Fuel cell system and control method and control device therefor

Abstract

The present application relates to the technical field of fuel cell, and provides a fuel cell system and a control method and a control device thereof. The control method comprises the following steps: after receiving a start request, determining a start mode of the fuel cell system, and sending a corresponding start command; when the start command is a cold start command, starting a cooling liquid pump and a cooling liquid heater in a cooling module, making the cooling liquid flow through a stack and a hydrogen circulation pump, and starting a hydrogen module and an air module to supply hydrogen and air to the stack; starting a load of the stack according to a preset load current, and adjusting the load current of the stack according to a minimum voltage of a single cell in the stack during the load process, so that the stack does not occur single low; when the cooling liquid temperature in the cooling module is greater than a first preset temperature threshold, the system cold start is completed, and a normal working process is entered. The present application can reduce the possibility of single low of the stack during the cold start process, and can improve the use quality of the fuel cell system.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a fuel cell system and its control method and control device. Background Technology

[0002] As a clean energy source with zero emissions and no pollution, fuel cells have become an important energy supply method in the automotive industry, shipbuilding industry, power generation, and aerospace industry.

[0003] Currently, achieving reliable cold start at low temperatures is one of the key technical indicators for fuel cell systems. To avoid single-low-temperature failures of the fuel cell stack during cold start due to icing of the stack or hydrogen circulation pump at low temperatures, traditional designs typically increase the shutdown purging time, flow rate, and pressure of the fuel cell system to ensure that the stack and hydrogen circulation pump remain dry and reduce the possibility of icing during cold start.

[0004] However, simply optimizing the purging strategy during fuel cell system shutdown is still insufficient to effectively prevent the stack or hydrogen circulation pump from freezing during cold starts, thus avoiding cold start failures. Furthermore, increasing the purging time, flow rate, and pressure during fuel cell system shutdown will also increase system hydrogen and energy consumption, prolong shutdown waiting time, and thus hinder the improvement of fuel cell performance. Summary of the Invention

[0005] In view of this, the present invention aims to propose a control method for a fuel cell system to improve the performance of the fuel cell system.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A control method for a fuel cell system, the control method comprising:

[0008] After receiving a start-up request, the fuel cell system determines the start-up mode of the fuel cell system and sends the corresponding start-up command.

[0009] When the start command is a cold start command, the coolant pump and coolant heater in the cooling module of the fuel cell system are turned on, so that the coolant flows through the stack and the hydrogen circulation pump, and the hydrogen module and air module of the fuel cell system are turned on to supply hydrogen and air to the stack.

[0010] The stack is started to load according to the preset load current, and during the load-loading process, the load current of the stack is adjusted according to the minimum voltage of a single cell in the stack to prevent the stack from experiencing a single low voltage.

[0011] When the temperature of the coolant in the cooling module is greater than a first preset temperature threshold, the fuel cell system completes its cold start and enters normal operation.

[0012] Wherein, "single low" means that the minimum voltage of a single cell in the stack is less than a preset voltage threshold.

[0013] Furthermore, determining the start-up mode of the fuel cell system after receiving a start-up request includes:

[0014] After the fuel cell system receives a power-on request, it acquires the ambient temperature.

[0015] When the ambient temperature is lower than the second preset temperature threshold, the start-up module of the fuel cell system is determined to be in cold start mode.

[0016] Wherein, the second preset temperature threshold is not greater than the first preset temperature threshold.

[0017] Furthermore, when the cooling module is turned on, the coolant heater operates at maximum heating power, and the cooling module operates in a small circulation mode in which the coolant does not pass through the coolant radiator.

[0018] Furthermore, the activation of the hydrogen module includes activating the hydrogen injection valve, sending a preset activation command to the hydrogen circulation pump, and causing the drain valve and nitrogen discharge valve to operate at a preset activation frequency.

[0019] Furthermore, the preset load current is set according to the start-up time requirement t of the fuel cell system, the total heat capacity Q of the fuel cell system, the heating power W1 of the coolant heater, and the heat generation power W2 of the stack corresponding to different load currents.

[0020] The startup time requirement t, the total system heat capacity Q, the heating power W1, and the heat generation power W2 satisfy the condition t = Q / (W1 + W2).

[0021] Furthermore, adjusting the load current of the fuel cell stack according to the minimum voltage of a single cell in the stack during the load-pull process includes:

[0022] During the loading process of the fuel cell stack, the minimum voltage of each individual cell in the fuel cell stack is continuously acquired;

[0023] Based on the obtained minimum voltage, the loading and unloading rate of the fuel cell stack load current is determined by a preset relationship, and the load current of the fuel cell stack is adjusted according to the determined loading and unloading rate.

[0024] The preset relationship is a calibrated relationship between the minimum voltage of a single cell in the fuel cell stack and the loading / unloading rate of the stack load current during cold start of the fuel cell system.

[0025] Furthermore, the relationship between the minimum voltage of a single cell in the stack and the loading / unloading rate of the stack's load current is expressed as s = kv + a;

[0026] Where s is the loading and unloading rate of the stack's load current, v is the minimum voltage of a single cell in the stack, and k and a are preset constant values.

[0027] Furthermore, after the fuel cell system has completed its cold start and entered normal operation, the control method further includes:

[0028] Obtain the temperature of the coolant in the cooling module;

[0029] When the temperature of the coolant is greater than the third preset temperature threshold, the cooling module is made to operate in a large circulation mode where the coolant passes through the coolant radiator.

[0030] The third preset temperature threshold is greater than the first preset temperature threshold.

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

[0032] The control method for the fuel cell system described in this invention, during cold start of the fuel cell system, involves activating the coolant heater to heat the coolant and initiating load loading of the stack according to a preset load current. During the load loading process, the load current of the stack is adjusted based on the minimum voltage of each individual cell, preventing single-cell low voltage. This dynamic load loading strategy during cold start not only avoids single-cell low voltage caused by conditions such as icing of the stack or hydrogen circulation pump, increasing the reliability of cold start, but also helps to avoid problems such as increased hydrogen and energy consumption and prolonged shutdown waiting time caused by increasing the system shutdown purging time, flow rate, and pressure. This is beneficial to improving the quality of fuel cell use.

[0033] Another object of the present invention is to provide a control device for a fuel cell system, which includes a determining module, a first control module, a second control module and a third control module;

[0034] The determining module is used to determine the start-up mode of the fuel cell system after the fuel cell system receives a start-up request, and send the corresponding start-up command.

[0035] The first control module is used to control the coolant pump and coolant heater in the cooling module of the fuel cell system to turn on when the start command is a cold start command, so that the coolant flows through the stack and the hydrogen circulation pump, and to control the hydrogen module and air module of the fuel cell system to turn on so as to supply hydrogen and air to the stack.

[0036] The second control module is used to start the load-bearing process of the fuel cell stack according to the preset load-bearing current, and adjust the load-bearing current of the fuel cell stack according to the minimum voltage of a single cell in the fuel cell stack during the load-bearing process, so as to prevent the fuel cell stack from experiencing a single low voltage.

[0037] The third control module is used to control the fuel cell system to complete a cold start and enable the fuel cell system to enter normal operation when the coolant temperature in the cooling module is greater than a first preset temperature threshold.

[0038] In addition, the present invention also provides a fuel cell system, wherein the fuel cell system is provided with a memory and a processor;

[0039] The memory stores computer-readable instructions, which, when executed by the processor, implement the control method for the fuel cell system as described above.

[0040] The control device and fuel cell system of the fuel cell system described in this invention have the same beneficial effects as the control method of the fuel cell system described above compared with the prior art, and will not be repeated here. Attached Figure Description

[0041] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0042] Figure 1 This is a schematic diagram of the fuel cell system described in an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the structure of some modules of the fuel cell system described in an embodiment of the present invention;

[0044] Figure 3 This is a flowchart of the control method for the fuel cell system described in an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram illustrating the operation of the cooling module in small circulation mode according to an embodiment of the present invention;

[0046] Figure 5 This is a schematic diagram of the large-circulation mode operation of the cooling module according to an embodiment of the present invention;

[0047] Figure 6 This is a schematic diagram of the control device of the fuel cell system according to an embodiment of the present invention;

[0048] Figure 7 This is a schematic diagram of the memory and processor in the fuel cell system described in an embodiment of the present invention;

[0049] Explanation of reference numerals in the attached figures:

[0050] 1. Fuel cell stack; 2. Hydrogen injection valve; 3. Gas-liquid separator; 4. Hydrogen circulation pump; 5. Drain valve; 6. Nitrogen purging valve; 7. Anode inlet temperature sensor; 8. Anode outlet temperature sensor; 9. Coolant pump; 10. Coolant radiator; 11. Thermostat; 12. Coolant heater; 13. Coolant inlet temperature sensor; 14. Coolant outlet temperature sensor;

[0051] 100. Cooling module; 200. Hydrogen module; 300. Air module; 400. Control module; 500. Exhaust module; 600. Determination module; 700. First control module; 800. Second control module; 900. Third control module;

[0052] 101. Stack cooling circuit; 102. Hydrogen pump cooling circuit; 401. Memory; 402. Processor. Detailed Implementation

[0053] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0054] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0055] In the description of this invention, it should be noted that the use of terms such as "upper," "lower," "inner," and "outer," indicating orientation or positional relationship, is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing the invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the use of terms such as "first" and "second" is also for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0056] Furthermore, in the description of this invention, unless otherwise explicitly specified, the connecting structures between mating components can be conventional in the art. Moreover, the terms "installation," "connection," "joining," and "connector" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0057] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0058] Example 1

[0059] This embodiment relates to a control method for a fuel cell system. The control method mainly involves optimizing the cold start strategy of the fuel cell system. During the cold start process, it can avoid the fuel cell stack 1 from becoming cold due to conditions such as icing or hydrogen circulation pump 4, thereby increasing the reliability of the fuel cell system during cold start and helping to improve the quality of use of the fuel cell system.

[0060] Specifically, for the fuel cell system in this embodiment, combined with Figure 1 and Figure 2 As shown, in terms of structure, it is similar to the existing proton exchange membrane fuel cell (PEMFC). It mainly includes a stack 1, and a cooling module 100, a hydrogen module 200, an air module 300, a control module 400, and an exhaust module 500 arranged mainly around the stack 1.

[0061] The fuel cell stack 1 generates electrical energy through the electrochemical reaction of fuel (hydrogen) and oxidant (oxygen) and outputs it externally. The cooling module 100 is used to supply coolant to the fuel cell stack 1 and other components that require cooling or heating, such as the hydrogen circulation pump 4, to prevent their temperatures from being too high or too low, which would affect the normal operation of the system. For example, during the low-temperature cold start of the fuel cell system, the module heats the components that need to be heated to speed up the cold start process of the system.

[0062] The cooling module 100 typically includes components such as a coolant circulation pump 9, a coolant radiator 10, a coolant heater 12, and a thermostat 11. Taking the cooling or heating of the fuel cell stack 1 and the hydrogen circulation pump 4 as an example, the cooling module 100 includes a fuel cell stack cooling circuit 101 and a hydrogen pump cooling circuit 102. Both the fuel cell stack cooling circuit 101 and the hydrogen pump cooling circuit 102 are connected in parallel within the overall circuit of the cooling module 100. The fuel cell stack cooling circuit 101 is used for cooling or heating the fuel cell stack 1, and the hydrogen pump cooling circuit 102 is used for cooling or heating the hydrogen circulation pump 4.

[0063] The aforementioned coolant circulation pump 9 drives the coolant flow, the coolant radiator 10 dissipates heat from the coolant into the environment to cool it down, the coolant heater 12 heats the coolant, and the thermostat 11 acts as a multi-way valve to control the flow direction and flow rate of the coolant in different directions, thereby enabling the operation of the large and small circulation modules of the cooling module 100. Furthermore, a coolant inlet temperature sensor 13 and a coolant outlet temperature sensor 14 are typically installed on the fuel cell stack cooling circuit 101 to detect the coolant inlet temperature and outlet temperature at the fuel cell stack 1, respectively.

[0064] The hydrogen module 200 is used to deliver hydrogen from the hydrogen source to the anode of the fuel cell stack 1. It generally includes a hydrogen injection valve 2, a gas-liquid separator 3, a hydrogen circulation pump 4, a drain valve 5, and a nitrogen venting valve 6. The hydrogen injection valve 2 is used to control the on / off of the hydrogen source and can also adjust the hydrogen supply. The gas-liquid separator 3 is used to separate moisture from the mixed gas discharged from the anode of the fuel cell stack 1. The hydrogen circulation pump 4 is used to reintroduce the hydrogen discharged from the anode of the fuel cell stack 1 into the anode of the fuel cell stack 1 to achieve the recycling of anode hydrogen. An ejector is generally also installed between the hydrogen circulation pump 4 and the inlet of the anode of the fuel cell stack 1.

[0065] The drain valve 5 is mainly used to drain the water separated by the gas-liquid separator 3, and the nitrogen vent valve 6 is mainly used to drain the nitrogen gas present in the anode of the fuel cell stack 1. In addition, in the hydrogen module 200, an anode inlet temperature sensor 7 and an anode outlet temperature sensor 8 are usually installed at the inlet and outlet of the anode of the fuel cell stack 1, respectively, to detect the inlet and outlet temperatures of the anode of the fuel cell stack 1.

[0066] The air module 300 is used to supply air to the cathode of the fuel cell stack 1, and it generally includes an air compressor, an intercooler, a humidifier, and multiple control valves. The control module 400 is used to control the overall operation of the fuel cell system according to preset control commands. In addition to the controller (e.g., fuel cell controller FCU) that can be installed in the system, the control module 400 also typically includes many detection and sensing components installed in the fuel cell system. These detection and sensing components, together with the corresponding controller, realize the operation control of the fuel cell system.

[0067] The exhaust module 500 is mainly used for the discharge of various exhaust gases from the fuel cell system. These exhaust gases include, for example, the exhaust gas generated by the hydrogen module 200 during anode purging of the fuel cell stack 1, the exhaust gas generated by the air module 300 during normal operation, and the exhaust gas generated during cathode purging or housing purging of the fuel cell stack 1. Furthermore, on the anode side of the fuel cell stack 1, i.e., in the hydrogen module 200, the drain valve 5 and nitrogen purging valve 6 are generally also connected to the exhaust module 500.

[0068] It should be pointed out that, Figure 1 and Figure 2 This example only provides a simple configuration of a fuel cell system for the purpose of describing the control method in this embodiment. In actual implementation, the above components, such as the fuel cell stack 1, cooling module 100, hydrogen module 200, air module 300, control module 400, and exhaust module 500, can be referred to the relevant structures in existing fuel cell systems, except for those specifically described in this embodiment. They will not be described again here.

[0069] Based on the above introduction to fuel cell systems, in the existing technology, when the fuel cell system is started up, especially during a cold start at low temperatures, in order to avoid a single low-temperature fault in the fuel cell stack 1 or hydrogen circulation pump 4 due to freezing at low temperatures, the traditional control strategy is usually to increase the shutdown purging time, flow rate, and pressure of the fuel cell system to ensure that the fuel cell stack 1 and hydrogen circulation pump 4 are as dry as possible, thereby reducing the possibility of freezing of the fuel cell stack 1 and hydrogen circulation pump 4 during a cold start.

[0070] However, the traditional methods described above, which only optimize the purging strategy when the fuel cell system is shut down, are still insufficient to effectively prevent the stack 1 or hydrogen circulation pump 4 from freezing during cold starts, thus avoiding cold start failures. Furthermore, increasing the purging time, flow rate, and pressure of the fuel cell system during shutdown also increases system hydrogen and energy consumption, and prolongs the system shutdown waiting time.

[0071] In view of this, in order to overcome the shortcomings of existing technologies and to improve the reliability of cold start of fuel cell systems, the overall design combines... Figure 3 As shown, the control method of the fuel cell system in this embodiment includes the following steps.

[0072] Step s01: After receiving the start-up request, the fuel cell system determines the start-up mode of the fuel cell system and sends the corresponding start-up command.

[0073] In step s01, taking the fuel cell system of this embodiment as an example mounted on a vehicle, the above-mentioned power-on request is generally issued by the vehicle controller or the like in the vehicle and received by the control module 400 of the fuel cell system.

[0074] After the fuel cell system receives the start-up request, the process of determining the start-up mode of the fuel cell system and sending the corresponding start-up command, as an example, may include obtaining the ambient temperature after the fuel cell system receives the start-up request, and determining that the start-up module of the fuel cell system is in cold start mode when the ambient temperature is less than a second preset temperature threshold.

[0075] In specific implementation, the second preset temperature threshold can be set by those skilled in the art according to the actual design requirements of the fuel cell system, and this invention does not limit it. Furthermore, as an example, the second preset temperature threshold can be 0°C, or a temperature value less than 0°C such as -1°C, -2°C, or -3°C.

[0076] In addition to determining the start-up module of the fuel cell system to be in cold start mode when the ambient temperature is lower than the second preset temperature threshold (such as 0°C), it should be noted that in actual implementation, when the ambient temperature is other values, such as not lower than the second preset temperature threshold, the start-up module of the fuel cell system can be determined to be in normal start-up mode.

[0077] Meanwhile, in addition to obtaining the ambient temperature to determine the start-up module of the fuel cell system, in specific implementations, the start-up module of the fuel cell system can also be determined based on other operating conditions, such as the temperature of the coolant in the cooling module 100. This embodiment does not impose any restrictions on this.

[0078] Step s02: When the start command is a cold start command, turn on the coolant pump 9 and coolant heater 12 in the cooling module 100 of the fuel cell system, so that the coolant flows through the stack 1 and the hydrogen circulation pump 4, and turn on the hydrogen module 200 and air module 300 of the fuel cell system to supply hydrogen and air to the stack 1.

[0079] In step s02, when the start-up mode of the fuel cell system is determined to be cold start mode, the control module 400 of the fuel cell system, and generally specifically the fuel cell controller FCU, sends corresponding cold start commands to each module of the system.

[0080] In a preferred embodiment, when the coolant pump 9 and coolant heater 12 in the cooling module 100 are activated to allow coolant to flow through the fuel cell stack 1 and the hydrogen circulation pump 4, the following combination is used: Figure 4 As shown, the coolant heater 12 can generally operate at maximum heating power, and the cooling module 100 also operates in a small circulation mode where the coolant does not pass through the coolant radiator 10.

[0081] In this way, by operating the coolant heater 12 at maximum heating power (i.e., full power), the coolant temperature can be rapidly increased, thereby quickly heating the fuel cell stack 1 and the hydrogen circulation pump 4, increasing the success rate of cold start of the fuel cell system. Furthermore, by operating the cooling module 100 in a small circulation mode, the coolant does not pass through the coolant radiator 10, preventing heat loss and also promoting rapid cooling of the coolant for better heating of the fuel cell stack 1 and the hydrogen circulation pump 4.

[0082] In this embodiment, the opening of the hydrogen module 200 and air module 300 of the fuel cell system generally includes opening the hydrogen injection valve 2, sending a preset opening command to the hydrogen circulation pump 4, and making the drain valve 5 and nitrogen discharge valve 6 work at a preset opening frequency.

[0083] In practice, the opening degree of hydrogen injection valve 2, the speed of hydrogen circulation pump 4, and the preset opening frequency of drain valve 5 and nitrogen discharge valve 6 can all be executed according to the relevant control methods preset in the fuel cell system.

[0084] Furthermore, it is worth noting that since the hydrogen circulation pump 4 may freeze during a cold start of the fuel cell system at low temperatures, the control module 400 only needs to send the corresponding start command to the hydrogen circulation pump 4 when the hydrogen module 200 is turned on, without needing to consider whether the hydrogen circulation pump 4 is frozen. Additionally, as an example, the preset opening frequencies of the drain valve 5 and the nitrogen venting valve 6 could be, for example, a 1-second open-5-second close for the drain valve 5, and a 0.1-second open-2-second close for the nitrogen venting valve 6.

[0085] The opening of the air module 300 generally involves the opening of the air compressor and the opening and closing control of the various control valves on the air supply and exhaust pipelines in the air module 300. For details, please refer to the air inlet control method during cold start of existing fuel cell systems, which will not be elaborated here.

[0086] Step s03: Start loading the fuel cell stack 1 according to the preset load current, and adjust the load current of the fuel cell stack 1 according to the minimum voltage of a single cell in the fuel cell stack 1 during the loading process, so as to prevent the fuel cell stack 1 from experiencing a single low voltage.

[0087] In step s03, as an example, the aforementioned preset load current can typically be set based on the start-up time requirement t of the fuel cell system, the total system heat capacity Q of the fuel cell system, the heating power W1 of the coolant heater 12, and the heat generation power W2 of the stack 1 corresponding to different load currents. Moreover, the above start-up time requirement t, total system heat capacity Q, heating power W1, and heat generation power W2 satisfy the following relationship: t = Q / (W1 + W2).

[0088] It should be noted that since the heating power W1 of the coolant heater 12 is generally fixed and varies little, the above-mentioned preset load current is mainly related to the start-up time of the fuel cell system. That is, the larger the load current of the stack 1, the more heat is generated in the stack 1 during the load-up process, and the shorter the system start-up time.

[0089] Furthermore, the total system heat capacity Q generally includes the heat capacity of all components of the fuel cell system, as well as the heat capacity of the coolant in the cooling module 100, and the total system heat capacity Q is usually determined during the development and design of the fuel cell system. The heat generation power W2 of the stack 1 corresponding to the different load currents mentioned above can also generally be determined during the development and design of the fuel cell system, or obtained through bench tests or other methods.

[0090] Therefore, based on the start-up time requirement t of the fuel cell system, the total heat capacity Q of the fuel cell system, and the heating power W1 of the coolant heater 12 (generally at full power during cold start), the heat generation power W2 of the fuel cell stack 1 can be obtained through the above relationship, and the preset load current can be determined based on the obtained heat generation power W2. The obtained preset load current is used as a setting parameter in the control module 400 of the fuel cell system, and the load-bearing process of the fuel cell stack 1 can be started according to the preset load current.

[0091] In this embodiment, regarding the adjustment of the load current of the fuel cell stack 1 based on the minimum voltage of a single cell in the fuel cell stack 1 during the load-bearing process, the main principle is that when the minimum voltage of a single cell in the fuel cell stack 1 is relatively stable, such as when the minimum voltage varies between ±0.02V, the load current is increased; and when the minimum voltage of a single cell in the fuel cell stack 1 exceeds the above range and decreases, the load current is decreased.

[0092] In a specific implementation, as a preferred embodiment, the loading current of the fuel cell stack 1 is adjusted according to the minimum voltage of a single cell in the fuel cell stack 1 during the loading process. For example, this may include continuously acquiring the minimum voltage of a single cell in the fuel cell stack 1 during the loading process, then determining the loading rate of the fuel cell stack 1 based on the acquired minimum voltage through a preset relationship, and adjusting the loading current of the fuel cell stack 1 according to the determined loading rate.

[0093] It is worth noting that, in practice, a voltage monitor installed in the fuel cell system can be used to detect the voltage of each cell in the stack 1 and obtain the minimum voltage of each cell.

[0094] Furthermore, as an example, the aforementioned preset relationship can generally be obtained through calibration, based on the correspondence between the minimum voltage of a single cell in stack 1 and the loading / unloading rate of the stack 1's load current during cold start of the fuel cell system. Moreover, the aforementioned relationship between the minimum voltage of a single cell in stack 1 and the loading / unloading rate of the stack 1's load current can be, for example, s = kv + a.

[0095] In the above relationship, s is the loading and unloading rate of the load current of stack 1, v is the minimum voltage of a single cell in stack 1, and k and a are preset constant values. k and a are obtained through calibration and usually vary depending on the fuel cell system.

[0096] It is worth noting that, in specific implementation, given that the minimum voltage of a single cell and the loading / unloading rate of the stack 1 load current can be considered to have a linear relationship, as an example, the calibration of the preset relationship mentioned above can be achieved by setting the fuel cell system on a test bench, and then starting the load test of stack 1 at a certain loading rate under a preset load current and a certain minimum voltage of a single cell. During the test, it is observed whether stack 1 will experience a single low voltage. If a single low voltage occurs, the loading rate is reduced until stack 1 does not experience a single low voltage, so as to obtain the loading / unloading rate of the load current that will not cause a single low voltage in stack 1 corresponding to the minimum voltage.

[0097] Through multiple bench tests, multiple sets of minimum voltages and their corresponding load current loading and unloading rates are obtained. The above-mentioned relationship can be obtained by fitting the obtained data, and the constant values ​​k and a in the relationship can be obtained from this.

[0098] It should be noted that, in addition to obtaining the above relationships based on bench tests and the data obtained from the tests, another feasible implementation method is to obtain a corresponding data table based on multiple sets of minimum voltages and their corresponding load current loading and unloading rates obtained from the tests. Then, the load current loading and unloading rate corresponding to a certain minimum voltage can be obtained by looking up the table. Furthermore, for data not shown in the table, it can be obtained by interpolation based on the data in the table.

[0099] One example of the above data table is shown in Table 1 below.

[0100] Table 1. Minimum Voltage and Load Current Loading / Unloading Rate Data

[0101] Minimum voltage (V) 0 0.2 0.4 0.6 …… Loading / unloading rate (A / s) -40 -20 0 +20 ……

[0102] Through step s03 above, the load current of fuel cell stack 1 is dynamically adjusted based on the continuously monitored minimum voltage of each individual cell. This embodiment ensures that fuel cell stack 1 will not experience a single low voltage during the load-bearing process, meaning that the minimum voltage of each individual cell in fuel cell stack 1 will not fall below a preset voltage threshold. This preset voltage threshold can be, for example, 0V, 0.1V, or 0.2V, and is typically 0V. Simultaneously, when the minimum voltage of each individual cell in fuel cell stack 1 is high, this embodiment can also dynamically increase the load current of fuel cell stack 1, allowing it to generate heat quickly and thus reducing the cold start time of the fuel cell system.

[0103] Step s04: When the temperature of the coolant in the cooling module 100 is greater than the first preset temperature threshold, the fuel cell system completes the cold start and enters the normal operation process.

[0104] In step s04, as the coolant heater 12 heats the coolant, especially the heat generated by the stack 1 during the loading process, the temperature of the coolant in the cooling module 100 continues to increase. When the coolant temperature is greater than the first preset temperature threshold, it can be regarded as a cold start of the fuel cell system.

[0105] If the hydrogen circulation pump 4 freezes before startup, it can generally operate normally under the control command received, thanks to the heating of the coolant. The fuel cell stack 1 can also generally respond normally to load demands and increase power. Meanwhile, after the fuel cell system completes its cold start, the coolant heater 12 can be turned off to reduce energy consumption, and the heat generated by the fuel cell stack 1 during load handling can be used to continue warming the coolant.

[0106] After the cold start is completed, the fuel cell system enters the normal operation process and can adjust the power of stack 1 according to the received power demand in order to output electrical energy.

[0107] In practical implementation, it is worth noting that the aforementioned second preset temperature threshold is generally not greater than the first preset temperature threshold. Furthermore, those skilled in the art can set the aforementioned first preset temperature threshold according to the specific design requirements of the fuel cell system, and this invention does not limit this setting. As an example, the aforementioned first preset temperature threshold can also be 0°C, or it can be a temperature value greater than 0°C, such as 1°C, 2°C, 3°C, or 5°C.

[0108] Furthermore, after the fuel cell system has completed its cold start and entered normal operation, as a preferred implementation, it is combined with... Figure 5As shown, the control method of this embodiment may further include, for example, acquiring the temperature of the coolant in the cooling module 100, and when the temperature of the coolant is greater than a third preset temperature threshold, causing the cooling module 100 to operate in a large circulation mode of the coolant passing through the coolant radiator 10.

[0109] At this time, when the temperature of the coolant exceeds the third preset temperature threshold, the cooling module 100 adopts a large circulation mode to dissipate heat from the coolant, so that the coolant is kept at a suitable temperature, thereby effectively cooling the fuel cell stack 1 and avoiding adverse effects on the operation of the fuel cell stack 1 due to overheating.

[0110] In a specific implementation, as a feasible approach, the coolant temperature can be detected by using a coolant inlet temperature sensor 13 and a coolant outlet temperature sensor 14 located at the coolant inlet and outlet of the fuel cell stack 1. The average value of the sum of the temperature values ​​detected by the coolant inlet temperature sensor 13 and the coolant outlet temperature sensor 14 is the coolant temperature required in this embodiment.

[0111] Regarding the aforementioned third preset temperature threshold, which is greater than the aforementioned first preset temperature threshold, those skilled in the art can set it according to the specific design requirements of the fuel cell system during specific implementation; this invention does not impose any limitations. Furthermore, as an example, the aforementioned third preset temperature threshold could be, for example, a temperature value such as 55℃, 60℃, or 65℃.

[0112] The control method of the fuel cell system in this embodiment adopts the above design. During the cold start of the fuel cell system, the coolant heater 12 is turned on to heat the coolant, and the stack 1 is started to load according to the preset load current. During the load-loading process, the load current of the stack 1 is adjusted according to the minimum voltage of the single cell in the stack 1, so that the stack 1 does not experience a single low voltage. By using the dynamic load-loading strategy during the cold start process, the single low voltage of the stack 1 due to icing of the stack 1 or the hydrogen circulation pump 4 can be avoided, which can increase the reliability of the cold start. At the same time, it also helps to avoid the problems of increased system hydrogen consumption and energy consumption and prolonged shutdown waiting time caused by increasing the system shutdown purging time, flow rate and pressure, which is conducive to improving the quality of fuel cell use.

[0113] Example 2

[0114] This embodiment relates to a control device for a fuel cell system. This control device is based on the control method described in Embodiment 1, and combines... Figure 6 As shown, the control device includes a determination module 600, a first control module 700, a second control module 800, and a third control module 900.

[0115] The aforementioned determining module 600 is used to determine the start-up mode of the fuel cell system after receiving a start-up request, and send the corresponding start-up command. The aforementioned first control module 700 is used to control the coolant pump 9 and coolant heater 12 in the cooling module 100 of the fuel cell system to turn on when the start-up command is a cold start command, so that coolant flows through the fuel cell stack 1 and the hydrogen circulation pump 4, and to control the hydrogen module 200 and air module 300 of the fuel cell system to turn on, so as to supply hydrogen and air to the fuel cell stack 1.

[0116] The second control module 800 is used to initiate the load-bearing process of the fuel cell stack 1 according to a preset load-bearing current, and to adjust the load-bearing current of the fuel cell stack 1 according to the minimum voltage of a single cell in the fuel cell stack 1 during the load-bearing process, so as to prevent the fuel cell stack 1 from experiencing a single low voltage. The third control module is used to control the fuel cell system to complete the cold start and enter the normal operation process when the coolant temperature in the cooling module 100 is higher than the first preset temperature threshold.

[0117] Specifically, in this embodiment, the determination of the start-up mode of the fuel cell system, the control of the coolant pump 9 and coolant heater 12 in the cooling module 100, the control of the start-up of the hydrogen module 200 and the air module 300, and the adjustment of the load current of the fuel cell stack 1 according to the minimum voltage of a single cell in the fuel cell stack 1 during the load-bearing process can all be found in the relevant descriptions in Embodiment 1.

[0118] Furthermore, in the specific implementation of the control device of this embodiment, the above-mentioned modules can be existing module products with data transmission, storage or computing functions. At the same time, the above-mentioned modules in this embodiment can be set up separately, or preferably, they can be integrated into the controller of the fuel cell system.

[0119] In practical applications, the control process of the fuel cell system during startup, especially during cold start, can still be referred to the relevant description in Embodiment 1, and will not be repeated here.

[0120] The control device of the fuel cell system in this embodiment implements the control method in Embodiment 1. On the one hand, by utilizing the dynamic load-bearing strategy during the cold start process, it can avoid the situation where the fuel cell stack 1 is low due to icing or other conditions such as icing of the fuel cell stack 1 or the hydrogen circulation pump 4, thereby increasing the reliability of the cold start. On the other hand, it also helps to avoid problems such as increased system hydrogen consumption and energy consumption, and prolonged shutdown waiting time caused by increasing the system shutdown purging time, flow rate and pressure, which is conducive to improving the quality of fuel cell use.

[0121] Example 3

[0122] This embodiment relates to a fuel cell system, combined with... Figure 7 As shown, the fuel cell system includes a memory 401 and a processor 402.

[0123] The memory 401 stores computer-readable instructions, which, when executed by the processor 402, enable the control method of the fuel cell system in Embodiment 1.

[0124] In specific implementation, the fuel cell system of this embodiment can be configured as described in Embodiment 1, and the memory 401 and processor 402 can generally be integrated into the controller of the fuel cell system.

[0125] The fuel cell system in this embodiment, by implementing the control method in Embodiment 1 and utilizing the dynamic load-bearing strategy during the cold start process, can avoid the situation where the fuel cell stack 1 is low due to icing or other conditions such as icing of the fuel cell stack 1 or the hydrogen circulation pump 4 during the cold start process. This can increase the reliability of the cold start. At the same time, it also helps to avoid problems such as increased system hydrogen consumption and energy consumption, and prolonged shutdown waiting time caused by increasing the system shutdown purging time, flow rate and pressure. This is beneficial to improving the quality of fuel cell use.

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A control method of a fuel cell system, characterized by, The control method includes: After receiving a start-up request, the fuel cell system determines the start-up mode of the fuel cell system and sends the corresponding start-up command. When the start command is a cold start command, the coolant pump (9) and coolant heater (12) in the cooling module (100) of the fuel cell system are turned on, so that the coolant flows through the stack (1) and the hydrogen circulation pump (4), and the hydrogen module (200) and air module (300) of the fuel cell system are turned on to supply hydrogen and air to the stack (1); The stack (1) is started to load according to the preset load current, and the load current of the stack (1) is adjusted according to the minimum voltage of a single cell in the stack (1) during the load process so that the stack (1) does not experience single low voltage. When the temperature of the coolant in the cooling module (100) is greater than the first preset temperature threshold, the fuel cell system completes the cold start and enters the normal operation process; Wherein, "single low" means that the minimum voltage of a single cell in the stack (1) is less than a preset voltage threshold.

2. The control method of a fuel cell system according to claim 1, characterized by, The step of determining the start-up mode of the fuel cell system after receiving a start-up request includes: After the fuel cell system receives a power-on request, it acquires the ambient temperature. When the ambient temperature is lower than the second preset temperature threshold, the start-up module of the fuel cell system is determined to be in cold start mode. Wherein, the second preset temperature threshold is not greater than the first preset temperature threshold.

3. The control method for a fuel cell system according to claim 1, characterized in that: When the cooling module (100) is turned on, the coolant heater (12) operates at maximum heating power, and the cooling module (100) operates in a small circulation mode in which the coolant does not pass through the coolant radiator (10).

4. The control method for a fuel cell system according to claim 1, characterized in that: The activation of the hydrogen module (200) includes activating the hydrogen injection valve (2), sending a preset activation command to the hydrogen circulation pump (4), and causing the drain valve (5) and nitrogen discharge valve (6) to operate at a preset activation frequency.

5. The control method for a fuel cell system according to claim 1, characterized in that: The preset load current is set according to the start-up time requirement t of the fuel cell system, the total heat capacity Q of the fuel cell system, the heating power W1 of the coolant heater (12), and the heat generation power W2 of the stack (1) corresponding to different load currents. The startup time requirement t, the total system heat capacity Q, the heating power W1, and the heat generation power W2 satisfy the condition t = Q / (W1 + W2).

6. The control method for a fuel cell system according to claim 1, characterized in that, The method of adjusting the load current of the fuel cell stack (1) according to the minimum voltage of a single cell in the stack (1) during the load-pull process includes: During the loading process of the fuel cell stack (1), the minimum voltage of each cell in the fuel cell stack (1) is continuously acquired; Based on the obtained minimum voltage, the loading rate of the charge current of the fuel cell stack (1) is determined by a preset relationship, and the charge current of the fuel cell stack (1) is adjusted according to the determined loading rate. The preset relationship is the relationship between the minimum voltage of a single cell in the fuel cell stack (1) and the loading and unloading rate of the load current of the fuel cell stack (1) during the cold start of the fuel cell system.

7. The control method for a fuel cell system according to claim 6, characterized in that: The relationship between the minimum voltage of a single cell in the stack (1) and the loading and unloading rate of the stack (1) is s=kv+a; Wherein, s is the loading and unloading rate of the load current of the stack (1), v is the minimum voltage of a single cell in the stack (1), and k and a are preset constant values.

8. The control method for a fuel cell system according to any one of claims 1 to 7, characterized in that, After the fuel cell system completes its cold start and enters normal operation, the control method further includes: Obtain the temperature of the coolant in the cooling module (100); When the temperature of the coolant is greater than the third preset temperature threshold, the cooling module (100) is made to operate in a large circulation mode where the coolant passes through the coolant radiator (10); The third preset temperature threshold is greater than the first preset temperature threshold.

9. A control device for a fuel cell system, characterized in that: It includes a determining module (600), a first control module (700), a second control module (800), and a third control module (900); The determining module (600) is used to determine the start-up mode of the fuel cell system after the fuel cell system receives a start-up request, and send the corresponding start-up command; The first control module (700) is used to control the coolant pump (9) and coolant heater (12) in the cooling module (100) of the fuel cell system to turn on when the start command is a cold start command, so that the coolant flows through the stack (1) and the hydrogen circulation pump (4), and to control the hydrogen module (200) and air module (300) of the fuel cell system to turn on so as to supply hydrogen and air to the stack (1); The second control module (800) is used to start the load-bearing of the fuel cell stack (1) according to the preset load-bearing current, and adjust the load-bearing current of the fuel cell stack (1) according to the minimum voltage of a single cell in the fuel cell stack (1) during the load-bearing process, so that the fuel cell stack (1) does not experience a single low voltage. The third control module is used to control the fuel cell system to complete a cold start and enable the fuel cell system to enter normal operation when the coolant temperature in the cooling module (100) is greater than a first preset temperature threshold.

10. A fuel cell system, characterized in that: The fuel cell system is equipped with a memory (401) and a processor (402); The memory (401) stores computer-readable instructions, which, when executed by the processor (402), implement the control method of the fuel cell system according to any one of claims 1 to 8.

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