Bypass flow control method and device, fuel cell air system and vehicle

Abstract

The invention relates to a bypass flow control method and device, a fuel cell air system and a vehicle, and relates to the technical field of batteries, and the method comprises the following steps: under the condition that an air compressor of the fuel cell air system is in a surge working condition, determining a bypass flow request value based on the surge control flow and in-pile flow of the air compressor; the surge control flow is the minimum flow threshold value of safe operation of the air compressor; determining an opening degree feed-forward value of a bypass valve of the fuel cell air system based on the bypass flow rate request value; and the opening degree of the bypass valve is controlled based on the opening degree feed-forward value so as to control the bypass flow of the fuel cell air system, and therefore the opening degree feed-forward value is used for predicting the opening degree needed by the bypass valve according to the bypass flow request value, and opening degree adjustment of the bypass valve can quickly respond to changes of the surge working condition of the air compressor. And the bypass flow can be quickly adjusted through the opening feedforward value, so that the air compressor can quickly recover stable operation.

Description

Technical Field

[0001] The present application relates to the field of battery technology, in particular to the field of hydrogen fuel cell vehicle technology, and specifically to a bypass flow control method, device, fuel cell air system and vehicle. Background Art

[0002] Hydrogen fuel cell vehicles use hydrogen fuel cells as a power source. As an important component of the air system of hydrogen fuel cells, the air compressor is used to compress the gas entering the air compressor and input it into the cathode of the fuel cell stack, participate in the electrochemical reaction inside the fuel cell stack, and generate electricity to drive the vehicle. During the operation of the air compressor, when the gas flow of the air compressor is too low and the inlet and outlet pressure ratio is too large, the air compressor will enter the surge working area, affecting the life and performance of the air compressor. At present, the air compressor is usually prevented from entering the surge condition by increasing the flow of the air compressor. It is mainly controlled by controlling the opening of the bypass valve to control the air flow through the bypass valve, so as to increase the flow of the air compressor and make the air compressor out of the surge condition.

[0003] In the related art, the estimated flow rate of the stack is calculated by an adaptive observation model, and the estimated bypass flow rate is determined based on the estimated flow rate of the stack and the air compressor flow rate, so as to control the opening of the bypass valve according to the estimated bypass flow rate and the expected bypass flow rate to achieve bypass flow control. In another related art, the actual bypass control amount of the bypass valve is determined based on the actual bypass air volume flowing through the bypass valve. Based on the actual bypass control amount, the closed-loop control result of the opening of the bypass valve is used as the feedback value of the PID control algorithm. The target value of the opening of the bypass valve is the larger value of the amount of air required for dilution of the tail gas concentration and the amount of air required to suppress the surge of the air compressor, and the PID closed-loop control is performed on the opening of the bypass valve. However, during the operation of the fuel cell air system, parameters such as the stack air flow rate and the bypass control flow rate will change rapidly. The above two methods control the opening of the bypass valve based on the estimated bypass flow rate, the expected bypass flow rate or the feedback opening of the bypass valve, which has a time lag, which is easy to cause the bypass flow to be unstable and cannot achieve accurate control of the bypass flow in the fuel cell air system. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a bypass flow control method, device, fuel cell air system and vehicle, aiming to solve the technical problem of inaccurate bypass flow control in the fuel cell air system in the related art.

[0005] In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows: In a first aspect, an embodiment of the present application provides a bypass flow control method, the method comprising: when an air compressor of a fuel cell air system is in a surge condition, determining a bypass flow request value based on the surge control flow and the stack inlet flow of the air compressor; the surge control flow is the minimum flow threshold for safe operation of the air compressor; based on the bypass flow request value, determining an opening feedforward value of a bypass valve of the fuel cell air system; based on the opening feedforward value, controlling the opening of the bypass valve to control the bypass flow of the fuel cell air system.

[0006] According to the above technical means, the bypass flow request value is determined by the surge control flow to determine the feedforward opening of the bypass valve to adjust the bypass valve opening, thereby increasing the air compressor flow, so that the gas flow entering the air compressor is not less than the minimum safe operating volume threshold, so that the air compressor can escape the surge condition. In addition, the bypass valve opening feedforward value is used to predict the required opening of the bypass valve according to the bypass flow request value, so that the bypass valve opening adjustment can quickly respond to changes in the air compressor surge condition. Therefore, based on the opening feedforward value, the bypass flow can be quickly adjusted, so that the air compressor can quickly resume stable operation, and reduce the flow fluctuation in the fuel cell air system caused by the bypass valve opening adjustment.

[0007] In one possible implementation, a bypass flow request value is determined based on the surge control flow and the stack flow of the air compressor, including: determining the difference between the surge control flow and the stack flow as the bypass flow standard value; and converting the bypass flow standard value into the bypass flow request value under the current operating conditions of the fuel cell air system based on the ambient temperature and pressure of the fuel cell air system.

[0008] According to the above technical means, the bypass flow standard condition value is determined by subtracting the surge control flow from the stack flow, which can ensure that the gas flow entering the air compressor is not lower than the surge control flow while meeting the gas flow demand of the fuel cell stack. In addition, the bypass flow standard condition value is converted into the bypass flow request value under the current working condition, taking into account the influence of ambient temperature and pressure on the gas state, so as to control the bypass flow more accurately.

[0009] In a possible implementation, based on the bypass flow request value, determining the opening feedforward value of the bypass valve of the fuel cell air system includes: determining the opening feedforward value of the bypass valve based on the bypass flow request value, the stack inlet temperature, the stack inlet pressure, and the ambient pressure.

[0010] According to the above technical means, the influence of environmental factors on the physical properties and flow characteristics of the gas is taken into account through the inlet temperature, inlet pressure and ambient pressure, so that the required opening of the bypass valve can be determined more accurately, thereby improving the control accuracy of the bypass flow.

[0011] In a possible implementation, based on the bypass flow request value, the stack entry temperature, the stack entry pressure, and the ambient pressure, the opening feedforward value of the bypass valve is determined, including: based on the bypass valve flow calculation model, determining the functional correspondence between the bypass valve opening and the stack entry pressure, the ambient pressure, the stack entry temperature, and the bypass flow request value; the bypass valve flow calculation model is used to characterize the quantitative relationship between the bypass flow and the pressure and temperature of the fuel cell air system; the bypass flow request value, the stack entry temperature, the stack entry pressure, and the ambient pressure are substituted into the functional correspondence to obtain the opening feedforward value of the bypass valve.

[0012] According to the above technical means, through the bypass valve flow calculation model, the influence of multiple factors such as the inlet pressure, ambient pressure, and inlet temperature on the bypass flow can be comprehensively considered to reduce the control error of the bypass flow. In this way, the bypass valve opening feedforward value matching the actual working conditions can be obtained, and the bypass flow can be controlled more accurately.

[0013] In a possible implementation, the opening of the bypass valve is controlled based on the opening feedforward value, including: determining the opening compensation value of the bypass valve of the fuel cell air system based on the bypass flow request value; and controlling the opening of the bypass valve based on the opening feedforward value and the opening compensation value.

[0014] According to the above technical means, the opening compensation value can correct the deviation of the opening feedforward value according to the actual operation of the fuel cell air system. The opening of the bypass valve is controlled based on the opening feedforward value and the opening compensation value, so that the opening of the bypass valve can quickly and accurately adapt to the dynamic changes of the fuel cell air system, and the actual opening of the bypass valve can more accurately meet the bypass flow request value, thereby improving the control accuracy of the bypass flow.

[0015] In one possible implementation, based on the bypass flow request value, determining an opening compensation value of a bypass valve of a fuel cell air system includes: inputting a difference between the bypass flow request value and an actual bypass flow value into a proportional integral derivative (PID) controller to obtain an opening compensation value of the bypass valve.

[0016] According to the above technical means, the PID controller can adjust the opening compensation value according to the rapid difference between the bypass flow request value and the actual value, reduce the error of the bypass flow, make the bypass flow quickly approach the bypass flow request value, and improve the control accuracy of the platform flow.

[0017] In one possible implementation, the surge control flow is determined in the following manner: based on the ratio between the stack inlet pressure and the ambient pressure of the fuel cell air system, the pressure ratio of the air compressor is determined; based on the pressure ratio of the air compressor and the surge control line, the surge control flow is determined; the surge control line is used to characterize the correspondence between the pressure ratio of the air compressor and the minimum flow threshold for safe operation of the air compressor.

[0018] According to the above technical means, the surge control flow is determined by the surge control line, so that the gas flow entering the air compressor is always not lower than the minimum safe operating flow threshold, which can avoid surge conditions or quickly exit surge conditions, so that the air compressor can operate safely and stably.

[0019] In a possible implementation, the method further includes: obtaining the air compressor pressure ratio and air compressor flow of the fuel cell air system at different air compressor speeds; determining the air compressor surge line based on the air compressor pressure ratio and air compressor flow of the fuel cell air system at different air compressor speeds; the air compressor surge line is used to characterize the corresponding relationship between the air compressor pressure ratio and the air compressor flow when surge occurs in the fuel cell air system at different air compressor speeds; and determining the surge control line based on the air compressor surge line.

[0020] According to the above technical means, the compressor surge line can be accurately determined through the compressor pressure ratio and compressor flow rate of the fuel cell air system at different compressor speeds. The accuracy of the surge control line is improved, and the surge boundary of the compressor is clarified. In this way, the bypass flow can be more accurately controlled based on the surge boundary value of the compressor.

[0021] In a possible implementation, when the surge control flow is greater than the stack inflow flow, the air compressor of the fuel cell air system is in a surge condition.

[0022] According to the above technical means, through the surge control flow and the inflow flow, it is possible to accurately determine whether the air compressor is in a surge condition. In this way, when the air compressor is in a surge condition, the bypass valve opening can be quickly adjusted to increase the air compressor flow so that the air compressor can be out of the surge condition.

[0023] In a second aspect, an embodiment of the present application provides a bypass flow control device, which includes: a determination module and a control module. The determination module is used to determine the bypass flow request value based on the surge control flow and the stack flow of the air compressor when the air compressor of the fuel cell air system is in a surge condition; the surge control flow is the minimum flow threshold for the safe operation of the air compressor; the determination module is also used to determine the opening feedforward value of the bypass valve of the fuel cell air system based on the bypass flow request value; the control module is used to control the opening of the bypass valve based on the opening feedforward value to control the bypass flow of the fuel cell air system.

[0024] In one possible implementation, a determination module is specifically used to determine the difference between the surge control flow and the stack flow as the bypass flow standard value; based on the ambient temperature and pressure of the fuel cell air system, the bypass flow standard value is converted into a bypass flow request value under the current operating condition of the fuel cell air system.

[0025] In a possible implementation manner, the determination module is specifically configured to determine the opening feedforward value of the bypass valve based on the bypass flow request value, the stack entry temperature, the stack entry pressure, and the ambient pressure.

[0026] In a possible implementation, a determination module is specifically used to determine a functional correspondence between a bypass valve opening and a stack inlet pressure, an ambient pressure, a stack inlet temperature, and a bypass flow request value based on a bypass valve flow calculation model; the bypass valve flow calculation model is used to characterize a quantitative relationship between a bypass flow and a pressure and a temperature of a fuel cell air system; the bypass flow request value, the stack inlet temperature, the stack inlet pressure, and the ambient pressure are substituted into the functional correspondence to obtain a bypass valve opening feedforward value.

[0027] In a possible implementation, the control module is specifically configured to determine an opening compensation value of a bypass valve of a fuel cell air system based on a bypass flow request value; and control the opening of the bypass valve based on an opening feedforward value and an opening compensation value.

[0028] In a possible implementation manner, the control module is specifically configured to input the difference between the bypass flow request value and the bypass flow actual value into a PID controller to obtain an opening compensation value of the bypass valve.

[0029] In one possible implementation, the surge control flow is determined in the following manner: based on the ratio between the stack inlet pressure and the ambient pressure of the fuel cell air system, the pressure ratio of the air compressor is determined; based on the pressure ratio of the air compressor and the surge control line, the surge control flow is determined; the surge control line is used to characterize the correspondence between the pressure ratio of the air compressor and the minimum flow threshold for safe operation of the air compressor.

[0030] In a possible implementation, the bypass flow control device further includes: an acquisition module. The acquisition module is used to acquire the air compressor pressure ratio and air compressor flow of the fuel cell air system at different air compressor speeds; the determination module is also used to determine the air compressor surge line based on the air compressor pressure ratio and air compressor flow of the fuel cell air system at different air compressor speeds; the air compressor surge line is used to characterize the corresponding relationship between the air compressor pressure ratio and the air compressor flow when the fuel cell air system surges at different air compressor speeds; the determination module is also used to determine the surge control line based on the air compressor surge line.

[0031] In a possible implementation, when the surge control flow is greater than the stack inflow flow, the air compressor of the fuel cell air system is in a surge condition.

[0032] In a third aspect, an embodiment of the present application provides a fuel cell air system, which includes: an air compressor, a bypass valve and a controller; the air compressor is used to compress the gas entering the air compressor; the bypass valve is used to control the bypass flow of the fuel cell air system; the controller is used to control the opening of the bypass valve based on the opening feedforward value and opening compensation value of the bypass valve when the air compressor is in a surge condition, and adjust the gas flow passing through the bypass valve to enable the air compressor to leave the surge condition.

[0033] In a fourth aspect, an embodiment of the present application provides a vehicle, comprising: a processor; a memory for storing instructions executable by the processor; wherein the processor is configured to execute the instructions to implement the bypass flow control method of any of the above embodiments.

[0034] In a fifth aspect, an embodiment of the present application provides a computer-readable storage medium having computer program instructions stored thereon, and when the computer program instructions are executed by a processor, the bypass flow control method of any of the above embodiments is implemented.

[0035] In a sixth aspect, an embodiment of the present application provides a computer program product, which includes computer program instructions, and when the computer program instructions are executed by a processor, the bypass flow control method of any of the above embodiments is implemented.

[0036] It should be noted that the technical effects brought about by any implementation method in the second to sixth aspects can refer to the technical effects brought about by the corresponding implementation method in the first aspect, and will not be repeated here.

[0037] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification are used to explain the principles of the present application, and do not constitute an improper limitation on the present application.

[0039] Figure 1 is a schematic structural diagram of a fuel cell air system according to an exemplary embodiment; Figure 2 is a gas direction schematic diagram of a fuel cell air system according to an exemplary embodiment; Figure 3is a flow chart showing a bypass flow control method according to an exemplary embodiment; Figure 4 is a flow chart showing another bypass flow control method according to an exemplary embodiment; Figure 5 is a flow chart showing another bypass flow control method according to an exemplary embodiment; Figure 6 is a flow chart showing another bypass flow control method according to an exemplary embodiment; Figure 7 is a schematic diagram of a bypass valve opening control logic according to an exemplary embodiment; Figure 8 is a flow chart showing another bypass flow control method according to an exemplary embodiment; Fig. 9 is a schematic diagram of a surge line and a surge control line of an air compressor according to an exemplary embodiment; Fig.10 is a flow chart showing another bypass flow control method according to an exemplary embodiment; Fig.11 is a block diagram of a bypass flow control device according to an exemplary embodiment; Fig.12 is a block diagram of a vehicle according to an exemplary embodiment. DETAILED DESCRIPTION

[0040] In order to enable ordinary persons in the art to better understand the technical solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings.

[0041] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims.

[0042] In the present application, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, article or device including the element.

[0043] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0044] As described in the background technology, surge conditions will damage the life of the air compressor and attenuate the performance of the air compressor. Methods for avoiding entering or leaving the surge condition include increasing the air compressor flow and reducing the air compressor back pressure. In a vehicle hydrogen fuel cell system, air compressor surge is generally avoided by increasing the air compressor flow. Specifically, a pipe is connected to the tail exhaust at the outlet end of the intercooler in the fuel cell air system, and a bypass valve is set on the pipe to control the opening and closing of the pipe, and the outlet end of the air compressor is connected to the inlet end of the intercooler. When it is monitored that the air compressor is about to enter a surge condition, the air flow through the bypass valve is controlled by controlling the opening of the bypass valve to increase the air compressor flow, so that the air compressor is out of the surge condition. Therefore, precise control of the bypass flow is the key to avoiding surge conditions.

[0045] In the related art, the bypass flow expectation value is inversely solved to obtain the adaptive feedforward control quantity of the bypass valve opening, and the difference between the bypass flow expectation value and the bypass flow estimation value is input into the integral controller to obtain the correction value of the bypass valve opening, and finally the bypass valve opening is controlled according to the adaptive feedforward control quantity and the correction value to achieve the control of the bypass flow. However, this method requires the setting of a complex observer to obtain the bypass flow expectation value and the bypass flow estimation value to control the bypass flow. This is not conducive to engineering practice, and the complex observer affects the control speed of the bypass flow, resulting in inaccurate bypass flow control in the fuel cell air system.

[0046] In view of this, the present application provides a bypass flow control method, which determines the bypass flow request value through the surge control flow to determine the feedforward opening of the bypass valve to adjust the bypass valve opening, thereby increasing the air compressor flow, so that the gas flow entering the air compressor is not less than the minimum safe operating volume threshold, so that the air compressor can escape from the surge condition. In addition, the bypass valve opening feedforward value is used to predict the required opening of the bypass valve according to the bypass flow request value, so that the bypass valve opening adjustment can quickly respond to changes in the air compressor surge condition. The bypass flow can be quickly adjusted through the opening feedforward value, so that the air compressor can quickly resume stable operation.

[0047] For ease of understanding, the bypass flow control method provided in the present application is specifically introduced below with reference to the accompanying drawings.

[0048] In some embodiments, the executor of the bypass flow control method provided in the embodiments of the present application may be a controller, a fuel cell air system, a battery system, a vehicle controller, or any device or equipment that can control the opening of the bypass valve in the battery cooling system, and the embodiments of the present application are not limited to this.

[0049] Figure 1 is a schematic structural diagram of a fuel cell air system according to an exemplary embodiment. Figure 1 As shown, the fuel cell air system 100 may include: an air filter 101 , an air compressor 102 , an intercooler 103 , a bypass valve 104 , a shut-off valve 105 , a fuel cell stack 106 , a back pressure valve 107 , a flow meter 108 and a pressure gauge 109 .

[0050] Among them, the air filter 101, the air compressor 102, and the intercooler 103 are connected in sequence. One outlet end of the intercooler 103 is connected to the bypass valve 104, and the other outlet end is connected to the stop valve 105. The stop valve 105, the stack 106, and the back pressure valve 107 are connected in sequence. The flow meter 108 is arranged at the inlet end of the air compressor 102. The pressure gauge 109 is arranged at the outlet end of the intercooler 103 on the stop valve 105 side.

[0051] In some embodiments, the air filter 101 is used to filter impurities (such as dust, particles, etc.) in the gas entering the fuel cell air system 100 to avoid damaging or blocking the airway.

[0052] In some embodiments, the air compressor 102 is used to compress the gas entering the air compressor 102 .

[0053] In some embodiments, the air compressor 102 is used to pressurize the gas entering the air compressor 102 to increase the oxygen concentration to meet the high-pressure environment required for the fuel cell stack 106 reaction.

[0054] In some embodiments, the intercooler 103 is used to cool the high-temperature gas after being pressurized by the air compressor 102, thereby reducing the gas temperature and preventing the efficiency of the fuel cell stack from being reduced or damaged due to overheating.

[0055] In some embodiments, the bypass valve 104 is used to control the bypass flow of the fuel cell air system 100 .

[0056] In some embodiments, the bypass valve 104 is also used to introduce part of the gas into the exhaust pipeline to dilute the residual hydrogen discharged from the anode side when the fuel cell stack 106 is shut down or purged.

[0057] In some embodiments, the shut-off valve 105 is used to cut off the gas path when the fuel cell air system 100 is shut down or maintained to prevent gas backflow or pressure leakage.

[0058] In some embodiments, the fuel cell stack 106 is used to convert hydrogen and oxygen into electrical energy through an electrochemical reaction.

[0059] In some embodiments, the back pressure valve 107 is used to maintain a constant outlet pressure of the fuel cell air system 100 to prevent the working point of the air compressor 102 from shifting or surging due to back pressure fluctuations.

[0060] In some embodiments, the flow meter 108 is used to detect the gas flow entering the air compressor 102, that is, the air compressor flow. The pressure meter 109 is used to detect the outlet gas pressure of the intercooler 103 on the side of the stop valve 105, that is, the stack pressure.

[0061] In some embodiments, the gas entering the fuel cell air system 100 for reaction may be bypassed to the atmosphere through the back pressure valve 107 and / or the bypass valve 104 .

[0062] In some embodiments, the fuel cell air system 100 further includes a controller (not shown in the figure). The controller is used to control the opening of the bypass valve 104 based on the opening feedforward value and the opening compensation value of the bypass valve 104 when the air compressor 102 is in a surge condition, and adjust the gas flow through the bypass valve 104 so that the air compressor 102 is out of the surge condition.

[0063] In some embodiments, the controller may be a PID controller.

[0064] In some embodiments, a thermometer (not shown in the figure) is arranged between the intercooler 103 and the stop valve 105 , and the thermometer is used to detect the inlet temperature of the gas.

[0065] In some embodiments, the gas flowing through the fuel cell air system 100 may be air, pure oxygen, oxygen-enriched air, inert gas or other mixed gases, which may be set based on the actual needs of the fuel cell stack 106 , and the embodiments of the present application are not limited to this.

[0066] In some embodiments, Figure 2 is a gas direction schematic diagram of a fuel cell air system according to an exemplary embodiment. Figure 2 As shown, after the gas is filtered by the air filter 101, it is compressed, pressurized and heated by the air compressor 102, and then cooled by the intercooler 103, and enters the fuel cell stack to participate in the electrochemical reaction. The bypass valve 104 is located between the intercooler 103 and the tail exhaust, and the gas is divided into two branches at the outlet of the intercooler 103. When the stop valve 105 and the back pressure valve 107 are opened, one branch goes to the inside of the fuel cell stack 106 through the stop valve 105, and the gas flow of this branch is the inflow flow. When the bypass valve 104 is opened, the other branch is discharged through the bypass valve 104, and the gas flow of this branch is the bypass flow.

[0067] In some embodiments, during the operation of the stack 106, the gas inflow and pressure can be set based on the actual current request of the stack 106, so that the fuel cell air system 100 supplies gas to the cathode side of the stack 106. When the bypass valve 104 is closed, the inflow is equal to the air compressor flow. When the bypass valve is open, the inflow is equal to the air compressor flow minus the bypass flow.

[0068] Figure 3 is a flow chart of a bypass flow control method according to an exemplary embodiment. Figure 3 As shown, the bypass flow control method includes the following steps: S301. When an air compressor of a fuel cell air system is in a surge condition, determine a bypass flow request value based on a surge control flow and a stack inflow flow of the air compressor.

[0069] Among them, the surge control flow is the minimum flow threshold for safe operation of the air compressor.

[0070] In some embodiments, when the surge control flow is greater than the stack inflow flow, the air compressor of the fuel cell air system is in a surge condition.

[0071] One possible implementation method is that when the surge control flow is greater than the stack inlet flow, it means that the minimum flow threshold for safe operation of the air compressor is greater than the stack inlet flow, then the air compressor flow is less than the minimum flow threshold for safe operation of the air compressor, the air compressor flow is too low, and the air compressor enters a surge condition.

[0072] In some embodiments, when the surge control flow is greater than the stack flow, the bypass flow request value required by the bypass valve can be calculated based on the surge control flow and the stack flow, so as to increase the bypass flow of the fuel cell air system by controlling the bypass valve, so that the air compressor can be out of the surge condition and meet the stack flow and stack pressure requirements.

[0073] It should be noted that when the surge control flow is less than or equal to the stack flow, it means that the air compressor flow is greater than or equal to the minimum flow threshold for safe operation of the air compressor, and the air compressor is in a non-surge condition, then the bypass flow request value is zero, and there is no need to open the bypass valve.

[0074] S302 : Determine an opening feedforward value of a bypass valve of a fuel cell air system based on the bypass flow rate request value.

[0075] The feedforward opening value is used to predict the required opening of the bypass valve based on the bypass flow request value, and pre-compensate the opening of the bypass valve so that the bypass flow of the fuel cell air system reaches the bypass flow request value.

[0076] In some embodiments, the above step S301 may be implemented as follows: determining the bypass valve opening feedforward value based on the bypass flow request value, the stack entry temperature, the stack entry pressure, and the ambient pressure.

[0077] One possible implementation method is to combine the bypass flow request value with the current inlet temperature, inlet pressure, and ambient pressure of the fuel cell air system to predict the bypass valve opening required by the fuel cell air system to escape from surge conditions under the current operating conditions, thereby obtaining a bypass valve opening feedforward value.

[0078] S303 . Based on the opening feedforward value, control the opening of the bypass valve to control the bypass flow of the fuel cell air system.

[0079] In some embodiments, the opening of the bypass valve may be adjusted based on the start-end feedforward value to adjust the bypass flow through the bypass valve and increase the compressor flow to allow the air compressor to escape from a surge condition.

[0080] It should be understood that the bypass flow request value is determined by the surge control flow to determine the feedforward opening of the bypass valve to adjust the bypass valve opening, thereby increasing the air compressor flow so that the gas flow entering the air compressor is not lower than the minimum safe operating volume threshold, so that the air compressor can escape from the surge condition.

[0081] In some embodiments, Figure 4 As shown, the above step S301 can be specifically implemented as the following steps S3011-S3012: S3011. Determine the difference between the surge control flow and the inflow flow as the bypass flow standard value.

[0082] S3012: Based on the ambient temperature and pressure of the fuel cell air system, convert the bypass flow rate standard condition value into a bypass flow rate request value under the current operating condition of the fuel cell air system.

[0083] In a possible implementation, when the air compressor of the fuel cell air system is in a surge condition, the bypass flow rate standard condition value is equal to the difference between the surge control flow rate and the stack inlet flow rate. The bypass flow rate standard condition value is standardized and converted into a bypass flow rate request value under the current ambient temperature and current pressure conditions of the fuel cell air system.

[0084] Exemplarily, the bypass flow request value may be determined by the following expressions (1) and (2): ; ; in, Indicates the bypass flow rate standard value. Indicates surge control flow. Indicates the current inflow flow of the fuel cell air system. Indicates the bypass flow request value. Indicates the ambient temperature of the fuel cell air system under standard operating conditions. Indicates the ambient temperature of the fuel cell air system under current operating conditions. Indicates the pressure of the fuel cell air system under standard operating conditions. Indicates the pressure of the fuel cell air system under the current working condition. The ambient temperature and pressure of the fuel cell air system under standard working conditions are set by relevant technicians according to the characteristics and requirements of the fuel cell air system, and the embodiments of the present application do not limit this.

[0085] It should be understood that the difference between the surge control flow and the stack flow is determined as the bypass flow standard value, so that the gas flow entering the air compressor is not lower than the surge control flow while meeting the flow demand of the fuel cell stack. In addition, the bypass flow standard value is converted into the bypass flow request value under the current working condition, taking into account the influence of ambient temperature and pressure on the gas state, so that the bypass flow can be controlled more accurately.

[0086] In some embodiments, Figure 5 As shown, the above step S302 can be specifically implemented as the following steps S3021-S3022: S3021. Based on the bypass valve flow calculation model, determine the functional correspondence between the bypass valve opening and the stack inlet pressure, the ambient pressure, the stack inlet temperature and the bypass flow request value.

[0087] Among them, the bypass valve flow calculation model is used to characterize the quantitative relationship between the bypass flow, pressure and temperature of the fuel cell air system.

[0088] S3022, substituting the bypass flow request value, the stack entry temperature, the stack entry pressure, and the ambient pressure into the function correspondence to obtain the bypass valve opening feedforward value.

[0089] In a possible implementation, the bypass valve flow calculation model is shown in the following expression (3): ; in, Indicates bypass flow. Indicates the flow coefficient of the bypass valve at different openings, There is a one-dimensional data mapping relationship with the bypass valve opening, which is used to reflect the relationship between the flow capacity and the opening of the bypass valve. A T Indicates the effective flow cross-sectional area of ​​the bypass valve corresponding to different openings, in m 2 . P 1Byp Indicates the pressure upstream of the bypass valve, in Pa. P 1Byp Equivalent to the pile pressure P inStk . P 2Byp Indicates the pressure downstream of the bypass valve, in Pa. P 2Byp Equivalent to environmental pressure. T 1Byp Indicates the air temperature upstream of the bypass valve, in K. T 1Byp Equivalent to the temperature of the pile T inStk . r represents the ideal gas constant, which is 287 J / (kg K) . k Indicates the adiabatic index. When the gas in the fuel cell air system is air, k The value of is usually 1.4.

[0090] Among them, the effective flow cross-sectional area of ​​the bypass valve corresponding to the above different openings is A T Determined by the following expression (4): ; in, Indicates the opening of the bypass valve in degrees. D Indicates the diameter of the bypass valve in meters.

[0091] In addition, the relationship between the bypass flow request value, the stack temperature, the stack pressure, the ambient pressure and the bypass valve opening feedforward value is as shown in the following expression (5): ; in, Indicates the bypass valve opening feedforward value. Indicates the bypass flow request value. Indicates the pile pressure. Indicates environmental pressure. Indicates the temperature of the pile.

[0092] Combining the above expressions (3), (4), and (5), when the bypass flow request is known, the following expression (6) can be obtained: ; It should be noted that in actual engineering applications, the temperature of the pile is generally used. Replace bypass valve upstream temperature , pile pressure Replace the bypass valve upstream pressure , environmental pressure Replace the bypass valve downstream pressure Therefore, the above expression (6) can be transformed into the following expression (7): ; In the above expression (7), D represents the diameter of the bypass valve, which is generally a constant. Therefore, As for the bypass valve opening A univariate function of . And, the flow coefficient It is a structural characteristic parameter related to the bypass valve opening. Considered as the bypass valve opening Therefore, the above expression (7) can be Considered as bypass valve opening The unary function of is shown in the following expression (8): ; Combining the above expressions (7) and (8) yields the following expression (9): ; From the above expression (9), we can see that r and k are constants, so we can use Considered as the upstream pressure ratio under the bypass valve , Pile pressure , Pile temperature , bypass flow request Therefore, substituting the bypass flow request value, the stack temperature, the stack pressure, and the ambient pressure into the above expression (9) yields .and For bypass valve opening The function is fitted by reverse calibration. , the bypass valve feedforward opening under different bypass flow requests can be calculated.

[0093] It should be noted that the reverse calibration fitting The process is as follows: A fuel cell air system test bench is built based on the structure of the fuel cell air system, and the shut-off valve and the back pressure valve are completely closed. The opening of the bypass valve is gradually increased from 0° to 90° at preset intervals. At each bypass valve opening, a PID controller is used to control the air compressor speed so that the downstream upstream pressure ratio of the bypass valve reaches the set value. The downstream upstream pressure ratio of the bypass valve, the air compressor flow (i.e., the bypass flow), the stack inlet temperature, the ambient pressure, and the stack inlet pressure are collected at each bypass valve opening. Among them, in the process of gradually increasing the bypass valve opening from 0° to 90°, the downstream upstream pressure ratio of the bypass valve decreases from 1 to the pressure ratio at which the air compressor surges at preset intervals. The downstream upstream pressure ratio of the bypass valve is the ratio between the ambient pressure and the stack inlet pressure. Substituting the collected bypass flow, stack inlet pressure, stack inlet temperature, and ambient pressure into the above expression (9) can obtain the corresponding bypass valve openings at different openings. . For different bypass valve openings and the corresponding bypass valve opening By fitting, we can get and The corresponding relationship between them is shown in the following expression (10): ; It should be understood that, through the bypass valve flow calculation model, the influence of multiple factors such as the inlet pressure, ambient pressure, and inlet temperature on the bypass flow can be comprehensively considered, the control error of the bypass flow can be reduced, the required opening of the bypass valve can be determined more accurately, and the control accuracy of the bypass flow can be improved.

[0094] In some embodiments, Figure 6 As shown, the above step S303 can be specifically implemented through the following steps S3031-S3032: S3031. Determine an opening compensation value of a bypass valve of a fuel cell air system based on a bypass flow request value.

[0095] In some embodiments, the above step S3031 can be implemented as follows: inputting the difference between the bypass flow request value and the bypass flow actual value into a PID controller to obtain an opening compensation value of the bypass valve.

[0096] One possible implementation method is to use a PID controller to perform PID closed-loop control on the opening of the bypass valve to achieve precise control of the bypass flow. Therefore, the difference between the bypass flow request value and the bypass flow actual value is input into the PID controller to obtain the bypass valve opening compensation value.

[0097] It should be noted that the actual value of the bypass flow is obtained as follows: by arranging a flow meter at the inlet end of the bypass valve to measure the actual value of the bypass flow or by calculating the actual value of the bypass flow through a throttle valve model. In addition, since the gas flow in the fuel cell air system can quickly follow the changes in the air compressor speed and valve body opening, the air compressor flow, bypass flow, and stack flow in the transient state can be used to reflect the flow of gas in the fuel cell air system.

[0098] S3032. Control the opening of the bypass valve based on the opening feedforward value and the opening compensation value.

[0099] One possible implementation method is to control the opening of the bypass valve based on the bypass valve opening compensation amount and the bypass valve opening feedforward value, so as to control the bypass flow, avoid surging of the air compressor, and ensure the inlet flow and inlet pressure of the fuel cell air system to maintain the normal operation of the stack.

[0100] Figure 7 FIG. 1 is a schematic diagram of a bypass valve opening control logic according to an exemplary embodiment. Figure 7 As shown, the ambient pressure, the stack pressure, the stack temperature and the bypass flow request value are input into the bypass valve feedforward opening calculation unit to obtain the bypass valve opening feedforward value. The difference between the bypass flow request value and the bypass flow actual value is input into the PID controller to obtain the bypass valve opening compensation value. Based on the bypass valve opening feedforward value and the bypass valve opening compensation value, the bypass valve opening request is obtained to control the bypass valve in the fuel cell air system. The bypass flow actual value can be collected from the fuel cell air system.

[0101] It should be understood that the opening of the bypass valve is controlled by the opening feedforward value and the opening compensation value. The control speed of the bypass flow is improved, so that the gas flow of the fuel cell air system can be stabilized in a faster time, and while quickly avoiding the air compressor surge condition, the fluctuation of the inflow flow caused by the opening of the bypass valve is suppressed to avoid affecting the electrochemical reaction of the fuel cell stack.

[0102] In some embodiments, Figure 8 As shown, the bypass flow control method provided in the embodiment of the present application also includes the following steps S801-S803: S801. Obtain the compressor pressure ratio and compressor flow rate of the fuel cell air system at different compressor speeds.

[0103] S802. Determine an air compressor surge line based on the air compressor pressure ratio and air compressor flow rate of the fuel cell air system at different air compressor speeds.

[0104] Among them, the air compressor surge line is used to characterize the corresponding relationship between the air compressor pressure ratio and the air compressor flow rate when the fuel cell air system surges at different air compressor speeds.

[0105] One possible implementation method is to treat the air filter, air compressor, intercooler and connecting pipes between the components in the fuel cell air system as an integral component. At preset air compressor speed intervals, gradually increase the air compressor speed from the lowest speed to the highest speed, and control the pressure at the intercooler outlet at each air compressor speed point. At preset pressure intervals, gradually increase the ambient pressure to the pressure when the air compressor surges, and use a back pressure valve at the intercooler outlet to control the outlet pressure. Collect the air filter inlet pressure, air filter inlet temperature, intercooler outlet pressure, air compressor speed, and air compressor flow at each air compressor speed point and each intercooler outlet pressure point.

[0106] Based on the preset standard temperature and standard pressure, the collected data such as air compressor speed and air compressor flow are processed into standard conditions through the following expressions (11) and (12) to obtain the air compressor standard speed and air compressor standard flow: ; ; in, Indicates the standard speed of the air compressor. Indicates the standard flow rate of the air compressor. Indicates the collected air compressor speed. Indicates standard temperature. Indicates the collected air filter inlet temperature. Indicates the collected air compressor flow. Indicates standard pressure. Indicates the collected air filter inlet pressure.

[0107] The air compressor pressure ratio is determined based on the following expression (13): ; in, Indicates the air compressor pressure ratio. Indicates the collected air filter inlet pressure. Indicates the collected intercooler outlet pressure.

[0108] The air compressor pressure ratio and the air compressor standard flow rate at each standard speed are fitted, with the air compressor standard flow rate as the horizontal axis and the air compressor pressure ratio as the vertical axis, to obtain the standard flow rate correspondence of the air compressor. In the standard flow rate correspondence of the air compressor, at each standard speed, the air compressor has a corresponding maximum air compressor pressure ratio value. When the air compressor pressure ratio is higher than the maximum air compressor pressure ratio value, the air compressor will surge. The air compressor standard flow rate corresponding to the maximum air compressor pressure ratio value is the minimum flow rate that the air compressor can reach at the standard speed. The minimum standard flow rate and the maximum air compressor pressure ratio value at each standard speed are fitted to obtain the air compressor surge line at each standard speed.

[0109] S803: Determine a surge control line based on the air compressor surge line.

[0110] One possible implementation method is to shift the air compressor surge line to the right along the horizontal axis where the air compressor standard flow is located by a preset range in engineering practice to obtain the air compressor surge control line. The preset range may be 5%-10% of the minimum standard flow.

[0111] Fig. 9 FIG. 1 is a schematic diagram of a surge line and a surge control line of an air compressor according to an exemplary embodiment. Fig. 9 As shown in the figure, the horizontal axis is the standard flow rate of the air compressor, in g / s. The vertical axis is the pressure ratio of the air compressor. The solid line represents the air compressor surge line. The dotted line represents the air compressor surge control line. The air compressor surge line is translated to the right along the horizontal axis to a preset range to obtain the air compressor surge control line.

[0112] It should be understood that by determining the surge control flow through the surge control line, the gas flow entering the air compressor is always not less than the minimum safe operating flow threshold, which can avoid the surge condition or quickly leave the surge condition, so that the air compressor can operate safely and stably. In addition, by determining the surge control flow through the pressure ratio of the air compressor combined with the surge control line, the surge control flow can be adjusted according to the actual working condition of the fuel cell air system, so as to accurately control the bypass flow under different working conditions.

[0113] In some embodiments, Fig.10 As shown, the surge control flow is determined by the following steps S1001-S1002: S1001. Determine the pressure ratio of the air compressor based on the ratio between the stack inlet pressure of the fuel cell air system and the ambient pressure.

[0114] One possible implementation method is that when the fuel cell air system is running, the stack entry pressure corresponding to the current request can be queried according to the current request of the fuel cell stack, or the stack entry pressure can be collected through a pressure gauge, and the ambient pressure of the fuel cell air system can be measured, and the ratio between the stack entry pressure and the ambient pressure can be determined as the pressure ratio of the air compressor.

[0115] S1002. Determine a surge control flow rate based on the pressure ratio of the air compressor and the surge control line.

[0116] The surge control line is used to characterize the corresponding relationship between the pressure ratio of the air compressor and the minimum flow threshold for safe operation of the air compressor.

[0117] In a possible implementation, the surge control line corresponding to the current speed can be queried based on the current speed of the air compressor, so that the standard flow rate of the air compressor corresponding to the pressure ratio of the air compressor can be queried through the surge control line, which is the surge control flow rate.

[0118] It should be understood that the compressor surge line can be accurately determined by the compressor pressure ratio and compressor flow rate of the fuel cell air system at different compressor speeds. The accuracy of the surge control line is improved, and the surge boundary of the compressor is clarified. In order to more accurately control the bypass flow based on the surge boundary value of the compressor.

[0119] The above mainly introduces the solution provided by the embodiment of the present application from the perspective of the method. In order to achieve the above functions, the bypass flow control device or vehicle includes a hardware structure and / or software module corresponding to the execution of each function. It should be easily appreciated by those skilled in the art that, in combination with the units and algorithm steps of each example described in the embodiments disclosed herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present application.

[0120] The embodiments of the present application can divide the bypass flow control device or the vehicle into functional modules according to the above method. For example, the bypass flow control device or the vehicle can include various functional modules corresponding to the various functional divisions, or two or more functions can be integrated into one processing module. The above integrated modules can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the division of modules in the embodiments of the present application is schematic and is only a logical functional division. There may be other division methods in actual implementation.

[0121] Fig.11 is a block diagram of a bypass flow control device according to an exemplary embodiment. Fig.11 The bypass flow control device 1100 includes: a determination module 1101 and a control module 1102 .

[0122] The determination module 1101 is used to determine the bypass flow request value based on the surge control flow and the stack inlet flow of the air compressor when the air compressor of the fuel cell air system is in a surge condition; the surge control flow is the minimum flow threshold for the safe operation of the air compressor; the determination module 1101 is also used to determine the opening feedforward value of the bypass valve of the fuel cell air system based on the bypass flow request value; the control module 1102 is used to control the opening of the bypass valve based on the opening feedforward value to control the bypass flow of the fuel cell air system.

[0123] In one possible implementation, the determination module 1101 is specifically used to determine the difference between the surge control flow and the stack flow as the bypass flow standard value; based on the ambient temperature and pressure of the fuel cell air system, the bypass flow standard value is converted into the bypass flow request value under the current operating condition of the fuel cell air system.

[0124] In a possible implementation manner, the determination module 1101 is specifically configured to determine the bypass valve opening feedforward value based on the bypass flow request value, the stack entry temperature, the stack entry pressure, and the ambient pressure.

[0125] In a possible implementation, the determination module 1101 is specifically used to determine the functional correspondence between the bypass valve opening and the stack inlet pressure, ambient pressure, stack inlet temperature and the bypass flow request value based on the bypass valve flow calculation model; the bypass valve flow calculation model is used to characterize the quantitative relationship between the bypass flow and the pressure and temperature of the fuel cell air system; the bypass flow request value, stack inlet temperature, stack inlet pressure and ambient pressure are substituted into the functional correspondence to obtain the bypass valve opening feedforward value.

[0126] In a possible implementation, the control module 1102 is specifically configured to determine an opening compensation value of a bypass valve of a fuel cell air system based on a bypass flow request value; and control the opening of the bypass valve based on an opening feedforward value and an opening compensation value.

[0127] In a possible implementation manner, the control module 1102 is specifically configured to input the difference between the bypass flow request value and the bypass flow actual value into a PID controller to obtain an opening compensation value of the bypass valve.

[0128] In one possible implementation, the surge control flow is determined in the following manner: based on the ratio between the stack inlet pressure and the ambient pressure of the fuel cell air system, the pressure ratio of the air compressor is determined; based on the pressure ratio of the air compressor and the surge control line, the surge control flow is determined; the surge control line is used to characterize the correspondence between the pressure ratio of the air compressor and the minimum flow threshold for safe operation of the air compressor.

[0129] In a possible implementation, the bypass flow control device 1100 further includes: an acquisition module 1103. The acquisition module 1103 is used to acquire the air compressor pressure ratio and air compressor flow of the fuel cell air system at different air compressor speeds; the determination module 1101 is also used to determine the air compressor surge line based on the air compressor pressure ratio and air compressor flow of the fuel cell air system at different air compressor speeds; the air compressor surge line is used to characterize the corresponding relationship between the air compressor pressure ratio and the air compressor flow when the fuel cell air system surges at different air compressor speeds; the determination module 1101 is also used to determine the surge control line based on the air compressor surge line.

[0130] In a possible implementation, when the surge control flow is greater than the stack inflow flow, the air compressor of the fuel cell air system is in a surge condition.

[0131] According to the above technical means, the bypass flow request value is determined by the surge control flow to determine the feedforward opening of the bypass valve to adjust the bypass valve opening, thereby increasing the air compressor flow, so that the gas flow entering the air compressor is not less than the minimum safe operating volume threshold, so that the air compressor can escape the surge condition. In addition, the bypass valve opening feedforward value is used to predict the required opening of the bypass valve according to the bypass flow request value, so that the bypass valve opening adjustment can quickly respond to changes in the air compressor surge condition. The bypass flow can be quickly adjusted through the opening feedforward value, so that the air compressor can quickly resume stable operation.

[0132] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0133] Fig.12 FIG. 1 is a block diagram of a vehicle according to an exemplary embodiment. Fig.12 As shown, vehicle 1200 includes, but is not limited to, a processor 1201 and a memory 1202 .

[0134] The memory 1202 is used to store executable instructions of the processor 1201. It can be understood that the processor 1201 is configured to execute instructions to implement the bypass flow method in the above embodiment.

[0135] It should be noted that those skilled in the art can understand that Fig.12 The vehicle structure shown in the figure does not constitute a limitation on the vehicle, and the vehicle may include Fig.12 More or fewer components may be shown, or certain components may be combined, or the components may be arranged differently.

[0136] The processor 1201 is the control center of the vehicle, which uses various interfaces and lines to connect various parts of the entire vehicle, and executes various functions of the vehicle and processes data by running or executing software programs and / or modules stored in the memory 1202, and calling data stored in the memory 1202, so as to monitor the vehicle as a whole. The processor 1201 may include one or more processing units. Optionally, the processor 1201 may integrate an application processor and a modem processor, wherein the application processor mainly processes the operating system, user interface, and application programs, etc., and the modem processor mainly processes wireless communications. It is understandable that the above-mentioned modem processor may not be integrated into the processor 1201.

[0137] The memory 1202 may be used to store software programs and various data. The memory 1202 may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application program required by at least one functional module (such as a determination unit, a processing unit, etc.), etc. In addition, the memory 1202 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0138] In an exemplary embodiment, a computer-readable storage medium including instructions is also provided, such as a memory 1202 including instructions, and the above instructions can be executed by the processor 1201 of the vehicle 1200 to implement the bypass flow method in the above embodiment.

[0139] In actual implementation, Fig.11 The functions of the determination module 1101, the control module 1102 and the acquisition module 1103 in the embodiment can be realized by Fig.12 The processor 1201 in the embodiment calls the computer program stored in the memory 1202 to implement. The specific execution process can refer to the description of the method part in the above embodiment, which will not be repeated here.

[0140] Optionally, the computer-readable storage medium may be a non-temporary computer-readable storage medium, for example, the non-temporary computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc.

[0141] In an exemplary embodiment, the present application also provides a computer program product including one or more instructions, which can be executed by the processor 1201 of the vehicle to implement the bypass flow method in the above embodiment.

[0142] It should be noted that when the instructions in the above-mentioned computer-readable storage medium or one or more instructions in the computer program product are executed by the vehicle's processor, the various processes of the above-mentioned method embodiment are implemented, and the same technical effect as the above-mentioned method can be achieved. To avoid repetition, they will not be repeated here.

[0143] Through the description of the above implementation methods, technical personnel in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0144] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of modules or units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0145] The units described as separate components may or may not be physically separated, and the components shown as units may be one physical unit or multiple physical units, that is, they may be located in one place or distributed in multiple different places. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0146] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0147] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application is essentially or the part that contributes to the prior art or the full classification part or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a device (which can be a single-chip microcomputer, chip, etc.) or a processor (processor) to execute the full classification part or part of the steps of each embodiment method of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, ROM, RAM, disk or CD and other media that can store program code.

[0148] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A bypass flow control method, characterized in that: The bypass flow control method comprises: When the air compressor of the fuel cell air system is in a surge condition, determining a bypass flow request value based on the surge control flow and the stack flow of the air compressor; the surge control flow is the minimum flow threshold for safe operation of the air compressor; Determining a bypass valve opening feedforward value based on the bypass flow request value, the stack entry temperature, the stack entry pressure, and the ambient pressure; Based on the opening feedforward value, the opening of the bypass valve is controlled to control the bypass flow of the fuel cell air system.

2. The bypass flow control method according to claim 1, characterized in that: The step of determining the bypass flow request value based on the surge control flow and the stack flow of the air compressor includes: Determine the difference between the surge control flow and the stack inlet flow as the bypass flow standard value; Based on the ambient temperature and pressure of the fuel cell air system, the bypass flow rate standard condition value is converted into a bypass flow rate request value under the current working condition of the fuel cell air system.

3. The bypass flow control method according to claim 1, characterized in that: The step of determining the bypass valve opening feedforward value based on the bypass flow request value, the stack entry temperature, the stack entry pressure, and the ambient pressure includes: Based on a bypass valve flow calculation model, determining a functional correspondence between the bypass valve opening and the stack inlet pressure, the ambient pressure, the stack inlet temperature and the bypass flow request value; the bypass valve flow calculation model is used to characterize a quantitative relationship between the bypass flow and the pressure and temperature of the fuel cell air system; Substituting the bypass flow request value, the stack entry temperature, the stack entry pressure, and the ambient pressure into the functional correspondence relationship, the opening feedforward value of the bypass valve is obtained.

4. The bypass flow control method according to claim 1, characterized in that: The controlling the opening of the bypass valve based on the opening feedforward value comprises: determining an opening compensation value of a bypass valve of the fuel cell air system based on the bypass flow request value; The opening degree of the bypass valve is controlled based on the opening degree feedforward value and the opening degree compensation value.

5. The bypass flow control method according to claim 4, characterized in that: The step of determining an opening compensation value of a bypass valve of the fuel cell air system based on the bypass flow request value comprises: The difference between the bypass flow request value and the bypass flow actual value is input into a proportional integral differential PID controller to obtain an opening compensation value of the bypass valve.

6. The bypass flow control method according to any one of claims 1 to 5, characterized in that: The surge control flow is determined by: Determining the pressure ratio of the air compressor based on the ratio between the stack inlet pressure of the fuel cell air system and the ambient pressure; The surge control flow is determined based on the pressure ratio of the air compressor and a surge control line; the surge control line is used to characterize the corresponding relationship between the pressure ratio of the air compressor and the minimum flow threshold for safe operation of the air compressor.

7. The bypass flow control method according to claim 6, characterized in that: The method further comprises: Obtaining the air compressor pressure ratio and air compressor flow rate of the fuel cell air system at different air compressor speeds; Based on the air compressor pressure ratio and air compressor flow rate of the fuel cell air system at different air compressor speeds, an air compressor surge line is determined; the air compressor surge line is used to characterize the corresponding relationship between the air compressor pressure ratio and the air compressor flow rate when the fuel cell air system surges at different air compressor speeds; The surge control line is determined based on the air compressor surge line.

8. The bypass flow control method according to any one of claims 1 to 5, characterized in that: When the surge control flow is greater than the stack inflow flow, the air compressor of the fuel cell air system is in a surge condition.

9. A fuel cell air system, characterized in that: The fuel cell air system comprises: an air compressor, a bypass valve and a controller; The air compressor is used to compress the gas entering the air compressor; The bypass valve is used to control the bypass flow of the fuel cell air system; The controller is used to control the opening of the bypass valve based on the opening feedforward value and the opening compensation value of the bypass valve when the air compressor is in a surge condition, and adjust the gas flow flowing through the bypass valve so that the air compressor is out of the surge condition; wherein the opening feedforward value of the bypass valve is determined based on the bypass flow request value, the stack entry temperature, the stack entry pressure, and the ambient pressure.

10. A bypass flow control device, characterized in that: The bypass flow control device comprises: a determination module and a control module; The determination module is used to determine the bypass flow request value based on the surge control flow and the stack flow of the air compressor when the air compressor of the fuel cell air system is in a surge condition; the surge control flow is the minimum flow threshold for the safe operation of the air compressor; The determination module is further used to determine the opening feedforward value of the bypass valve based on the bypass flow request value, the stack entry temperature, the stack entry pressure, and the ambient pressure; The control module is used to control the opening of the bypass valve based on the opening feedforward value to control the bypass flow of the fuel cell air system.

11. A vehicle, characterized in that: The vehicle comprises: processor; a memory for storing instructions executable by the processor; The processor is configured to execute the instructions to implement the bypass flow control method according to any one of claims 1 to 8.

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