A fuel cell partial power section humidification control method and system

Abstract

The present disclosure relates to the technical field of fuel cell humidification, and provides a fuel cell power segment humidification control method and system. The method is applied to a fuel cell bypass humidification system with a bypass type membrane tube humidifier and a mixing chamber, and the bypass type membrane tube humidifier has a first throttle valve and a second throttle valve, and comprises the following steps: obtaining the output power of the fuel cell stack; comparing the output power of the fuel cell stack with a first power threshold and a second power threshold respectively to determine the current power segment; querying a double-throttle valve humidification distribution calibration table to determine the target opening of the first throttle valve and the second throttle valve and perform corresponding adjustment; making at least one of the adjusted humidified air and the un-humidified bypass air enter the mixing chamber to form the stack gas for the fuel cell stack; and repeatedly obtaining the operating parameters and continuously controlling the two throttle valves. The present disclosure realizes precise humidification in different power segments through independent control of the double throttle valves, reduces the volume of the humidifier and the flow resistance of the system, and reduces the parasitic power consumption of the air compressor.

Description

Technical Field

[0001] This disclosure relates to the field of fuel cell humidification technology, and more specifically, to a fuel cell power segment humidification control method and system. Background Technology

[0002] During the operation of a proton exchange membrane fuel cell, the air typically needs to be humidified before entering the stack to maintain the water content of the proton exchange membrane and its proton conductivity, thereby improving the stack's power generation performance and operational stability. Therefore, the fuel cell air supply system usually includes components such as an air compressor, intercooler, and humidifier. The humidifier utilizes the moisture concentration difference between the hot, humid exhaust gas discharged from the stack cathode and the intake air to humidify the intake air.

[0003] In existing fuel cell systems, membrane humidifiers are typically designed based on the system's maximum airflow rate to meet humidification requirements under all operating conditions. Simultaneously, to reduce air resistance under high flow rates, some solutions employ bypass lines, bypass valves, or three-way proportional valves to regulate the airflow entering the humidifier, allowing some air to bypass the humidifier before entering the fuel cell stack. However, these solutions still have certain shortcomings. On one hand, designing the humidifier based on maximum airflow rate tends to result in a larger size and greater system integration space, while also increasing flow resistance as air passes through the humidifier. On the other hand, when using a single bypass valve or three-way proportional valve for flow regulation, a coupling relationship exists between the two airflow paths, making it difficult to achieve precise airflow distribution under different operating conditions, thus affecting the operating efficiency and control performance of the fuel cell air supply system.

[0004] Therefore, how to reduce the size of the humidifier and the air flow resistance while ensuring the humidification effect of the fuel cell, and improve the air flow regulation effect under different operating conditions, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this disclosure is to provide a fuel cell power segment humidification control method and system, which solves the problems mentioned in the background art.

[0006] According to a first aspect, this disclosure provides a fuel cell power segment humidification control method, applied to a fuel cell bypass humidification system having a bypass membrane tube humidifier and a mixing chamber, wherein the bypass membrane tube humidifier has a first throttle valve and a second throttle valve, comprising: Step S1: Obtain the actual operating parameters of the fuel cell system, including the stack output power; Step S2: The output power of the fuel cell stack is compared with a preset first power threshold and a second power threshold to determine the current power segment of the fuel cell system; wherein, the current power segment includes a low power segment, a medium power segment and a high power segment, and the first power threshold is less than the second power threshold; Step S3: Query the pre-established dual throttle humidification distribution calibration table to determine the target opening degree of the first throttle and the second throttle, and control the first throttle and the second throttle to adjust according to the corresponding target opening degree, so as to execute full humidification control, mixed humidification control and full bypass control in the low power segment, medium power segment and high power segment respectively; wherein, the dual throttle humidification distribution calibration table is used to calibrate the opening degree combination of the first throttle and the second throttle; Step S4: At least one of the humidified air regulated by the first throttle valve and the unhumidified bypass air regulated by the second throttle valve enters the mixing chamber and forms the feed gas supplied to the fuel cell stack. Step S5: Return to step S1, continuously acquire the actual operating parameters of the fuel cell system, and continuously control the first throttle valve and the second throttle valve according to the updated operating parameters.

[0007] Optionally, in step S3, when the fuel cell system is in the low power range, the full humidification control specifically involves: controlling the first throttle valve to open to a first preset opening degree and controlling the second throttle valve to close, so that humidified air enters the fuel cell stack.

[0008] Optionally, in step S3, when the fuel cell system is in the medium power range, the mixing and humidification control specifically involves controlling the first throttle valve and the second throttle valve to be in the open state simultaneously, so that the humidified air and the unhumidified bypass air are mixed through the mixing chamber and then enter the fuel cell stack. Specifically, the target opening of the first throttle valve gradually decreases as the output power of the fuel cell stack increases, while the target opening of the second throttle valve gradually increases as the output power of the fuel cell stack increases.

[0009] Optionally, in step S3, when the fuel cell system is in the high-power range, the full bypass control specifically involves: controlling the first throttle valve to close and controlling the second throttle valve to open to a second preset opening degree, so that unhumidified bypass air enters the fuel cell stack.

[0010] Optionally, in step S2, when the output power is less than or equal to the first power threshold, it is determined to be the low power segment; when the output power is greater than the first power threshold and less than the second power threshold, it is determined to be the medium power segment; when the output power is greater than or equal to the second power threshold, it is determined to be the high power segment.

[0011] Optionally, the first power threshold P1 and the second power threshold P2 are based on the rated power P of the fuel cell system. max The preset condition is met, satisfying the preset relationship: 0.2P max ≤P1≤0.4P max And 0.6P max ≤P2≤0.8P max .

[0012] Optionally, in step S3, a pre-established dual throttle humidification distribution calibration table is queried to determine the target opening of the first throttle and the second throttle, specifically including: Query the pre-established dual throttle humidification distribution calibration table to obtain the ratio R of the humidification branch flow rate to the total inlet air flow rate corresponding to the current power segment; wherein, in the low power segment, the ratio R is 1; in the medium power segment, the ratio R is between 0 and 1, and decreases monotonically with the increase of the output power; in the high power segment, the ratio R is 0. Based on the total in-reactor air flow requirement Q and the aforementioned ratio R, the target humidification branch flow rate Q1 and the target bypass branch flow rate Q2 are calculated. The target humidification branch flow rate Q1 is converted into the target opening of the first throttle valve, and the target bypass branch flow rate Q2 is converted into the target opening of the second throttle valve.

[0013] Optionally, in step S1, the actual operating parameters may include one or more of the following: fuel cell stack current, current density, air flow requirement, intercooler outlet temperature, stack coolant temperature, ambient temperature, air compressor speed, air compressor pressure ratio, stack inlet pressure, and stack pressure drop.

[0014] Optionally, between step S4 and step S5, the method further includes: The power segment switching protection step employs at least one control method among setting a hysteresis interval, delay judgment, and smooth transition of throttle opening when switching between low power segment, medium power segment, and high power segment, so that the first throttle and the second throttle are adjusted according to a preset change rate to avoid sudden changes in the inlet air flow and pressure fluctuations.

[0015] Optionally, after the power segment switching protection step, the method further includes: The protection correction step involves acquiring one or more operating status signals of the fuel cell system, including stack voltage consistency, minimum single-cell voltage of the stack, stack voltage drop, air compressor pressure ratio, air flow deviation, coolant temperature, and stack high-frequency impedance, and correcting the target opening of the first throttle valve and the second throttle valve based on the operating status signals. Specifically, when a risk of membrane dryness is detected, the opening of the first throttle valve is increased or the opening of the second throttle valve is decreased; when a risk of water accumulation is detected, the opening of the second throttle valve is increased or the opening of the first throttle valve is decreased.

[0016] According to a second aspect, this disclosure provides a fuel cell bypass humidification system, comprising: An air compressor is used to compress outside air; An intercooler, connected to the air compressor, is used to cool the compressed air; A bypass-type membrane tube humidifier is connected to the intercooler. The bypass-type membrane tube humidifier is provided with a membrane tube humidification zone and a bypass air chamber. The membrane tube humidification zone is used to humidify the cooled air. The first throttle valve is located on the dry outlet end cap of the bypass membrane tube humidifier and corresponds to the outlet of the membrane tube humidification zone. It is used to adjust the flow rate of the humidified air after humidification by the membrane tube humidification zone. The second throttle valve is located on the dry outlet end cap of the bypass membrane tube humidifier and corresponds to the outlet of the bypass air chamber. It is used to adjust the flow rate of unhumidified bypass air passing through the bypass air chamber. A mixing chamber is used to receive at least one of humidified air flowing out through the first throttle valve and unhumidified bypass air flowing out through the second throttle valve, and to form the feed gas supplied to the fuel cell stack. The fuel cell stack is connected to the mixing chamber and is used to receive the gas fed into the mixing chamber. The controller is connected to the first throttle valve, the second throttle valve, and the air compressor signal respectively, and is used to execute the fuel cell power segment humidification control method as described in any one of claims 1 to 10.

[0017] Optionally, both the first throttle valve and the second throttle valve are integrated into the dry outlet end cap of the bypass membrane tube humidifier, and the mixing chamber is disposed within the dry outlet end cap or downstream of the dry outlet end cap.

[0018] Optionally, the controller stores a dual throttle humidification distribution calibration table. The controller is used to query the dual throttle humidification distribution calibration table according to the acquired actual operating parameters, and determine the target opening of the first throttle and the second throttle based on the query result.

[0019] Optionally, the membrane area of ​​the membrane tube humidification zone is determined based on the full humidification requirement of the fuel cell system in the low-power range and the partial humidification requirement in the medium-power range. Air in the high-power range of the fuel cell system bypasses the membrane tube humidification zone through the bypass air chamber and enters the fuel cell stack.

[0020] Optionally, both the first throttle valve and the second throttle valve are electronic throttle valves, butterfly valves, or proportional valves.

[0021] As can be seen from the above technical solutions, the fuel cell power segment humidification control method and system in the exemplary embodiments of this disclosure have at least the following advantages and positive effects: First, by setting a first power threshold and a second power threshold, the operating conditions are divided into three power segments: low, medium, and high. Correspondingly, three control modes are executed: full humidification, mixed humidification, and full bypass. This allows the external humidification amount to be adaptively adjusted according to the changes in the self-generated water capacity of the fuel cell stack. When the low power segment produces less water, sufficient external humidification is used to prevent the membrane from drying out. When the high power segment produces more water, humidification is cut off and dry air is used to assist in drainage, thereby optimizing fuel cell stack water management across the entire operating range.

[0022] Second, by querying the pre-established dual-throttle humidification distribution calibration table, the target opening of the first and second throttle valves can be determined independently, so that the air flow of the humidification branch and the bypass branch are decoupled and do not interfere with each other. This avoids the problem of insufficient control accuracy caused by the coupling of two flow paths in the traditional single-valve scheme, and can achieve clear switching and stable maintenance of the three states of full humidification, mixed humidification and full bypass.

[0023] Third, when full bypass control is implemented in the high-power segment, air bypasses the membrane tube humidification area and enters the fuel cell stack directly through the bypass air chamber, which significantly reduces the intake air resistance and air compressor parasitic power consumption under high airflow conditions, and improves the net efficiency of the fuel cell system under high power output conditions.

[0024] Fourth, since the high-power segment does not require airflow through the membrane tube humidification zone, the membrane area of ​​the membrane tube humidification zone can be designed mainly based on the full humidification requirements of the low-power segment and the partial humidification requirements of the medium-power segment. Compared with traditional humidifiers designed according to the maximum airflow of the system, this can effectively reduce the volume, weight and system layout space occupied by the humidifier.

[0025] Fifth, by setting the cyclic control mechanism in step S5, the method can continuously adjust the opening of the first and second throttle valves according to changes in operating parameters.

[0026] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings: Figure 1 A flowchart of a fuel cell power segment humidification control method according to an embodiment of the present disclosure is shown; Figure 2 A structural block diagram of a fuel cell bypass humidification system according to an embodiment of the present disclosure is shown; Figure 3 A partial structural block diagram of a fuel cell bypass humidification system according to an embodiment of the present disclosure is shown.

[0028] Illustration: 100. Air compressor; 200. Intercooler; 300. Bypass-type membrane humidifier; 310. Membrane humidification zone; 320. Bypass chamber; 330. Moisture side channel; 340. Dry outlet end cap; 400. First throttle valve; 500. Second throttle valve; 600. Mixing chamber; 700. Fuel cell stack; 800. Controller. Detailed Implementation

[0029] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be more thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art.

[0030] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0031] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0032] To facilitate understanding of the technical solutions disclosed herein, the symbols and parameters involved in this disclosure are explained below: P represents the current output power of the fuel cell stack; P max P1 represents the rated power of the fuel cell system; P2 represents the first power threshold; P1 represents the second power threshold, and P1 is less than P2; I represents the stack current; J represents the current density; Q represents the total inlet air flow requirement; Q1 represents the target flow rate of the humidified gas controlled by the first throttle valve 400; Q2 represents the target flow rate of the unhumidified bypass air controlled by the second throttle valve 500; R represents the proportion of the humidified branch flow rate to the total inlet air flow rate. A1 represents the opening degree of the first throttle valve at 400°; A2 represents the opening degree of the second throttle valve at 500°; Tca represents the intercooler outlet temperature; Tst represents the fuel cell stack coolant inlet or outlet temperature; Tamb represents the ambient temperature; n represents the air compressor speed; π represents the air compressor pressure ratio; Pin represents the fuel cell stack inlet pressure; ΔPstack represents the fuel cell stack pressure drop.

[0033] The fuel cell power segment humidification control method and system provided by the exemplary embodiments of this disclosure will be further described below with reference to the accompanying drawings.

[0034] Figure 1 A flowchart of a fuel cell power segment humidification control method according to an embodiment of the present disclosure is shown; Figure 2 A structural block diagram of a fuel cell bypass humidification system according to an embodiment of the present disclosure is shown; Figure 3 A partial structural block diagram of a fuel cell bypass humidification system according to an embodiment of the present disclosure is shown. Figure 2 In the diagram, solid arrows indicate the direction of air or exhaust flow, while dashed arrows indicate control, feedback, or communication connections between the controller 800 and actuators or operating parameters.

[0035] like Figure 2 and Figure 3 As shown, the fuel cell bypass humidification system provided in this embodiment is installed in the fuel cell air supply path. The system includes an air compressor 100, an intercooler 200, a bypass membrane humidifier 300, a first throttle valve 400, a second throttle valve 500, a mixing chamber 600, a fuel cell stack 700, and a controller 800.

[0036] The air compressor 100 has its inlet connected to an external air filter or intake pipe, and its outlet connected to the inlet of the intercooler 200. The air compressor 100 compresses outside air and sends it to the intercooler 200. The outlet of the intercooler 200 is connected to the dry air inlet side of the bypass-type membrane tube humidifier 300. The dry air inlet side receives the cooled air and distributes it to the membrane tube humidification zone 310 and the bypass air chamber 320. The intercooler 200 cools the compressed, high-temperature air, ensuring that the air temperature entering the dry air side of the humidifier is within a suitable range for fuel cell stack intake and moisture exchange.

[0037] The bypass-type membrane tube humidifier 300 internally includes a membrane tube humidification zone 310, a bypass air chamber 320, and a moisture side flow channel 330. The membrane tube humidification zone 310 contains hollow fiber membrane tubes or other air... The gas-moisture exchange membrane module has a moisture-side flow channel 330 connected to the cathode exhaust port of the fuel cell stack 700. The hot, humid exhaust gas discharged from the cathode outlet of the fuel cell stack 700 enters the moisture-side flow channel 330 of the bypass-type membrane tube humidifier 300. Moisture in the hot, humid exhaust gas is transferred through the membrane material to the dry air in the membrane tube humidification zone 310. After moisture exchange, the exhaust gas is discharged from the bypass-type membrane tube humidifier 300. The moisture-side flow channel 330 receives the hot, humid exhaust gas discharged from the stack cathode and allows moisture in the hot, humid exhaust gas to be transferred through the membrane material to the dry air in the membrane tube humidification zone 310. The bypass air chamber 320 is an air passage that does not pass through the membrane tube humidification zone 310. No membrane tube array is installed inside it, and the flow resistance when air flows through it is less than that of the membrane tube humidification zone 310.

[0038] Because this disclosure controls the first throttle valve 400 to be closed or nearly closed in the high-power range, all or almost all of the air bypasses the membrane humidification zone 310 through the bypass air chamber 320 and enters the fuel cell stack 700. Therefore, the membrane area of ​​the membrane humidification zone 310 does not need to be designed according to the maximum airflow rate of the fuel cell system across the entire power range. The membrane area of ​​the membrane humidification zone 310 is determined jointly based on the full humidification requirements in the low-power range and the partial humidification requirements in the medium-power range of the fuel cell system. This design can significantly reduce the number of membrane tubes, membrane area, housing volume, and weight of the bypass-type membrane humidifier 300, which is beneficial for the miniaturization and weight reduction of the fuel cell system.

[0039] The bypass-type membrane tube humidifier 300 has a dry outlet end cap 340 on its dry air outlet side. A first throttle valve 400 is located on the dry outlet end cap 340 and corresponds to the dry air outlet of the membrane tube humidification zone 310. The first throttle valve 400 is used to regulate the flow rate of humidified air after humidification in the membrane tube humidification zone 310. A second throttle valve 500 is also located on the dry outlet end cap 340 and corresponds to the outlet of the bypass air chamber 320. The second throttle valve 500 is used to regulate the flow rate of unhumidified bypass air passing through the bypass air chamber 320. Both the first throttle valve 400 and the second throttle valve 500 are independently controllable valves, such as electronic throttle valves, butterfly valves, or proportional valves, and both are signal-connected to the controller 800. The first throttle valve 400 and the second throttle valve 500 can be installed separately in the dry outlet end cap 340. The first throttle valve 400 and the second throttle valve 500 are equipped with a sealing structure to reduce leakage in the closed state, thereby improving the flow path isolation effect in the full humidification mode and the full bypass mode.

[0040] In some embodiments, the first throttle valve 400 and the second throttle valve 500 are integrated into a dual throttle valve control assembly, which is integrated with the dry outlet end cap 340 of the bypass membrane humidifier 300, the mixing chamber 600, or the air inlet connection structure of the fuel cell stack 700 to reduce the volume of external connection pipelines and system layout.

[0041] A mixing chamber 600 is disposed within the dry outlet end cap 340, downstream of the dry outlet end cap 340, or in the air inlet manifold of the fuel cell stack 700. The mixing chamber 600 receives at least one of the humidified air flowing out through the first throttle valve 400 and the unhumidified bypass air flowing out through the second throttle valve 500, and mixes the two gases to form the feed gas. The outlet of the mixing chamber 600 is connected to the air inlet of the fuel cell stack 700. The fuel cell stack 700 receives the mixed feed gas and participates in the electrochemical reaction on the cathode side. The feed gas refers to the air supplied to the cathode inlet of the fuel cell stack after being mixed in the mixing chamber.

[0042] The controller 800 is connected to the first throttle valve 400, the second throttle valve 500, and the air compressor 100 respectively. The controller 800 is also used to acquire the actual operating parameters of the fuel cell system. The actual operating parameters include one or more of the following: stack output power P, stack current I, current density J, air flow demand Q, intercooler outlet temperature Tca, stack coolant temperature Tst, ambient temperature Tamb, air compressor speed n, air compressor pressure ratio π, stack inlet pressure Pin, and stack pressure drop ΔPstack.

[0043] All of the above parameters can be obtained from the existing sensors or control variables of the fuel cell system, without the need for an additional stack inlet humidity sensor. The controller 800 internally stores a dual throttle humidification distribution calibration table, which is pre-established during system development or bench calibration.

[0044] During the calibration process, the opening combinations of the first throttle valve 400 and the second throttle valve 500 are pre-calibrated for different operating conditions such as fuel cell power or fuel cell current, air flow rate, intercooler outlet temperature, fuel cell coolant temperature, ambient temperature, and air compressor pressure ratio. This calibration process can be determined through test data such as bench humidity measurement, single cell or fuel cell voltage stability, fuel cell voltage drop, drainage status, air compressor power consumption, and durability boundaries. However, the aforementioned humidity measurement is only used in the development and calibration phase and is not used as a necessary closed-loop input for vehicle operation.

[0045] Specifically, the calibration table may include a first calibration table and a second calibration table. The first calibration table is used to determine the low-power, medium-power, and high-power segments based on power or current; the second calibration table is used to determine the opening degree A1 of the first throttle 400 and the opening degree A2 of the second throttle 500 in each power segment. The second calibration table may also use the ratio R of the humidification branch flow rate to the total inlet air flow rate as an intermediate value.

[0046] Wherein, the proportion R represents the ratio of the humidified air flow rate output by the first throttle valve 400 after humidification in the membrane tube humidification zone 310 to the total inlet air flow rate. When the proportion R is 1 or close to 1, the system is in full humidification state; when the proportion R is between 0 and 1, the system is in mixed humidification state; when the proportion R is 0 or close to 0, the system is in full bypass state.

[0047] During the development and calibration phase, multiple representative power operating points can be selected to obtain corresponding operating parameters of the fuel cell system, such as airflow requirements, intercooler outlet temperature, and stack coolant temperature. The opening degrees of the first throttle valve 400 and the second throttle valve 500 are then adjusted to ensure the stack operation meets predetermined water management requirements. For each operating point, the corresponding opening degree A1 of the first throttle valve 400, the opening degree A2 of the second throttle valve 500, and the humidification branch flow rate ratio R are recorded, forming a dual-throttle humidification distribution calibration table. During vehicle operation, the controller 800 directly queries the calibration table to obtain the corresponding control quantities based on the current operating parameters, without requiring recalibration.

[0048] In one embodiment, Table 1 is an example of dual throttle humidification distribution calibration.

[0049] Table 1. Dual Throttle Humidification Distribution Calibration Table: like Figure 1As shown in the embodiments of this disclosure, a fuel cell power segment humidification control method is also provided, including the following steps: In step S1, the controller 800 acquires the actual operating parameters of the fuel cell system, including the stack output power P. Simultaneously, the controller 800 can also acquire parameters such as the stack current I, current density J, total in-stack airflow demand Q, intercooler outlet temperature Tca, stack coolant temperature Tst, ambient temperature Tamb, air compressor speed n, air compressor pressure ratio π, stack inlet pressure Pin, or stack pressure drop ΔPstack.

[0050] In step S2, the controller 800 compares the stack output power P with a preset first power threshold P1 and a second power threshold P2 to determine the current power range of the fuel cell system. The current power range includes a low power range, a medium power range, and a high power range, and the first power threshold P1 is less than the second power threshold P2.

[0051] Specifically, when P ≤ P1, it is determined to be in the low-power segment; when P1 < P < P2, it is determined to be in the medium-power segment; and when P ≥ P2, it is determined to be in the high-power segment. The first power threshold P1 and the second power threshold P2 are based on the rated power P of the fuel cell system. max Preset to meet 0.2P max ≤P1≤0.4P max And 0.6P max ≤P2≤0.8P max .

[0052] In one specific implementation, P1 is 0.3P. max P2 is 0.7P max However, this value can be adjusted based on the fuel cell stack's water production characteristics, the membrane tube's humidification capacity, and the system calibration results. P1 and P2 can also be corrected based on the intercooler outlet temperature Tca, the fuel cell stack coolant temperature Tst, or the ambient temperature Tamb. For example, under low temperature or cold start conditions, the participation ratio of the humidification branch can be appropriately increased, while under high temperature or high water production conditions, the participation ratio of the bypass branch can be appropriately increased.

[0053] In step S3, the controller 800 queries the pre-established dual throttle humidification distribution calibration table to determine the target opening degree of the first throttle 400 and the second throttle 500, and controls the first throttle 400 and the second throttle 500 to adjust according to the corresponding target opening degree, so as to perform full humidification control, mixed humidification control and full bypass control in the low power segment, medium power segment and high power segment respectively; the dual throttle humidification distribution calibration table is used to calibrate the opening degree combination of the first throttle 400 and the second throttle 500.

[0054] Specifically, the process of determining the target opening in step S3 includes: First, the pre-established dual-throttle humidification distribution calibration table is consulted to obtain the proportion R of the humidification branch flow rate to the total feed air flow rate corresponding to the current power range. Specifically, in the low-power range, the proportion R is 1 or close to 1; in the medium-power range, the proportion R is between 0 and 1, and decreases monotonically with the increase of the fuel cell output power P, meaning that the R value in the medium-power range decreases monotonically with increasing power or current, causing the proportion of humidified gas output from the first throttle 400 to gradually decrease, and the proportion of unhumidified bypass air output from the second throttle 500 to gradually increase; in the high-power range, the proportion R is 0 or close to 0.

[0055] Then, the controller 800 calculates the target humidification branch flow rate Q1=R×Q and the target bypass branch flow rate Q2=(1-R)×Q based on the total in-reactor air flow rate requirement Q and the ratio R.

[0056] Finally, based on the valve flow characteristics of the first throttle valve 400 and the second throttle valve 500, the pressure difference before and after the valves, and the preset opening conversion table, Q1 and Q2 are converted into the target openings of the first throttle valve 400 and the second throttle valve 500, respectively. The opening conversion table can be obtained by calibrating the throttle valve flow characteristics. For different pressure difference conditions before and after the valves, a correspondence between the target flow and the throttle valve opening is established in advance. The controller 800 determines the target opening of the first throttle valve 400 and the second throttle valve 500 respectively by looking up a table or interpolation based on the calculated target flow Q1, Q2 and the current pressure difference. When the target flow is between adjacent calibration points, linear interpolation can be used to determine the corresponding opening.

[0057] In another implementation, the calibration table can also directly store the first throttle base opening A1_base and the second throttle base opening A2_base corresponding to different power ranges and operating conditions. The controller 800 can directly look up the table to obtain the base opening and then make corrections based on temperature, pressure or airflow correction coefficients.

[0058] In step S3, the following three control modes are executed according to the determined power segment.

[0059] When the fuel cell system is in the low-power range, the controller 800 performs full humidification control. The controller 800 controls the first throttle valve 400 to open to a first preset opening degree (e.g., fully open or close to 100%), and controls the second throttle valve 500 to close or be at its minimum opening degree (e.g., 0% or close to 0%), so that all or almost all of the cooled air from the intercooler 200 outlet enters the membrane tube humidification zone 310. The first preset opening degree is the opening value when the first throttle valve 400 is fully open or close to fully open, for example, an opening range of 90% to 100%. Within the membrane tube humidification zone 310, dry air absorbs moisture from the hot, humidified exhaust gas in the wet side channel 330 through the membrane material, becoming humidified air. This humidified air is output from the first throttle valve 400 on the dry outlet end cap 340 and enters the fuel cell stack 700 via the mixing chamber 600. This mode is used to prevent membrane drying under low load or low water production conditions, improving voltage stability in the low-power range.

[0060] When the fuel cell system is in the medium power range, the controller 800 performs mixing and humidification control. The controller 800 controls the first throttle valve 400 and the second throttle valve 500 to be open at the same time, so that a part of the air is humidified in the membrane tube humidification zone 310 and then output from the first throttle valve 400, while the other part of the air is not humidified and is output from the second throttle valve 500 through the bypass air chamber 320. The two streams of air are mixed in the mixing chamber 600 and then enter the fuel cell stack 700.

[0061] As the fuel cell stack output power P gradually increases within the mid-power range, the controller 800 executes a reverse opening adjustment strategy according to the calibration table. Specifically, the target opening of the first throttle valve 400 gradually decreases with increasing fuel cell stack output power P, while the target opening of the second throttle valve 500 gradually increases. This causes the external humidification ratio to gradually decrease as the fuel cell stack's self-generated water capacity increases. For example, when the fuel cell stack output power P is close to the first power threshold P1, the opening of the first throttle valve 400 is larger, and the opening of the second throttle valve 500 is smaller. As the fuel cell stack output power P gradually approaches the second power threshold P2, the opening of the first throttle valve 400 gradually decreases, and the opening of the second throttle valve 500 gradually increases. This causes the proportion of humidified gas outlet flow rate to gradually decrease, while the proportion of unhumidified bypass air outlet flow rate to gradually increase. This stage does not rely on real-time humidity sensor feedback but is controlled based on the power-temperature-flow-opening mapping relationship obtained from bench calibration.

[0062] When the fuel cell system is in the high-power range, the controller 800 performs full bypass control. The controller 800 controls the first throttle valve 400 to be closed or at its minimum opening (e.g., 0% or close to 0%), and controls the second throttle valve 500 to open to a second preset opening (e.g., fully open or close to 100%). This allows all or almost all of the cooled air from the intercooler 200 outlet to bypass the membrane humidification zone 310 through the bypass air chamber 320, be output through the second throttle valve 500, and enter the fuel cell stack 700 after passing through the mixing chamber 600. The second preset opening is the opening value when the second throttle valve 500 is fully open or close to fully open, for example, an opening range of 90% to 100%. In the high-power range, due to the large water production of the fuel cell stack, the relatively dry, unhumidified, high-flow-rate air entering the fuel cell stack 700 can carry away excess moisture inside the stack, helping to reduce the risk of local water accumulation in the stack and further improving the water management stability in the high-power range.

[0063] In step S4, at least one of the humidified air regulated by the first throttle valve 400 and the unhumidified bypass air regulated by the second throttle valve 500 enters the mixing chamber 600. After mixing in the mixing chamber 600, it forms the feed gas supplied to the fuel cell stack 700. The feed gas then enters the cathode inlet of the fuel cell stack 700 to participate in the electrochemical reaction.

[0064] In step S5, the controller 800 returns to step S1, cyclically acquires the actual operating parameters of the fuel cell system, and continuously controls the first throttle valve 400 and the second throttle valve 500 based on the updated operating parameters.

[0065] In some embodiments of this disclosure, the control method further includes step S0 before step S1, which involves establishing and storing a dual throttle humidification distribution calibration table. During the fuel cell system development or bench calibration phase, the opening combinations of the first throttle 400 and the second throttle 500 are pre-calibrated for different stack power or stack current, air flow rate, intercooler outlet temperature, stack coolant temperature, ambient temperature, air compressor pressure ratio, and other operating conditions.

[0066] The calibration process is determined through test data such as bench humidity measurement, single-cell or stack voltage stability, stack voltage drop, drainage status, air compressor power consumption, and durability boundaries. However, the aforementioned humidity measurements are only used during the development and calibration phase and are not considered necessary closed-loop inputs for vehicle operation. The calibration tables include a first calibration table and a second calibration table. The first calibration table is used to determine the low-power, medium-power, and high-power segments based on power or current. The second calibration table is used to determine the opening degree of the first throttle valve 400 and the second throttle valve 500 at each power segment. Alternatively, the second calibration table uses the ratio R of the humidification branch flow rate to the total inlet air flow rate as an intermediate value.

[0067] Further, in step S3, if the calibration table outputs the ratio R of the humidification branch flow rate to the total inlet air flow rate, then the controller 800 calculates the target humidification branch flow rate Q1 = R × Q based on the total inlet air flow rate requirement Q, and calculates the target bypass branch flow rate Q2 = (1-R) ​​× Q; the controller 800 then converts Q1 and Q2 into the target openings of the first throttle valve 400 and the second throttle valve 500 respectively, based on the valve flow characteristics of the first throttle valve 400 and the second throttle valve 500, the valve-to-valve pressure difference, or the preset opening conversion table. When the calibration table directly outputs the basic opening of the first throttle valve 400 and the basic opening of the second throttle valve 500, the controller 800 directly adopts the corresponding basic opening and corrects it according to the temperature, pressure, or air flow correction coefficient.

[0068] Between steps S4 and S5, this disclosure also includes a power segment switching protection step. When switching between low power segment, medium power segment and high power segment, the controller 800 employs at least one control method among setting a hysteresis interval, delay judgment and smooth transition of throttle opening, so that the first throttle 400 and the second throttle 500 are adjusted according to a preset change rate to avoid sudden changes in the inlet air flow and pressure fluctuations.

[0069] For example, when the fuel cell stack output power P increases from the low power range to the medium power range, the output power P needs to continuously exceed P1 and maintain this level for a preset time before switching; when the output power P decreases from the medium power range to the low power range, a cut-off threshold lower than the first power threshold P1 can be set. The opening degrees of the first throttle valve 400 and the second throttle valve 500 are gradually adjusted according to a preset rate of change to avoid sudden changes in the two flow paths, fluctuations in the inlet pressure, or disturbances in the air compressor control.

[0070] Following the power segment switching protection step, this disclosure also includes a protection correction step. The controller 800 acquires one or more operating status signals from the fuel cell system, including stack voltage consistency, minimum single-cell voltage, stack voltage drop ΔPstack, air compressor pressure ratio π, air flow deviation, coolant temperature Tst, and stack high-frequency impedance. Based on these operating status signals, it corrects the target opening of the first throttle valve 400 and the second throttle valve 500. This correction is a boundary protection based on existing stack operating status signals and does not require the use of a stack inlet humidity sensor.

[0071] When the above signals indicate a risk of membrane dryness (e.g., increased high-frequency impedance of the fuel cell stack meeting a preset membrane dryness risk condition, or a drop in minimum single-cell voltage or deterioration in voltage consistency), the controller 800 increases the opening of the first throttle valve 400 or decreases the opening of the second throttle valve 500 to increase the proportion of humidified air. When a risk of water accumulation is indicated (e.g., increased fuel cell stack voltage drop ΔPstack meeting a preset water accumulation risk condition), the controller 800 increases the opening of the second throttle valve 500 or decreases the opening of the first throttle valve 400 to increase the proportion of unhumidified bypass air and enhance drainage.

[0072] Furthermore, the risk of membrane dryness can be comprehensively determined based on one or more operating status signals among the lowest single-cell voltage of the fuel cell stack, voltage consistency, and high-frequency impedance of the fuel cell stack. When the above operating status signals continue for a preset time and meet the characteristics of membrane dryness, the controller 800 performs a protection correction by increasing the proportion of the humidification branch. The risk of water accumulation can be comprehensively determined based on operating status signals such as fuel cell stack voltage drop and airflow deviation. When the above signals continue for a preset time and meet the characteristics of water accumulation, the controller 800 performs a protection correction by increasing the proportion of the bypass branch.

[0073] The above determination is only a protective correction based on the existing operating status signals of the fuel cell system and does not change the main control strategy based on the preset calibration table.

[0074] In one specific embodiment of this disclosure, the rated power P of the fuel cell system max The power threshold is 100kW, the first power threshold P1 is set to 30kW, and the second power threshold P2 is set to 70kW.

[0075] When the fuel cell output power P≤30kW, the controller 800 performs full humidification control, the first throttle valve 400 opening is 100%, and the second throttle valve 500 opening is 0%.

[0076] When 30kW < fuel cell output power P < 70kW, controller 800 performs mixed humidification control. The proportional gain R value in the calibration table decreases linearly from close to 1 to close to 0. The opening of the first throttle 400 decreases from large to small, and the opening of the second throttle 500 increases from small to large. For example, when P = 40kW, R = 0.7; when P = 50kW, R = 0.4; and when P = 60kW, R = 0.2.

[0077] When P ≥ 70kW, controller 800 performs full bypass control, with the first throttle valve 400 opening at 0% and the second throttle valve 500 opening at 100%. The above values ​​are for illustrative purposes only and can be adjusted according to the fuel cell stack type, water production characteristics, and system calibration results in actual applications.

[0078] In another embodiment of this disclosure, the membrane area of ​​the membrane tube humidification zone 310 is not designed according to the maximum airflow of the system, but is mainly determined based on the full humidification requirements in the low-power range and the partial humidification requirements in the medium-power range. Since the high-power range does not require airflow through the membrane tube humidification zone 310, and the air bypasses the membrane tube humidification zone 310 through the bypass air chamber 320 to enter the fuel cell stack 700, the number of membrane tubes and the membrane area can be significantly reduced, thereby reducing the housing volume, weight, and system layout space occupation of the bypass-type membrane tube humidifier 300.

[0079] In another embodiment of this disclosure, the first throttle valve 400 and the second throttle valve 500 are both integrated within the dry outlet end cap 340, and the mixing chamber 600 is also disposed within the dry outlet end cap 340, forming an integrated dual throttle valve dry outlet end cap assembly, thereby reducing the number of external pipes and connectors, improving system integration and consistency of flow control for the two outlets.

[0080] In another embodiment of this disclosure, the first throttle valve 400 and the second throttle valve 500 may be provided with a sealing structure to reduce leakage in the closed state, thereby improving the flow path isolation effect in the full humidification and full bypass modes.

[0081] In summary, this disclosure achieves precise segmented control of humidification across the entire power range of a fuel cell by dividing power segments, independent control of dual throttle valves, calibration table mapping adjustment, and protection correction based on stack status, without relying on inlet humidity sensors. This effectively balances stack water management performance, system efficiency, and integrated compactness.

[0082] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the following claims.

[0083] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A fuel cell power segment humidification control method, applied to a fuel cell bypass humidification system having a bypass membrane humidifier and a mixing chamber, wherein the bypass membrane humidifier has a first throttle valve and a second throttle valve, characterized in that, include: Step S1: Obtain the actual operating parameters of the fuel cell system, including the stack output power; Step S2: The output power of the fuel cell stack is compared with a preset first power threshold and a second power threshold to determine the current power segment of the fuel cell system; wherein, the current power segment includes a low power segment, a medium power segment and a high power segment, and the first power threshold is less than the second power threshold; Step S3: Query the pre-established dual throttle humidification distribution calibration table to determine the target opening degree of the first throttle and the second throttle, and control the first throttle and the second throttle to adjust according to the corresponding target opening degree, so as to execute full humidification control, mixed humidification control and full bypass control in the low power segment, medium power segment and high power segment respectively; wherein, the dual throttle humidification distribution calibration table is used to calibrate the opening degree combination of the first throttle and the second throttle; Step S4: At least one of the humidified air regulated by the first throttle valve and the unhumidified bypass air regulated by the second throttle valve enters the mixing chamber and forms the feed gas supplied to the fuel cell stack. Step S5: Return to step S1, continuously acquire the actual operating parameters of the fuel cell system, and continuously control the first throttle valve and the second throttle valve according to the updated operating parameters.

2. The fuel cell power segment humidification control method according to claim 1, characterized in that, In step S3, when the fuel cell system is in the low power range, the full humidification control specifically involves: controlling the first throttle valve to open to a first preset opening degree and controlling the second throttle valve to close, so that humidified air enters the fuel cell stack.

3. The fuel cell power segment humidification control method according to claim 1, characterized in that, In step S3, when the fuel cell system is in the medium power range, the mixing and humidification control specifically involves controlling the first throttle valve and the second throttle valve to be in the open state simultaneously, so that the humidified air and the unhumidified bypass air are mixed through the mixing chamber and then enter the fuel cell stack. Specifically, the target opening of the first throttle valve gradually decreases as the output power of the fuel cell stack increases, while the target opening of the second throttle valve gradually increases as the output power of the fuel cell stack increases.

4. The fuel cell power segment humidification control method according to claim 1, characterized in that, In step S3, when the fuel cell system is in the high-power range, the full bypass control specifically involves: controlling the first throttle valve to close and controlling the second throttle valve to open to the second preset opening degree, so that unhumidified bypass air enters the fuel cell stack.

5. The fuel cell power segment humidification control method according to claim 1, characterized in that, In step S2, when the output power is less than or equal to the first power threshold, it is determined to be the low power segment; when the output power is greater than the first power threshold and less than the second power threshold, it is determined to be the medium power segment; when the output power is greater than or equal to the second power threshold, it is determined to be the high power segment.

6. The fuel cell power segment humidification control method according to claim 5, characterized in that, The first power threshold P1 and the second power threshold P2 are based on the rated power P of the fuel cell system. max The preset condition is met, satisfying the preset relationship: 0.2P max ≤P1≤0.4P max And 0.6P max ≤P2≤0.8P max .

7. The fuel cell power segment humidification control method according to claim 1, characterized in that, In step S3, the pre-established dual throttle humidification distribution calibration table is queried to determine the target opening of the first throttle and the second throttle, specifically including: Query the pre-established dual throttle humidification distribution calibration table to obtain the ratio R of the humidification branch flow rate to the total inlet air flow rate corresponding to the current power segment; wherein, in the low power segment, the ratio R is 1; in the medium power segment, the ratio R is between 0 and 1, and decreases monotonically with the increase of the output power; in the high power segment, the ratio R is 0. Based on the total in-reactor air flow requirement Q and the aforementioned ratio R, the target humidification branch flow rate Q1 and the target bypass branch flow rate Q2 are calculated. The target humidification branch flow rate Q1 is converted into the target opening of the first throttle valve, and the target bypass branch flow rate Q2 is converted into the target opening of the second throttle valve.

8. The fuel cell power segment humidification control method according to claim 1, characterized in that, In step S1, the actual operating parameters also include one or more of the following: fuel cell stack current, current density, air flow requirement, intercooler outlet temperature, stack coolant temperature, ambient temperature, air compressor speed, air compressor pressure ratio, stack inlet pressure, and stack pressure drop.

9. The fuel cell power segment humidification control method according to claim 1, characterized in that, Between step S4 and step S5, the following is also included: The power segment switching protection step employs at least one control method among setting a hysteresis interval, delay judgment, and smooth transition of throttle opening when switching between low power segment, medium power segment, and high power segment, so that the first throttle and the second throttle are adjusted according to a preset change rate to avoid sudden changes in the inlet air flow and pressure fluctuations.

10. A fuel cell bypass humidification system, characterized in that, include: An air compressor is used to compress outside air; An intercooler, connected to the air compressor, is used to cool the compressed air; A bypass-type membrane tube humidifier is connected to the intercooler. The bypass-type membrane tube humidifier is provided with a membrane tube humidification zone and a bypass air chamber. The membrane tube humidification zone is used to humidify the cooled air. The first throttle valve is located on the dry outlet end cap of the bypass membrane tube humidifier and corresponds to the outlet of the membrane tube humidification zone. It is used to adjust the flow rate of the humidified air after humidification by the membrane tube humidification zone. The second throttle valve is located on the dry outlet end cap of the bypass membrane tube humidifier and corresponds to the outlet of the bypass air chamber. It is used to adjust the flow rate of unhumidified bypass air passing through the bypass air chamber. A mixing chamber is used to receive at least one of humidified air flowing out through the first throttle valve and unhumidified bypass air flowing out through the second throttle valve, and to form the feed gas supplied to the fuel cell stack. The fuel cell stack is connected to the mixing chamber and is used to receive the gas fed into the mixing chamber. The controller is connected to the first throttle valve, the second throttle valve, and the air compressor signal respectively, and is used to execute the fuel cell power segment humidification control method as described in any one of claims 1 to 9.

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