Open-circuit purging method and device of fuel cell system and storage medium

Abstract

The invention discloses an open circuit purging method and device of a fuel cell system and a storage medium, the fuel cell system comprises an electric pile and a DC-DC module which are connected with each other, the method comprises the following steps: under the condition that the fuel cell system is shut down, according to an under-voltage protection voltage of the electric pile, a first target value of a low side current is determined, the low-side current is the current output to the DC-DC module by the electric pile, and the first target value is greater than 0A; blowing the electric pile according to the first target value, and obtaining the current voltage of the electric pile; under the condition that the current voltage is discharged to the under-voltage protection voltage, the DC-DC module is controlled to discharge the current voltage to the safety voltage of the galvanic pile, a second target value of the low-side current is determined, and the second target value is 0A; and purging the galvanic pile according to the second target value. According to the technical scheme, the voltage of the electric pile can be prevented from being continuously in a high-potential state during open-circuit purging of the fuel cell system, and the fault rate of the fuel cell system is reduced.

Description

Technical Field

[0001] The present application belongs to the field of fuel cell technology, and in particular, relates to an open-circuit purge method, device and storage medium for a fuel cell system. Background Art

[0002] As a major automobile country, China has a huge automobile market. While automobiles bring economic benefits, they are also accompanied by huge energy consumption and environmental pollution. As competition in the automobile field becomes increasingly fierce, various companies and universities have begun to engage in research on automobiles with fuel cell systems.

[0003] The fuel cell system includes a stack and a DC-DC module. The stack generates electricity through chemical reactions. The DC-DC module is connected to the stack and steps up and down the current output by the stack to meet the power requirements of the vehicle. When the fuel cell system is shut down, it will first perform a closed-circuit purge process and then an open-circuit purge process to discharge some of the water inside the stack and keep the water content of the stack within an appropriate range.

[0004] Currently, during the open-circuit purge process, the current output by the battery stack to the DC-DC module (i.e., the low-side current of the DC-DC module) mostly uses a fixed value of 0A. This causes the battery stack voltage to be continuously in a high-potential state, which not only damages the battery stack structure, but also poses a high-voltage safety hazard, thereby causing failure of the fuel cell system. Summary of the invention

[0005] The embodiments of the present application provide an open-circuit purge method, device and storage medium for a fuel cell system, thereby reducing the failure rate of the fuel cell system at least to a certain extent during the open-circuit purge of the fuel cell system.

[0006] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0007] According to a first aspect of an embodiment of the present application, an open circuit purge method for a fuel cell system is provided, the fuel cell system comprising a fuel cell stack and a DC-DC module connected to each other, the method comprising:

[0008] When the fuel cell system is shut down, determining a first target value of a low-side current according to an undervoltage protection voltage of the fuel cell stack, wherein the low-side current is a current output from the fuel cell stack to the DC-DC module, and the first target value is greater than 0A;

[0009] Purging the fuel cell stack according to the first target value, and acquiring a current voltage of the fuel cell stack;

[0010] When the current voltage is discharged to the undervoltage protection voltage, controlling the DC-DC module to discharge the current voltage to the safety voltage of the battery stack, and determining a second target value of the low-side current, wherein the second target value is 0A;

[0011] The fuel cell stack is purged according to the second target value.

[0012] In some embodiments, the fuel cell system further includes a hydrogen subsystem, the hydrogen subsystem including a hydrogen inlet valve, a proportional valve, a drain valve, and a nitrogen exhaust valve, and the method further includes:

[0013] The hydrogen inlet valve, the proportional valve, the drain valve and the nitrogen exhaust valve are controlled to be closed.

[0014] In some embodiments, the fuel cell system further includes an air subsystem, the air subsystem including an air compressor, an inlet shut-off valve, an outlet shut-off valve, and a back pressure valve, and the method further includes:

[0015] controlling the speed of the air compressor according to the target purge flow rate of the fuel cell stack;

[0016] Controlling the openings of the stack inlet stop valve and the stack outlet stop valve to reach maximum openings;

[0017] The opening of the back pressure valve is controlled according to the ambient temperature.

[0018] In some embodiments, the fuel cell system further includes a hydrogen subsystem and an air subsystem, and after purging the fuel cell stack according to the second target value, the method further includes:

[0019] Determining a third target value of the low-side current according to the current voltage; wherein the third target value is less than the first target value;

[0020] The components of the hydrogen subsystem and the air subsystem are purged according to the third target value.

[0021] In some embodiments, determining the third target value of the low-side current according to the current voltage includes:

[0022] When the current voltage is less than the first preset value, determining the third target value to be 0A;

[0023] When the current voltage is greater than a second preset value, the third target value is determined to be a value between 0A and the first target value; wherein the second preset value is greater than the first preset value.

[0024] In some embodiments, the hydrogen subsystem includes a hydrogen inlet valve, a proportional valve, a drain valve, a nitrogen drain valve, and a hydrogen circulation pump, and the method further includes:

[0025] Controlling the hydrogen inlet valve, the water discharge valve and the nitrogen discharge valve to open;

[0026] controlling the duty cycle of the proportional valve according to the target pressure of hydrogen;

[0027] The rotation speed of the hydrogen circulation pump is controlled to be the minimum rotation speed.

[0028] In some embodiments, the air subsystem includes an air compressor, a stack inlet shut-off valve, a stack outlet shut-off valve, a back pressure valve, and a bypass valve, and the method further includes:

[0029] controlling the speed of the air compressor according to the ambient temperature;

[0030] Controlling the stack inlet stop valve, the stack outlet stop valve and the back pressure valve to close;

[0031] The opening of the bypass valve is controlled to reach a maximum opening.

[0032] In some embodiments, the fuel cell system includes a thermal management subsystem, the thermal management subsystem includes a temperature control valve, a water pump, and a cooling fan, and after purging the components of the hydrogen subsystem and the air subsystem according to the third target value, the method further includes:

[0033] Controlling the opening of the temperature control valve to reach a maximum opening;

[0034] Controlling the rotation speed of the water pump to be the rated rotation speed of the water pump;

[0035] The rotation speed of the cooling fan is controlled to be the rated rotation speed of the cooling fan.

[0036] According to a second aspect of an embodiment of the present application, an open-circuit purge device for a fuel cell system is provided, comprising a processor and a memory, wherein the memory stores computer program instructions that can be executed by the processor, and when the processor executes the computer program instructions, the steps of the method described in any one of the first aspects above are implemented.

[0037] According to a third aspect of an embodiment of the present application, a computer-readable storage medium is provided, in which computer program instructions are stored. When the computer program instructions are executed by a processor, the processor is prompted to implement the steps of the method described in any one of the first aspects above.

[0038] In the present application, when the fuel cell system is shut down, according to the undervoltage protection voltage of the stack, a first target value of the low-side current is determined, wherein the low-side current is the current output from the stack to the DC-DC module, and the first target value is greater than 0A; the stack is purged according to the first target value, and the current voltage of the stack is obtained; when the current voltage is discharged to the undervoltage protection voltage, the DC-DC module is controlled to discharge the current voltage to the safe voltage of the stack, and the second target value of the low-side current is determined, wherein the second target value is 0A; the stack is purged according to the second target value. The above technical solution can prevent the voltage of the stack from being continuously in a high potential state when the fuel cell system is open-circuited and purged, thereby reducing the failure rate of the fuel cell system.

[0039] 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

[0040] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0041] Figure 1 A schematic structural diagram of a fuel cell system in one embodiment is shown;

[0042] Figure 2 A schematic flow chart of an open circuit purge method for a fuel cell system in one embodiment is shown;

[0043] Figure 3 A block diagram of a closed circuit purge device for a fuel cell system in one embodiment is shown;

[0044] Figure 4 A schematic structural diagram of a closed-circuit purge device for a fuel cell system in one embodiment is shown.

[0045] Explanation of the reference numerals: 1-air subsystem; 2-hydrogen subsystem; 3-thermal management subsystem; 4-fuel cell stack; 5-DC-DC module; 100-air filter; 101-air flow meter; 102-air compressor; 103-intercooler; 104-humidifier; 105-back pressure valve; 106-stack inlet shut-off valve; 107-stack outlet shut-off valve; 108-bypass valve; 201-hydrogen circulation pump; 202-proportional valve; 203-hydrogen inlet valve; 601-gas-liquid separator; 602-drain valve; 603-nitrogen exhaust valve; 604-mixer. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0047] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0048] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0049] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0050] It should also 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 objects used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those shown or described.

[0051] In order to make those skilled in the art better understand the present application, firstly, Figure 1 The fuel cell system involved in the present application is briefly described.

[0052] Figure 1 FIG. 2 shows a schematic diagram of the structure of a fuel cell system in one embodiment. Figure 1As shown, in some embodiments, the fuel cell system includes: an air subsystem 1, a hydrogen subsystem 2, a thermal management subsystem 3, a fuel cell stack 4 and a DC-DC module 5, etc., wherein the air subsystem 1 may include an air filter 100, an air flow meter 101, an air compressor 102, an intercooler 103, a humidifier 104, a back pressure valve 105, an inlet stop valve 106, an outlet stop valve 107 and a bypass valve 108. The air subsystem 1 opens the inlet stop valve 106, and adjusts the air entering the fuel cell stack 4 through the air compressor 102 and the back pressure valve 105. The flow rate of the anode; the hydrogen subsystem 2 may include a hydrogen circulation pump 201, a proportional valve 202 and a hydrogen inlet valve 203. The hydrogen subsystem 2 opens the hydrogen inlet valve 203, and adjusts the flow rate and pressure of hydrogen entering the anode of the stack 4 through the proportional valve 202 and the hydrogen circulation pump 201; the thermal management subsystem 3 may include a water pump 301, a temperature control valve 302, a heat dissipation device 303, etc. The thermal management subsystem 3 controls the flow direction of the coolant through the temperature control valve 302, and controls the temperature of the coolant entering and leaving the stack 4 through the water pump 301 and the heat dissipation device 303 (such as a cooling fan). The above three subsystems provide the stack with suitable temperature, oxygen and hydrogen according to the power required by the vehicle control unit. The stack 4 generates electricity through the chemical reaction of oxygen and hydrogen, and the DC-DC module 5 performs step-up and step-down processing on the current output by the stack 4 to meet the power requirements of the whole vehicle.

[0053] In the related art, when the low-side current of the DC-DC module is 0A during open-circuit purging, there will be many problems: first, because the voltage discharge of the battery stack is not considered, the voltage of the battery stack cannot be quickly discharged, and there is a high-voltage safety hazard; second, the voltage of the battery stack is continuously in a high potential state, which will damage the life of the battery stack; third, the residual air inside the fuel cell system is not consumed, and the oxygen in the battery stack continues to consume the hydrogen in the battery stack after the shutdown is completed, causing the hydrogen pressure difference to be negative, causing damage to the battery stack structure. These problems are likely to cause failures in the fuel cell system. The embodiment of the present application controls the low-side current to the first target value for purging when the battery stack is purged, and after the voltage of the battery stack is discharged to the undervoltage protection voltage, the voltage of the battery stack is discharged to a safe voltage by controlling the DC-DC module, so that the voltage of the battery stack is discharged after the fuel cell system is shut down, avoiding the voltage of the battery stack from being continuously in a high potential state, and reducing the failure rate of the fuel cell system.

[0054] Figure 2 FIG. 1 is a flow chart of an open circuit purge method for a fuel cell system in one embodiment. Figure 2 As shown, in some embodiments, an open circuit purge method for a fuel cell system can be applied to the above fuel cell system, and the method can include the following steps:

[0055] Step 201, when the fuel cell system is shut down, determine a first target value of the low-side current according to the undervoltage protection voltage of the stack, wherein the low-side current is the current output from the stack to the DC-DC module, and the first target value is greater than 0A;

[0056] Step 202, purging the fuel cell stack according to the first target value, and obtaining the current voltage of the fuel cell stack;

[0057] Step 203, when the current voltage is discharged to the undervoltage protection voltage, control the DC-DC module to discharge the current voltage to the safety voltage of the battery stack, and determine a second target value of the low-side current, wherein the second target value is 0A;

[0058] Step 204: purge the fuel cell stack according to the second target value.

[0059] It is understandable that after the fuel cell system is shut down, it is usually necessary to first perform a closed-circuit purge with a larger low-side current, and then perform an open-circuit purge with a low-side current of 0A to discharge some of the water inside the stack and control the water content of the stack within an appropriate range. In the embodiment of the present application, after the fuel cell system is shut down, the low-side current is controlled in stages during the open-circuit purge.

[0060] First, different undervoltage protection voltages and first target values ​​of low-side currents can be calibrated. Then, according to the undervoltage protection voltage of the battery stack (for example, 60V), the first target value of the corresponding low-side current is determined by looking up the table. The first target value is small but greater than 0A, for example, 10A. The battery stack is purged with the first target value to discharge the current voltage of the battery stack.

[0061] When the current voltage of the battery stack reaches the undervoltage protection voltage, the DC-DC module executes the undervoltage protection function. At this time, the second target value of the low-side current of the DC-DC module is set to 0A, the current discharge is stopped, the battery stack is purged with 0A, and the discharge relay in the DC-DC module is controlled to close to discharge the current voltage to the safe voltage of the battery stack (for example, 35V).

[0062] During the purge process, the hydrogen subsystem and the air subsystem can also be controlled synchronously.

[0063] In some embodiments, the hydrogen inlet valve, the proportional valve, the drain valve, and the nitrogen exhaust valve may be controlled to be closed to stop the hydrogen supply to the anode of the fuel cell stack.

[0064] In some embodiments, the speed of the air compressor can also be controlled according to the target purge flow of the fuel cell stack; the openings of the inlet and outlet stop valves can be controlled to reach the maximum openings; and the opening of the back pressure valve can be controlled according to the ambient temperature.

[0065] It can be understood that the target air flow rate can be set according to the target purge flow rate of the fuel cell stack. The larger the target purge flow rate, the larger the target air flow rate. The speed of the air compressor is then closed-loop controlled according to the target air flow rate.

[0066] The opening of the back pressure valve can be obtained by looking up the table according to the ambient temperature. The lower the ambient temperature, the smaller the opening of the back pressure valve. At this time, the air inlet pressure will be greater, which can increase the purge intensity.

[0067] Since the anode of the fuel cell stack stops supplying hydrogen, the hydrogen will be exhausted and the current voltage of the fuel cell stack will decrease over time. In some embodiments, the fuel cell stack purge phase can be ended when the current voltage is less than a third preset value (eg, 10V).

[0068] The embodiment of the present application determines the first target value of the low-side current according to the undervoltage protection voltage of the stack when the fuel cell system is shut down, wherein the low-side current is the current output by the stack to the DC-DC module, and the first target value is greater than 0A; the stack is purged according to the first target value, and the current voltage of the stack is obtained; when the current voltage is discharged to the undervoltage protection voltage, the DC-DC module is controlled to discharge the current voltage to the safe voltage of the stack, and the second target value of the low-side current is determined, wherein the second target value is 0A; the stack is purged according to the second target value. The above technical solution can prevent the voltage of the stack from being continuously in a high potential state when the fuel cell system is open-circuited and purged, thereby reducing the failure rate of the fuel cell system.

[0069] It should be noted that the above embodiment describes the steps of purging the fuel cell stack during open circuit purging. The purpose of the fuel cell stack purging stage is to stop the hydrogen supply to the anode, and to allow air to enter the fuel cell stack by controlling the components of the cathode to discharge part of the water in the fuel cell stack, so that the water content in the fuel cell stack is within a set range.

[0070] In addition to the stack purge stage, the open-circuit purge can also include a component purge stage and a cooling purge stage. The purpose of the component purge stage is to purge away the residual liquid water in the components of the air subsystem and the hydrogen subsystem; the purpose of the cooling purge stage is to quickly reduce the coolant inlet temperature to below 40°C by controlling the components of the thermal management subsystem, so as to liquefy the water vapor in the fuel cell system and purge away the residual liquid water in the components of the fuel cell system.

[0071] After the stack purge phase is over, the stack inlet and outlet shut-off valves are closed and the bypass valve is opened to prevent air from entering the stack. The current voltage of the stack will increase. At this time, in order to further reduce the amount of water produced when hydrogen consumes oxygen in the stack after the fuel cell system is shut down, and to shorten the duration of the high potential of the stack, a low current control strategy is adopted during the component purge phase.

[0072] In some embodiments, during the component purge stage, a third target value of the low-side current can be determined based on the current voltage; the components of the hydrogen subsystem and the air subsystem are purged according to the third target value, wherein the third target value is less than the first target value.

[0073] During the implementation process, when the current voltage is less than the first preset value, the third target value is determined to be 0A; when the current voltage is greater than the second preset value, the third target value is determined to be a value between 0A and the first target value; wherein the second preset value is greater than the first preset value.

[0074] Taking the first preset value as A1 and the second preset value as A1+10A as an example, if the current voltage is less than A1, the third target value is determined to be 0A, and if the current voltage is greater than A1+10A, the third target value is determined to be a value between 0A and the first target value (e.g., 5A) to reduce the current voltage to below A1, and if the current voltage is between A1 and A1+10A, the third target value remains unchanged. Through the design of the second preset value, frequent fluctuations of the low-side current are avoided, and the stability of the control is improved.

[0075] In some embodiments, during the component purging stage, the hydrogen inlet valve, the drain valve, and the nitrogen exhaust valve can be controlled to open; the duty cycle of the proportional valve can be controlled according to the hydrogen target pressure; and the speed of the hydrogen circulation pump can be controlled to the minimum speed. Among them, the duty cycle of the proportional valve can be obtained by closed-loop control according to the hydrogen target pressure.

[0076] In some embodiments, during the component purging stage, the speed of the air compressor can be controlled according to the ambient temperature; the inlet stop valve, outlet stop valve and back pressure valve can be controlled to be closed; and the opening of the bypass valve can be controlled to reach the maximum opening.

[0077] Among them, the speed of the air compressor can be set according to the ambient temperature. The lower the ambient temperature, the higher the possibility of residual water in the components freezing, and the purge flow needs to be increased. Therefore, the higher the target purge flow, the higher the speed of the air compressor.

[0078] It can be understood that by closing the inlet and outlet shut-off valves, air can be prevented from entering the fuel cell stack and reacting with hydrogen to produce water; by controlling the opening of the bypass valve to the maximum opening, the water and air purged from the components can be discharged.

[0079] During the component purge stage, low current control is used to blow away residual liquid water in the components. When the low current control time reaches the upper limit value, that is, the duration of the component purge stage reaches the preset duration, the fuel cell control unit can send a shutdown command to the DC-DC module to stop the low current control and end the component purge stage.

[0080] By performing low current control during the component purging stage and reducing the current voltage of the fuel cell stack to below the first preset value, the amount of water produced by subsequent hydrogen and oxygen consumption can be further reduced, while the high potential duration is shortened, thereby increasing the life of the fuel cell stack.

[0081] In some embodiments, during the cooling and purging stage, the opening of the temperature control valve can be controlled to reach the maximum opening; the speed of the water pump can be controlled to be the rated speed of the water pump; and the speed of the cooling fan can be controlled to be the rated speed of the cooling fan.

[0082] It is understandable that since the DC-DC module is turned off during the component purge stage, the current control strategy is not involved in the cooling and purge stage. By controlling the opening of the temperature control valve to the maximum opening, the cooling circuit of the thermal management subsystem can be switched to the large circulation mode, so that the temperature of the coolant entering the stack can be quickly reduced; by controlling the speed of the water pump to the rated speed of the water pump, the heat can be quickly removed through a large flow rate, so that the temperature of the coolant entering the stack can be quickly reduced; by setting the speed of the cooling fan to the rated speed, the heat dissipation speed of the cooling circuit in the large circulation mode can be accelerated.

[0083] During the cooling and purging stage, the control strategies of the air subsystem and the hydrogen subsystem are consistent with those in the component purging stage and will not be repeated here.

[0084] By controlling the components of the thermal management subsystem during the cooling and purge phase of the open-circuit purge process, the inlet temperature of the coolant is quickly reduced to a specified value, and the water vapor in the fuel cell system is liquefied before purging, thereby avoiding the freezing of condensed water in the fuel cell system due to the decrease in internal temperature of the fuel cell system, which may lead to failure in starting the fuel cell system.

[0085] The embodiment of the present application purges the components of the battery stack and the fuel cell system at different stages and at different coolant inlet temperatures, thereby improving the purge effect, removing residual liquid water in the battery stack and the components, and avoiding the occurrence of startup failure of the fuel cell system.

[0086] The following describes an apparatus embodiment of the present application, which can be used to perform the open-circuit purge method of the fuel cell system in the above-mentioned embodiment of the present application. For details not disclosed in the apparatus embodiment of the present application, please refer to the above-mentioned embodiment of the open-circuit purge method of the fuel cell system of the present application.

[0087] See also Figure 3 , shows a block diagram of an open circuit purge device of a fuel cell system in an embodiment of the present application. Figure 3As shown, the open-circuit purge device of the fuel cell system of an embodiment of the present application includes: a first current determination module 301, used to determine a first target value of a low-side current according to an undervoltage protection voltage of the battery stack when the fuel cell system is shut down, wherein the low-side current is the current output by the battery stack to the DC-DC module, and the first target value is greater than 0A; a first purge module 302, used to purge the battery stack according to the first target value, and obtain the current voltage of the battery stack; a second current determination module 303, used to control the DC-DC module to discharge the current voltage to the safe voltage of the battery stack when the current voltage is discharged to the undervoltage protection voltage, and determine the second target value of the low-side current, wherein the second target value is 0A; a second purge module 304, used to purge the battery stack according to the second target value.

[0088] In some embodiments of the present application, based on the aforementioned scheme, the open-circuit purge device of the fuel cell system also includes a hydrogen subsystem control module (not shown) for controlling the closure of the hydrogen inlet valve, the proportional valve, the drain valve and the nitrogen exhaust valve.

[0089] In some embodiments of the present application, based on the aforementioned scheme, the open-circuit purge device of the fuel cell system also includes an air subsystem control module (not shown), which is used to control the speed of the air compressor according to the target purge flow of the fuel cell stack; control the opening of the inlet shut-off valve and the outlet shut-off valve to reach the maximum opening; and control the opening of the back-pressure valve according to the ambient temperature.

[0090] In some embodiments of the present application, based on the aforementioned scheme, the open-circuit purge device of the fuel cell system also includes a component purge module (not shown), which is used to determine the third target value of the low-side current according to the current voltage; and purge the components of the hydrogen subsystem and the air subsystem according to the third target value; wherein the third target value is less than the first target value.

[0091] In some embodiments of the present application, based on the aforementioned scheme, the component purge module is also used to determine that the third target value is 0A when the current voltage is less than the first preset value; and to determine that the third target value is a value between 0A and the first target value when the current voltage is greater than the second preset value; wherein the second preset value is greater than the first preset value.

[0092] In some embodiments of the present application, based on the aforementioned scheme, the component purge module is also used to control the opening of the hydrogen inlet valve, the drain valve and the nitrogen exhaust valve; control the duty cycle of the proportional valve according to the hydrogen target pressure; and control the speed of the hydrogen circulation pump to the minimum speed.

[0093] In some embodiments of the present application, based on the aforementioned scheme, the component purge module is also used to control the speed of the air compressor according to the ambient temperature; control the closure of the inlet shut-off valve, the outlet shut-off valve and the back pressure valve; and control the opening of the bypass valve to reach the maximum opening.

[0094] In some embodiments of the present application, based on the aforementioned scheme, the open-circuit purge device of the fuel cell system also includes a cooling purge module (not shown), which is used to control the opening of the temperature control valve to reach the maximum opening; control the speed of the water pump to the rated speed of the water pump; and control the speed of the cooling fan to the rated speed of the cooling fan.

[0095] Based on the same inventive concept, the present application also provides an open circuit purge device for a fuel cell system, referring to Figure 4 , shows a schematic diagram of the structure of an open-circuit purge device of a fuel cell system in an embodiment of the present application, wherein the open-circuit purge device of the fuel cell system includes one or more memories 404, one or more processors 402, and at least one computer program (computer program instruction) stored in the memory 404 and executable on the processor 402, and the processor 402 implements the method described above when executing the computer program.

[0096] Among them, Figure 4 In the embodiment of the present invention, a bus architecture (represented by bus 400) is shown, which may include any number of interconnected buses and bridges, and bus 400 links various circuits including one or more processors represented by processor 402 and memory represented by memory 404. Bus 400 may also link various other circuits such as peripherals, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. Bus interface 405 provides an interface between bus 400 and receiver 401 and transmitter 403. Receiver 401 and transmitter 403 may be the same element, namely a transceiver, providing a unit for communicating with various other devices over a transmission medium. Processor 402 is responsible for managing bus 400 and general processing, while memory 404 may be used to store data used by processor 402 when performing operations.

[0097] Based on the same inventive concept, an embodiment of the present application provides a computer-readable storage medium, in which computer program instructions are stored. When the computer program instructions are executed by a processor, the processor is prompted to implement the steps of the method as described above.

[0098] Based on the same inventive concept, an embodiment of the present application provides a computer program product, including a computer program. When the computer program product is executed by a processor, it prompts the processor to implement the steps of the method as described above.

[0099] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored as one or more instructions or codes on a computer-readable medium or transmitted via a computer-readable medium. Other examples and implementations are within the scope and spirit of the present application and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hard wiring, or a combination of any of these. In addition, each functional unit may be integrated into a processing unit, each unit may exist physically separately, or two or more units may be integrated into one unit.

[0100] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, 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 units or modules, which can be electrical or other forms.

[0101] The units described as separate components may or may not be physically separated, and the components of the control device may or may not be physical units, that is, they may be located in one place or distributed in multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0102] 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 computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly or all or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, disk or optical disk, etc., which can store computer program instructions.

[0103] The above description is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of the claims of the present application.

Claims

1. An open circuit purge method for a fuel cell system, characterized in that: The fuel cell system includes a fuel cell stack and a DC-DC module connected to each other, and the method includes: When the fuel cell system is shut down, determining a first target value of a low-side current according to an undervoltage protection voltage of the fuel cell stack, wherein the low-side current is a current output from the fuel cell stack to the DC-DC module, and the first target value is greater than 0A; Purging the fuel cell stack according to the first target value, and acquiring a current voltage of the fuel cell stack; When the current voltage is discharged to the undervoltage protection voltage, controlling the DC-DC module to discharge the current voltage to the safety voltage of the battery stack, and determining a second target value of the low-side current, wherein the second target value is 0A; The fuel cell stack is purged according to the second target value.

2. The open circuit purge method of a fuel cell system according to claim 1, characterized in that: The fuel cell system further includes a hydrogen subsystem, the hydrogen subsystem including a hydrogen inlet valve, a proportional valve, a drain valve and a nitrogen exhaust valve, and the method further includes: The hydrogen inlet valve, the proportional valve, the drain valve and the nitrogen exhaust valve are controlled to be closed.

3. The open circuit purge method of a fuel cell system according to claim 2, characterized in that: The fuel cell system further includes an air subsystem, the air subsystem including an air compressor, a stack inlet shut-off valve, a stack outlet shut-off valve and a back pressure valve, and the method further includes: controlling the speed of the air compressor according to the target purge flow rate of the fuel cell stack; Controlling the openings of the stack inlet stop valve and the stack outlet stop valve to reach maximum openings; The opening of the back pressure valve is controlled according to the ambient temperature.

4. The open circuit purge method of a fuel cell system according to claim 1, characterized in that: The fuel cell system further includes a hydrogen subsystem and an air subsystem. After purging the fuel cell stack according to the second target value, the method further includes: Determining a third target value of the low-side current according to the current voltage; wherein the third target value is less than the first target value; The components of the hydrogen subsystem and the air subsystem are purged according to the third target value.

5. The open circuit purge method of a fuel cell system according to claim 4, characterized in that: Determining a third target value of the low-side current according to the current voltage includes: When the current voltage is less than the first preset value, determining the third target value to be 0A; When the current voltage is greater than a second preset value, the third target value is determined to be a value between 0A and the first target value; wherein the second preset value is greater than the first preset value.

6. The open circuit purge method of a fuel cell system according to claim 4, characterized in that: The hydrogen subsystem includes a hydrogen inlet valve, a proportional valve, a drain valve, a nitrogen drain valve and a hydrogen circulation pump, and the method further includes: Controlling the hydrogen inlet valve, the water discharge valve and the nitrogen discharge valve to open; controlling the duty cycle of the proportional valve according to the target pressure of hydrogen; The rotation speed of the hydrogen circulation pump is controlled to be the minimum rotation speed.

7. The open circuit purge method of a fuel cell system according to claim 4, characterized in that: The air subsystem includes an air compressor, a stack inlet stop valve, a stack outlet stop valve, a back pressure valve and a bypass valve, and the method further includes: controlling the speed of the air compressor according to the ambient temperature; Controlling the stack inlet stop valve, the stack outlet stop valve and the back pressure valve to close; The opening of the bypass valve is controlled to reach a maximum opening.

8. The open circuit purge method of a fuel cell system according to claim 4, characterized in that: The fuel cell system includes a thermal management subsystem, and the thermal management subsystem includes a temperature control valve, a water pump, and a cooling fan. After purging the components of the hydrogen subsystem and the air subsystem according to the third target value, the method further includes: Controlling the opening of the temperature control valve to reach a maximum opening; Controlling the rotation speed of the water pump to be the rated rotation speed of the water pump; The rotation speed of the cooling fan is controlled to be the rated rotation speed of the cooling fan.

9. An open circuit purge device for a fuel cell system, comprising a processor and a memory, characterized in that: The memory stores computer program instructions that can be executed by the processor, and when the processor executes the computer program instructions, the steps of the method according to any one of claims 1 to 8 are implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer program instructions, which, when executed by a processor, prompt the processor to implement the steps of the method according to any one of claims 1 to 8.

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