A fuel cell system and control method thereof

Abstract

The present invention relates to a fuel cell system and a control method thereof. The system comprises a fuel cell stack, a hydrogen circuit, an air circuit, a cooling circuit, a control module and an environmental monitoring module. The hydrogen circuit, the air circuit and the cooling circuit are all connected to the fuel cell stack. The control module receives information from each circuit and the environmental monitoring module, and regulates each circuit through calculation. The air circuit comprises an intake pipeline, an air compressor, a cathode flow control module, a humidifier, a throttle valve and an exhaust pipeline. The intake pipeline, the air compressor, the humidifier and the inlet end of the fuel cell stack are connected in sequence through pipelines. The outlet end of the fuel cell stack is connected in sequence with the humidifier, the throttle valve and the exhaust pipeline. The cooling circuit comprises a second pressure controller, a heater, a multi-module heat dissipation module and a flow control module. The present invention solves the shortcomings of general fuel cells and improves the system's adaptability to different environments.

Description

Technical Field

[0001] The present invention relates to the field of fuel cell engines, and in particular to a fuel cell system and a method thereof. Background Art

[0002] The fuel cell system is a device that uses a fuel cell stack as its core, hydrogen as fuel, and air as an oxidant to supply, discharge, and generate electricity. The system can be mainly divided into three circuits: hydrogen circuit, air circuit, and cooling circuit. The hydrogen circuit is a fuel input channel, and high-purity hydrogen is introduced from an external gas source (such as a hydrogen storage bottle or a hydrogen production device). The hydrogen passage plays a role in fuel pressure flow control, reaction gas recycling, and water vapor separation. The air circuit is responsible for transporting, pressurizing, and humidifying the oxidant (i.e., air) required for the fuel cell reaction. The cooling circuit is mainly used for heat management and transportation to ensure that the stack can be quickly raised to the optimal temperature and quickly remove the large heat generated by the stack.

[0003] However, in general fuel cell systems, there are the following disadvantages: 1. The performance of vehicles traveling long distances across altitudes is reduced due to environmental changes; 2. The vehicle has low adaptability and low performance in areas with large temperature changes in the morning and evening, summer and winter; 3. There is no adjustment function for the humidification degree of the vehicle's cathode gas humidity, which may cause excessive water content in the gas entering the fuel cell stack, causing the fuel cell stack to be flooded, affecting performance and damaging the fuel cell stack; 4. After the fuel cell system is shut down, air can enter the fuel cell stack from the air compressor, resulting in a high oxygen content in the fuel cell stack; 5. During the startup and shutdown hydrogen purge process of the fuel cell system, the air compressor is not running, the throttle is not opened, and the tail exhaust hydrogen concentration is large, which will create a fire hazard; 6. When starting at low temperature, the water in the fuel cell stack is discharged through high-pressure air, and the inlet and outlet gases of the fuel cell stack are all subjected to a humidifier for heat and moisture exchange. The discharged water vapor will re-enter the fuel cell stack after exchange through the humidifier, and the water cannot be effectively removed.

[0004] Since different fuel cells have different structural characteristics, operating conditions and other system integration differences, the traditional fuel cell system design process is mainly designed and developed around the operating conditions and structure of the current fuel cell stack, and has low adaptability to other fuel cells. Therefore, it is necessary to design a system design solution that can solve the above technical problems and is compatible with most fuel cells with different requirements, so that the system product is more competitive and adaptable and has the freedom of self-regulation. Summary of the invention

[0005] In order to solve the above technical problems, the first object of the present invention is to provide a fuel cell system with a large controllable degree of freedom that can match the power stacks in each stage. The second object of the present invention is to provide a control method for the above fuel cell system.

[0006] In order to achieve the above first invention objective, the present invention adopts the following technical solutions:

[0007] A fuel cell system comprises a fuel cell stack, a hydrogen circuit, an air circuit, a cooling circuit, a control module and an environmental monitoring module, wherein the hydrogen circuit, the air circuit and the cooling circuit are all connected to the fuel cell stack, and the control module receives information from each circuit and the environmental monitoring module, and regulates each circuit through calculation;

[0008] The hydrogen circuit includes an intake pipe, a first pressure controller, a water-gas separator, a circulation pump, a pressure switch and an exhaust pipe. The first pressure controller and the pressure switch are both arranged on the intake pipe. The intake pipe, the fuel cell stack and the exhaust pipe are connected in sequence. The circulation pump is arranged between the intake pipe and the exhaust pipe. Two water-gas separators are respectively arranged on the pipelines at the inlet and outlet ends of the circulation pump, and the two water-gas separators are connected to the exhaust pipe through a solenoid valve. A solenoid valve connected to the exhaust pipe is also arranged on the pipeline at the inlet end of the circulation pump.

[0009] The air circuit includes an intake pipeline, an air compressor, a cathode flow control module, a humidifier, a throttle valve and an exhaust pipeline. The intake pipeline, the air compressor, the humidifier and the inlet end of the fuel cell stack are connected in sequence through pipelines. The outlet end of the fuel cell stack is connected with the humidifier, the throttle valve and the exhaust pipeline in sequence. The pipeline connecting the cathode flow control module to the fuel cell stack is normally closed, and the pipeline connected to the air compressor and the exhaust pipeline and the air compressor itself are normally open. The cathode flow control module and the fuel cell stack, the humidifier and the exhaust pipeline are controlled by the control module.

[0010] The cooling circuit includes a second pressure controller, a heater, a multi-module heat dissipation module and a flow control module. The second pressure controller is connected to the inlet end of the fuel cell stack, and the outlet end of the fuel cell stack is respectively connected to the heater and the multi-module heat dissipation module. The flow control module is respectively connected to the second pressure controller, the heater and the multi-module heat dissipation module, and the opening is controlled by the control module.

[0011] As a preferred solution, the solenoid valve on the water-gas separator at the outlet end of the circulation pump is a normally open solenoid valve, and a one-way valve is also provided on the pipeline after the normally open solenoid valve.

[0012] As a preferred solution, the solenoid valve on the water-gas separator at the inlet end of the circulating pump is a normally closed drain valve, and the solenoid valve on the pipeline at the inlet end of the circulating pump is a normally closed exhaust valve; a liquid level sensor is also provided on the water-gas separator.

[0013] As a preferred solution, the cathode flow control module is a four-way valve, including an air inlet and three air outlets, the air inlet is connected to the air compressor, and the three air outlets are respectively connected to the fuel cell stack, the humidifier, and the exhaust pipeline.

[0014] As a preferred solution, the cathode flow control module adopts a structure of one or more series-parallel combinations of two-way valves and three-way valves.

[0015] As a preferred solution, a sensor is further provided on the exhaust pipe, and the sensor is connected to the control module.

[0016] As a preferred solution, the cooling circuit also includes a deionizer and a water tank, the outlet end of the water tank is connected to the second pressure controller, the two inlet ends of the water tank are connected to the outlet end of the fuel cell stack, and one of the inlet ends is also provided with a deionizer.

[0017] As a preferred solution, the control module includes a calculation unit and an execution signal generating unit. The calculation unit receives the ambient temperature and vehicle running speed parameters provided by the environmental monitoring module, and also obtains the real-time temperature and pressure of the cooling circuit from the temperature and pressure sensors arranged at the inlet and outlet of the battery stack. The parameters finally calculated by the calculation unit are summarized in the execution signal generating unit, and the execution signal generating unit sends signals to the first pressure controller, the second pressure controller, the flow control module, the heater and the multi-module heat dissipation module.

[0018] As a preferred solution, the environmental monitoring module includes an environmental temperature measurement unit and an information exchange unit. The environmental temperature measurement unit collects temperature information of the surrounding environment during the operation of the system through a temperature sensor arranged in the system; the information exchange unit obtains the driving speed of the vehicle during operation by communicating with the whole vehicle; the environmental monitoring module transmits the environmental temperature and vehicle running speed signals to the control module, and the control module evaluates and regulates the natural heat dissipation capacity of the vehicle by coordinating the signal with other parameters.

[0019] In order to achieve the above second invention object, the present invention adopts the following technical solution:

[0020] A control method for a fuel cell system includes the fuel cell system as described above, wherein the system regulates a hydrogen circuit, an air circuit, and a cooling circuit in three stages: startup, normal operation, and shutdown through a control module:

[0021] During the startup phase, the control module regulates the air circuit and the cooling circuit respectively.

[0022] Air circuit: First, the control module closes the outlet of the cathode flow module and only opens the outlet connected to the exhaust pipeline, so that air can directly enter the exhaust pipeline to dilute the excessively high hydrogen concentration in the exhaust pipeline; then, the control module switches the outlet closed by the cathode flow module and only opens the outlet connected to the fuel cell stack, so that air can directly enter the fuel cell stack without passing through the humidifier, and blow out the water in the fuel cell stack;

[0023] Cooling circuit: The control module controls the corresponding passage of the flow control module to open, so that all the coolant flows through the heater to heat up. The heated coolant is pumped into the fuel cell stack by the second pressure controller to exchange heat with the cooler interior of the fuel cell stack to increase the temperature of the fuel cell stack.

[0024] During the normal operation phase, the control module regulates the hydrogen circuit, air circuit and cooling circuit respectively.

[0025] Hydrogen circuit: The control module controls the solenoid valve on the water-gas separator to open at a fixed time to discharge the stored water. During the water discharge process, the control module controls the opening time of the solenoid valve to retain some liquid water and close the water-gas separator drainage pipe. At the same time, the control module regulates the opening time and opening interval of the solenoid valve at the inlet end of the circulation pump, so that the excessive accumulated nitrogen can be discharged regularly.

[0026] Air circuit: The control module controls the cathode flow control module so that the air first enters the humidifier and then the fuel cell stack. At the same time, the air outlet of the cathode flow control module directly connected to the fuel cell stack is also opened proportionally under the control of the control module.

[0027] Cooling circuit: According to the signal received by the control module, if the system still has a heat dissipation capacity greater than the heat dissipation demand when the multi-module heat dissipation module is not turned on, the control module calculates the expected opening of the second pressure controller according to the heat generation power of the system, and adjusts the temperature in the system through the coolant flow;

[0028] If the system still has a heat dissipation capacity greater than the heat dissipation demand when the multi-module heat dissipation module is not turned on, the coolant flowing through the multi-module heat dissipation module and the heater can be proportionally distributed by adjusting the flow control module to control the coolant temperature in the cooling pipeline;

[0029] If the system's self-heating capacity cannot meet the system's heat dissipation requirements, the flow control module allows all the coolant to flow through the multi-module heat dissipation module, and the coolant flow control in the second pressure controller and the speed control in each module of the multi-module heat dissipation module are combined to provide the system with additional heat dissipation capacity;

[0030] During the shutdown phase, the control module regulates the air circuit. The control module closes the outlet of the cathode flow module and only opens the outlet connected to the exhaust pipeline, so that air directly enters the exhaust pipeline to dilute the excessively high hydrogen concentration in the exhaust pipeline.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention uses a control module to control the electromagnetic valve on the water-gas separator to open at a fixed time to discharge the stored water. During the water discharge process, the control module controls the opening time of the electromagnetic valve to retain part of the liquid water and close the drainage pipe of the water-gas separator. This prevents excessive gas from being discharged from the system from the drainage port to cause fuel waste, thereby improving fuel utilization.

[0033] The present invention optimizes the air circuit of the fuel cell system by arranging a cathode flow control module on the air circuit, and can control the flow direction, flow rate, humidity, etc. of the air, thereby reducing the hydrogen concentration in the exhaust gas discharged from the fuel cell to below 75% of the flammable limit; and can seal the fuel cell stack when the fuel cell is shut down to prevent air from entering the fuel cell stack; and can control the humidity and flow rate of the air entering the stack.

[0034] The present invention adopts a control module to adjust the flow control module so that the coolant flowing out of the fuel cell stack can flow into the multi-module heat dissipation device and the heater in proportion according to the heat dissipation demand and then flow into the fuel cell stack for circulation. During auxiliary startup, the flow control module allows all the coolant to flow into the heater, thereby achieving the effect of quickly heating up the fuel cell stack. When the fuel cell stack is dissipating heat, the circulation pipeline of the coolant can also be selected as needed, making the system temperature control strategy more flexible.

[0035] In summary, the system design of the present invention adds a cathode flow control module in the air circuit and its pipeline design, as well as an environmental detection module and a control module signal feedback strategy, which solves the shortcomings listed in general fuel cells and improves the system's adaptability to different environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings in the specification, which constitute a part of the present application, are used to provide a further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute a limitation on the present application.

[0037] Figure 1 It is a schematic diagram of the overall structure of the system of the present invention;

[0038] Figure 2 is a schematic diagram of a hydrogen circuit of the present invention;

[0039] Figure 3 is a schematic diagram of an air circuit of the present invention;

[0040] Figure 4 is a schematic diagram of a cooling circuit of the present invention;

[0041] Figure 5 It is a schematic diagram of the principle of the control module of the present invention regulating the cooling circuit. DETAILED DESCRIPTION

[0042] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0043] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0044] In addition, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0045] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise clearly specified.

[0046] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0048] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0049] This embodiment provides a fuel cell system, such as Figure 1 As shown, the system includes a fuel cell stack 1, a hydrogen circuit 2, an air circuit 3, a cooling circuit 4, a control module 5 and an environmental monitoring module 6, wherein the fuel cell stack 1 converts chemical energy into electrical energy and is the most important power generation equipment in the system; the hydrogen circuit 2, the air circuit 3, and the cooling circuit 4 are connected to the fuel cell stack 1 and are the most important modules in the system for transporting fuel, oxidant, and coolant to the fuel cell stack 1; the control module 5 receives the sensor readings in each circuit and the environmental monitoring module 6 readings, and sends signals to the main components of each circuit for regulation after calculation; the environmental monitoring module 6 contains sensors to collect and detect the environment around the system, and returns environmental signals to the control module 5 for adaptive calculation. The following is a detailed description of the system of the present invention divided into four parts: hydrogen circuit, air circuit, cooling circuit, environmental monitoring module, and control module:

[0050] 1. Hydrogen circuit

[0051] like Figure 2As shown, the hydrogen circuit 2 includes an intake pipe, a first pressure controller 201, a water-gas separator 202, a circulation pump 203, a pressure switch 204 and an exhaust pipe. The first pressure controller 201 and the pressure switch 204 are both arranged on the intake pipe. The intake pipe, the fuel cell stack 1 and the exhaust pipe are connected in sequence. The circulation pump 203 is arranged between the intake pipe and the exhaust pipe. The two water-gas separators 202 are respectively arranged on the pipelines at the inlet and outlet ends of the circulation pump 203, and the two water-gas separators 202 are connected to the exhaust pipe through a solenoid valve. The solenoid valve on the water-gas separator 202 at the outlet end of the circulation pump 203 is a normally open solenoid valve 205, and a one-way valve 208 is also provided on the pipeline after the normally open solenoid valve 205. A solenoid valve connected to an exhaust pipe is also provided on the pipeline at the inlet end of the circulation pump 203; the solenoid valve on the water-gas separator 202 at the inlet end of the circulation pump 203 is a normally closed drain valve 206, and the solenoid valve on the pipeline at the inlet end of the circulation pump 203 is a normally closed exhaust valve 207; a liquid level sensor 209 is also provided on the water-gas separator 202.

[0052] Dry hydrogen is connected to the system hydrogen loop from a high-pressure gas source, and the hydrogen flow and pressure in the hydrogen loop are controlled by the first pressure controller. After the dry hydrogen and the circulating hydrogen merge in the water-gas separator, they enter the fuel cell stack through the pipeline, react with the oxidant (air), and are discharged from the fuel cell stack after the reaction.

[0053] During the system design process, the fuel cell stack requires a higher dose of hydrogen to react, and there is residual unreacted hydrogen in the gas leaving the fuel cell stack, so a hydrogen circulation device is designed. The hydrogen recycled from the tail gas is pressurized by the circulation pump and re-enters the fuel cell stack for secondary reaction, which improves the utilization rate of hydrogen and the system performance. Since there is a large amount of water vapor mixed in the circulating hydrogen, it may produce strands of liquid water when it encounters a colder pipe wall or mixes with the hydrogen at a lower temperature at the inlet. Therefore, a water-gas separator is set at the confluence of the dry hydrogen inlet and the circulating hydrogen to prevent strands of liquid water from flowing into the fuel cell stack. At the same time, a water-gas separator is also set between the fuel cell stack outlet and the hydrogen circulation device to prevent liquid water carried in the hydrogen from directly flowing into the hydrogen circulation device and damaging parts.

[0054] The normally open solenoid valve 205 is responsible for discharging the water stored in the front water degassing device, and the liquid level height is collected by the liquid level sensor to determine the opening time and duration of the normally open solenoid valve 205;

[0055] The normally closed drain valve 206 is responsible for discharging the water stored in the rear drainage gas separator, and the normally closed exhaust valve 207 is responsible for regularly discharging the nitrogen accumulated in the pipeline, which is an exhaust solenoid valve. In an emergency, the normally open solenoid valve 205, the normally closed drain valve 206 and the normally closed exhaust valve 207 can all be used to discharge the excess gas in the system pipeline.

[0056] The difference between the normally closed and normally open solenoid valves lies in the opening and closing conditions of the solenoid valves when the power is on or off: the normally closed solenoid valve is in a closed state when the power is not on, and the normally open solenoid valve is in a fully open state when the power is not on. In this design, the front row solenoid valve uses a normally open solenoid valve, and the rear row drainage and exhaust solenoid valves use a normally closed solenoid valve.

[0057] The one-way valve is installed behind the front normally open solenoid valve in the hydrogen circuit. Its function is to control the one-way flow of gas. The front gas can only flow from inside the system to outside the system, and external air cannot enter the system through the one-way valve. It assists the normally open solenoid valve to close the system to prevent air from flowing into the fuel cell stack when it is shut down to form a hydrogen-air interface and cause damage to the fuel cell stack.

[0058] In the present invention, the normally open solenoid valve 205, the normally closed drain valve 206, the normally closed exhaust valve 207 and the one-way valve can distribute and control the flow rate according to the following various working conditions:

[0059] When the system is operating normally:

[0060] The normally open solenoid valve 205 and the normally closed drain valve 206 are connected to the bottom of the front and rear water-gas separators. The liquid level is collected by the liquid level sensor. In order to prevent the liquid level fluctuation caused by the bumps during the operation of the vehicle, the liquid level sensor collects the liquid level for multiple times continuously to determine whether the liquid level exceeds the set value within a period of time. If it exceeds the threshold, a signal is sent to the normally open solenoid valve 205 and the normally closed drain valve 206 to discharge the stored water. During the water storage and discharge process, the opening time of the solenoid valve is controlled to retain some liquid water, and the water-gas separator drainage pipe is closed to prevent excessive gas from being discharged from the system from the drain port, causing fuel waste, thereby improving fuel utilization.

[0061] The normally closed exhaust valve 207 is connected to the upper part of the tail gas separator to prevent the separated liquid water from mixing in. After the fuel cell stack has been running for a long time, a lot of nitrogen will accumulate in the hydrogen circuit, affecting the performance of the fuel cell stack. The normally closed exhaust valve 207 is regulated by the control module to adjust its opening time and opening interval, so that the excessive accumulated nitrogen can be discharged regularly, and the hydrogen concentration in the exhaust gas can be minimized to maintain the operating performance of the fuel cell stack, reduce fuel waste, and improve fuel utilization.

[0062] When the system is in normal shutdown state:

[0063] The normally open solenoid valve 205 is in a fully open state when not powered on during normal shutdown, and cooperates with the one-way valve to close the front exhaust pipe. The normally closed drain valve 206 is in a closed state when not powered on during normal shutdown, and can directly close the hydrogen pipeline to prevent outside air from entering the hydrogen pipeline, forming a hydrogen-oxygen interface in the fuel cell stack, and damaging the performance of the fuel cell stack.

[0064] When the system is in normal shutdown state, in order to further seal the fuel cell stack, the hydrogen loop will be enriched with hydrogen to maintain pressure, that is, the anode pipeline has a higher air pressure than the outside air pressure in the shutdown state. The one-way valve can remain closed under this pressure state, and the normally closed drain valve 206 prevents external gas from entering the loop.

[0065] When the system is in emergency power-off state:

[0066] The front row uses a normally open solenoid valve, which can keep the solenoid valve fully open when the power is off. When the pressure controller cannot be closed normally, it can discharge excess hydrogen entering the pipeline to prevent damage to the fuel cell stack due to excessive pressure in the hydrogen pipeline.

[0067] In the early stage of selection, the diameter of the solenoid valve needs to be accurately calculated. Since the air compressor still has a certain speed in the emergency power-off state, which is slower than the regulation speed of the hydrogen pipeline, in order to ensure that the pressure difference between the cathode and anode pipelines in the fuel cell stack is within the allowable range, the exhaust solenoid valve in the hydrogen circuit needs to consider the gas discharge speed when fully opened, and cooperate with the air pipeline to prevent damage to the fuel cell stack caused by excessive pressure difference between the cathode and anode.

[0068] When the system is in low temperature shutdown state:

[0069] Due to the low external environment, there is more condensed water at the drain solenoid valve, which will freeze under low temperature conditions. Therefore, the selected solenoid valve has a heating function, which can speed up the melting of ice in the valve, speed up the low-temperature startup speed, and prevent water and gas accumulation caused by ice.

[0070] 2. Air circuit

[0071] like Figure 3 As shown, the air circuit 3 includes an intake pipeline, an air compressor 301, a cathode flow control module 302, a humidifier 303, a throttle 304 and an exhaust pipeline. The intake pipeline, the air compressor 301, the humidifier 303 and the inlet end of the stack 1 are connected in sequence through pipelines, and the outlet end of the stack 1 is connected to the humidifier 303, the throttle 304 and the exhaust pipeline in sequence, and the cathode flow control module 302 and the air compressor 301 are always connected, and the cathode flow control module 302 and the stack 1, the humidifier 303, and the exhaust pipeline are controlled by the control module 5. A sensor is also provided on the exhaust pipeline, and the sensor is connected to the control module 5.

[0072] The air circuit can control the direction, flow rate, humidity and other parameters of the air, reduce the hydrogen concentration in the tail exhaust of the fuel cell, seal the stack when the fuel cell is turned off, and prevent air from entering the stack. In the air circuit, the air compressor is mainly responsible for pressurizing the air in the atmosphere and pumping it into the air pipeline to provide the stack with enough oxidant for reaction; the humidifier is responsible for exchanging the humidity and temperature of the newly entered dry cold air with the humid hot air coming out of the stack, so that the air enters the stack in the best reaction state. This process does not require additional power consumption and is a spontaneous heat and moisture exchange, which improves the system's working efficiency; the throttle cooperates with the air compressor to control the speed of the air compressor and the opening of the tail exhaust throttle to regulate the air flow and pressure in the air circuit.

[0073] The cathode flow control module is used as a flow distribution valve and can be composed of a four-way valve or multiple three-way valves or two-way valves or other structures. It is installed between the air compressor and the humidifier, and adopts a one-inlet and three-outlet method to connect three pipelines: P is the normally open cathode flow module inlet, connected to the air compressor outlet; A outlet is connected to the tail exhaust, and this flow channel does not pass through the humidifier and the fuel cell stack; B outlet leads to the humidifier, and enters the fuel cell stack for reaction after humidification and temperature exchange with the hot and humid air at the fuel cell stack outlet; C outlet is the third outlet, which enters the fuel cell stack directly in the form of a bypass without passing through the humidifier.

[0074] The cathode flow control module can adjust and control the flow distribution according to the following working conditions:

[0075] The fuel cell needs to be purged with hydrogen during the system startup and shutdown process. During this process, the stack does not need air supply. The lack of air to dilute the hydrogen at the tail exhaust will lead to a high concentration, which poses a high risk of hidden dangers. The cathode flow module is used to close the two air passages B and C to prevent air from flowing into the stack, and the tail exhaust passage A is opened. When there is no air supply to the stack, air is directly passed into the tail exhaust pipeline to dilute the excessively high hydrogen concentration at the tail exhaust, thereby reducing the safety risks of the tail exhaust during the purge process.

[0076] During the normal operation of the fuel cell system, air with a certain humidity is required. The cathode flow control module controls the air to enter the humidifier from outlet B, and conducts water heat exchange with the hot and humid air at the outlet of the fuel cell stack, and then enters the fuel cell stack for reaction after the humidity and temperature are increased. This process can recycle the heat and water produced by the fuel cell stack to improve system efficiency.

[0077] During normal operation of the fuel cell system, outlet C is opened in a certain proportion while outlet B is opened. The outlet gas bypasses the humidifier without humidifying or heating the gas, thereby regulating the overall humidity and temperature of the gas at the stack inlet to prevent the stack inlet from being too high in temperature or humidity.

[0078] During the startup of the fuel cell, high-pressure air is needed to blow out the water in the stack. Since the outlet pipe of the stack is connected to the humidifier, the water vapor brought out by the gas will exchange water vapor with the dry and cold gas in the humidifier. Therefore, the C outlet is opened to prevent the water vapor from being brought back into the stack by the humidified gas through the humidifier, thereby improving the purge efficiency and reducing the startup time.

[0079] 3. Cooling circuit

[0080] like Figure 4 As shown, the cooling circuit 4 includes a second pressure controller 401, a heater 402, a multi-module heat dissipation module 403 and a flow control module 404. The second pressure controller 401 is connected to the inlet end of the fuel cell stack 1, and the outlet end of the fuel cell stack 1 is respectively connected to the heater 402 and the multi-module heat dissipation module 403. The flow control module 404 is respectively connected to the second pressure controller 401, the heater 402, and the multi-module heat dissipation module 403, and the opening is controlled by the control module 5.

[0081] The cooling circuit also includes a deionizer 405 and a water tank 406. The outlet end of the water tank 406 is connected to the second pressure controller 401. The two inlet ends of the water tank 406 are connected to the outlet end of the fuel cell stack 1, and one of the inlet ends is also provided with a deionizer 405. The heater adopts a pipeline PTC heater; the second pressure controller 401 adopts a vehicle centrifugal water pump.

[0082] The cooling circuit is one of the most important thermal management modules for the battery stack in the system. The coolant is pressurized by the second pressure controller and enters the battery stack. It absorbs the heat generated by the battery stack through the flow channel inside the battery stack and is discharged from the outlet of the battery stack after heating. The cooling circuit includes two sets of inner and outer cycles. The inner cycle is provided with a heater, and the outer cycle is provided with a multi-module heat dissipation module. The multi-module heat dissipation device includes a frame, a fan, a heat conducting plate and a coolant flow channel. A plurality of coolant flow channels are arranged on the frame at intervals, and a plurality of heat conducting plates are arranged between adjacent coolant flow channels. A plurality of fans that can be started and stopped separately are arranged on the frame and located on one side of the coolant flow channel. The operation status of a single fan can be controlled by the control module to control the heat dissipation.

[0083] The flow control module can use a variety of control strategies such as temperature control and electromagnetic control, and can adjust the flow distribution of internal and external circulation pipelines according to the real-time temperature of the coolant. The flow control module can be composed of a three-way valve or multiple two-way valves, which include two coolant inlets a and b and a coolant outlet p. The outlet p leads to the second pressure controller and then to the battery stack; the inlet a is connected to the heater in the internal circulation; the inlet b is connected to the multi-module heat dissipation module of the external circulation.

[0084] The internal and external circulation in the cooling circuit can be used to distribute and control the flow rate according to the following working conditions:

[0085] When the fuel cell system is started cold, the temperature of the stack is low. The flow control module starts the internal circulation and closes the external circulation, allowing all the coolant to flow through the heater to heat up. The heated coolant is pumped into the stack by the second pressure controller to exchange heat with the colder interior of the stack, raising the stack temperature, allowing the stack to enter the suitable operating temperature area at a faster speed, thereby increasing the startup speed.

[0086] After the fuel cell system is started, the system still has a heat dissipation capacity greater than the heat dissipation demand when the multi-module heat dissipation module is not turned on. The control module calculates the expected opening of the pressure controller based on the system heat generation power and adjusts the temperature in the system through the coolant flow.

[0087] After the fuel cell system is started, when the system still has a heat dissipation capacity greater than the heat dissipation demand when the multi-module heat dissipation module is not turned on, the flow control module can also be used to adjust the flow distribution ratio of the internal and external circulations to control the proportion of heat dissipation and heating, thereby controlling the coolant temperature in the cooling pipeline.

[0088] After the fuel cell system is started, if the system's self-heating capacity cannot meet the system's heat dissipation requirements, the flow control module closes the internal circulation pipeline, and all the coolant flows through the external circulation and passes through the multi-module heat dissipation module. The flow control of the coolant in the second pressure controller and the speed control of each module of the multi-module heat dissipation module are combined to provide the system with additional heat dissipation capacity. The temperature of the coolant is fed back to the control module through the temperature sensor installed in the pipeline, and the control module calculates the speed distribution of each module in the multi-module heat dissipation module, and real-time multi-speed heat dissipation.

[0089] 4. Environmental monitoring module and control module

[0090] like Figure 5 As shown, the environment monitoring module and the control module adjust and control the operating status of the main components of the system by receiving vehicle driving information, ambient temperature, and sensor feedback. The control module and the environment detection module communicate through the CAN protocol.

[0091] The environmental monitoring module 6 includes an environmental temperature measuring unit 602 and an information interaction unit 601. The environmental temperature measuring unit 602 collects the temperature information of the surrounding environment during the operation of the system through a temperature sensor arranged in the system; the information interaction unit 601 obtains the driving speed of the vehicle during operation by communicating with the whole vehicle; the environmental monitoring module 6 transmits the environmental temperature and vehicle running speed signals to the control module 5, and the control module 5 evaluates and regulates the natural heat dissipation capacity of the vehicle by coordinating the signal with other parameters.

[0092] The control module 5 includes a calculation unit 501 and an execution signal generating unit 502. The calculation unit 501 receives the ambient temperature and vehicle running speed parameters provided by the environmental monitoring module 6, and also obtains the real-time temperature and pressure of the cooling circuit from the temperature and pressure sensors arranged at the inlet and outlet of the fuel cell stack 1. The parameters finally calculated by the calculation unit 501 are summarized in the execution signal generating unit 502, and the execution signal generating unit 502 sends a signal to the first pressure controller 201, the second pressure controller 401, the flow control module 404, the heater 402 and the multi-module heat dissipation module 403.

[0093] The calculation part can complete the following functions:

[0094] 1. Receive the operation conditions of the fuel cell stack and calculate the heat generated by the fuel cell stack reaction. Combined with the feedback signal of the fuel cell stack inlet temperature sensor in the cooling circuit, estimate and judge the coolant flow required by the fuel cell stack.

[0095] 2. Calculate the target speed of the pressure regulator based on the preset coolant inlet and outlet expected values ​​and the stack heat generation power parameters.

[0096] 3. Integrate the ambient temperature of the fuel cell engine, vehicle speed and other parameters to calculate the natural heat dissipation capacity of the cooling circuit without the assistance of components during vehicle operation;

[0097] 4. Receive the temperature sensor feedback signal at the outlet of the fuel cell stack in the cooling circuit, and calculate the required heat dissipation of the fuel cell engine system by combining the preset coolant inlet temperature expectation value and the coolant flow feedback signal;

[0098] 5. Receive the system ambient temperature fed back by the environmental monitoring module, calculate the heat dissipation of a single module and multiple modules in different combinations in the multi-module heat dissipation module, and match them to obtain the optimal operation plan of the multi-module heat dissipation module.

[0099] The parameters finally calculated by the calculation unit are summarized to the execution signal generation unit, and the execution signal generation unit sends signals to the second pressure controller, flow control module, heater and multi-module heat dissipation module. The following parameters are regulated respectively:

[0100] 1. The speed opening parameter of the second pressure controller adjusts the coolant flow and pressure entering the fuel cell stack;

[0101] 2. The flow control module controls the opening of the internal and external circulation channels to control the ratio of coolant flowing through the internal and external circulations;

[0102] 3. Heater on / off working signal to control the heating of coolant in the internal circulation pipeline;

[0103] 4. The opening and closing and speed arrangement of each module of the multi-module heat dissipation module.

[0104] The cooling circuit of the fuel cell engine system has two main working modes: heating and cooling. The cooling mode is divided into natural cooling and auxiliary cooling according to the cooling demand. For these working conditions, the control flow of the control module is as follows:

[0105] Heating mode:

[0106] When the fuel cell engine system is started, the temperature of the fuel cell stack and the coolant are both lower than the operating temperature. The control module sends a signal to adjust the opening of the flow control module, open the internal circulation and close the external circulation, turn on the power of the heater, and allow all the coolant to flow into the internal circulation. After the coolant is heated by the heater, it transports heat into the fuel cell stack, causing the temperature of the fuel cell stack to quickly rise to the operating temperature.

[0107] Cooling mode:

[0108] Natural heat dissipation condition: The natural heat dissipation condition is that in the multi-module heat dissipation module, the heat dissipation capacity when all heat dissipation modules are turned off is still greater than the heat dissipation demand of the system. The heat dissipation condition under this condition can be controlled by controlling the speed of the second pressure controller in the cooling circuit and the ratio of the internal and external circulation flow controlled by the flow control module. The control process under this condition is:

[0109] The calculation unit in the control module analyzes the real-time ambient temperature, vehicle speed, heat generation of the fuel cell stack, and coolant inlet and outlet temperatures to calculate the coolant flow requirement, and obtains the required speed signal of the second pressure controller, which is sent to the pressure regulator by the execution signal generation unit to adjust the coolant flow.

[0110] The calculation unit comprehensively considers the coolant inlet and outlet temperatures, the system's natural heat dissipation, and the coolant demand flow rate to calculate the proportional distribution of the coolant in the internal and external circulations, and obtains the flow control module opening signal, which is sent to the flow control module by the execution signal generation unit to distribute and regulate the coolant flow rates flowing through the internal and external circulations.

[0111] Auxiliary heat dissipation condition: Auxiliary heat dissipation condition is a condition where the required heat dissipation is higher than the natural heat dissipation of the system. In this condition, all coolant needs to flow into the multi-module heat dissipation module to reduce the temperature after gas-liquid heat exchange. This process requires the cooling circuit to be regulated according to the following process:

[0112] The calculation unit in the control module analyzes the real-time ambient temperature, vehicle speed, heat generation of the fuel cell stack, and coolant inlet and outlet temperatures to calculate the coolant flow requirement, and obtains the pressure controller's required speed signal, which is sent to the pressure regulator by the execution signal generation unit to adjust the coolant flow.

[0113] The execution signal generating unit in the control module outputs an opening adjustment signal to the flow control module, closes the inner circulation, and fully opens the outer circulation, so that all the coolant flows into the outer circulation radiator for heat dissipation.

[0114] The calculation unit in the control module calculates the heat dissipation capacity of different cooling fan working combinations in the multi-module heat dissipation module by comprehensively considering the ambient temperature near the fuel cell engine, selects the optimal heat dissipation solution, and executes the signal generation unit to send an enable signal to the fan.

[0115] The desired coolant inlet temperature is set, and the control module adjusts the speed of the enabled fan to close the loop and adjust the temperature of the coolant entering the fuel cell stack.

[0116] In summary, the system design of the present invention adds a cathode flow control module in the air circuit and its pipeline design, as well as an environmental detection module and a control module signal feedback strategy, which solves the shortcomings listed in general fuel cells and improves the system's adaptability to different environments.

[0117] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0118] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A control method for a fuel cell system, characterized in that: A fuel cell system is provided, the system comprising a fuel cell stack (1), a hydrogen circuit (2), an air circuit (3), a cooling circuit (4), a control module (5) and an environmental monitoring module (6), wherein the hydrogen circuit (2), the air circuit (3) and the cooling circuit (4) are all connected to the fuel cell stack (1), and the control module (5) receives information from each circuit and the environmental monitoring module (6), and regulates each circuit through calculation; The hydrogen circuit (2) comprises an intake pipe, a first pressure controller (201), a water-gas separator (202), a circulation pump (203), a pressure switch (204) and an exhaust pipe, wherein the first pressure controller (201) and the pressure switch (204) are both arranged on the intake pipe, the intake pipe, the fuel cell stack (1) and the exhaust pipe are sequentially connected, the circulation pump (203) is arranged between the intake pipe and the exhaust pipe, two water-gas separators (202) are respectively arranged on the pipelines at the inlet end and the outlet end of the circulation pump (203), and the two water-gas separators (202) are both connected to the exhaust pipe via a solenoid valve, and a solenoid valve connected to the exhaust pipe is also arranged on the pipeline at the inlet end of the circulation pump (203); The air circuit (3) comprises an air intake pipeline, an air compressor (301), a cathode flow control module (302), a humidifier (303), a throttle valve (304) and an exhaust pipeline; the air intake pipeline, the air compressor (301), the humidifier (303) and the inlet end of the fuel cell stack (1) are connected in sequence through pipelines; the outlet end of the fuel cell stack (1) is connected in sequence with the humidifier (303), the throttle valve (304) and the exhaust pipeline; the pipeline connecting the cathode flow control module (302) and the fuel cell stack is normally closed, the pipeline connecting the air compressor (301) and the exhaust pipeline and the air compressor (301) itself are normally open; the cathode flow control module (302) and the fuel cell stack (1), the humidifier (303) and the exhaust pipeline are controlled by the control module (5); The cooling circuit (4) comprises a second pressure controller (401), a heater (402), a multi-module heat dissipation module (403) and a flow control module (404); the second pressure controller (401) is connected to the inlet end of the fuel cell stack (1); the outlet end of the fuel cell stack (1) is respectively connected to the heater (402) and the multi-module heat dissipation module (403); the flow control module (404) is respectively connected to the second pressure controller (401), the heater (402) and the multi-module heat dissipation module (403), and the opening is controlled by the control module (5); The system regulates the hydrogen circuit (2), the air circuit (3) and the cooling circuit (4) through the control module in the three stages of startup, normal operation and shutdown: During the startup phase, the control module (5) regulates the air circuit (3) and the cooling circuit (4) respectively. Air circuit (3): First, the control module (5) closes the air outlet of the cathode flow control module (302) and only opens the air outlet connected to the exhaust pipeline, so that air directly enters the exhaust pipeline to dilute the excessively high hydrogen concentration in the exhaust pipeline; then, the control module (5) switches the air outlet closed by the cathode flow control module (302) and only opens the air outlet connected to the fuel cell stack (1), so that air directly enters the fuel cell stack (1) without passing through the humidifier (303), thereby blowing out the water stored in the fuel cell stack (1); Cooling circuit (4): the control module (5) controls the corresponding passage of the flow control module (404) to open, so that all the coolant flows through the heater (402) to be heated and heated, and the heated coolant is pumped into the fuel cell stack (1) by the second pressure controller (401) to exchange heat with the cooler interior of the fuel cell stack (1) to increase the temperature of the fuel cell stack; During the normal operation phase, the control module (5) regulates the hydrogen circuit (2), the air circuit (3) and the cooling circuit (4) respectively. Hydrogen circuit (2): the control module (5) controls the solenoid valve on the water-gas separator (202) to open at a fixed time to discharge the stored water. During the water storage discharge process, the control module (5) controls the opening time of the solenoid valve to retain some liquid water and close the water-gas separator drainage pipe. At the same time, the control module (5) regulates the opening time and opening interval of the solenoid valve at the inlet end of the circulation pump (203) so that excessive accumulated nitrogen can be discharged regularly. Air circuit (3): the control module (5) controls the cathode flow control module (302) so that air first enters the humidifier (303) and then enters the fuel cell stack (1). At the same time, the air outlet of the cathode flow control module (302) directly connected to the fuel cell stack (1) is also opened in proportion under the control of the control module (5); Cooling circuit (4): Based on the signal received by the control module (5), if the system still has a heat dissipation capacity greater than the heat dissipation demand when the multi-module heat dissipation module (403) is not turned on, the control module (5) calculates the expected opening degree of the second pressure controller (401) based on the heat generation power of the system, and adjusts the temperature in the system by the coolant flow rate; If the system still has a heat dissipation capacity greater than the heat dissipation demand when the multi-module heat dissipation module (403) is not turned on, the coolant flowing through the multi-module heat dissipation module (403) and the heater (402) can be proportionally distributed by adjusting the flow control module (404), thereby controlling the coolant temperature in the cooling pipeline; If the self-heating capacity of the system cannot meet the heat dissipation requirements of the system, the flow control module (404) allows all the coolant to flow through the multi-module heat dissipation module (403), and cooperates with the flow control of the coolant in the second pressure controller (401) and the speed control in each module of the multi-module heat dissipation module (403) to provide additional heat dissipation capacity for the system; During the shutdown phase, the control module (5) regulates the air circuit. The control module (5) closes the air outlet of the cathode flow control module (302) and only opens the air outlet connected to the exhaust pipeline, so that air directly flows into the exhaust pipeline to dilute the excessively high hydrogen concentration in the exhaust pipeline.

2. A fuel cell system control method according to claim 1, characterized in that: The solenoid valve on the water-gas separator (202) at the outlet end of the circulation pump (203) is a normally open solenoid valve (205), and a one-way valve (208) is further provided on the pipeline after the normally open solenoid valve (205). The normally open solenoid valve (205) is in a fully open state when no power is supplied.

3. The control method of a fuel cell system according to claim 1, characterized in that: The solenoid valve on the water-gas separator (202) at the inlet end of the circulation pump (203) is a normally closed drain valve (206), and the solenoid valve on the pipeline at the inlet end of the circulation pump (203) is a normally closed exhaust valve (207). The water-gas separator (202) is also provided with a liquid level sensor (209), and the normally closed drain valve (206) and the normally closed exhaust valve (207) are in a closed state when no power is supplied.

4. The control method of a fuel cell system according to claim 1, characterized in that: The cathode flow control module (302) is a four-way valve, comprising an air inlet and three air outlets, the air inlet being connected to the air compressor (301), and the three air outlets being connected to the fuel cell stack (1), the humidifier (303), and the exhaust pipeline, respectively.

5. The control method of a fuel cell system according to claim 1, characterized in that: The cathode flow control module (302) adopts a structure of one or more series-parallel combinations of two-way valves and three-way valves.

6. The control method of a fuel cell system according to claim 1, characterized in that: The exhaust pipe is also provided with a sensor, which is connected to the control module (5).

7. The control method of a fuel cell system according to claim 1, characterized in that: The cooling circuit also includes a deionizer (405) and a water tank (406), wherein the outlet end of the water tank (406) is connected to the second pressure controller (401), and both inlet ends of the water tank (406) are connected to the outlet end of the fuel cell stack (1), and one of the inlet ends is also provided with a deionizer (405).

8. The control method of a fuel cell system according to claim 1, characterized in that: The control module (5) comprises a calculation unit (501) and an execution signal generation unit (502). The calculation unit (501) receives the ambient temperature and vehicle running speed parameters provided by the environment monitoring module (6), and also obtains the real-time temperature and pressure of the cooling circuit from the temperature and pressure sensors arranged at the inlet and outlet of the fuel cell stack (1). The parameters finally calculated by the calculation unit (501) are summarized in the execution signal generation unit (502), and the execution signal generation unit (502) sends a signal to the first pressure controller (201), the second pressure controller (401), the flow control module (404), the heater (402) and the multi-module heat dissipation module (403).

9. The control method of a fuel cell system according to claim 1, characterized in that: The environment monitoring module (6) comprises an environment temperature measuring unit (602) and an information exchange unit (601). The environment temperature measuring unit (602) collects temperature information of the surrounding environment during the operation of the system through a temperature sensor arranged in the system. The information exchange unit (601) obtains the driving speed of the vehicle during the operation of the vehicle by communicating with the whole vehicle. The environment monitoring module (6) transmits the environment temperature and vehicle running speed signals to the control module (5). The control module (5) evaluates and regulates the natural heat dissipation capacity of the vehicle by coordinating the signal with other parameters.

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