) as an oxidant are respectively supplied to the anode and cathode of the membrane electrode assembly through the flow channels of the separator plate. Hydrogen can be supplied to the anode and air can be supplied to the cathode. The hydrogen supplied to the anode is decomposed into hydrogen ions (protons) and electrons by the catalyst of the electrode layer formed on both sides of the electrolyte membrane. Among these, only the hydrogen ions selectively pass through the electrolyte membrane, which is a cation exchange membrane, and are transmitted to the cathode. At the same time, the electrons can be transmitted to the cathode through the gas diffusion layer, which is a conductor, and the separator plate. At the cathode, the hydrogen ions supplied through the electrolyte membrane and the electrons transmitted through the separator plate can react with the oxygen in the air supplied to the cathode by the air supply device to generate water. At this time, due to the movement of the hydrogen ions that occurs, a flow of electrons through the external conductor is generated, and a current can be generated by such a flow of electrons.

[0023] The first valve 20 can switch the flow path of the first cooling water on the first cooling line 110 to either the first connecting line 130 where the heater 50 is located or the fuel cell stack 10. For example, the first valve 20 may be connected to one end of the first pump 30, one end of the first connecting line 130, and one end of the fuel cell stack 10 on the first cooling line 110. The first valve 20 may include a variety of valve means that can selectively switch the flow path of the first cooling water. As an example, the first valve 20 may be a three-way valve. In this case, the first valve 20 may include a first port 21 connected to the first cooling line 110 so that the first cooling water pumped by the first pump 30 flows into it, a second port 22 connected to the first cooling line 110 so that the first cooling water passing through the first valve 20 flows into the fuel cell stack 10, and a third port 23 connected to one end of the first connecting line 130. By opening and closing the second port 22 and third port 23 of the first valve 20, the flow path of the first cooling water may be switched to either the heater 50 of the first connecting line 130 or the fuel cell stack 10. That is, if the second port 22 is opened and the third port 23 is closed, the first cooling water flows into the fuel cell stack 10, and conversely, if the third port 23 is opened and the second port 22 is closed, the first cooling water may flow into the heater 50 via the first connecting line 130.

[0024] The first connecting line 130 can form a heating loop (heating circulation path) with the first cooling line 110 to heat the first cooling water. For example, the first cooling water flowing along the first connecting line 130 may be heated as it passes through a heater 50 provided in the first connecting line 130. One end of the first connecting line 130 may be connected to the first cooling line 110 at a first point located between the outlet of the first pump 30 and the fuel cell stack 10, and the other end of the first connecting line 130 may be connected to the first cooling line 110 at a second point located between the inlet of the first pump 30 and the fuel cell stack 10. Here, the inlet of the first pump 30 may be defined as the inlet through which the first cooling water flows into the first pump 30. The outlet of the first pump 30 may be defined as the outlet through which the first cooling water that has passed through the first pump 30 is discharged. Furthermore, the section between the outlet of the first pump 30 and the fuel cell stack 10 can be defined as the section through which the first cooling water discharged from the first pump 30 flows to the first cooling water inlet (not shown) of the fuel cell stack 10. Also, the section between the inlet of the first pump 30 and the fuel cell stack 10 can be defined as the section through which the first cooling water discharged from the cooling water outlet (not shown) of the fuel cell stack 10 flows to the inlet of the first pump 30.

[0025] The first pump 30 may be configured to force the flow of the first cooling water. The first pump 30 may include a variety of means for pumping the first cooling water, and the type and number of the first pump 30 are not limited in this document.

[0026] The second valve 40 can switch the flow path of the first coolant on the first cooling line 110 to either the first radiator 60 or the fuel cell stack 10. For example, the second valve 40 may be provided on the first cooling line 110 so as to be located between the first pump 30 and the first radiator 60, and may be connected to one end of the third connecting line 140 and to the outlet of the first radiator 60. The second valve 40 may include a variety of valve means that can selectively switch the flow path of the first coolant to either the first radiator 60 or the fuel cell stack 10. As an example, the second valve 40 may be a four-way valve or a three-way valve. In the case of a three-way valve, the second valve 40 includes a first port 41 connected to a third connecting line 140, a second port 42 connected to a first cooling line 110 so that the first coolant passing through the first radiator 60 flows in, and a third port 44 connected to the first cooling line 110 so that the first coolant flows into the first pump 30. A four-way valve of the second valve 40 may further include a third port 43 connected to one end of the second connecting line 150. The flow path of the first coolant may be switched to the first radiator 60 or the fuel cell stack 10 by opening or closing the first port 41 or the second port 42 of the second valve 40. In other words, if the first port 41 is opened and the second port 42 is closed, the first coolant flows into the fuel cell stack 10 without passing through the first radiator 60. Conversely, if the second port 42 is opened and the first port 41 is closed, the first coolant may flow into the fuel cell stack 10 after passing through the first radiator 60.

[0027] The second connection line 150 can form a heating loop with the first cooling line 110 to heat the HVAC unit 90. For example, the second connection line 150 can form a loop to heat a heating heater (not shown) of the HVAC unit 90. One end of the second connection line 150 is connected to the first cooling line 110 between a first point (where one end of the first connection line 130 is connected to the first cooling line 110) and the inlet of the fuel cell stack 10, so that a portion of the first cooling water can circulate through the second connection line 150. The other end of the second connection line 150 may be connected to the first cooling line 110 between the first pump 30 and a second point (where the other end of the first connection line 130 is connected to the first cooling line 110).

[0028] The second connection line 150 may be equipped with an ion filter 95 for filtering ions from the first cooling water that has passed through the air conditioning unit 90. If the electrical conductivity of the first cooling water increases due to system corrosion or exudation, electricity will flow through the first cooling water, causing problems such as a short circuit in the fuel cell stack 10 or current flowing to the first cooling water side. Therefore, the first cooling water must maintain a low electrical conductivity. The ion filter 95 may be set to remove ions contained in the first cooling water so that the electrical conductivity of the first cooling water can be maintained below a certain level. In this way, during a cold start when the supply of first cooling water flowing to the fuel cell stack 10 is cut off (the second port 22 of the first valve 20 is cut off), the first cooling water circulates via the heater 50 of the first connection line 130 (heating loop) and at the same time circulates along the second connection line 150, so that filtering (removal of ions contained in the first cooling water) by the ion filter 95 provided in the second connection line 150 is possible even during a cold start. Therefore, it is possible to obtain the advantageous effect of maintaining the electrical conductivity of the first cooling water flowing into the fuel cell stack 10 immediately after cold start below a certain level.

[0029] The third connecting line 140 can form a cooling loop with the first cooling line 110 to cool the first cooling water. For example, one end of the third connecting line 140 may be connected to the first cooling line 110 between the first pump 30 and the first radiator 60, and the other end of the third connecting line 140 may be connected to the first cooling line 110 between the cooling water outlet of the fuel cell stack 10 and the first radiator 60.

[0030] The first radiator 60 may be configured to cool the first coolant. The first radiator 60 may be formed in a variety of structures capable of cooling the first coolant, and the present invention is not limited or restricted by the type and structure of the first radiator 60. The first radiator 60 may be connected to a first reservoir 62 in which the first coolant is stored.

[0031] The fuel cell system may include a first temperature sensor 112 that measures the temperature of the first cooling water between the fuel cell stack 10 and a first point (first valve 20), a second temperature sensor 114 that measures the temperature of the first cooling water between the other end of the first connecting line 130 and the first pump 30, and a third temperature sensor 116 that measures the temperature of the first cooling water at the heater 50. Based on the temperatures measured by the first temperature sensor 112, the second temperature sensor 114, and the third temperature sensor 116, the fuel cell system can control the inflow rate of the first cooling water flowing into the fuel cell stack 10. For example, if the measured temperature of the first cooling water circulating along the first cooling line 110 is lower than a preset target temperature, the inflow rate of the first cooling water can be controlled to be lower than a preset set flow rate. Thus, when the measured temperature of the first cooling water is low, by controlling the inflow rate of the first cooling water flowing into the fuel cell stack 10 to a low level, it is possible to obtain the advantageous effect of minimizing thermal shock and performance degradation caused by the difference between the temperature of the first cooling water stagnating inside the fuel cell stack 10 and the temperature of the first cooling water flowing into the fuel cell stack 10.

[0032] The second cooling line 120 is configured to pass through the vehicle's electrical components 200, and the second coolant can circulate along the second cooling line 120. Here, the vehicle's electrical components 200 may be understood as components that use the vehicle's power supply as an energy source, and the present invention is not limited or restricted by the type and number of electrical components 200. As an example, the electrical components 200 may include at least one of the following: a BHDC (bi-directional high voltage DC-DC converter) 210 provided between the fuel cell stack 10 and the vehicle's high-voltage battery (not shown); a BPCU (blower pump control unit) 220 that controls a blower (not shown) that supplies outside air for driving the fuel cell stack 10; an LDC (low-voltage DC-DC converter) 230 that converts the DC high voltage supplied by the high-voltage battery to DC low voltage; an air compressor (ACP) 240 that compresses the air supplied to the fuel cell stack 10; and an air cooler 250. Although not shown in Figures 1 or 2, the electrical component 200 may further include a DC-DC buck / boost converter.

[0033] A second pump 205 may be provided on the second cooling line 120 for forcibly circulating the second cooling water. The second pump 205 may include pumping means capable of pumping the second cooling water, and the type and characteristics of the second pump 205 are not limited or restrictive.

[0034] A second radiator 70 for cooling the second coolant may be located on the second cooling line 120. The second radiator 70 may be formed in a variety of structures capable of cooling the second coolant, and the type and structure of the second radiator 70 are not limited or restricted. The second radiator 70 may be connected to a second reservoir 72 in which the second coolant is stored.

[0035] In one embodiment, the first radiator 60 and the second radiator 70 may be configured to be cooled simultaneously by a single cooling fan 80, as shown in Figure 1. For example, the first radiator 60 and the second radiator 70 may be arranged side by side, and the cooling fan 80 may be configured to blow outside air onto the first radiator 60 and the second radiator 70. By having the first radiator 60 and the second radiator 70 cooled simultaneously by a single cooling fan 80, the structure of the fuel cell system can be simplified, design flexibility and space utilization can be improved, and the power consumption for cooling the first radiator 60 and the second radiator 70 can be minimized. Such a cooling fan 80 configuration may be referred to as a "dual type".

[0036] In other embodiments, as shown in Figure 2, a first cooling fan 80 for cooling the first radiator 60 and a second cooling fan 85 for cooling the second radiator 70 may be separately provided. In this case, the fuel cell system can eliminate parameters related to the thermal load of the electrical components 200 when controlling the rotational speed of the first cooling fan 80. Such a cooling fan structure 80, 85 may be referred to as a "multi-type" structure.

[0037] The heat exchanger 300 may be configured to allow the first coolant and the second coolant to exchange heat with each other. When the heat exchanger 300 is included, the first cooling line 110 and the second cooling line 120 can constitute a thermal management system (TMS) line in which the first and second coolants can flow while exchanging heat. In this case, the first or second coolant may be used as a cooling medium or heat medium on the TMS line. For example, since the temperature of the second coolant that cools the electrical components is set to be relatively lower than the temperature of the first coolant that cools the fuel cell stack 10, the fuel cell system can lower the temperature of the first coolant without increasing the capacity of the first radiator 60 and the cooling fan 80 by allowing the first and second coolants to exchange heat with each other, thereby improving the cooling efficiency of the fuel cell stack 10 and obtaining advantageous effects that improve safety and reliability. Furthermore, since the fuel cell system can lower the temperature of the first cooling water while the vehicle is stopped and airflow cannot be used (for example, construction machinery), it can ensure high-power operation of the fuel cell stack 10, thereby providing advantageous effects that improve safety and durability.

[0038] In one embodiment, the heat exchanger 300 is connected to a first cooling line 110 between the outlet of the first radiator 60 and the fuel cell stack 10, and a second cooling line 120 can connect the outlet of the second radiator 70 to electrical components via the heat exchanger 300. For example, the first coolant may flow along the heat exchanger 300 connected to the first cooling line 110, and the second cooling line 120 can pass through the inside of the heat exchanger 300 so as to be exposed to the first coolant (for example, the first coolant flows along the second cooling line 120). In this way, the fuel cell system can lower the temperature of the first coolant flowing into the fuel cell stack 10 through mutual heat exchange between the first and second coolants. The first temperature of the first coolant after passing through the first radiator 60 may be higher than the second temperature of the second coolant after passing through the second radiator 70, and the third temperature of the first coolant after passing through the heat exchanger 300 may be lower than the first temperature. For example, the first temperature of the first coolant may be approximately 10°C higher than the second temperature of the second coolant, and the third temperature of the first coolant after passing through the heat exchanger 300 (exchanging heat with the second coolant) may be 1°C lower than the first temperature.

[0039] The heat exchanger 300 shown in Figures 1 and 2 is positioned separately from the first radiator 60, but in other embodiments, the heat exchanger 300 may be directly connected to the first radiator 60. For example, the heat exchanger 300 may be connected to a designated position (upper left end) of the first radiator 60, but is not limited thereto.

[0040] In the case of vehicles that require high output even when stationary, such as construction machinery, the cooling performance of the electrical components 200 must be guaranteed. Therefore, the fuel cell system according to this embodiment can determine the rotation speed of the second pump 205 by considering the rotation speed of the cooling fan 80 or 85, the ambient temperature, and the target cooling performance of the electrical components 200. Furthermore, the fuel cell system can optimize the cooling performance within the fuel cell system where the first cooling line 110 and the second cooling line 120 coexist by determining the rotation speed of the second pump 205 by considering at least one of the following: the arrangement of the heat exchanger 300, the structure of the cooling fan (e.g., dual type or multi type), and the inflow air volume of the radiators 60 and 70.

[0041] Figure 3 shows block diagrams of fuel cell systems in various embodiments. The configurations shown in Figure 3 may be hardware devices or programs (or applications) containing instructions.

[0042] Referring to Figure 3, the temperature measuring unit 312 may include at least one of the temperature sensors 112, 114, and 116 shown in Figures 1 and 2. The temperature measuring unit 312 can measure the temperature of the cooling water passing through the fuel cell stack 10 or the electrical components 200. The power consumption measuring unit 314 can measure the power consumption of the electrical components 200. The ambient temperature measuring unit 316 can measure the ambient temperature of the fuel cell system at specified intervals.

[0043] The control unit 520 may be a hardware device such as a processor or a CPU (central processing unit), or a program implemented by a processor. The control unit 320 can determine the rotational speeds of the first pump 30, the cooling fan 80 or 85, and the second pump 205 based on information measured via the temperature measuring unit 312, the power consumption measuring unit 314, and the ambient temperature measuring unit 316. To implement this, the control unit 320 may include a first target cooling performance calculation unit 321, a second target cooling performance calculation unit 322, a cooling fan control unit 323, a first pump control unit 324, and a second pump control unit 325. The first target cooling performance calculation unit 321 can calculate the target cooling performance of the fuel cell stack 10 based on the output and efficiency of the fuel cell stack 10. The second target cooling performance calculation unit 322 can calculate the target cooling performance of the electrical components 200 based on the power consumption and inefficiency of the electrical components 200. The cooling fan control unit 323 can determine the rotational speed of the cooling fan 80 or 85, the first pump control unit 324 can determine the rotational speed of the first pump 30, and the second pump control unit 325 can determine the rotational speed of the second pump 205. In this embodiment, each of the components included in the control unit 320 may be embodied as a separate module, chip, or program, or as a single integrated module. Figure 4 shows the operational flow of a fuel cell system for controlling cooling water temperature in various embodiments.

[0044] Referring to FIG. 4, the control unit 320 determines the rotation speed of the cooling fan 80 based on the cooling water temperature at the inlet of the fuel cell stack 10 and the outside air temperature (the first outside air temperature), determines the target cooling performance of the electrical component 200 based on the power consumption of the electrical component 200, and then can determine the rotation speed of the second pump 205 based on the re-measured outside air temperature (the second outside air temperature), the rotation speed of the cooling fan 80, and the target cooling performance of the electrical component 200. The control unit 320 can determine the flow rate of the second cooling water for the electrical component 200 to meet the target cooling performance, and determine the rotation speed of the second pump 205 based on the determined flow rate. When the fuel cell system includes multi-type cooling fans 80 and 85, the control unit 320 can determine the rotation speed of the second pump 205 using the rotation speed of the cooling fan 85.

[0045] The control unit 320 can store, as a database, table information (e.g., a look-up table) indicating the relationship among the target cooling performance of the electrical component 200, the rotation speed of the cooling fan 80, the outside air temperature, and the rotation speed of the second pump 205. For example, the table information can be represented by the following [Table 1].

[0046]

Table 1

[0047] In [Table 1], the target cooling performance and the rotation speed of the cooling fan can have the relationships of 0 < A < B and 0 < a < b, respectively. Since the performance of the second pump 205 is finite, the control unit 320 sets the rotation speed of the second pump 205 above a certain level to the maximum rotation speed. On the contrary, when the second pump 205 rotates below a certain level, since it has no influence on the cooling performance, the control unit 320 can set the rotation speed of the second pump 205 below a certain level to the minimum rotation speed. Since the values indicating the outside air temperature, the target cooling performance, and the rotation speed of the cooling fan are discrete, the values between the values shown in the table information can be processed by interpolation.

[0048] The control unit 320 can determine the rotation speed of the cooling fan 80 based on at least one of the target cooling performance of the fuel cell stack 10 and the rotation speed of the first pump 30. In this case, the control unit 320 can determine the target cooling performance of the fuel cell stack 10 based on the output and efficiency of the fuel cell stack 10, and then determine the rotation speed of the first pump 30 based on the determined target cooling performance and the cooling water temperature at the outlet of the fuel cell stack 10.

[0049] The control unit 320 can determine the target cooling performance of the electrical components 200 based on the power consumption and inefficiency of the electrical components 200. For example, the second target cooling performance calculation unit 322 can determine the target cooling performance (CP) of the electrical components 200 using the following formula 1.

[0050]

number

[0051] In [Equation 1], power n is the power consumption of each configuration of electrical components 200 (e.g., 210, 220, 230, 240, 250), 1-Effn is the inefficiency of each configuration of electrical components 200, and a is the weighted value. N is a natural number and can be changed depending on the number of components in the electrical components 200.

[0052] Even if the radiators 60 and 70 are a dual type sharing a cooling fan 80, the control unit 320 can determine the amount of airflow into the radiators 60 and 70 depending on the area and airflow resistance of each radiator 60 and 70, since the amount of airflow into the radiators 60 and 70 may differ depending on the area and airflow resistance of each radiator, the control unit 320 according to this embodiment can calculate the amount of airflow into the second radiator 70 by considering the rotation speed of the cooling fan 80 and the area and airflow resistance of the second radiator 70, and then determine the rotation speed of the second pump 205 by further considering the calculated amount of airflow.

[0053] If the rotational speed of the second pump 205 is at its maximum, the control unit 320 can increase the rotational speed of the cooling fan 80 to ensure the cooling performance of the electrical components 200. If the rotational speed of the cooling fan 80 is also at its maximum, the fuel cell system can further include a heat exchanger 300 to exchange heat between the first cooling water and the second cooling water.

[0054] Figure 5 shows an operational flowchart for determining the pump rotation speed according to various embodiments. The operations described below can be implemented by a fuel cell system or a configuration of a fuel cell system (e.g., control unit 320).

[0055] Referring to Figure 5, in operation 510, the control unit 320 can determine the rotation speed of the cooling fan 80 based on the cooling water temperature at the inlet of the fuel cell stack 10 and the first ambient temperature.

[0056] In operation 520, the control unit 320 can calculate the amount of air flowing into the second radiator 70 based on the area and airflow resistance of the second radiator 70. In some embodiments, the control unit 320 may omit operation 520.

[0057] In operation 530, the control unit 320 can determine the target cooling performance of the electrical components 200 based on the power consumption.

[0058] In operation 540, the control unit 320 can determine the rotation speed of the second pump 205 based on the target cooling performance of the electrical components 200, the rotation speed of the cooling fan 80, and the second ambient temperature. The second ambient temperature may be the ambient temperature measured after the first ambient temperature has been measured.

[0059] Figure 6 shows an operation flow chart for determining the target cooling performance using various embodiments. The operation shown in Figure 6 may be an example of operation 530 in Figure 5.

[0060] Referring to Figure 6, in operation 610, the control unit 320 can measure the power consumption of the electrical components 200. The electrical components 200 may consist of multiple components, in which case the control unit 320 can measure the power consumption of each of the multiple electrical components 200.

[0061] In operation 620, the control unit 320 can calculate the amount of heat generated by each of the electrical components 200 based on the measured power consumption and the inefficiency (1 - efficiency) of the electrical components 200.

[0062] In operation 630, the control unit 320 can determine the target cooling performance for the entire electrical component 200 by summing up the calculated heat generation amounts for each component.

[0063] Figure 7 shows an operation flow diagram for determining the rotation speed of the pump and the rotation speed of the cooling fan using various embodiments.

[0064] Referring to Figure 7, in operation 710, the control unit 320 can measure the ambient temperature (e.g., second ambient temperature).

[0065] In operation 720, the control unit 320 can determine the rotation speed of the second pump 205 based on the ambient temperature and the rotation speed of the cooling fan 80 (e.g., operation 540 in Figure 5).

[0066] In operation 730, the control unit 320 can check whether the cooling performance of the electrical components 200 meets the target cooling performance at the determined rotational speed of the second pump 205. If the cooling performance of the electrical components 200 meets the target cooling performance, in operation 740, the control unit 320 can store the determined rotational speed of the second pump 205 and the rotational speed of the cooling fan 80. The control unit 320 can control the operation of the second pump 205 and the cooling fan 80 based on the stored rotational speeds.

[0067] If the cooling performance of the electrical component 200 does not meet the target cooling performance, in operation 750, the control 320 can check whether the rotational speed of the second pump 205 is equal to or greater than the maximum rotational speed. If the rotational speed of the second pump 205 is less than the maximum rotational speed, the control unit 320 can increase the rotational speed of the second pump 205 in operation 760 and repeat operations 710 to 730. If the rotational speed of the second pump 205 is equal to or greater than the maximum rotational speed, the control unit 320 can increase the rotational speed of the cooling fan 80 in operation 770 and repeat operations 710 to 730.

Claims

1. A fuel cell system, Fuel cell stack and A first cooling line through which the first cooling water passing through the fuel cell stack is circulated, A first pump is positioned on the first cooling line and configured to pump the first cooling water, A first radiator is positioned on the first cooling line and configured to cool the first coolant, Multiple electrical components, A second cooling line through which the second cooling water circulates via the aforementioned plurality of electrical components, A second pump is positioned on the second cooling line and configured to pump the second cooling water, A second radiator is positioned on the second cooling line and configured to cool the second cooling water, A cooling fan configured to blow outside air onto at least one of the first radiator and the second radiator, The system includes the first pump, the second pump, and a control unit connected to the cooling fan, wherein the control unit is The rotation speed of the cooling fan is determined based on the cooling water temperature at the inlet of the fuel cell stack and the first ambient temperature measured by the ambient temperature measuring unit. Based on the power consumption of the aforementioned multiple electrical components, the target cooling performance of the electrical components is determined, and A fuel cell system configured to determine the rotation speed of the second pump based on the target cooling performance of the electrical components, the rotation speed of the cooling fan, and the second ambient temperature measured by the ambient temperature measuring unit after the first ambient temperature has been measured.

2. The control unit, The fuel cell system according to claim 1, further configured to determine the rotational speed of the second pump based on the area and airflow resistance of the second radiator.

3. The control unit, The power consumption of each of the aforementioned multiple electrical components is measured, Based on the power consumption and the inefficiencies of each of the multiple electrical components, the amount of heat generated by each of the multiple electrical components is calculated, and The fuel cell system according to claim 1, wherein the system is configured to determine the target cooling performance of the electrical components by summing up the heat generated.

4. The control unit, When the rotational speed of the second pump satisfies the cooling performance of the electrical components, the rotational speed of the second pump and the rotational speed of the cooling fan are stored, and The fuel cell system according to claim 1, wherein, at the rotational speed of the second pump, if the cooling performance of the electrical components does not meet the target cooling performance of the electrical components, the rotational speed of the second pump or the rotational speed of the cooling fan is set to increase.

5. The control unit, If the rotational speed of the second pump is less than the maximum rotational speed, increase the rotational speed of the second pump, and The fuel cell system according to claim 4, wherein the rotation speed of the cooling fan is set to increase if the rotation speed of the second pump is equal to or greater than the maximum rotation speed.

6. The control unit, The fuel cell system according to claim 1, further configured to determine the rotational speed of the cooling fan based on at least one of the output of the fuel cell stack, the efficiency of the fuel cell stack, and the rotational speed of the first pump.

7. The fuel cell system according to claim 1, further comprising a heat exchanger disposed on the first cooling line and the second cooling line and configured to exchange heat between the first cooling water and the second cooling water.

8. A method for operating a fuel cell system, The operation of determining the rotation speed of the cooling fan based on the cooling water temperature at the inlet of the fuel cell stack and the first ambient temperature measured by the ambient temperature measurement unit, An operation to determine the target cooling performance of multiple electrical components based on the power consumption of those electrical components, A method comprising determining the target cooling performance of the electrical components, the rotational speed of the cooling fan, and the rotational speed of a pump configured to pump coolant through the plurality of electrical components based on a second ambient temperature measured by the ambient temperature measuring unit after the first ambient temperature has been measured.

9. The method according to claim 8, further comprising the operation of determining the rotational speed of the pump based on the area and airflow resistance of a radiator configured to cool the coolant.

10. The operation for determining the target cooling performance of the aforementioned electrical component is: The operation of measuring the power consumption of each of the aforementioned multiple electrical components, An operation to calculate the amount of heat generated by each of the multiple electrical components based on the power consumption and the inefficiency of each of the multiple electrical components, The method according to claim 8, further comprising the operation of determining the target cooling performance of the electrical components by summing up the heat generated.

11. When the rotational speed of the pump satisfies the target cooling performance of the electrical components, the operation of storing the rotational speed of the pump and the rotational speed of the cooling fan is performed. The method according to claim 8, further comprising: increasing the rotation speed of the pump or the cooling fan if, at the rotation speed of the pump, the cooling performance of the electrical components does not meet the target cooling performance of the electrical components.

12. The operation of increasing the rotational speed of the pump or the rotational speed of the cooling fan is: If the rotational speed of the pump is less than the maximum rotational speed, the operation to increase the rotational speed of the pump is performed. The method according to claim 11, further comprising the action of increasing the rotation speed of the cooling fan if the rotation speed of the pump is equal to or greater than the maximum rotation speed.

13. The operation for determining the rotation speed of the cooling fan is as follows: The method according to claim 8, further comprising determining the rotational speed of the cooling fan based on at least one of the output of the fuel cell stack, the efficiency of the fuel cell stack, and the rotational speed of a pump configured to pump cooling water through the fuel cell stack.

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