Fuel cell system and method for thermal management

Abstract

A fuel cell system includes: a sensor device that measures a coolant temperature and an external air temperature at an inlet of a fuel cell; a cooling fan that cools the coolant; and a cooling fan controller that is connected to the sensor device and the cooling fan. The cooling fan controller determines an RPM of the cooling fan based on the external air temperature and an output value of the fuel cell, and corrects the RPM of the cooling fan based on the coolant temperature at the inlet of the fuel cell.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority from Korean Patent Application No. 10-2020-0188353 filed in the Korean Intellectual Property Office on December 30, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to a technique for thermal management in a fuel cell system. Background Art

[0003] A fuel cell system can generate electrical energy using a fuel cell stack. For example, when hydrogen is used as a fuel for a fuel cell stack, it may be an alternative solution to global environmental problems, and therefore, research and development of fuel cell systems have been ongoing. A fuel cell system may include: 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 to the fuel cell stack, which is an oxidant required for the electrochemical reaction; and a thermal management system (TMS) that releases 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.

[0004] The thermal management system may be a cooling device that circulates an antifreeze (as a coolant) through the fuel cell stack to maintain the fuel cell stack at an appropriate temperature (e.g., 60°C to 70°C). The thermal management system may include: a TMS line through which the coolant circulates; a reservoir in which the coolant is stored; a pump that circulates the coolant; an ion filter that removes ions contained in the coolant; and a radiator that radiates the heat of the coolant to the outside. In addition, the thermal management system may include: a heater that heats the coolant; and a HVAC unit (e.g., a heater for heating) that cools and heats the interior of a device (e.g., a vehicle) including a fuel cell system by using the coolant. The thermal management system may maintain the power electronic components of the vehicle as well as the fuel cell stack at an appropriate temperature. Summary of the invention

[0005] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0006] In one general aspect, a fuel cell system includes: a sensor device configured to measure a coolant temperature at an inlet of a fuel cell and to measure an external air temperature; a cooling fan configured to cool the coolant; and a cooling fan controller connected to the sensor device and the cooling fan. The cooling fan controller is configured to determine the revolutions per minute (RPM) of the cooling fan based on the external air temperature and an output value of the fuel cell, and to correct the RPM of the cooling fan based on the coolant temperature at the inlet of the fuel cell.

[0007] The sensor device may include: a coolant temperature sensor configured to measure a coolant temperature at an inlet of the fuel cell; and an outside air temperature sensor configured to measure an outside air temperature.

[0008] The cooling fan controller can be configured to: calculate a heating value of the fuel cell based on an output value of the fuel cell; calculate a coolant temperature at an outlet of the fuel cell based on the heating value of the fuel cell and a coolant temperature at an inlet of the fuel cell; calculate an air flow rate or wind speed at a target coolant temperature at an inlet of the fuel cell based on the coolant temperature at the outlet of the fuel cell and an outside air temperature; and determine an RPM of the cooling fan based on the air flow rate or wind speed.

[0009] The cooling fan controller can be configured to: determine whether the output value of the fuel cell is in a low output segment; when the output value of the fuel cell is in the low output segment, determine whether the coolant temperature at the inlet of the fuel cell is higher than or equal to a first threshold; when the coolant temperature at the inlet of the fuel cell is higher than or equal to the first threshold, correct the RPM of the cooling fan; and when the coolant temperature at the inlet of the fuel cell is lower than the first threshold, perform control to turn off the cooling fan.

[0010] The cooling fan controller may be configured to determine that the output value of the fuel cell is in the low output section if the output value of the fuel cell is less than a second threshold or if it is determined that the RPM of the cooling fan is zero.

[0011] The cooling fan controller may be configured to correct the RPM of the cooling fan from 0 to a minimum RPM if the coolant temperature at the inlet of the fuel cell is higher than or equal to a first threshold.

[0012] The fuel cell system may include: a first cooling line configured to circulate a first coolant, the first cooling line configured to pass through the fuel cell; a first radiator disposed on the first cooling line and configured to cool the first coolant; a second cooling line configured to circulate a second coolant, the second cooling line configured to pass through the power electronic component; and a second radiator disposed on the second cooling line and configured to cool the second coolant. The cooling fan may be configured to cool the first radiator, or may be configured to cool the first radiator and the second radiator simultaneously.

[0013] In another general aspect, a method for operating a fuel cell system includes: measuring a coolant temperature at an inlet of the fuel cell; measuring an outside air temperature; determining a revolution per minute (RPM) of a cooling fan based on the outside air temperature and an output value of the fuel cell; and correcting the RPM of the cooling fan based on the coolant temperature at the inlet of the fuel cell.

[0014] Determining the RPM of the cooling fan may include: calculating a heating value of the fuel cell based on an output value of the fuel cell; calculating a coolant temperature at an outlet of the fuel cell based on the heating value of the fuel cell and a coolant temperature at an inlet of the fuel cell; calculating an air flow rate or wind speed at a target coolant temperature at an inlet of the fuel cell based on the coolant temperature at the outlet of the fuel cell and an outside air temperature; and determining the RPM of the cooling fan based on the air flow rate or wind speed.

[0015] The method may include: determining whether the output value of the fuel cell is in a low output section; determining whether the coolant temperature at the inlet of the fuel cell is higher than or equal to a first threshold; and if the coolant temperature at the inlet of the fuel cell is higher than or equal to the first threshold, correcting the RPM of the cooling fan from 0 to a minimum RPM, or if the coolant temperature at the inlet of the fuel cell is lower than the first threshold, performing control to shut down the cooling fan.

[0016] Other features and aspects will be apparent from the following detailed description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description in conjunction with the accompanying drawings.

[0018] Figure 1 A fuel cell system according to various embodiments is shown;

[0019] Figure 2 A fuel cell system according to various embodiments is shown;

[0020] Figure 3Another example of a fuel cell system according to various embodiments is shown;

[0021] Figure 4 Another example of a fuel cell system according to various embodiments is shown;

[0022] Figure 5 is a block diagram of a fuel cell system controlling a cooling fan according to various embodiments;

[0023] Figure 6 is an operational flow chart for controlling a cooling fan according to various embodiments;

[0024] Figure 7 is a flowchart of operations for determining the RPM of a cooling fan according to various embodiments; and

[0025] Figure 8 is a flow chart of operations for correcting the RPM of a cooling fan according to various embodiments.

[0026] With regard to the description of the drawings, the same or similar reference numbers may be used to refer to the same or similar components. DETAILED DESCRIPTION

[0027] Below, various embodiments of the present disclosure may be described with reference to the accompanying drawings. Therefore, those skilled in the art will recognize that the various embodiments described herein may be modified, equivalent and / or substituted in various ways without departing from the scope and spirit of the present disclosure.

[0028] It should be understood that the various embodiments of the present disclosure and the terms used therein are not intended to limit the technical features set forth herein to specific embodiments, but include various variations, equivalents or substitutes of the corresponding embodiments. With respect to the description of the accompanying drawings, similar reference numerals may be used to refer to similar or related elements. It should be understood that the singular form of a noun corresponding to an item may include one or more things, unless the relevant context explicitly indicates otherwise. As used herein, each of the phrases 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 be included in any one or all possible combinations of the items listed together in one of the corresponding phrases. As used herein, terms such as "first" and "second" or "first" and "second" may be used to simply distinguish a corresponding component from another component, and do not limit the component in other aspects (e.g., importance or order). It should be understood that if an element (e.g., a first element) is referred to as being “coupled with another element (e.g., a second element)”, “coupled to another element (e.g., the second element)”, “connected with another element (e.g., the second element)”, or “connected to another element (e.g., the second element)”, whether or not there is an “operably” or “communicative” term, this means that the element can be coupled to the other elements directly (e.g., by wire), wirelessly, or via a third element.

[0029] As used herein, the term "module" may include a unit implemented in hardware, software, or firmware, and may be used interchangeably with other terms such as "logic," "logic block," "component," or "circuit." A module may be a single integral component, or its smallest unit or component, adapted to perform one or more functions. For example, according to one embodiment, a module may be implemented in the form of an application-specific integrated circuit (ASIC).

[0030] The various embodiments described herein may be implemented as software (e.g., a program) that includes one or more instructions stored in a storage medium (e.g., an internal memory or an external memory) that is readable by a machine. For example, a machine may call at least one of the one or more instructions stored in a storage medium and execute it with or without one or more other components under the control of a processor. This allows the machine to be operated to perform at least one function according to at least one instruction called. The one or more instructions may include code generated by a compiler or code executable by an interpreter. The machine-readable storage medium may be provided in the form of a non-transitory storage medium. Among them, the term "non-transitory" only means that the storage medium is a tangible device and does not include signals (e.g., electromagnetic waves), but this term does not distinguish between a location where data is semi-permanently stored in a storage medium and a location where data is temporarily stored in a storage medium.

[0031] According to one embodiment, the method according to various embodiments of the present disclosure may be included and provided in a computer program product. The computer program product may be traded between a seller and a buyer as a product. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., a compact disc read only memory (CD-ROM)), or distributed online (e.g., downloaded or uploaded) via an application store, or distributed directly between two user devices. If distributed online, at least a portion of the computer program product may be temporarily generated or at least temporarily stored in a machine-readable storage medium (e.g., a memory of a manufacturer's server, a server of an application store, or a relay server).

[0032] According to various embodiments, each of the above-mentioned components (e.g., a module or a program) may include a single entity or multiple entities, and some of the multiple entities may be respectively arranged in different components. According to various embodiments, one or more of the above-mentioned components may be omitted, or one or more other components may be added. Alternatively or additionally, multiple components (e.g., modules or programs) may be integrated into a single component. In this case, according to various embodiments, the integrated component may still perform one or more functions of each of the multiple components in the same or similar manner as they were performed by corresponding components in the multiple components before integration. According to various embodiments, the operations performed by a module, a program or another component may be performed sequentially, in parallel, repeatedly or heuristically, or one or more of the operations may be performed or omitted in a different order, or one or more other operations may be added.

[0033] Figure 1 and Figure 2 A fuel cell system according to various embodiments is shown.

[0034] Reference Figure 1 , a fuel cell system for a vehicle may include: a first cooling line 110 that passes through a fuel cell stack 10 of the vehicle and through which a first coolant circulates; a second cooling line 120 that passes through a power electronic component 200 of the vehicle and through which a second coolant circulates; and a heat exchanger 300 that allows the first coolant and the second coolant to exchange heat with each other. The first cooling line 110 and the second cooling line 120 may constitute a thermal management system (TMS) line through which the first coolant and the second coolant flow while exchanging heat with each other. In this case, the first coolant or the second coolant may be used as a cooling medium or a heating medium in the TMS line.

[0035] The fuel cell system may include: a first connecting line 130, which forms a heating circuit (heat circulation path) with the first cooling line 110; a second connecting line 150, which forms a cooling / heating circuit with the first cooling line 110; and a third connecting line 140, which forms a cooling circuit with the first cooling line 110 to cool the first coolant. Figure 2 As shown, 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 .

[0036] The first cooling line 110 may be configured to form a cooling circuit for cooling the first coolant or a heating circuit for heating the first coolant (increasing the temperature of the first coolant) according to the state of the vehicle. For example, the first cooling line 110 may form a heating circuit to ensure the cold start capability when the vehicle is initially started, and may form a cooling circuit to radiate the heat generated from the fuel cell stack 10 to the outside during vehicle driving. The fuel cell stack 10, the first valve 20, the first pump 30, the second valve 40, and the first radiator 60 may be disposed on the first cooling line 110 through which the first coolant circulates.

[0037] The fuel cell stack 10 (or referred to as a "fuel cell") may form a structure capable of generating electricity through an oxidation-reduction reaction of a fuel (e.g., hydrogen) and an oxidant (e.g., air). For example, the fuel cell stack 10 may include: a membrane electrode assembly (MEA) in which a catalyst electrode layer (where an electrochemical reaction occurs) is attached to both sides of an electrolyte membrane through which hydrogen ions move; a gas diffusion layer (GDL) that evenly distributes reactant gas and transports generated electricity; a gasket and a fastening mechanism for maintaining airtightness and appropriate fastening pressure of the reactant gas and the first coolant; and a bipolar plate that allows the reactant gas and the first coolant to move.

[0038] In the fuel cell stack 10, hydrogen as a fuel and air (oxygen) as an oxidant can be supplied to the negative electrode and the positive electrode of the membrane electrode assembly respectively through the fluid channel of the bipolar plate. Hydrogen can be supplied to the negative electrode, and air can be supplied to the positive electrode. The hydrogen supplied to the negative electrode can be decomposed into hydrogen ions (protons) and electrons by the catalyst of the electrode layer formed on both sides of the electrolyte membrane. Only hydrogen ions can be selectively transported to the positive electrode through the electrolyte membrane (which is a cation exchange membrane), while electrons can be transported to the positive electrode through the gas diffusion layer and the bipolar plate, which are both conductors. At the positive electrode, the hydrogen ions provided by the electrolyte membrane and the electrons transported by the bipolar plate can react with the oxygen in the air supplied to the positive electrode by the air supply device to produce water. Due to the movement of the hydrogen ions, an electron flow through the external conductor can be generated, and an electric current can be generated by the electron flow.

[0039] The first valve 20 can switch the flow path of the first coolant in the first cooling line 110 to the first connecting line 130 provided with the heater 50, or the fuel cell stack 10. For example, on the first cooling line 110, the first valve 20 can 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. The first valve 20 may include various valve devices capable of selectively switching the flow path of the first coolant. For 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 to allow the first coolant pumped by the first pump 30 to flow into the first valve 20; a second port 22 connected to the first cooling line 110 to allow the first coolant passing through the first valve 20 to flow into the fuel cell stack 10; and a third port 23 connected to one end of the first connecting line 130. As the second port 22 or the third port 23 of the first valve 20 is opened or closed, the flow path of the first coolant may be switched to the heater 50 or the fuel cell stack 10 of the first connecting line 130. That is, when the second port 22 is opened and the third port 23 is closed, the first coolant may flow into the fuel cell stack 10. Conversely, when the third port 23 is opened and the second port 22 is closed, the first coolant may flow into the heater 50 through the first connecting line 130.

[0040] In order to heat the first coolant, the first connecting line 130 may form a heating loop (heat circulation path) with the first cooling line 110. For example, the first coolant flowing along the first connecting line 130 may be heated while passing through the heater 50 installed on 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, and the other end of the first connecting line 130 may be connected to the first connecting line 110 at a second point, wherein the first point is located between the outlet of the first pump 30 and the fuel cell stack 10, and the second point is 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 an inlet through which the first coolant flows into the first pump 30. The outlet of the first pump 30 may be defined as an outlet through which the first coolant flowing through the first pump 30 is released. The section between the outlet of the first pump 30 and the fuel cell stack 10 may be defined as a section through which the first coolant released from the first pump 30 flows to the coolant inlet (not shown) of the fuel cell stack 10. A section between the inlet of the first pump 30 and the fuel cell stack 10 may be defined as a section through which the first coolant released from a coolant outlet (not shown) of the fuel cell stack 10 flows into the inlet of the first pump 30 .

[0041] The first pump 30 may be configured to force the first coolant to flow. The first pump 30 may include various means capable of pumping the first coolant, and in the present disclosure, no particular limitation is imposed on the type of the first pump 30 and the number of the first pumps 30 .

[0042] The second valve 40 may switch the flow path of the first coolant in the first cooling line 110 to 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 that the second valve 40 is 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 one end of the second connecting line 150. The second valve 40 may include various valve devices capable of selectively switching the flow path of the first coolant to the first radiator 60 or the fuel cell stack 10. For example, the second valve 40 may be a four-way valve. In this case, the second valve 40 may include: a first port 41 connected to the third connecting line 140; a second port 42 connected to the first cooling line 110 so that the first coolant passing through the first radiator 60 flows into the second valve 40; a third port 43 connected to one end of the second connecting line 150; and a fourth port 44 connected to the first cooling line 110 so that the first coolant flows into the first pump 30. As the first port 41 and the second port 42 of the second valve 40 are opened or closed, the flow path of the first coolant may be switched to the first radiator 60 or the fuel cell stack 10. That is, when the first port 41 is opened and the second port 42 is closed, the first coolant may flow into the fuel cell stack 10 without passing through the first radiator 60. On the contrary, when 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.

[0043] The second connecting line 150 may form a cooling / heating loop with the first cooling line 110 to cool / heat the HVAC unit 90. For example, the second connecting line 150 may form a loop for a heater (not shown) for heating the HVAC unit 90. One end of the second connecting line 150 may be connected to the first cooling line 110 between a first point (a point where one end of the first connecting line 130 is connected to the first cooling line 110) and an inlet of the fuel cell stack 10, and a portion of the first coolant may circulate through the second connecting line 150. The other end of the second connecting line 150 may be connected to the first cooling line 110 between the first pump 30 and a second point (a point where the other end of the first connecting line 130 is connected to the first cooling line 110).

[0044] An ion filter 95 may be provided on the second connecting line 150, which may filter ions of the first coolant passing through the HVAC unit 90. When the conductivity of the first coolant increases due to corrosion or seepage of the system, electricity may flow into the first coolant, so the fuel cell stack 10 may be short-circuited or current may flow to the first coolant. Therefore, the first coolant must be able to maintain low conductivity. In order to maintain the conductivity of the first coolant below a predetermined level, the ion filter 95 may be configured to remove ions contained in the first coolant. During a cold start operation in which the supply of the first coolant to the fuel cell stack 10 is stopped (or the second port 22 of the first valve 20 is closed), the first coolant may circulate while passing through the heater 50 (heating circuit) of the first connecting line 130, and may circulate along the second connecting line 150. Therefore, even during a cold start operation, filtering (removing ions contained in the first coolant) can be performed by the ion filter 95 provided on the second connecting line 150. Therefore, the conductivity of the first coolant flowing into the fuel cell stack 10 immediately after the cold start operation can be maintained below a predetermined level.

[0045] In order to cool the first coolant, the third connecting line 140 may form a cooling loop with the first cooling line 110. 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 160, and the other end of the third connecting line 140 may be connected to the first cooling line 110 between the coolant outlet of the fuel cell stack 10 and the first radiator 60.

[0046] The first radiator 60 may be configured to cool the first coolant. The first radiator 60 may be formed in various structures capable of cooling the first coolant, and the present disclosure is not limited 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.

[0047] The fuel cell system may include: a first temperature sensor 112 that measures the temperature of the first coolant between the fuel cell stack 10 and the first point (the first valve 20); a second temperature sensor 114 that measures the temperature of the first coolant 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 coolant in 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 may control the inflow rate of the first coolant flowing into the fuel cell stack 10. For example, when the measured temperature of the first coolant circulating along the first cooling line 110 is lower than a preset target temperature, the inflow rate of the first coolant may be controlled to be lower than a preset flow rate. When the measured temperature of the first coolant is lower than the preset target temperature, by controlling the inflow rate of the first coolant flowing into the fuel cell stack 10 to be lower than the preset flow rate, thermal shock and performance degradation caused by the difference between the temperature of the first coolant stagnating in the fuel cell stack 10 and the temperature of the first coolant flowing into the fuel cell stack 10 may be minimized.

[0048] The second cooling line 120 may be configured to pass through the power electronic components 200 of the vehicle, and the second coolant may circulate along the second cooling line 120. Here, the power electronic components 200 of the vehicle may be understood as components that use the power of the vehicle as an energy source, and the present disclosure is not limited by the type and number of the power electronic components 200 of the vehicle. For example, the power electronic component 200 may include at least one of the following: a second pump 205 for pumping a second coolant; a bi-directional high voltage DC-DC converter (BHDC) 210 provided between the fuel cell stack 10 and a high voltage battery (not shown) of the vehicle; a blower pump control unit (BPCU) 220 controlled to drive a blower (not shown) for supplying external air to the fuel cell stack 10; a low-voltage DC-DC converter (LDC) 230 for converting a DC high voltage supplied from the high voltage battery into a DC low voltage; an air compressor (ACP) 240 for compressing air to be supplied to the fuel cell stack 10; or an air cooler 250.

[0049] A second pump (not shown) for forcing the second coolant to flow may be provided on the second cooling line 120. The second pump may include a pumping device capable of pumping the second coolant, and no particular limitation is imposed on the type and features of the second pump.

[0050] A second radiator 70 for cooling the second coolant may be provided on the second cooling line 120. The second radiator 70 may be formed in various structures capable of cooling the second coolant, and no particular limitation is imposed on the type and structure of the second radiator 70. The second radiator 70 may be connected to a second reservoir 72 in which the second coolant is stored.

[0051] In one embodiment, the first radiator 60 and the second radiator 70 may be configured to be cooled simultaneously by one cooling fan 80. 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 external air toward the first radiator 60 and the second radiator 70. By cooling the first radiator 60 and the second radiator 70 simultaneously with one cooling fan 80, the structure of the fuel cell system may be simplified, the degree of freedom of design and space utilization may be improved, and the power consumption for cooling the first radiator 60 and the second radiator 70 may be minimized.

[0052] The heat exchanger 300 may be configured to allow the first coolant and the second coolant to exchange heat with each other. The temperature of the second coolant used to cool the power electronic component 200 is set to be lower than the temperature of the first coolant used to cool the fuel cell stack 10. Therefore, by allowing the first coolant and the second coolant to exchange heat with each other, the fuel cell system can achieve a reduction in the temperature of the first coolant, an improvement in the cooling efficiency of the fuel cell stack 10, and an improvement in safety and reliability, even without increasing the capacity of the first radiator 60 and the cooling fan 80. In addition, the fuel cell system can reduce the temperature of the first coolant in a stopped state of a vehicle (e.g., a construction machine) that cannot use vehicle induced wind. Therefore, the fuel cell system can ensure high-power operation of the fuel cell stack 10 and can improve safety and durability.

[0053] In one embodiment, the heat exchanger 300 may be connected to the first cooling line 110 between the outlet of the first radiator 60 and the fuel cell stack 10, and the second cooling line 120 may pass through the heat exchanger 300 and may connect the outlet of the second radiator 70 and the power electronic component 200. 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 may pass through the interior of the heat exchanger 300 to be exposed to the first coolant (e.g., to allow the first coolant to flow around the second cooling line 120). As described above, through the heat exchange between the first coolant and the second coolant, the temperature of the first coolant flowing into the fuel cell stack 10 may be reduced. The first temperature of the first coolant passing through the first radiator 60 may be higher than the second temperature of the second coolant passing through the second radiator 70, and the third temperature of the first coolant passing through the heat exchanger 300 may be lower than the first temperature. For example, the first temperature of the first coolant may be about 10° C. higher than the second temperature of the second coolant, and the third temperature of the first coolant passing through the heat exchanger 300 (or exchanging heat with the second coolant) may be 1° C. lower than the first temperature.

[0054] When a vehicle equipped with a fuel cell system is traveling, the first coolant flowing into the fuel cell stack 10 may be cooled not only by the cooling fan 80 but also by the vehicle induced wind generated according to the vehicle speed. When the vehicle is in a stopped state, the vehicle induced wind may not be generated, and therefore, the first coolant may be cooled by the cooling fan 80. However, in a vehicle (such as a construction machine) that performs tasks such as leveling or loading even in a stopped state, the cooling capacity by the cooling fan 80 may be insufficient. The fuel cell system according to the present embodiment may determine the RPM of the cooling fan 80 in consideration of the output value of the fuel cell stack 10, thereby effectively cooling the fuel cell stack 10 even in the absence of the vehicle induced wind. In addition, even in the low output section of the fuel cell stack 10, the fuel cell system according to the present embodiment may correct the RPM of the cooling fan 80 according to the coolant temperature, thereby more accurately adjusting the cooling capacity.

[0055] Figure 3 and Figure 4 Other examples of fuel cell systems according to various embodiments are shown.

[0056] Figure 1 and Figure 2 The heat exchanger 300 in the heat exchanger 300 is separately arranged from the first radiator 60, and Figure 3The heat exchanger 300' in the embodiment can be directly connected to the first radiator 60. The heat exchanger 300' can be formed in various structures that can be connected to the first radiator 60, and no special restrictions are imposed on the structure and connection structure of the heat exchanger 300'. For example, the heat exchanger 300' can be connected to a specified position (upper left) of the first radiator 60. However, the specified position of the first radiator 60 to which the heat exchanger 300' is connected can vary.

[0057] Reference Figure 4 , the cooling fan 80 for cooling the first radiator 60 and the second cooling fan for cooling the second radiator 70 may be separately provided. In this case, the fuel cell system may exclude parameters related to the heat load of the power electronic component 200 when controlling the RPM of the cooling fan 80.

[0058] Figure 5 is a block diagram of a fuel cell system for controlling a cooling fan according to various embodiments. Figure 5 , the fuel cell system may include a sensor device 510 , a cooling fan controller 520 , and a cooling fan 530 .

[0059] The cooling fan 530 may be configured to cool the first coolant passing through the fuel cell stack 10. The cooling fan 530 may correspond to, for example, Figure 1 or Figure 4 The cooling fan 80.

[0060] The sensor device 510 may include at least one sensor capable of measuring temperature. For example, the external air temperature sensor 512 may measure the air temperature outside the fuel cell system (or vehicle). The external air temperature sensor 512 may be disposed on the front surface of the first radiator 60 or the second radiator 70. The coolant temperature sensor 514 may measure a point corresponding to the inlet of the fuel cell stack 10 (e.g., corresponding to Figure 1 According to one embodiment, the outside air temperature sensor 512 and the coolant temperature sensor 514 may be implemented as one integrated module or as separate components.

[0061] The cooling fan controller 520 may be a hardware or software module for controlling the cooling fan 530 in the fuel cell system. The cooling fan controller 520 may be electrically connected to the sensor device 510 and the cooling fan 530, and may perform the overall operation of the fuel cell system controlling the RPM of the cooling fan 530. For example, the cooling fan controller 520 may determine the RPM of the cooling fan 530 in consideration of the external air temperature measured by the sensor device 510 and the output value of the fuel cell stack 10. The output value of the fuel cell stack 10 (or the output value of the fuel cell) may be determined by a controller of the fuel cell stack 10 (e.g., a fuel cell control unit (FCU)). Based on the coolant temperature at the inlet of the fuel cell stack 10 measured by the sensor device 510, the cooling fan controller 520 may correct the determined RPM of the cooling fan 530. Specifically, the cooling fan controller 520 may correct the RPM of the cooling fan 530 in the low output section (where the output value of the fuel cell is less than a threshold value), thereby ensuring the cooling performance in the case where a heat load of the fuel cell stack 10 or the power electronic component 200 may occur when the vehicle is in a stopped state.

[0062] Figure 6 is an operational flow chart for controlling a cooling fan according to various embodiments. Figures 6 to 8 The operations in the operational flowchart may be implemented by the fuel cell system, or may be implemented by a component (eg, cooling fan controller 520) included in the fuel cell system.

[0063] Reference Figure 6 In operation 610, the fuel cell system may measure the outside air temperature and the coolant temperature at the inlet of the fuel cell through the sensor device 510. The fuel cell system may measure the outside air temperature and the coolant temperature at each specific period or each time a specific event (e.g., starting, traveling, stopping, or operating a vehicle) occurs.

[0064] In operation 620, the fuel cell system may determine the RPM of the cooling fan 530 through the cooling fan controller 520. The cooling fan controller 520 may determine the RPM of the cooling fan 530 based on the external air temperature and the output value of the fuel cell (or the fuel cell stack 10).

[0065] In operation 630, the fuel cell system may correct the RPM of the cooling fan 530 through the cooling fan controller 520. The cooling fan controller 520 may correct the RPM of the cooling fan 530 based on the coolant temperature at the inlet of the fuel cell.

[0066] Figure 7is a flowchart of operations for determining the RPM of a cooling fan according to various embodiments. For example, Figure 7 The operation can be expressed as Figure 6 An example of operation 620 is shown.

[0067] Reference Figure 7 In operation 710, the fuel cell system may calculate a heating value of the fuel cell based on the output value of the fuel cell. The heating value may correspond to an internal loss of the fuel cell, and the cooling fan controller 520 may calculate the heating value as a difference between the output value / output efficiency and the output value.

[0068] In operation 720, the fuel cell system may calculate the coolant temperature at the outlet of the fuel cell based on the heating value of the fuel cell and the coolant temperature at the inlet of the fuel cell. In this case, the cooling fan controller 520 may calculate the coolant temperature at the outlet of the fuel cell by applying the target coolant temperature at the inlet of the fuel cell required to maintain a suitable temperature of the fuel cell, without using the coolant temperature at the inlet of the fuel cell measured by the sensor device 510. The coolant temperature at the outlet of the fuel cell may correspond to the temperature of the radiator (e.g., Figure 1 According to one embodiment, the coolant temperature at the inlet of the first radiator 60 is further based on the pump (e.g., Figure 1 The cooling fan controller 520 may calculate the coolant temperature at the outlet of the fuel cell based on the RPM of the first pump 30).

[0069] In operation 730 , the fuel cell system may calculate an air flow rate or wind speed of the cooling fan 530 for a target coolant temperature at an inlet of the fuel cell based on the coolant temperature at the outlet of the fuel cell and the outside air temperature.

[0070] In operation 740, based on the calculated air flow rate or wind speed, the fuel cell system may determine the RPM of the cooling fan 530. According to an embodiment, the cooling fan controller 520 may store table information (e.g., a lookup table) in a database indicating the relationship between the external air temperature, the output value of the fuel cell, and the RPM of the cooling fan 530. For example, the table information may be as shown in the following Table 1.

[0071] [Table 1]

[0072]

[0073] In Table 1, the output value of the fuel cell may have a relationship of 0<A<B<C<D<E. Although the RPM of the cooling fan 530 increases as the output value of the fuel cell or the external air temperature increases, the RPM of the cooling fan 530 is not necessarily directly proportional to the output value of the fuel cell or the external air temperature. The performance of the cooling fan 530 may be limited, and the cooling fan controller 520 may set the cooling fan RPM of a predetermined level or higher to the maximum RPM. For example, W 40E , W 50D and W 50E It may be the maximum RPM and may be the same. On the contrary, when the cooling fan 530 rotates at an RPM lower than a predetermined level, there may be no effect on the cooling performance, and therefore, the cooling fan controller 520 may set the cooling fan RPM of a predetermined level or lower to the minimum RPM.

[0074] The values ​​representing the outside air temperature, the output value of the fuel cell, and the RPM of the cooling fan 530 may be discrete, and thus values ​​between the values ​​represented in the table information may be processed by interpolation. For example, when the outside air temperature is 0 and the output value of the fuel cell is between A and B, the cooling fan controller 520 may set the RPM of the cooling fan 530 to W. OA . For example, in the case where the vehicle (e.g., construction machinery) stops, when the output value of the fuel cell is less than A, the cooling fan controller 520 may set the RPM of the cooling fan 530 to 0. In this case, the cooling performance may be significantly reduced due to an increase or decrease in the heat load of the power electronic component 200 or the ventilation resistance on the air flow path. In order to ensure the cooling performance, the fuel cell system according to the present embodiment may correct the determined RPM based on the coolant temperature at the inlet of the fuel cell.

[0075] Figure 8 is a flow chart of operations for correcting the RPM of a cooling fan according to various embodiments.

[0076] Reference Figure 8 In operation 810, the fuel cell system may determine whether the output value of the fuel cell is in the low output section through the cooling fan controller 520. The low output section may represent, for example, a case where the output value of the fuel cell is less than a specified threshold value (e.g., "A" in Table 1) or the determined RPM of the cooling fan 530 is 0. When the output value of the fuel cell is not in the low output section, the fuel cell system may repeat operation 810.

[0077] When the output value of the fuel cell is in the low output section, the fuel cell system may determine whether the coolant temperature at the inlet of the fuel cell is higher than or equal to a threshold value through the cooling fan controller 520 in operation 820 .

[0078] When the coolant temperature at the inlet of the fuel cell is higher than or equal to the threshold value, the fuel cell system may correct the RPM of the cooling fan 530 through the cooling fan controller 520 in operation 830. In this case, the cooling fan controller 520 may set the RPM of the cooling fan 530, which is set to 0, to the minimum RPM, thereby reducing unnecessary power consumption while ensuring cooling performance.

[0079] When the coolant temperature at the inlet of the fuel cell is lower than a threshold value, the fuel cell system may perform control to turn off the cooling fan 530 through the cooling fan controller 520 .

[0080] According to an embodiment of the present disclosure, a fuel cell system can improve the safety and durability of a fuel cell while ensuring high power of a fuel cell stack.

[0081] According to an embodiment of the present disclosure, a fuel cell system can improve cooling performance even in a stopped state of a vehicle, thereby improving safety and durability of the fuel cell.

[0082] According to the embodiments of the present disclosure, a fuel cell system can prevent cooling performance from being deteriorated due to a heat load of a power electronic component.

[0083] Furthermore, the present disclosure can provide various effects confirmed directly or indirectly.

[0084] Although the present disclosure has been described above with reference to exemplary embodiments and the accompanying drawings, the present disclosure is not limited thereto, but various modifications and changes may be made by those skilled in the art without departing from the spirit and scope of the present disclosure as claimed in the following claims.

Claims

1. A fuel cell system, comprising: a sensor device configured to measure a coolant temperature at an inlet of the fuel cell and to measure an outside air temperature; a cooling fan configured to cool the coolant; as well as a cooling fan controller connected to the sensor device and the cooling fan; Wherein, the cooling fan controller is configured as: determining the rpm of the cooling fan based on the outside air temperature and the output value of the fuel cell; and based on the coolant temperature at the inlet of the fuel cell, correcting the revolutions per minute of the cooling fan, Wherein, the cooling fan controller is configured as: calculating a heating value of the fuel cell based on an output value of the fuel cell; calculating a coolant temperature at an outlet of the fuel cell based on a heating value of the fuel cell and a coolant temperature at an inlet of the fuel cell; calculating an air flow rate or wind speed for a target coolant temperature at an inlet of the fuel cell based on the coolant temperature at the outlet of the fuel cell and the outside air temperature; and determining the revolutions per minute of the cooling fan based on the air flow rate or wind speed, correcting the determined rpm of the cooling fan in a low output section in which an output value of the fuel cell is less than a preset threshold value, The output value of the fuel cell is the power of the fuel cell.

2. The fuel cell system according to claim 1, wherein: The sensor device comprises: a coolant temperature sensor configured to measure a coolant temperature at an inlet of the fuel cell; and An outside air temperature sensor is configured to measure the outside air temperature.

3. The fuel cell system according to claim 1, wherein: The cooling fan controller is configured to: determining whether the output value of the fuel cell is in a low output section; When the output value of the fuel cell is in the low output section, determining whether the coolant temperature at the inlet of the fuel cell is higher than or equal to a first threshold; When the coolant temperature at the inlet of the fuel cell is higher than or equal to the first threshold, correcting the RPM of the cooling fan; and In a case where the coolant temperature at the inlet of the fuel cell is lower than the first threshold value, control is performed to turn off the cooling fan.

4. The fuel cell system according to claim 3, wherein: The cooling fan controller is configured to determine that the output value of the fuel cell is in a low output section when the output value of the fuel cell is less than a second threshold or when it is determined that the rpm of the cooling fan is 0.

5. The fuel cell system according to claim 4, wherein: The cooling fan controller is configured to correct the rpm of the cooling fan from 0 to a minimum rpm if the coolant temperature at the inlet of the fuel cell is higher than or equal to the first threshold.

6. The fuel cell system according to claim 1, further comprising: a first cooling line configured to circulate a first coolant, the first cooling line configured to pass through the fuel cell; a first radiator disposed on the first cooling line and configured to cool the first coolant; a second cooling line configured to circulate a second coolant, the second cooling line configured to pass through the power electronic component; and a second radiator disposed on the second cooling line and configured to cool the second coolant; Wherein, the cooling fan is configured to cool the first radiator and the second radiator simultaneously.

7. The fuel cell system according to claim 1, further comprising: a first cooling line configured to circulate a first coolant, the first cooling line configured to pass through the fuel cell; a first radiator disposed on the first cooling line and configured to cool the first coolant; a second cooling line configured to circulate a second coolant, the second cooling line configured to pass through the power electronic component; and a second radiator disposed on the second cooling line and configured to cool the second coolant; Wherein, the cooling fan is configured to cool the first radiator.

8. A method for operating a fuel cell system, the method comprising: measuring a coolant temperature at an inlet of the fuel cell; Measure outside air temperature; determining the RPM of a cooling fan based on the outside air temperature and the output value of the fuel cell; and based on the coolant temperature at the inlet of the fuel cell, correcting the revolutions per minute of the cooling fan, Wherein, determining the revolutions per minute of the cooling fan comprises: calculating a heating value of the fuel cell based on an output value of the fuel cell; calculating a coolant temperature at an outlet of the fuel cell based on a heating value of the fuel cell and a coolant temperature at an inlet of the fuel cell; calculating an air flow rate or wind speed for a target coolant temperature at an inlet of the fuel cell based on the coolant temperature at the outlet of the fuel cell and the outside air temperature; and determining the revolutions per minute of the cooling fan based on the air flow rate or wind speed, correcting the determined rpm of the cooling fan in a low output section in which an output value of the fuel cell is less than a preset threshold value, The output value of the fuel cell is the power of the fuel cell.

9. The method according to claim 8, further comprising: determining whether the output value of the fuel cell is in a low output section; determining whether a coolant temperature at an inlet of the fuel cell is greater than or equal to a first threshold; as well as When the coolant temperature at the inlet of the fuel cell is higher than or equal to the first threshold, the revolutions per minute of the cooling fan are corrected from 0 to the minimum revolutions per minute, or when the coolant temperature at the inlet of the fuel cell is lower than the first threshold, control is performed to turn off the cooling fan.

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