Humidity control method, device and system for fuel cell stack

Abstract

The invention relates to a humidity control method, device and system for a fuel cell stack, and relates to the field of fuel cells. The method comprises the steps that when water quantity information of a water storage tank in a humidifying loop of the fuel cell stack reaches a first preset threshold value, the intake air moisture content of an air inlet loop of the fuel cell stack is obtained, and the water storage tank is used for collecting liquid water generated by the fuel cell stack and used for humidifying. According to the intake air moisture content and a preset target intake air moisture content, the water outlet flow of a water storage tank used for humidifying the fuel cell stack in the humidifying loop is determined, and according to the water outlet flow, the humidifying loop is controlled to provide liquid water for the air inlet loop, so that an intercooler in the air inlet loop can supply the liquid water to the air inlet loop based on heat absorbed by cooling the air inlet loop. And / or the liquid water is heated and evaporated through a heater, so that humidification is carried out when air is supplied to the air inlet loop. Through the method, a proper humidity condition can be provided for the fuel cell stack at low cost.

Description

Technical Field

[0001] The present invention relates to the field of fuel cell technology, and in particular to a humidity control method, device and system for a fuel cell stack. Background Art

[0002] Proton exchange membrane hydrogen and oxygen fuel cells (hereinafter referred to as fuel cells) are an efficient and clean energy conversion device, which promotes their large-scale application in transportation and distributed power generation.

[0003] During fuel cell stack operation, humidity management is a key factor affecting fuel cell stack performance. Proton exchange membrane fuel cells (PEMFCs) rely on moisture within the membrane to maintain effective proton conduction. A suitable humidity level not only improves membrane conductivity but also prevents mechanical damage. However, in the actual operation of electric vehicles, the fuel cell stack is exposed to variable environmental conditions, and humidity levels can fluctuate with temperature and load. Excessively low humidity can cause the membrane to dry out, increase the internal resistance of the fuel cell stack, and shorten its service life, thereby affecting the power output and range of the vehicle or other electrical devices. Summary of the Invention

[0004] The object of the present invention is to provide a method, device and system for controlling humidity of a fuel cell stack, so as to provide suitable humidity conditions for the fuel cell stack at a low cost.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] According to a first aspect of the present invention, a method for controlling humidity of a fuel cell stack is provided, comprising:

[0007] When water level information of a water storage tank in a humidification circuit of a fuel cell stack reaches a first preset threshold, obtaining the intake air moisture content of an intake circuit of the fuel cell stack; wherein the water storage tank is used to collect liquid water generated by the fuel cell stack and use it for humidification;

[0008] determining, according to the intake air moisture content and a preset target intake air moisture content, a water outlet flow rate of the water storage tank in the humidification circuit for humidifying the fuel cell stack;

[0009] According to the water outlet flow rate, the humidification circuit is controlled to provide liquid water to the intake circuit, so that the intercooler in the intake circuit absorbs heat based on cooling the intake circuit and / or evaporates the liquid water by heating through the heater, so as to humidify the air when the intake circuit supplies air.

[0010] In one embodiment, obtaining the moisture content of the intake air of the intake loop of the fuel cell stack includes:

[0011] collecting the relative humidity of the intake air of the intake circuit, the first intake air temperature and intake air pressure compressed by the air compressor, and the second intake air temperature after the intake circuit is cooled by the intercooler;

[0012] The intake air moisture content of the air intake circuit is determined based on the intake air relative humidity, the first intake air temperature, the intake air pressure, and the second intake air temperature.

[0013] In one embodiment, determining the intake air moisture content of the intake circuit according to the intake air relative humidity, the first intake air temperature, the intake air pressure, and the second intake air temperature includes:

[0014] determining a first partial pressure of water vapor in an intake air environment based on the intake air relative humidity, the first intake air temperature, and the second intake air temperature;

[0015] determining a second partial pressure of dry gas in an intake environment from which the water vapor has been removed based on a difference between the intake pressure and the actual partial pressure of the water vapor;

[0016] The moisture content of the intake air of the air intake circuit is determined based on the ratio between the first partial pressure and the second partial pressure.

[0017] In one embodiment, controlling the humidification circuit to provide liquid water to the air inlet circuit according to the water outlet flow rate includes:

[0018] A humidification control instruction is sent to the humidification circuit three-way valve in the humidification circuit, wherein the humidification control instruction is used to control the water supply port of the humidification circuit three-way valve to open, so that the humidification circuit provides liquid water to the air inlet circuit.

[0019] In one embodiment, it further includes:

[0020] collecting the air intake flow rate of the air intake circuit;

[0021] The determining, based on the intake air moisture content and a preset target intake air moisture content, the water outlet flow rate of the water storage tank in the humidification circuit for humidifying the fuel cell stack comprises:

[0022] determining a unit humidification amount according to a difference between the intake air moisture content and a preset target intake air moisture content;

[0023] The water outlet flow rate of the water storage tank is determined according to the product between the air intake flow rate of the air intake circuit and the unit humidification capacity.

[0024] In one embodiment, it further includes:

[0025] Obtaining heat absorption power for evaporating the liquid water and heat dissipation power of the intercooler;

[0026] According to the heat absorption power and the heat dissipation power, it is determined whether the liquid water is evaporated by the intercooler based on the heat absorbed by cooling the air intake circuit, and / or whether the liquid water is evaporated by heating through the heater.

[0027] In one embodiment, obtaining the heat absorption power for evaporating the liquid water and the heat dissipation power of the intercooler includes:

[0028] collecting the outlet water temperature of the humidification circuit;

[0029] Determining the heat absorption power for evaporating the liquid water according to the outlet water temperature, the outlet water flow rate, and the latent heat coefficient of vaporization of water; and

[0030] The heat dissipation power of the intercooler is determined according to the intake air flow rate, the water outlet temperature, the first intake air temperature, the second intake air temperature, the constant-pressure specific heat capacity of gas, and the constant-pressure specific heat capacity of water vapor.

[0031] In one embodiment, determining, based on the heat absorption power and the heat dissipation power, to evaporate the liquid water by using the intercooler based on the heat absorbed by cooling the air intake circuit, and / or to evaporate the liquid water by heating the heater, includes:

[0032] When the first intake air temperature reaches a preset temperature threshold and the heat absorption power is less than or equal to the heat dissipation power of the intercooler, determining to evaporate the liquid water by the intercooler based on the heat absorbed by the intercooler based on cooling the intake circuit;

[0033] or,

[0034] When the heat absorption power is greater than the heat dissipation power of the intercooler, it is determined to evaporate the liquid water by heating through the heater, and a heating control instruction is sent to the heater, wherein the heating control instruction is used to instruct the heater to start heating.

[0035] In one embodiment, sending a heating control instruction to the heater includes:

[0036] When the first intake air temperature reaches a preset temperature threshold, determining a first compensation heat dissipation power according to a difference between the heat absorption power and the heat dissipation power, and sending a heating control instruction to the heater according to the first compensation heat dissipation power;

[0037] or,

[0038] When the first intake air temperature does not reach a preset temperature threshold, a second compensating heat dissipation power is determined according to the heat absorption power, and a heating control instruction is sent to the heater according to the second compensating heat dissipation power.

[0039] In one embodiment, it further includes:

[0040] When water level information of a water storage tank in a humidification circuit of a fuel cell stack reaches a second preset threshold, a drainage control instruction is sent to a humidification circuit three-way valve in the humidification circuit, wherein the drainage control instruction is used to control a drainage port of the humidification circuit three-way valve to open, so as to drain part of the liquid water in the water storage tank until the water level information is within a third preset threshold range;

[0041] The second preset threshold is greater than the first preset threshold, and the third preset threshold is an intermediate value between the first preset threshold and the second preset threshold.

[0042] In one embodiment, when the water amount information of the water storage tank in the humidification circuit of the fuel cell stack reaches a first preset threshold, obtaining the intake air moisture content of the intake circuit of the fuel cell stack includes:

[0043] When the water amount information of the water storage tank in the humidification circuit of the fuel cell stack reaches a first preset threshold, the function flag bit of the humidification circuit is determined to be in a humidification state, wherein the function flag bit is used to indicate whether the humidification circuit is currently in a humidification state or a non-humidification state;

[0044] According to the function flag, the intake air moisture content of the intake loop of the fuel cell stack is obtained.

[0045] In one embodiment, before obtaining the intake air moisture content of the intake loop of the fuel cell stack according to the function flag, the method further includes:

[0046] Obtaining the current power generation current of the fuel cell stack;

[0047] Determining whether the fuel cell stack has a humidification requirement based on a comparison result between the voltage and impedance corresponding to the current generated current and a voltage threshold and an impedance threshold corresponding to the current generated current;

[0048] When the fuel cell stack has a humidification requirement, the intake air moisture content of the intake loop of the fuel cell stack is obtained according to the function flag.

[0049] According to a second aspect of the present invention, there is provided a fuel cell control device, comprising:

[0050] Memory, processor;

[0051] The memory stores computer-executable instructions;

[0052] The processor executes the computer-executable instructions stored in the memory, so that the processor executes the humidity control method for the fuel cell stack as described in any one of the first aspects above.

[0053] According to a third aspect of the present invention, a humidity control system for a fuel cell stack is provided, comprising a fuel cell control unit, a fuel cell stack, an air inlet circuit, and a humidification circuit; wherein,

[0054] The fuel cell control unit is used to execute the humidity control method for the fuel cell stack provided in any one of the first aspects above;

[0055] The air inlet circuit includes an air compressor for compressing air, and an intercooler connected to the air compressor, wherein the intercooler is connected to the air inlet of the fuel cell stack and is used to supply pressurized and cooled gas to the fuel cell stack;

[0056] The humidification circuit includes a water tank and a first flow meter. The water tank is connected to the intercooler through the first flow meter and is used to provide liquid water to the air inlet circuit under the control of the fuel cell control unit to achieve humidification when supplying gas to the fuel cell stack.

[0057] In one embodiment, the system further comprises a first gas-water separator provided on the hydrogen exhaust path of the fuel cell stack, and / or a second gas-water separator provided on the air exhaust path of the fuel cell stack; wherein the first gas-water separator and the second gas-water separator are respectively connected to the water storage tank;

[0058] The first gas-water separator is used to perform gas-water separation on the hydrogen that has not participated in the reaction in the fuel cell stack, and to transport the separated liquid water to the water storage tank;

[0059] and / or,

[0060] The second gas-water separator is used to perform gas-water separation operations on the air that does not participate in the reaction in the fuel cell stack, and to transport the separated liquid water to the water storage tank.

[0061] In one embodiment, the humidification circuit further comprises a humidification circuit three-way valve disposed between the first flow meter and the water storage tank;

[0062] The humidification circuit three-way valve is used to open the water supply end of the humidification circuit three-way valve under the control of the fuel cell control unit to provide liquid water to the air inlet circuit; or, under the control of the fuel cell control unit, open the drainage end of the humidification circuit three-way valve to discharge part of the liquid water in the water tank.

[0063] In one embodiment, the humidification circuit further includes a first temperature sensor, which is disposed on one side of the water supply end and is used to collect the outlet water temperature of the humidification circuit.

[0064] In one embodiment, the air inlet circuit further includes a second flow meter provided on the air inlet side of the air compressor, a second temperature sensor and a pressure sensor provided on the air outlet side of the air compressor, and a third temperature sensor and a humidity sensor provided on the air outlet side of the intercooler;

[0065] The second flow meter is used to collect the intake flow rate of the intake circuit; the second temperature sensor is used to collect the first intake temperature of the air compressed by the air compressor; the pressure sensor is used to collect the intake pressure of the air compressed by the air compressor; the third temperature sensor is used to collect the second intake temperature after the intake circuit is cooled by the intercooler; the humidity sensor is used to collect the intake relative humidity of the intake circuit.

[0066] In one embodiment, the system further comprises a heater disposed on one side of the intercooler outlet, wherein the heater is configured to heat the liquid water in the humidification circuit to evaporate the liquid water.

[0067] In one embodiment, the system also includes a mixing valve arranged on one side of the air compressor inlet, and the heater is specifically arranged between the mixing valve and the connecting pipe between the intercooler outlet, and is used to mix the humidified steam evaporated by the heater and the inlet air of the air compressor, and transport it to the fuel cell stack through the inlet air circuit.

[0068] The humidity control method, device and system for the fuel cell stack provided by the present invention do not rely on a traditional humidifier to control the intake humidity. The liquid water generated by the fuel cell stack (such as water generated by separating hydrogen and air, or water generated by the reaction of the fuel cell stack, etc.) is recovered by using a water tank. When the water amount in the water tank reaches a certain threshold, the water outlet flow rate of the water tank is calculated according to the intake air humidity content and the target intake air humidity content. The water is combined with the heat of the existing intercooler or evaporated into water vapor by heating with a heater to achieve humidification of the fuel cell stack. The structure is simpler, the rational use of resources is realized, the humidification cost is effectively reduced, and a better humidification effect can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 This is one of the structural schematic diagrams of a humidity control system for a fuel cell stack provided by an embodiment of the present invention;

[0070] Figure 2 This is a second structural diagram of a humidity control system for a fuel cell stack provided by an embodiment of the present invention;

[0071] Figure 3 A schematic flow chart of a humidity control method for a fuel cell stack provided in an embodiment of the present invention;

[0072] Figure 4a A schematic flow chart of a humidification control method based on the operating state of a fuel cell stack provided in an embodiment of the present invention;

[0073] Figure 4b A schematic flow chart of a method for determining the operating status of a fuel cell stack provided by an embodiment of the present invention;

[0074] Figure 5 1 is a flow chart of a method for controlling water storage capacity in a water storage tank provided by an embodiment of the present invention;

[0075] Figure 6 A schematic flow chart of a method for calculating water flow rate provided by an embodiment of the present invention;

[0076] Figure 7 A schematic flow chart of a heating control method provided in an embodiment of the present invention;

[0077] Figure 8 A schematic structural diagram of a fuel cell control device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0078] The following describes the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art will readily appreciate the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the various details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are intended only to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

[0079] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0080] In the description of the present invention, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. In addition, in the description of the present invention, unless otherwise specified, "multiple" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the previous and subsequent associated objects are in an "or" relationship.

[0081] It should be noted that due to space limitations, this specification does not exhaustively list all optional implementation methods. After reading this specification, those skilled in the art should be able to understand that as long as the technical features do not contradict each other, any combination of technical features can constitute an optional implementation method. The following is a detailed description of each embodiment.

[0082] A fuel cell stack is a device that converts the chemical energy contained in hydrogen and oxygen into electrical energy for output. The reaction product is water, making it environmentally friendly and efficient, making it an ideal on-board power system. The membrane electrode is the core of the fuel cell stack's power generation. Excessive dryness increases the membrane's internal resistance, while excessive moisture can easily cause flooding. Therefore, maintaining a properly moistened membrane is crucial for efficient fuel cell stack power generation.

[0083] In order to control humidity, some related technologies install a membrane humidifier on the fuel cell stack air inlet pipeline, using the humidified gas at the cathode outlet to humidify the fresh air at the fuel cell stack air inlet. However, the membrane humidifier has a complex structure, high cost and large size, which is not conducive to cost reduction and compact layout of the fuel cell system. In some related technologies, the humidified exhaust gas at the fuel cell stack air outlet is used to humidify the inlet air. Liquid water droplets are inevitably present in the humidified exhaust gas. After mixing with the inlet air and then entering the air compressor, the liquid water droplets will damage the air compressor, and the increase in the inlet gas flow rate will additionally increase the power consumption of the air compressor.

[0084] In view of this, embodiments of the present invention provide a method, device, and system for controlling humidity in a fuel cell stack. The method obtains the intake air humidity content of the fuel cell stack's air inlet circuit when the water level information in a water storage tank in the fuel cell stack's humidification circuit reaches a first preset threshold. The water storage tank is used to collect liquid water generated by the fuel cell stack and use it for humidification. Subsequently, based on the intake air humidity content and a preset target intake air humidity content, the method determines the water flow rate out of the water storage tank in the humidification circuit used to humidify the fuel cell stack. Based on the water flow rate, the method controls the humidification circuit to supply liquid water to the air inlet circuit. This allows the intercooler in the air inlet circuit to absorb heat from cooling the air inlet circuit, and / or evaporates the liquid water through heating by a heater, thereby humidifying the air supplied to the air inlet circuit. During this process, the control of intake air humidity does not require reliance on traditional humidifiers. Instead, the liquid water produced by the fuel cell stack (such as water produced by separating hydrogen and air, or water generated by the reaction of the fuel cell stack, etc.) is recovered through a water tank. When the water level in the water tank reaches a certain threshold, the water outlet flow rate of the water tank is calculated based on the intake air moisture content and the target intake air moisture content. The fuel cell stack is humidified by combining the heat of the existing intercooler and the heating of the heater to evaporate the water vapor, which effectively reduces the cost of the humidifier and achieves a better humidification effect.

[0085] Please refer to Figure 1 , Figure 1 This is one of the structural diagrams of a humidity control system for a fuel cell stack provided in this embodiment. Figure 1 As shown, the system includes a fuel cell control unit 110, a fuel cell stack 120, an air inlet circuit 130, and a humidification circuit 140; wherein,

[0086] A fuel cell control unit 110 is used to execute a humidity control method for a fuel cell stack; an air inlet circuit 130 includes an air compressor 131 for compressing air, and an intercooler 132 connected to the air compressor 131, the intercooler 132 is connected to the air inlet of the fuel cell stack 120, and is used to supply pressurized and cooled gas to the fuel cell stack; a humidification circuit 140 includes a water tank 141 and a first flow meter 142, the water tank 141 is connected to the intercooler through the first flow meter, and is used to provide liquid water to the air inlet circuit under the control of the fuel cell control unit, so as to achieve humidification when supplying gas to the fuel cell stack 120.

[0087] The Fuel Cell Control Unit (FCCU) 110 is a key component in the fuel cell system, responsible for managing and controlling the operation of the fuel cells. In this embodiment, the FCCU serves as the executor of the humidity control method described in the following method embodiments, controlling the humidity of the fuel cell stack, for example by issuing humidification control instructions to the humidification circuit.

[0088] The air inlet circuit 130 is the circuit for the fuel cell stack's air inlet. This circuit collects air from the external environment, compresses it through an air compressor, and cools it through an intercooler before delivering it to the fuel cell stack's air inlet 120. The fuel cell stack uses the oxygen in the air to perform an electrochemical reaction, releasing electrical energy. Specifically, the air inlet circuit first passes the collected air through an air compressor, which compresses it to the required pressure level, enabling the fuel cell stack to efficiently perform the reaction. Since the compressed air heats up after passing through the compressor, to prevent the high temperature from adversely affecting the fuel cell stack's performance, the compressed air is cooled through an intercooler before being delivered to the fuel cell stack's air inlet. At this point, the oxygen in the air participates in an electrochemical reaction on the fuel cell stack's cathode side, combining with protons and electrons to produce water. Within the fuel cell stack, hydrogen is decomposed into protons and electrons on the anode side. The protons migrate through the proton exchange membrane to the cathode side, where they combine with oxygen from the air and electrons that have reached the cathode through the external circuit to produce water and release electrical energy.

[0089] The humidification circuit 140 replaces the humidifier used in related art. This embodiment utilizes a water storage tank within the humidification circuit to collect water generated by the fuel cell stack. This water can be separated from unreacted hydrogen at the anode, unreacted air at the cathode, or reaction-generated water, achieving water recycling. Under the control of the fuel cell control unit, the humidification circuit provides a corresponding water output flow rate to the air inlet circuit (this output flow rate is calculated by the fuel cell control unit). A first flow meter measures the output flow rate (Q2) in real time and feeds this data back to the fuel cell control unit. Based on this feedback, the control unit controls the humidification circuit to stop or resume humidification, thereby improving humidity control accuracy and responsiveness. Furthermore, the humidification circuit is connected to the intercooler in the air inlet circuit. The heat generated by the intercooler cooling the compressed air in the air compressor evaporates into water vapor. This process uses the heat removed from the compressed air by the intercooler to heat the water, simultaneously cooling the intercooler, achieving thermal energy recycling, and reducing economic costs.

[0090] By way of further example, in combination Figure 2 As shown, Figure 2 This is the second structural diagram of the humidity control system of the fuel cell stack provided in this embodiment, which provides a more detailed structure of the system.

[0091] In one embodiment, the system also includes a first gas-water separator 151 arranged on the hydrogen exhaust path of the fuel cell stack 120, and / or a second gas-water separator 152 arranged on the air exhaust path of the fuel cell stack; wherein the first gas-water separator 151 and the second gas-water separator 152 are respectively connected to the water storage tank 141; the first gas-water separator 151 is used to perform gas-water separation operations on the hydrogen that does not participate in the reaction in the fuel cell stack 120, and transport the separated liquid water to the water storage tank; and / or the second gas-water separator 152 is used to perform gas-water separation operations on the air that does not participate in the reaction in the fuel cell stack, and transport the separated liquid water to the water storage tank 141.

[0092] For example, Figure 2 As shown, the first gas-water separator 151, the hydrogen cylinder 153, and the hydrogen circulation pump 154 ​​constitute a hydrogen supply module. The hydrogen cylinder 153 is used to provide hydrogen to the fuel cell stack. The first gas-water separator 151 is used to separate the unreacted hydrogen (hydrogen mixed with water vapor) in the fuel cell stack from gas and water, transporting the separated liquid water to a water storage tank, and then re-transporting the separated hydrogen to the fuel cell stack via the hydrogen circulation pump 154 ​​for reaction to generate electricity, thereby achieving the recycling of hydrogen and the collection of liquid water. Correspondingly, the unreacted air (air mixed with water vapor) in the fuel cell stack 120 is separated from gas and water by the second gas-water separator 152, and the separated liquid water is transported to a water storage tank for collection. The separated air can be discharged into the environment, thus achieving the recycling of resources.

[0093] In one embodiment, the humidification circuit 140 further includes a humidification circuit three-way valve 143 disposed between the first flowmeter 142 and the water tank 141. The humidification circuit three-way valve 143 is configured to, under the control of the fuel cell control unit 110, open a water supply port a of the humidification circuit three-way valve 143 to supply liquid water to the air inlet circuit; or, under the control of the fuel cell control unit 110, open a drain port b of the humidification circuit three-way valve to drain some of the liquid water from the water tank. Furthermore, a water inlet port c of the humidification circuit three-way valve 143 is connected to the water tank 141.

[0094] A three-way valve is a valve with three ports. By controlling the valve's opening and closing states and the connectivity between the ports, it can switch and distribute fluids between different paths. It can include internal control components such as a valve core, which changes the position of the valve core through mechanical or electromagnetic actuation, thereby changing the direction of fluid flow. For example, common three-way valves have two basic structures: T-type and L-type. T-type three-way valves can switch and mix fluids between three paths, while L-type three-way valves are mainly used to switch between two paths.

[0095] In this embodiment, the humidification circuit three-way valve connects the water tank, the first flow meter, and the drain port. When the fuel cell stack needs to humidify the air entering the fuel cell stack, the humidification circuit three-way valve, under the control of the fuel cell control unit (FCCU), opens the passage between the water tank and the first flow meter. Water in the water tank can flow through the first flow meter and then mix into the air inlet circuit, humidifying the air in the air inlet circuit to meet the fuel cell stack's humidity requirements. When the liquid level in the water tank reaches a threshold, the FCCU controls the three-way valve to open the drain port (which can be connected to the atmosphere) to drain excess water from the water tank, preventing the system from operating normally due to excessive water levels. When the water level drops to an appropriate value (such as the lower limit or intermediate value), the FCCU controls the three-way valve to close the drain port, stopping drainage.

[0096] By setting a three-way valve in the humidification circuit to control the water output and drainage of the water tank in the humidification circuit, the on-off and flow direction of the water channel can be controlled more accurately, further improving the stable and efficient operation of the fuel cell stack.

[0097] In some embodiments, in addition to setting a three-way valve in the humidification circuit and controlling the three-way valve in the humidification circuit to achieve humidification control of the humidification circuit, the humidification circuit can also be controlled by other means, such as water pumps, solenoid valves, and other forms. The present invention does not specifically limit this.

[0098] In one embodiment, the humidification circuit 140 further includes a first temperature sensor 144, which is disposed on the side of the water supply end a and is used to collect the outlet water temperature T3 of the humidification circuit 140. By providing a temperature sensor, such as a thermometer, in the humidification circuit 140, the outlet water temperature of the humidification circuit can be effectively collected to facilitate the subsequent calculation of heat absorption power or heat dissipation power, thereby achieving sufficient evaporation of liquid water.

[0099] In one embodiment, the air intake circuit 130 further includes a second flow meter 133 disposed on the air intake side of the air compressor 131, a second temperature sensor 134 and a pressure sensor 135 disposed on the air outlet side of the air compressor 131, and a third temperature sensor 136 and a humidity sensor 137 disposed on the air outlet side of the intercooler 132; the second flow meter 133 is used to collect the intake air flow rate (Q1) of the air intake circuit 130; the second temperature sensor 134 is used to collect the first intake air temperature (T1) compressed by the air compressor 131; the pressure sensor 135 is used to collect the intake air pressure (P) compressed by the air compressor 131; the third temperature sensor 136 is used to collect the second intake air temperature (T2) after the air intake circuit 130 is cooled by the intercooler 132; and the humidity sensor 137 is used to collect the intake relative humidity (R) of the air intake circuit.

[0100] In this embodiment, the temperature sensor may be a thermocouple, and the humidity sensor may be a hygrometer. Optionally, an air filter (air filter) 160 may be provided in the air inlet circuit. This air filter may be positioned before the second flow meter, so that the ambient air is filtered for impurities before the air flow rate is collected and delivered to the air compressor for compression.

[0101] The above structure effectively collects the temperature and pressure of the first gas compressed by the air compressor, the temperature of the second gas after cooling through the intercooler, and the relative humidity of the intake air in the air intake circuit. It is understood that the relative humidity of the intake air reflects the current humidity state of the air, namely, the percentage of the actual water vapor density in the air to the saturated water vapor density at the same temperature. The intake air moisture content quantifies the water vapor content in the air from a more specific mass ratio perspective. This embodiment measures relative humidity and calculates the intake water moisture content based on parameters such as temperature and pressure, allowing for more accurate determination of the difference in humidity between the air before and after humidification.

[0102] In one embodiment, the system further includes a heater 170 disposed at one side of an air outlet of the intercooler 132 . The heater 170 is configured to heat the liquid water in the humidification circuit 140 to evaporate the liquid water.

[0103] In one example of this embodiment, the heater can be arranged between the intercooler outlet and the fuel cell stack air inlet pipeline. After the liquid water evaporates through the heat of the intercooler, if the heat of the intercooler is insufficient, the heater can be turned on for heating to ensure that the gas is fully evaporated and then transported to the fuel cell stack.

[0104] In another example of this embodiment, the heater can also be set on another pipeline of the cold air outlet. In other words, the intercooler outlet can be connected to two branches, one branch is connected to the fuel cell stack air inlet pipeline, and the other branch can be connected to the intake circuit direction (such as before the air compressor, in some embodiments, it can also be after the air compressor and before the intercooler, which is not particularly limited in this embodiment). After the liquid water is fully heated and evaporated into gaseous water, it is sent back to the intake circuit direction to mix with the intake air, and then cooled again by the intercooler before being delivered to the fuel cell stack. Optionally, in the case of two branches, when the FCCU controls the heater to turn on, the other branch can be closed. When the heater is turned off (turned off after heating the liquid water), the branch of the heater is closed and the other branch is opened (for example, control valves can be set on the two branches to realize the opening and closing of the two different branches), so that the humidified gas is delivered to the fuel cell stack for reaction.

[0105] For another example of this embodiment, the system may also include a mixing valve 180 arranged on the air inlet side of the air compressor 131, and the heater 170 is specifically arranged between the connecting pipe between the mixing valve 180 and the air outlet of the intercooler 132, for mixing the humidified steam evaporated by the heater 170 and the inlet air of the air compressor 131, and delivering it to the fuel cell stack through the inlet air circuit.

[0106] For example, a mixing valve can be installed between the air filter and the air compressor to mix the inlet air and the humidified steam, and a heater can be installed in the pipeline between the intercooler and the mixing valve to supplement the heat when the intercooler's heat dissipation demand is low.

[0107] Optionally, the FCCU can determine whether to turn on the heater provided at the rear end of the intercooler as needed to ensure that the liquid water is fully evaporated. When the heater is turned on, the mixing valve provided in front of the air inlet compressor can be opened at the same time to fully mix the water vapor generated by the intercooler with the inlet air to complete humidification and further transport it to the fuel cell stack.

[0108] In some embodiments, the heater 160 can also be positioned in the humidification circuit, for example, between the intercooler and the first flow meter. Liquid water evaporates through the heater, becomes vaporized water, and is mixed with air cooled by the intercooler before being delivered to the fuel cell stack. This embodiment does not specifically limit the specific location of the heater.

[0109] In some embodiments, the system may also include a cooling system 190, which is connected to the intercooler 132 and the fuel cell stack 120, respectively, to cool the intercooler 132 and the fuel cell stack 120. Optionally, switches may be provided on the intercooler 132 and the cooling system 190. Since the intercooler 132 in this embodiment can be cooled by liquid water, there is no need to rely heavily on the cooling system 190 for cooling. For example, when the ambient temperature is moderate and the evaporative cooling effect of liquid water is sufficient, the switch can disconnect the cooling system from the intercooler, allowing the intercooler to cool solely by evaporation of the humidifying water. When the ambient temperature is too high or the humidifying water supply is insufficient, the cooling system can be activated to assist the intercooler in cooling, while the fuel cell stack continues to be cooled by the cooling system. The FCCU can control the on / off of this switch. This selective cooling mechanism can be flexibly switched based on actual operating conditions, effectively saving energy and resource consumption in the cooling system while ensuring system reliability.

[0110] The above technical solution eliminates the need for traditional humidifiers to control intake air humidity. Using a simple structural design, while achieving resource recycling, humidity control is more precise. When the fuel cell stack becomes dry, the fuel cell stack can be re-humidified to prevent membrane drying, thereby extending the service life of the fuel cell stack. Furthermore, the solution not only humidifies the fuel cell stack but also utilizes heat from the intercooler to evaporate liquid water, providing additional cooling for the intercooler. In some embodiments, the humidification circuit can also be connected to an external fuel cell stack that requires humidification, thereby matching the external humidification of the fuel cell stack to a certain extent.

[0111] To facilitate understanding of the humidity control method for a fuel cell stack provided by an embodiment of the present invention, the humidity control method for a fuel cell stack provided by this embodiment can be understood in conjunction with the structural content of the above system, and similar related contents will not be further described in this embodiment. Figure 3 As shown, the execution subject of this method can be Figure 1 or Figure 2 In the fuel cell control unit 110, the method may include the following steps S301-S303.

[0112] Step S301: When the water amount information of the water tank in the humidification circuit of the fuel cell stack reaches a first preset threshold, the intake air moisture content of the intake circuit of the fuel cell stack is obtained; wherein the water tank is used to collect liquid water generated by the fuel cell stack and use it for humidification.

[0113] It should be noted that those skilled in the art may set or adjust the first preset threshold value based on actual applications or experience. By initiating the humidification process when the water level in the water tank reaches a certain value, it is possible to effectively avoid interruptions in the humidification process or ineffective humidification operations due to insufficient water, thereby affecting the stability of the entire system. Reaching the first preset threshold value may be greater than the first preset threshold value.

[0114] In one embodiment, the FCCU may execute a humidification control process according to the function flag of the humidification circuit to improve the humidification control efficiency. Specifically, the above step S301 may include the following steps:

[0115] When the water level information of the water storage tank in the humidification circuit of the fuel cell stack reaches a first preset threshold, the function flag bit of the humidification circuit is determined to be in a humidification state, and the function flag bit is used to indicate whether the humidification circuit is currently in a humidification state or a non-humidification state;

[0116] According to the function flag bit, the intake air moisture content of the intake circuit of the fuel cell stack is obtained.

[0117] In this embodiment, the humidification circuit's function flag indicates whether the circuit is currently in a humidification-enabled or non-humidification state. The "enabled" or "non-humidification" state corresponds to whether the system can execute humidification instructions, respectively. For example, the humidification circuit's function flag, 1, indicates a humidification-enabled state, while 0 indicates a non-humidification state. The FCCU can update the function flag in real time based on the water level in the water storage tank to determine the humidification circuit's operating status, thereby improving humidification control efficiency.

[0118] In some embodiments, the water tank can be drained by monitoring the water level information in the water tank to further optimize the humidification function. Specifically, the method can further include the following steps: when the water level information in the water tank in the humidification circuit of the fuel cell stack reaches a second preset threshold, sending a drainage control instruction to the humidification circuit three-way valve in the humidification circuit, the drainage control instruction being used to control the opening of the drainage port of the humidification circuit three-way valve to drain some of the liquid water in the water tank until the water level information is within a third preset threshold range; wherein the second preset threshold is greater than the first preset threshold, and the third preset threshold is an intermediate value between the first preset threshold and the second preset threshold.

[0119] It should be noted that those skilled in the art may adaptively set the second preset threshold value based on actual applications and experience, and this embodiment does not specifically limit this.

[0120] Furthermore, by identifying the humidification requirements of the fuel cell stack, the fuel cell stack is humidified to avoid situations such as inappropriate humidification or excessive humidification, thereby improving humidification adaptability. Specifically, before obtaining the intake air humidity content of the intake air loop of the fuel cell stack according to the function flag in the above step, the following steps may also be included:

[0121] Obtain the current power generation current of the fuel cell stack;

[0122] Determine whether the fuel cell stack has a humidification requirement based on a comparison result between the voltage and impedance corresponding to the current power generation current and the voltage threshold and impedance threshold corresponding to the current power generation current;

[0123] When the fuel cell stack has a humidification requirement, the intake air moisture content of the intake loop of the fuel cell stack is obtained according to the function flag.

[0124] It can be understood that the impedance in this embodiment refers to high-frequency impedance.

[0125] Specifically, the current fuel cell stack operating state parameters, including the current fuel cell stack generated current I, corresponding voltage U, and current high-frequency impedance R, are obtained. Optionally, the generated current I and corresponding voltage U can be collected by a fuel cell load system, while the high-frequency impedance R can be measured using a constant-frequency internal resistance meter or an AC electrochemical impedance meter connected to the stack. Preferably, to avoid the impact of interference fluctuations on the measurement results, the generated current I, corresponding voltage U, and high-frequency impedance R can be averaged over a period of time t. Optionally, after calculating ΔU = |U - U0| and ΔR = R - R0 (where U0 is a reference voltage and R0 is a reference high-frequency resistance, representing the relatively stable standard voltage and standard high-frequency impedance of the fuel cell stack under suitable humidity conditions, which are constant values), ΔU and ΔR are compared with the thresholds ΔU0 and ΔR0 specified by the stack manufacturer, respectively, to obtain a comparison result. When ΔU ≥ ΔU0 and ΔR ≥ ΔR0, the fuel cell stack is determined to be in a relatively dry state, and the humidification control process is executed.

[0126] In one example, to improve the accuracy of fuel cell stack operating parameter acquisition, data is collected while the system is operating at constant power. Specifically, the fuel cell system controller (FCCU) obtains the system power demand and, based on the power demand, categorizes the fuel cell system operating states into constant power, power loading, and power shedding. When the fuel cell system is operating at constant power, the FCCU obtains real-time fuel cell stack operating parameters to determine the fuel cell stack's state (whether it is in a dry state).

[0127] In this way, when the fuel cell stack needs humidification, real-time humidification can be performed, and at the same time, situations such as over-humidification can be effectively avoided, thereby effectively improving the humidification adaptability.

[0128] In one embodiment, in the above step S301, the intake air moisture content of the intake circuit of the fuel cell stack is obtained, which can be: collecting the intake relative humidity of the intake circuit, the first intake temperature and intake pressure compressed by the air compressor, and the second intake temperature after the intake circuit is cooled by the intercooler; and determining the intake air moisture content of the intake circuit based on the intake relative humidity, the first intake temperature, the intake pressure and the second intake temperature.

[0129] For example, the first compressed intake air temperature T1 can be obtained by a thermocouple arranged after the air compressor, and the second cooled intake air temperature T2 can be obtained by a thermocouple arranged after the intercooler. The air pressure P after being pressurized by the air compressor can be obtained by a pressure sensor arranged after the air compressor. The intake air relative humidity, that is, the air humidity C0 before humidification, can be obtained by a (relative) humidity sensor arranged after the intercooler (in some embodiments, the humidity sensor can also be arranged at other positions in its intake circuit, which is just one example). The collected data are used to calculate the intake air moisture content of the intake circuit.

[0130] Specifically, the intake air moisture content of the intake circuit can be determined based on the intake air relative humidity, the first intake air temperature, the intake air pressure, and the second intake air temperature in the following manner:

[0131] determining a first partial pressure of water vapor in the intake air environment based on the intake air relative humidity, the first intake air temperature, and the second intake air temperature;

[0132] determining a second partial pressure of dry gas in the intake environment from which water vapor has been removed based on a difference between the intake pressure and the actual partial pressure of water vapor;

[0133] The moisture content of the intake air of the air intake circuit is determined based on the ratio between the first partial pressure and the second partial pressure.

[0134] Alternatively, the calculation formula for the intake air moisture content M0 may be as follows:

[0135]

[0136] The numerator in the above formula represents the first partial pressure of water vapor in the intake air environment, i.e., the actual partial pressure of water vapor in the air. The denominator represents the actual partial pressure of dry air after removing the actual partial pressure of water vapor in the air, i.e., the second partial pressure. For example, based on moist air theory, this formula uses 0.622 to balance the difference in properties between dry air and water vapor. The water vapor content is represented by the pre-humidification air humidity C0 combined with the saturated water vapor pressure calculated by T2. The air pressure P after pressurization by the air compressor is also considered. By combining these factors, the intake air moisture content M0 of the intake circuit can be calculated relatively accurately.

[0137] Step S302: Determine the water flow rate of the water tank in the humidification circuit for humidifying the fuel cell stack according to the intake air moisture content and the preset target intake air moisture content.

[0138] For example, the target intake air humidity M1 can also be calculated using the above-mentioned intake air humidity calculation. For example, an appropriate intake air relative humidity C1 can be set according to the dryness of the fuel cell stack (those skilled in the art can adaptively set C1 based on actual applications or empirical values), and the target intake air humidity can be calculated based on T1, T2, and P. Specifically, the following formula can be used:

[0139]

[0140] Accordingly, the formula principle of M1 is similar to that of M0 above, and the relevant explanation will not be repeated here.

[0141] In one embodiment, the required water outlet flow rate can be calculated by combining the intake air flow rate, intake air moisture content, and target intake air moisture content to improve the calculation accuracy of the water outlet flow rate and thereby achieve a refined humidification effect. Specifically, the method may further include the following steps: collecting the intake air flow rate of the air inlet circuit. The above-mentioned step S302 determines the water outlet flow rate of the water storage tank in the humidification circuit used for humidifying the fuel cell stack based on the intake air moisture content and the preset target intake air moisture content. This can be done by: determining the unit humidification amount based on the difference between the intake air moisture content and the preset target intake air moisture content; and determining the water outlet flow rate of the water storage tank based on the product of the intake air flow rate of the air inlet circuit and the unit humidification amount.

[0142] For example, the air intake flow rate can be collected by a second flow meter arranged behind the air compressor, and the water flow rate Q2 of the humidification circuit can be calculated in combination with the above-mentioned relevant parameters. Specifically, , where That is, the unit humidification capacity. Combining the above formula, the calculation formula of Q2 can be converted into:

[0143]

[0144] In this way, the required water outlet flow rate is calculated by combining the intake air flow rate, intake air moisture content and target intake air moisture content, so as to improve the calculation accuracy of the water outlet flow rate and thus achieve a refined humidification effect.

[0145] Step S303: Control the humidification circuit to provide liquid water to the air intake circuit based on the water outlet flow rate, so that the intercooler in the air intake circuit absorbs heat based on the cooling of the air intake circuit, and / or evaporates the liquid water by heating through the heater, so as to humidify the air when the air intake circuit is supplied.

[0146] For example, the FCCU can realize water supply to the humidification circuit by controlling the water outlet switch of the humidification circuit (which can be a humidification circuit three-way valve or other switch provided on the circuit), and monitor the water outlet flow rate of the humidification circuit in real time. When the water outlet flow rate reaches the water outlet flow rate determined in the above step S302, the humidification circuit is controlled to stop providing liquid water.

[0147] For example, the liquid water may be evaporated using only the heat absorbed by the intercooler (for cooling the inlet air), or may be evaporated using only the heating by the heater, or may be evaporated using both the intercooler and the heater to achieve humidification of the air intake.

[0148] Combined with the above-mentioned water tank water quantity control logic, the FCCU controls the opening and closing of the humidification port of the humidification circuit three-way valve based on the system moisture demand reflected by the water outlet flow rate. When the humidification conditions are met and the water quantity in the water tank is reasonable, it accurately adjusts the process of supplying liquid water to the inlet circuit to maintain the appropriate humidity level in the inlet circuit and ensure the stable operation of the fuel cell system.

[0149] Instead of using a humidifier to humidify the fuel cell stack in the related art, this embodiment collects water generated by the fuel cell stack by controlling the water tank of the humidification circuit, and achieves more refined humidification control by controlling the water outlet flow of the water tank, with a simpler structure and lower cost.

[0150] In one embodiment, the above step S303 controls the humidification circuit to provide liquid water to the air inlet circuit according to the water outlet flow rate, which can be achieved by sending a humidification control instruction to the humidification circuit three-way valve in the humidification circuit. The humidification control instruction is used to control the water supply port of the humidification circuit three-way valve to open, so that the humidification circuit provides liquid water to the air inlet circuit.

[0151] It should be noted that the humidification circuit three-way valve has been introduced in detail in the above system embodiment, and will not be described in detail here. For related descriptions, please refer to the above embodiment.

[0152] To facilitate the understanding of the embodiments of the present invention, the humidification control method for the above fuel cell stack operating state is combined with Figure 4a and Figure 4b As shown, Figure 4a As shown, the process includes the following:

[0153] S401, obtaining current fuel cell stack operating status parameters;

[0154] S402, analyzing the state parameter data to determine the operating state of the fuel cell stack (hereinafter referred to as the stack);

[0155] S403: When it is determined that the stack is in a relatively dry state, prepare to execute the humidification program and proceed to the subsequent step S404; otherwise, return to step S402 to determine the stack operation state in real time;

[0156] S404, obtaining the function flag of the humidification circuit;

[0157] S405, determining whether the humidification circuit is capable of executing the humidification instruction. Whether the humidification circuit is capable of executing the humidification instruction may be determined by the amount of water stored in the humidification circuit;

[0158] S406: When the humidification circuit feedback indicates that the humidification program can be executed, the humidification instruction is executed according to the stack requirements;

[0159] S407. When the high-frequency internal resistance of the fuel cell stack (i.e., high-frequency impedance) meets the requirements of the fuel cell stack manufacturer, humidification can be completed.

[0160] Furthermore, for the judgment method of the fuel cell stack operating state, such as Figure 4b As shown, the process includes the following:

[0161] S4021. Obtain the current fuel cell stack operating status parameters, including the current fuel cell stack generated current I, the corresponding voltage U, and the current high-frequency internal resistance (i.e., impedance) R. Optionally, the generated current I and the corresponding voltage U can be collected by the fuel cell load system, and the high-frequency impedance R can be measured and collected using a fixed-frequency internal resistance meter or an AC electrochemical impedance meter connected to the stack. Preferably, to avoid the impact of interference fluctuations on the measurement results, the generated current I, the corresponding voltage U, and the high-frequency internal resistance R are all averaged over a period of time t.

[0162] S4022. Calculate the difference ΔU between the standard voltage U0 and the standard high-frequency internal resistance R0 corresponding to the voltage U, the high-frequency internal resistance R, and the generated current I, i.e., ΔU = |U - U0|, ΔR = R - R0;

[0163] S4023. Compare ΔU and ΔR with the thresholds ΔU0 and ΔR0 specified by the stack manufacturer, respectively.

[0164] S4024: When ΔU>ΔU0 and ΔR>ΔR0, it is determined that the fuel cell stack is in a dry state.

[0165] Furthermore, with respect to the water storage capacity control method of the water storage tank in the above-mentioned fuel cell stack intake humidity control device, as Figure 5 As shown, the process includes the following:

[0166] S501, obtaining water volume information L of a water storage tank in a humidification circuit;

[0167] S502: Compare the acquired water storage capacity L with the water storage capacity lower limit threshold L1 (i.e., the first preset threshold). When L≤L1, set the water tank status flag (i.e., the function flag) to a non-humidification state, and close the humidification port of the humidification circuit three-way valve.

[0168] S503, when L>L1, the water tank status flag is set to the humidification state;

[0169] S504, when L1<L<L2, close the drain port of the three-way valve of the humidification circuit;

[0170] S505, when L≥L2, open the drain port of the three-way valve of the humidification circuit to drain excess water in the water storage tank;

[0171] S506. When L=L3, execute step S507;

[0172] S507: Close the drain port of the humidification circuit three-way valve to stop draining. Optionally, to avoid frequent opening and closing of the drain port, an intermediate value L3 (also the third preset threshold) between L1 and L2 (also the second preset threshold) can be selected as a drain stop flag.

[0173] Furthermore, the calculation method for the humidification amount (i.e., water inlet flow) of the fuel cell stack is as follows: Figure 6 As shown, the process includes the following:

[0174] S601: When the fuel cell control system FCCU determines that the stack needs to be humidified, it starts to send a humidification instruction;

[0175] S602: Obtain the air flow rate Q1 using a flow meter located before the air compressor in the air inlet circuit; obtain the cooled air temperature T2 using a thermocouple located after the intercooler; obtain the air pressure P after pressurization by the air compressor using a pressure sensor located after the air compressor; and obtain the air humidity C0 before humidification using a relative humidity sensor located after the intercooler;

[0176] S603, setting an appropriate intake air relative humidity C1 according to the dryness of the fuel cell stack;

[0177] S604. Calculate the water flow Q2 of the humidification circuit based on the above-mentioned relevant parameters. The water flow is measured by a flow meter provided on the humidification circuit. The specific calculation process can be found in the above formula section.

[0178] S605, opening the three-way valve of the humidification circuit to allow liquid water in the humidification circuit to flow into the intercooler to generate humidification steam;

[0179] S606: Determine whether to turn on the heater provided at the rear end of the intercooler as needed to ensure that the liquid water is fully evaporated;

[0180] S607. Open the mixing valve in front of the air compressor at the air inlet to fully mix the water vapor generated by the intercooler with the inlet air to complete humidification.

[0181] In some embodiments, to ensure sufficient evaporation of the liquid water and further optimize the humidification effect, the method may further include the following steps: obtaining the heat absorption power used to evaporate the liquid water and the heat dissipation power of the intercooler; and determining, based on the heat absorption power and the heat dissipation power, whether to evaporate the liquid water by using the heat absorbed by the intercooler based on cooling the air intake circuit and / or to evaporate the liquid water by heating the heater.

[0182] As mentioned in the previous embodiments, liquid water evaporation requires heat. The intercooler generates a certain amount of heat when cooling the compressed air from the air compressor. The intercooler absorbs this heat to evaporate the liquid water, producing water vapor. This process also cools the intercooler. This embodiment determines the heat utilization method by comparing the heat absorption power required to evaporate the liquid water and the intercooler's heat dissipation power. If the intercooler's heat dissipation power is sufficient to meet the heat absorption power required for liquid water evaporation, the heat generated by the intercooler cooling the air inlet circuit can be used solely to evaporate the liquid water, achieving heat recovery and reuse. If the intercooler's heat dissipation power is insufficient, additional heat from the heater can be used to evaporate the liquid water, ensuring sufficient evaporation and improving the humidification effect.

[0183] Next, the process of obtaining the heat absorption power for evaporating liquid water and the heat dissipation power of the intercooler in the above steps is further introduced: collecting the outlet water temperature of the humidification circuit; determining the heat absorption power for evaporating liquid water based on the outlet water temperature, outlet water flow rate, and latent heat coefficient of vaporization of water; and determining the heat dissipation power of the intercooler based on the intake air flow rate, outlet water temperature, first intake air temperature, second intake air temperature, constant-pressure specific heat capacity of gas, and constant-pressure specific heat capacity of water vapor.

[0184] Specifically, the outlet water temperature T3 of the humidification circuit can be collected by the first temperature sensor on the humidification circuit, and the heat absorption power H0 of evaporating liquid water (hereinafter referred to as evaporation heat absorption power) can be calculated using the outlet water temperature, outlet water flow rate and latent heat coefficient of water. The calculation formula can be as follows:

[0185]

[0186] Where, is the latent heat of vaporization of water. The latent heat of vaporization of water can be a constant value, and its specific value can be obtained by looking up the table of relevant state parameters during actual operation.

[0187] Accordingly, the calculation formula for the intercooler's heat dissipation power H1 can be adopted as follows:

[0188]

[0189] Where, is the constant pressure specific heat capacity of air, is the constant pressure specific heat capacity of water vapor. These two values ​​are constants, and m is the mass of water vapor carried per unit mass of dry air. In the process of calculating the heat dissipation power of the intercooler, the heat dissipation contribution of dry air and water vapor in the cooling process is comprehensively considered. Q1 air flow and constant pressure specific heat capacity of air The product between represents the dry air heat capacity, is the water vapor mass flow rate associated with air, Q2 is the humidification water flow rate, represents the heat capacity of water vapor. The sum of the two heat capacities multiplied by the temperature difference (T1−T2) gives the intercooler heat dissipation power.

[0190] Through the above calculation method, the heat absorption power required to evaporate liquid water and the heat dissipation power of the intercooler can be calculated more accurately, and then it can be determined whether the intercooler can evaporate the liquid water independently or in combination with (or independently of) the heater to heat the evaporated liquid water.

[0191] In one embodiment, in the above steps, determining whether to evaporate liquid water by using heat absorbed by the intercooler based on cooling the air intake circuit and / or to evaporate liquid water by heating the heater based on the heat absorption power and the heat dissipation power can be performed as follows:

[0192] Method 1: When the first intake air temperature reaches a preset temperature threshold and the heat absorption power is less than or equal to the heat dissipation power of the intercooler, it is determined to evaporate liquid water based on the heat absorbed by the intercooler based on cooling the intake circuit.

[0193] For example, when the first intake air temperature, i.e., the air compressor outlet temperature T1, is greater than 100°C (in some embodiments, other preset thresholds may be determined based on actual applications or empirical values), and the evaporative heat absorption power H0 is less than or equal to the intercooler heat dissipation power H1 (or H1 = evaporative heat absorption power H0), the intercooler can generally provide sufficient heat to evaporate the liquid water, and heating can be performed solely by the intercooler.

[0194] Alternatively, considering that the intercooler has a large heat dissipation power, after evaporating the liquid water, the humidified gas may still have an excessively high temperature. The cooling system can provide additional heat dissipation power H2: H2 = H1 H0, thereby reducing the intake air temperature delivered to the fuel cell stack, thereby protecting the fuel cell stack from the effects of excessively high temperature gases.

[0195] Method 2: When the heat absorption power is greater than the heat dissipation power of the intercooler, it is determined that the liquid water is evaporated by heating through the heater, and a heating control instruction is sent to the heater, the heating control instruction is used to instruct the heater to start heating.

[0196] When the evaporation heat absorption power is greater than the heat dissipation power of the intercooler, it indicates that the heat dissipation power of the intercooler is insufficient to fully evaporate the liquid water. In this embodiment, the heater is determined to heat the evaporated liquid water, and the heater is started by sending a heating control instruction to the heater to achieve compensatory heating of the liquid water, thereby achieving sufficient evaporation of the liquid water and improving the humidification effect.

[0197] Furthermore, the heating control instruction sent to the heater in the second embodiment can be sent as follows: when the first intake air temperature reaches a preset temperature threshold, a first compensation heat dissipation power is determined based on the difference between the heat absorption power and the heat dissipation power, and the heating control instruction is sent to the heater based on the first compensation heat dissipation power. Alternatively, when the first intake air temperature does not reach the preset temperature threshold, a second compensation heat dissipation power is determined based on the heat absorption power, and the heating control instruction is sent to the heater based on the second compensation heat dissipation power.

[0198] For example, when the air compressor outlet temperature T1 is greater than 100°C and the intercooler heat dissipation power H1 is less than the evaporation heat absorption power H0, the heater on the rear end pipeline of the intercooler is activated to provide additional heating power H3 (W), which is the first compensation heat dissipation power: .

[0199] When the air compressor outlet temperature T1 is less than 100℃, the heater on the rear end pipeline of the intercooler is started to provide additional heating power H4 (W), which is the second compensatory heat dissipation power: H4 = H0.

[0200] This embodiment takes into account different heat supply and demand conditions. When T1>100°C, the air compressor outlet temperature is higher, and the difference between the two can be used to determine the first compensating heat dissipation power for precise control. When T1<100°C, the heat provided by the intercooler itself is also lower. In this case, the second compensating heat dissipation power can be directly determined based on the evaporation heat absorption power H0 to ensure sufficient evaporation of liquid water and further meet the humidification requirements.

[0201] In order to facilitate the understanding of the heating control method of the liquid water in the humidification circuit in this embodiment, Figure 7 As shown, the process includes the following:

[0202] S701, obtaining the temperature T3 of the humidification water (i.e., the liquid water output from the water storage tank) in the humidification circuit through a thermocouple provided in the humidification circuit;

[0203] S702, calculating the heat absorption power H0 of the evaporated humidified water. For the specific calculation process, please refer to the above formula;

[0204] S703, obtaining the air temperature T1 at the air compressor outlet. When T1 is less than 100°C, the heater may be controlled to start, wherein the heating power of the heater may be H = H0;

[0205] S704: Calculate the intercooler heat dissipation power H1. For the specific calculation process, refer to the above formula.

[0206] S705, comparing the evaporation heat absorption power H0 with the intercooler heat dissipation power H1. When H1 < H0, the heater may be started, wherein the heating power of the heater may be H = H0 - H1.

[0207] S706. When H1>H0, there is no need to start the heater, and the cooling system can provide additional cooling capacity H2 = H1-H0.

[0208] Figure 8 FIG. 1 is a schematic structural diagram of a fuel cell control device provided by an embodiment of the present invention. Figure 8 As shown, it includes: a memory 801, a processor 802;

[0209] The memory 801 stores computer-executable instructions;

[0210] The processor 802 executes the computer-executable instructions stored in the memory 801 , so that the processor executes the humidity control method for the fuel cell stack corresponding to the above-mentioned method embodiment.

[0211] Optionally, the fuel cell control device may be the fuel control unit FCCU in the above embodiment.

[0212] It should be noted that the above-mentioned device provided in this embodiment can implement the method provided in the above-mentioned method embodiment. The relevant principles and effects can be referred to the corresponding method embodiment or system embodiment, and will not be elaborated here.

[0213] Those skilled in the art will appreciate that all or part of the steps in the above-described method embodiments can be implemented using hardware associated with program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0214] Finally, it should be noted that those skilled in the art will readily identify other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art not disclosed herein. The present invention is not limited to the precise structure described above and illustrated in the accompanying drawings, and various modifications and variations may be made without departing from the scope thereof. The scope of the present invention is limited solely by the appended claims.

[0215] The above embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Any equivalent substitution or modification made by those skilled in the art based on the present invention is within the protection scope of the present invention.

Claims

1. A method for controlling humidity of a fuel cell stack, characterized in that: include: When water level information of a water storage tank in a humidification circuit of a fuel cell stack reaches a first preset threshold, obtaining an intake air moisture content of an intake circuit of the fuel cell stack; wherein the water storage tank is used to collect liquid water generated by the fuel cell stack and use it for humidification, and the intake air moisture content is determined based on a first partial pressure of water vapor in an intake air environment and a second partial pressure of dry gas in the intake air environment from which the water vapor has been removed; determining, according to the intake air moisture content and a preset target intake air moisture content, a water outlet flow rate of the water storage tank in the humidification circuit for humidifying the fuel cell stack; According to the water outlet flow rate, the humidification circuit is controlled to provide liquid water to the intake circuit, so that the intercooler in the intake circuit absorbs heat based on cooling the intake circuit and / or evaporates the liquid water by heating through the heater, so as to humidify the air when the intake circuit supplies air.

2. The method according to claim 1, characterized in that The obtaining of the intake air moisture content of the intake loop of the fuel cell stack includes: collecting the relative humidity of the intake air of the intake circuit, the first intake air temperature and intake air pressure compressed by the air compressor, and the second intake air temperature after the intake circuit is cooled by the intercooler; determining a first partial pressure of water vapor in an intake air environment based on the intake air relative humidity, the first intake air temperature, and the second intake air temperature; determining a second partial pressure of dry gas in an intake environment from which the water vapor has been removed based on a difference between the intake pressure and the actual partial pressure of the water vapor; The moisture content of the intake air of the air intake circuit is determined based on the ratio between the first partial pressure and the second partial pressure.

3. The method according to claim 1, characterized in that The step of controlling the humidification circuit to provide liquid water to the air inlet circuit according to the water outlet flow rate includes: A humidification control instruction is sent to the humidification circuit three-way valve in the humidification circuit, wherein the humidification control instruction is used to control the water supply port of the humidification circuit three-way valve to open, so that the humidification circuit provides liquid water to the air inlet circuit.

4. The method according to any one of claims 1 to 3, characterized in that Also includes: collecting the air intake flow rate of the air intake circuit; The determining, based on the intake air moisture content and a preset target intake air moisture content, the water outlet flow rate of the water storage tank in the humidification circuit for humidifying the fuel cell stack comprises: determining a unit humidification amount according to a difference between the intake air moisture content and a preset target intake air moisture content; The water outlet flow rate of the water storage tank is determined according to the product between the air intake flow rate of the air intake circuit and the unit humidification capacity.

5. The method according to any one of claims 1 to 3, characterized in that Also includes: Obtaining heat absorption power for evaporating the liquid water and heat dissipation power of the intercooler; According to the heat absorption power and the heat dissipation power, it is determined whether the liquid water is evaporated by the intercooler based on the heat absorbed by cooling the air intake circuit, and / or whether the liquid water is evaporated by heating through the heater.

6. The method according to claim 5, characterized in that The obtaining of the heat absorption power for evaporating the liquid water and the heat dissipation power of the intercooler includes: collecting the outlet water temperature of the humidification circuit; Determining the heat absorption power for evaporating the liquid water according to the outlet water temperature, the outlet water flow rate, and the latent heat coefficient of vaporization of water; and The heat dissipation power of the intercooler is determined according to the intake air flow rate, the water outlet temperature, the first intake air temperature, the second intake air temperature, the constant-pressure specific heat capacity of gas, and the constant-pressure specific heat capacity of water vapor.

7. The method according to claim 5, characterized in that The step of determining, based on the heat absorption power and the heat dissipation power, whether to evaporate the liquid water by using the intercooler based on the heat absorbed by the intercooler for cooling the air intake circuit, and / or to evaporate the liquid water by heating the heater, comprises: When the first intake air temperature reaches a preset temperature threshold and the heat absorption power is less than or equal to the heat dissipation power of the intercooler, determining to evaporate the liquid water by the intercooler based on the heat absorbed by the intercooler based on cooling the intake circuit; or, When the heat absorption power is greater than the heat dissipation power of the intercooler, it is determined to evaporate the liquid water by heating through the heater, and a heating control instruction is sent to the heater, wherein the heating control instruction is used to instruct the heater to start heating.

8. The method according to claim 7, characterized in that The sending of a heating control instruction to the heater includes: When the first intake air temperature reaches a preset temperature threshold, determining a first compensation heat dissipation power according to a difference between the heat absorption power and the heat dissipation power, and sending a heating control instruction to the heater according to the first compensation heat dissipation power; or, When the first intake air temperature does not reach a preset temperature threshold, a second compensating heat dissipation power is determined according to the heat absorption power, and a heating control instruction is sent to the heater according to the second compensating heat dissipation power.

9. The method according to any one of claims 1-3 and 6-8, characterized in that Also includes: When water level information of a water storage tank in a humidification circuit of a fuel cell stack reaches a second preset threshold, a drainage control instruction is sent to a humidification circuit three-way valve in the humidification circuit, wherein the drainage control instruction is used to control a drainage port of the humidification circuit three-way valve to open, so as to drain part of the liquid water in the water storage tank until the water level information is within a third preset threshold range; The second preset threshold is greater than the first preset threshold, and the third preset threshold is an intermediate value between the first preset threshold and the second preset threshold.

10. The method according to any one of claims 1-3 and 6-8, characterized in that When the water amount information of the water storage tank in the humidification circuit of the fuel cell stack reaches a first preset threshold, obtaining the intake air moisture content of the intake circuit of the fuel cell stack includes: When the water amount information of the water storage tank in the humidification circuit of the fuel cell stack reaches a first preset threshold, the function flag bit of the humidification circuit is determined to be in a humidification state, wherein the function flag bit is used to indicate whether the humidification circuit is currently in a humidification state or a non-humidification state; According to the function flag, the intake air moisture content of the intake loop of the fuel cell stack is obtained.

11. The method according to claim 10, characterized in that Before obtaining the intake air moisture content of the intake loop of the fuel cell stack according to the function flag, the method further includes: Obtaining the current power generation current of the fuel cell stack; Determining whether the fuel cell stack has a humidification requirement based on a comparison result between the voltage and impedance corresponding to the current generated current and a voltage threshold and an impedance threshold corresponding to the current generated current; When the fuel cell stack has a humidification requirement, the intake air moisture content of the intake loop of the fuel cell stack is obtained according to the function flag.

12. A fuel cell control device, characterized in that: include: Memory, processor; The memory stores computer-executable instructions; The processor executes the computer-executable instructions stored in the memory, so that the processor executes the humidity control method for the fuel cell stack according to any one of claims 1 to 11.

13. A humidity control system for a fuel cell stack, characterized in that: It includes a fuel cell control unit, a fuel cell stack, an air inlet circuit, and a humidification circuit; wherein, The fuel cell control unit is configured to execute the humidity control method for a fuel cell stack according to any one of claims 1 to 11; The air inlet circuit includes an air compressor for compressing air, and an intercooler connected to the air compressor, wherein the intercooler is connected to the air inlet of the fuel cell stack and is used to supply pressurized and cooled gas to the fuel cell stack; The humidification circuit includes a water tank and a first flow meter. The water tank is connected to the intercooler through the first flow meter and is used to provide liquid water to the air inlet circuit under the control of the fuel cell control unit to achieve humidification when supplying gas to the fuel cell stack.

14. The system according to claim 13, wherein: It also includes a first gas-water separator provided on the hydrogen exhaust path of the fuel cell stack, and / or a second gas-water separator provided on the air exhaust path of the fuel cell stack; wherein the first gas-water separator and the second gas-water separator are respectively connected to the water storage tank; The first gas-water separator is used to perform gas-water separation on the hydrogen that has not participated in the reaction in the fuel cell stack, and to transport the separated liquid water to the water storage tank; and / or, The second gas-water separator is used to perform gas-water separation operations on the air that does not participate in the reaction in the fuel cell stack, and to transport the separated liquid water to the water storage tank.

15. The system according to claim 13 or 14, characterized in that The humidification circuit further includes a humidification circuit three-way valve disposed between the first flow meter and the water storage tank; The humidification circuit three-way valve is used to open the water supply end of the humidification circuit three-way valve under the control of the fuel cell control unit to provide liquid water to the air inlet circuit; or, under the control of the fuel cell control unit, open the drainage end of the humidification circuit three-way valve to discharge part of the liquid water in the water tank.

16. The system according to claim 15, wherein: The humidification circuit further includes a first temperature sensor, which is arranged at one side of the water supply end and is used to collect the outlet water temperature of the humidification circuit.

17. The system according to claim 13 or 14, characterized in that The air inlet circuit further includes a second flow meter arranged on the air inlet side of the air compressor, a second temperature sensor and a pressure sensor arranged on the air outlet side of the air compressor, and a third temperature sensor and a humidity sensor arranged on the air outlet side of the intercooler; The second flow meter is used to collect the intake flow rate of the intake circuit; the second temperature sensor is used to collect the first intake temperature of the air compressed by the air compressor; the pressure sensor is used to collect the intake pressure of the air compressed by the air compressor; the third temperature sensor is used to collect the second intake temperature after the intake circuit is cooled by the intercooler; the humidity sensor is used to collect the intake relative humidity of the intake circuit.

18. The system according to claim 13 or 14, characterized in that The invention also includes a heater arranged on one side of the air outlet of the intercooler, and the heater is used to heat the liquid water in the humidification circuit to evaporate the liquid water.

19. The system according to claim 18, wherein: It also includes a mixing valve arranged on one side of the air compressor inlet, and the heater is specifically arranged between the mixing valve and the connecting pipe between the intercooler outlet, and is used to mix the humidified steam evaporated by the heater and the inlet air of the air compressor, and transport it to the fuel cell stack through the inlet air circuit.

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