Control method and device of fuel cell system, fuel cell system and vehicle

Abstract

This application relates to a control method, apparatus, fuel cell system, and vehicle for a fuel cell system. The method includes: determining a first state of a cooling fan based on the current PWM signal and the previous PWM signal of the fuel cell stack; determining a second state of the cooling fan based on the current speed increment and the required speed increment of the cooling fan; determining a third state of the cooling fan based on the transient heat dissipation of the radiator; determining a fault level of the cooling fan based on the first, second, and third states; matching a control strategy for the fuel cell system according to the fault level; and controlling the fuel cell system according to the control strategy. This solves the problem of fuel cell overheating caused by the lack of negative feedback in the cooling fan of the fuel cell system, when the cooling fan fails. It provides a solution for monitoring the cooling fan speed and handling faults during fuel cell system operation, ensuring the service life of the fuel cell system and its components.

Description

Technical Field

[0001] This application relates to the field of fuel cell technology, and in particular to a control method, apparatus, fuel cell system, and vehicle for a fuel cell system. Background Technology

[0002] Fuel cell systems generate a significant amount of heat while outputting electrical energy. Dissipating this heat effectively and maintaining a reasonable operating temperature range is crucial. Currently, most OEMs use low-pressure fans for cooling fuel cell systems. In practice, the controller calculates or estimates the required fan speed and issues commands. The fan speed constantly changes with the fuel cell system's power and the surrounding environment, but there is no feedback information regarding the fan speed. This severely limits the controller's ability to control instantaneous temperature changes in the fuel cell system.

[0003] In related technologies, the speed of the cooling fan in a fuel cell system is controlled by either the VCU (Vehicle Control Unit) or the FCU (Fuel Cell Control Unit). However, because the controller lacks sufficient pins to handle feedback signals, it cannot determine whether the fan is operating at the predetermined speed after issuing a command for the fan speed. If the cooling fan malfunctions, the fuel cell system will continue to operate according to the program for a certain period of time until it overheats and then executes a shutdown command, significantly damaging the lifespan of the fuel cell system and other components.

[0004] In addition, a malfunctioning cooling fan can eventually lead to overheating of the fuel cell system. However, there are many possible causes for cooling fan failure, such as a faulty DC-DC power supply to the vehicle, problems with the fan wiring harness, or damage to the fan itself. During testing and after-sales troubleshooting, it may be necessary to thoroughly examine each issue to find the problem.

[0005] In summary, there is currently a lack of a strategy for monitoring the cooling fan speed of fuel cell systems during testing, operation, and after-sales processes, which urgently needs to be addressed. Summary of the Invention

[0006] This application provides a control method, device, fuel cell system, and vehicle for a fuel cell system, to solve problems such as overheating of the fuel cell caused by the fuel cell system controller's inability to obtain feedback signals from the cooling fan when the cooling fan fails. It provides a solution for monitoring the cooling fan speed and handling faults during the operation of the fuel cell system, thus ensuring the service life of the fuel cell system and its components.

[0007] The first aspect of this application provides a control method for a fuel cell system, including the following steps:

[0008] Acquire the current PWM (Pulse Width Modulation) signal of the fuel cell stack and the previous PWM signal, the current power increment and demand power increment of the cooling fan in the fuel cell system, and the transient heat dissipation of the radiator;

[0009] The first state of the cooling fan is determined based on the current PWM signal and the previous PWM signal, the second state of the cooling fan is determined based on the current speed increment and the required speed increment, and the third state of the cooling fan is determined based on the transient heat dissipation of the heat sink.

[0010] The fault level of the cooling fan is determined based on the first state, the second state, and the third state, and the control strategy of the fuel cell system is matched according to the fault level, and the fuel cell system is controlled according to the control strategy.

[0011] Optionally, in some embodiments, determining the first state of the cooling fan based on the current PWM signal and the previous PWM signal includes:

[0012] Obtain the current voltage and current values ​​of the DC-DC converter corresponding to the current PWM signal, as well as the previous voltage and current values ​​of the DC-DC converter corresponding to the previous PWM signal;

[0013] Obtain the first theoretical power corresponding to the PWM signal at the current moment and the second theoretical power corresponding to the PWM signal at the previous moment;

[0014] The power at the current moment is obtained by multiplying the voltage value at the current moment and the current value at the current moment, and the power at the previous moment is obtained by multiplying the voltage value at the previous moment and the current value at the previous moment;

[0015] The first state of the cooling fan is determined based on the current power, the first theoretical power, the previous power, and the second theoretical power.

[0016] Optionally, in some embodiments, determining the first state of the cooling fan based on the current power, the first theoretical power, the previous power, and the second theoretical power includes:

[0017] Calculate the first difference between the first theoretical power and the power at the current moment, and calculate the second difference between the second theoretical power and the power at the previous moment;

[0018] If the first ratio of the first difference to the power at the current moment and the second ratio of the second difference to the power at the previous moment are both less than the first preset threshold, then the first state is determined to be a normal operating state; otherwise, the first state is determined to be an abnormal operating state.

[0019] Optionally, in some embodiments, determining the second state of the cooling fan based on the current speed increment and the required speed increment includes:

[0020] Get the current power of the cooling fan, the previous power of the cooling fan, the current total power, the previous total power, the sum of the power of multiple devices at the current time, and the sum of the power of multiple devices at the previous time;

[0021] Calculate the first difference between the total power at the current moment and the total power at the previous moment, the second difference between the power at the current moment and the power at the previous moment, and the third difference between the sum of the power of multiple devices at the current moment and the sum of the power of multiple devices at the previous moment;

[0022] The current speed increment is determined based on the first difference, the second difference, and the third difference. When the current speed increment is inconsistent with the speed demand increment, the second state of the cooling fan is determined to be an abnormal operating state.

[0023] Optionally, in some embodiments, determining the third state of the cooling fan based on the transient heat dissipation of the heat sink includes:

[0024] Obtain air density, air specific heat, and the air temperature difference between the front and back sides of the radiator;

[0025] The air mass is obtained based on the transient heat dissipated by the radiator, the specific heat of the air, and the temperature difference between the front and back sides of the radiator.

[0026] The airflow rate is obtained based on the air quality and air density, and the current fan speed of the cooling fan is determined based on the airflow rate. The duty cycle at the current moment is determined based on the current fan speed. When the difference between the current duty cycle and the previous duty cycle is greater than a third preset threshold, the third state of the cooling fan is determined to be an abnormal operating state.

[0027] Optionally, in some embodiments, before determining the third state of the cooling fan based on the transient heat dissipation of the heat sink, the method further includes:

[0028] The specific heat of the fuel cell antifreeze, the mass of the antifreeze flowing through the radiator, and the temperature difference between the inlet and outlet water temperatures of the radiator are obtained.

[0029] The transient heat dissipation is obtained based on the specific heat of the fuel cell antifreeze, the mass of the antifreeze flowing through the radiator, and the temperature difference between the inlet and outlet water temperatures of the radiator.

[0030] Optionally, in some embodiments, determining the fault level of the cooling fan based on the first state, the second state, and the third state, and matching the control strategy of the fuel cell system according to the fault level, includes:

[0031] If the first state, the second state, and the third state are all normal operating states, then the fault level of the cooling fan is determined to be level 0, and the control strategy is to maintain the operating state of the fuel cell system.

[0032] If the first state is the normal operating state, and the second state or the third state is the abnormal operating state, then the failure level of the cooling fan is determined to be the first level, and the control strategy is to maintain the operating state of the fuel cell system while issuing an acoustic alarm and / or an optical alarm.

[0033] If the first state is the normal operating state, or if both the second state and the third state are the abnormal operating states, then the fault level of the cooling fan is determined to be the second level, and the control strategy is to limit the operating power of the fuel cell system according to a preset limiting strategy.

[0034] If both the first state and the second state are abnormal operating states and the third state is the normal operating state, or if both the first state and the third state are abnormal operating states and the second state is the normal operating state, or if the first state, the second state, and the third state are all abnormal operating states, then the fault level of the cooling fan is determined to be level three, and the control strategy is to control the fuel cell system to shut down according to a preset restriction strategy.

[0035] A second aspect of this application provides a control device for a fuel cell system, comprising:

[0036] The acquisition module is used to acquire the current pulse width modulation (PWM) signal of the fuel cell stack and the previous PWM signal, the current power increment and demand power increment of the cooling fan in the fuel cell system, and the transient heat dissipation of the radiator.

[0037] The determination module is used to determine the first state of the cooling fan based on the current PWM signal and the previous PWM signal, determine the second state of the cooling fan based on the current speed increment and the required speed increment, and determine the third state of the cooling fan based on the transient heat dissipation of the heat sink.

[0038] The control module is configured to determine the fault level of the cooling fan based on the first state, the second state, and the third state, match the control strategy of the fuel cell system according to the fault level, and control the fuel cell system according to the control strategy.

[0039] Optionally, in some embodiments, the determining module is specifically used for:

[0040] Obtain the current voltage and current values ​​of the DC-DC converter corresponding to the current PWM signal, as well as the previous voltage and current values ​​of the DC-DC converter corresponding to the previous PWM signal;

[0041] Obtain the first theoretical power corresponding to the PWM signal at the current moment and the second theoretical power corresponding to the PWM signal at the previous moment;

[0042] The power at the current moment is obtained by multiplying the voltage value at the current moment and the current value at the current moment, and the power at the previous moment is obtained by multiplying the voltage value at the previous moment and the current value at the previous moment;

[0043] The first state of the cooling fan is determined based on the current power, the first theoretical power, the previous power, and the second theoretical power.

[0044] Optionally, in some embodiments, the determining module is further configured to:

[0045] Calculate the first difference between the first theoretical power and the power at the current moment, and calculate the second difference between the second theoretical power and the power at the previous moment;

[0046] If both the first ratio of the first difference to the current power and the second ratio of the second difference to the previous power are less than a first preset threshold, the first state is determined to be a normal operating state; otherwise, the first state is determined to be an abnormal operating state.

[0047] Optionally, in some embodiments, the determining module is specifically used for:

[0048] Get the current power of the cooling fan, the previous power of the cooling fan, the current total power, the previous total power, the sum of the power of multiple devices at the current time, and the sum of the power of multiple devices at the previous time;

[0049] Calculate the first difference between the total power at the current moment and the total power at the previous moment, the second difference between the power at the current moment and the power at the previous moment, and the third difference between the sum of the power of multiple devices at the current moment and the sum of the power of multiple devices at the previous moment;

[0050] The current speed increment is determined based on the first difference, the second difference, and the third difference. When the current speed increment is inconsistent with the speed demand increment, the second state of the cooling fan is determined to be an abnormal operating state.

[0051] Optionally, in some embodiments, the determining module is specifically used for:

[0052] Obtain air density, air specific heat, and the air temperature difference between the front and back sides of the radiator;

[0053] The air mass is obtained based on the transient heat dissipated by the radiator, the specific heat of the air, and the temperature difference between the front and back sides of the radiator.

[0054] The airflow rate is obtained based on the air quality and air density, and the current fan speed of the cooling fan is determined based on the airflow rate. The duty cycle at the current moment is determined based on the current fan speed. When the difference between the current duty cycle and the previous duty cycle is greater than a third preset threshold, the third state of the cooling fan is determined to be an abnormal operating state.

[0055] Optionally, in some embodiments, before determining the third state of the cooling fan based on the transient heat dissipation of the heat sink, the determining module is further configured to:

[0056] The specific heat of the fuel cell antifreeze, the mass of the antifreeze flowing through the radiator, and the temperature difference between the inlet and outlet water temperatures of the radiator are obtained.

[0057] The transient heat dissipation is obtained based on the specific heat of the fuel cell antifreeze, the mass of the antifreeze flowing through the radiator, and the temperature difference between the inlet and outlet water temperatures of the radiator.

[0058] Optionally, in some embodiments, the control module is specifically used for:

[0059] If the first state, the second state, and the third state are all normal operating states, the fault level of the cooling fan is determined to be level 0, and the control strategy is to maintain the operating state of the fuel cell system.

[0060] When the first state is the normal operating state and the second state or the third state is the abnormal operating state, the failure level of the cooling fan is determined to be the first level, and the control strategy is to maintain the operating state of the fuel cell system while issuing an acoustic alarm and / or an optical alarm.

[0061] If the first state is the normal operating state, or if both the second state and the third state are the abnormal operating states, the fault level of the cooling fan is determined to be the second level, and the control strategy is to limit the operating power of the fuel cell system according to a preset limiting strategy.

[0062] If the first state and the second state are both abnormal operating states and the third state is the normal operating state, or if the first state and the third state are both abnormal operating states and the second state is the normal operating state, or if the first state, the second state, and the third state are all abnormal operating states, the fault level of the cooling fan is determined to be level three, and the control strategy is to control the fuel cell system to shut down according to a preset restriction strategy.

[0063] A third aspect of this application provides a fuel cell system, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the control method of the fuel cell system as described in the above embodiments.

[0064] A fourth aspect of this application provides a vehicle including the fuel cell system described in the above embodiments.

[0065] Therefore, this application determines the first state of the cooling fan by acquiring the current PWM signal and the previous PWM signal of the fuel cell stack, determines the second state of the cooling fan based on the current speed increment and the required speed increment, and determines the third state of the cooling fan based on the transient heat dissipation of the radiator. Based on the first, second, and third states, the fault level of the cooling fan is determined, and the control strategy of the fuel cell system is matched according to the fault level. The fuel cell system is then controlled according to the control strategy. Thus, this application effectively solves the problem of fuel cell overheating caused by the fuel cell system controller's inability to obtain cooling fan feedback signals during cooling fan failure. It provides a solution for monitoring the cooling fan speed and handling faults during fuel cell system operation, ensuring the service life of the fuel cell system and its components.

[0066] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0067] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0068] Figure 1This is a flowchart of a control method for a fuel cell system provided according to an embodiment of this application;

[0069] Figure 2 This is a schematic diagram illustrating the power supply principle of a cooling fan according to a specific embodiment of this application;

[0070] Figure 3 This is a schematic diagram of a fuel cell heat dissipation cycle according to a specific embodiment of this application;

[0071] Figure 4 This is a block diagram of the control device for a fuel cell system provided according to an embodiment of this application;

[0072] Figure 5 This is a block diagram of a fuel cell system provided according to an embodiment of this application. Detailed Implementation

[0073] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0074] The following describes a control method, apparatus, fuel cell system, and vehicle for a fuel cell system according to embodiments of this application, with reference to the accompanying drawings. Addressing the problem mentioned in the background art where the fuel cell system controller cannot obtain feedback signals from the cooling fan, leading to overheating of the fuel cell when the cooling fan fails, this application provides a control method for a fuel cell system. In this method, the current pulse width modulation (PWM) signal and the previous PWM signal of the fuel cell stack are acquired, along with the current power increment and demand power increment of the cooling fan in the fuel cell system, and the transient heat dissipation of the radiator. A first state of the cooling fan is determined based on the current and previous PWM signals; a second state is determined based on the current and demand speed increments; and a third state is determined based on the transient heat dissipation of the radiator. The fault level of the cooling fan is determined based on the first, second, and third states, and a control strategy for the fuel cell system is matched according to the fault level. The fuel cell system is then controlled according to the control strategy. This solves the problem of fuel cell overheating caused by the fuel cell system controller's inability to obtain feedback signals from the cooling fan when the cooling fan fails. It provides a solution for monitoring the cooling fan speed and handling faults during fuel cell system operation, ensuring the service life of the fuel cell system and its components.

[0075] Specifically, Figure 1 This is a flowchart illustrating a control method for a fuel cell system provided in an embodiment of this application.

[0076] like Figure 1 As shown, the control method for this fuel cell system includes the following steps:

[0077] In step S101, the current pulse width modulation (PWM) signal of the fuel cell stack and the previous PWM signal are obtained, as well as the current power increment and demand power increment of the cooling fan in the fuel cell system and the transient heat dissipation of the radiator.

[0078] On the one hand, this application considers that pulse width modulation (PWM) signals can be used to control the output power and current of fuel cell stacks, and uses the two measured PWM signals as the basis for judgment to deduce the state of the cooling fan. On the other hand, this application considers the cooling fan speed state by measuring the actual power increment and theoretical power increment of the cooling fan. Furthermore, this application also considers that the heat dissipated by the radiator affects the working state of the cooling fan; therefore, it is also necessary to obtain the transient heat dissipation of the radiator to provide a basis for monitoring the state of the cooling fan.

[0079] It should be noted that this application monitors the real-time speed of the cooling fan in the fuel cell system from the above three levels, and verifies and checks them against each other, thereby avoiding inaccurate judgments caused by misjudgment or failure, and quickly determining whether the cooling fan has malfunctioned. The following examples will specifically illustrate the control logic of the fuel cell system of this application.

[0080] In step S102, the first state of the cooling fan is determined based on the current PWM signal and the previous PWM signal, the second state of the cooling fan is determined based on the current speed increment and the required speed increment, and the third state of the cooling fan is determined based on the transient heat dissipation of the heat sink.

[0081] Optionally, in some embodiments, determining the first state of the cooling fan based on the current PWM signal and the previous PWM signal includes: obtaining the current voltage and current values ​​of the DC-DC converter corresponding to the current PWM signal, and the previous voltage and current values ​​of the DC-DC converter corresponding to the previous PWM signal; obtaining the first theoretical power corresponding to the current PWM signal and the second theoretical power corresponding to the previous PWM signal; obtaining the current power by multiplying the current voltage and current values, and obtaining the previous power by multiplying the previous voltage and current values; and determining the first state of the cooling fan based on the current power, the first theoretical power, the previous power, and the second theoretical power.

[0082] It is understood that this application can obtain the voltage and current values ​​of the DC-DC converter corresponding to the PWM signal, and then calculate the actual detected power value. The actual power value is then compared with the theoretical power value, and the state of the cooling fan is determined by the difference between the two.

[0083] Specifically, Figure 2 This is a schematic diagram illustrating the power supply principle of a cooling fan according to a specific embodiment of this application, as shown below. Figure 2 As shown, hydrogen fuel cell vehicles are powered by fuel cells and power batteries, and the power is distributed centrally to a central power distribution unit. The radiator fan of the fuel cell system is powered by a dedicated low-voltage DC-DC module. Therefore, this application can calculate the instantaneous power supply current and voltage of the low-voltage DC-DC module, and then obtain the power value of the radiator fan by multiplying the power supply current and voltage.

[0084] For example, at the current moment, the FCU sends a PWM signal PWM1, which corresponds to a current I1 and a voltage U1 in the low-voltage DC-DC converter. Therefore, the current cooling fan power W1 corresponding to PWM1 is U1I1. After a period of time, another PWM signal PWM2 is sent, which corresponds to a current I2 and a voltage U2 in the low-voltage DC-DC converter. Therefore, the current cooling fan power W2 corresponding to PWM2 is U2I2. Thus, the embodiments of this application can measure and calculate the measured values ​​of the power of the two cooling fans.

[0085] Preferably, the time interval between the two data collections in this application embodiment can be 2 seconds. Therefore, this application can effectively ensure the timeliness of cooling fan monitoring and ensure the safety of the fuel cell system.

[0086] Furthermore, this application provides a correspondence between cooling fan power and PWM. Table 1 is a table showing the correspondence between cooling fan power, PWM, and static pressure. By referring to Table 1, this application can obtain the theoretical cooling fan power value W3 corresponding to PWM1 and the theoretical cooling fan power value W4 corresponding to PWM2.

[0087] Table 1

[0088]

[0089] Furthermore, in some embodiments, determining the first state of the cooling fan based on the current power, the first theoretical power, the previous power, and the second theoretical power includes: calculating a first difference between the first theoretical power and the current power, and calculating a second difference between the second theoretical power and the previous power; if the first ratio of the first difference to the current power and the second ratio of the second difference to the previous power are both less than a first preset threshold, then the first state is determined to be a normal operating state; otherwise, the first state is determined to be an abnormal operating state.

[0090] Based on the above embodiments, the first difference ΔS1 = (W3-W1) and the second difference ΔS2 = (W4-W2) in this application embodiment, the first ratio ΔS1 = (W3-W1)×100% / W1 and the second ratio ΔS2 = (W4-W2)×100% / W2 in this application embodiment, and further, in order to evaluate the cooling fan speed status, a first preset threshold is set. The first preset threshold is used to compare with the first ratio and the second ratio. When both the first ratio and the second ratio exceed the first preset threshold, the first state of this application embodiment is an abnormal operating state, that is, the cooling fan has malfunctioned.

[0091] Preferably, the first preset threshold in this embodiment of the application can be 10%.

[0092] Therefore, this application can use the above-mentioned table lookup method to intuitively determine the numerical difference between the theoretical value and the actual measured value of the cooling fan power, and use two data collections at 2-second intervals as the basis for judgment to verify the status of the cooling fan from the perspective of functional safety.

[0093] Optionally, in some embodiments, determining the second state of the cooling fan based on the current speed increment and the required speed increment includes: obtaining the current power of the cooling fan, the previous power of the cooling fan, the current total power, the previous total power, the sum of the power of multiple devices at the current time, and the sum of the power of multiple devices at the previous time; calculating a first difference between the current total power and the previous total power, a second difference between the current power and the previous power, and a third difference between the sum of the power of multiple devices at the current time and the sum of the power of multiple devices at the previous time; determining the current speed increment based on the first difference, the second difference, and the third difference, and determining the second state of the cooling fan as an abnormal operating state when the current speed increment is inconsistent with the required speed increment.

[0094] Specifically, such as Figure 1 As shown, all high and low voltage power consumption of the vehicle module is distributed by the power electronics unit. Therefore, this application can classify each low-voltage power channel by measurement, for example, W1, W2, W3, W4..., and then add the power values ​​sequentially to obtain the total power W. 总 =W1+W2+W3+W4+…, In this embodiment of the application, the cooling fan circuit is taken out separately, and the total power W is... 总 Divided into cooling fan power W 风扇 The sum of the power of multiple devices W 其他 In addition, in order to verify whether the increase in cooling fan power is consistent with the actual increase or decrease direction, and thus determine whether the increase in speed is correct, this application requires data collection twice.

[0095] For example, the power of the cooling fan at the previous moment was W. 风扇1 The current power of the cooling fan is W. 风扇2 The total power at the previous moment was W. 总1 The total power at the current moment is W. 总2 The sum of the power of the multiple devices at the previous moment was W. 其他1 The sum of the power of multiple devices at the current moment is W. 其他2 ,but

[0096] W 总1 =W 风扇1 +W 其他1 (W1+W2+W3+W4+…);

[0097] W 总2 =W 风扇2 +W 其他2 (W1+W2+W3+W4+…);

[0098] Furthermore, the first difference ΔW in the embodiments of this application 总 =W 总2 -W 总1 The second difference ΔW 风扇 =W 风扇2 -W 风扇1 The third difference ΔW 其他 =W 其他2 -W 其他1 ,but

[0099] ΔW 总 (W 总2 -W 总1 )=ΔW 风扇 (W 风扇2 -W 风扇1 )+ΔW 其他 (W 其他2 -W 其他1 );

[0100] Therefore, this application can determine the following judgment logic based on the sign and magnitude of the three terms on the left and right sides of the above equation:

[0101] In ΔW 总 If ΔW > 0, 其他 If ΔW < 0, then ΔW 风扇 If the value is greater than 0, it is determined that the cooling fan speed has increased, meaning that the second state of the cooling fan is an abnormal operating state.

[0102] In ΔW 总 If ΔW < 0 其他 If ΔW > 0, then ΔW 风扇 If the value is less than 0, the cooling fan speed is determined to be reduced, meaning the second state of the cooling fan is an abnormal operating state.

[0103] Therefore, this application can utilize the above-mentioned incremental method, that is, to determine whether the increase or decrease of the cooling fan speed is consistent with the general direction of the actual increase or decrease by the incremental method before and after, and to consider the cooling fan speed status from the perspective of the vehicle's power consumption.

[0104] Optionally, in some embodiments, before determining the third state of the cooling fan based on the transient heat dissipation of the radiator, the method further includes: obtaining the specific heat of the fuel cell antifreeze, the mass of the antifreeze flowing through the radiator, and the temperature difference between the inlet and outlet water temperatures of the radiator; and obtaining the transient heat dissipation based on the specific heat of the fuel cell antifreeze, the mass of the antifreeze flowing through the radiator, and the temperature difference between the inlet and outlet water temperatures of the radiator.

[0105] Specifically, Figure 3 This is a schematic diagram of a fuel cell heat dissipation cycle according to a specific embodiment of this application, as shown below. Figure 3 As shown, the fuel cell heat dissipation circuit includes a fuel cell, a water pump, a radiator, heat dissipation pipes, and several sensors. This embodiment requires first obtaining the specific heat C of the fuel cell antifreeze. 水 The mass m of antifreeze flowing through the radiator 水 The temperature difference ΔT between the inlet and outlet water temperatures of the radiator 水 The heat dissipated by the radiator in a transient manner is Q. 水 =C 水 m 水 ΔT 水 .

[0106] Furthermore, in some embodiments, determining the third state of the cooling fan based on the transient heat dissipation of the radiator includes: acquiring air density, air specific heat, and the air temperature difference between the front and back sides of the radiator; obtaining air mass based on the transient heat dissipation of the radiator, air specific heat, and the air temperature difference between the front and back sides of the radiator; obtaining air flow rate based on air mass and air density; determining the current fan speed of the cooling fan based on the air flow rate; determining the duty cycle at the current moment based on the current fan speed; and determining the third state of the cooling fan as an abnormal operating state when the difference between the current duty cycle and the previous duty cycle is greater than a third preset threshold.

[0107] Specifically, based on the principle of energy conservation, this application states that almost all the heat dissipated by the cooling fan, excluding factors such as radiation, is transferred to the air. Therefore, the transient heat dissipation Q of the radiator is... 水 Heat of air Q 空

[0108] They are equal. Therefore, embodiments of this application require obtaining the air density ρ. 空 Specific heat of air C 空 The temperature difference ΔT between the front and back sides of the radiator 空 Then Q 水 =C水 m 水 ΔT 水 =C 空 m 空 ΔT 空 =Q 空 Therefore, this application can calculate the air mass m. 空 =m 水 ·(C 水 ΔT 水 ) / (C 空 ΔT 空 ), and because m 空 =q 空 ρ 空 Therefore, this application can obtain the air flow rate q. 空 .

[0109] Furthermore, this application can determine the duty cycle at the current moment by obtaining the cooling fan speed according to the static pressure-flow-speed curve of the cooling fan, subtract it from the duty cycle at the previous moment, and determine whether the difference between the two exceeds a third preset threshold within a certain duration. If the difference between the two exceeds the third preset threshold, the third state of the cooling fan is determined to be an abnormal operating state.

[0110] Preferably, the duration in the above embodiment can be 5 seconds, and the third preset threshold can be 20%.

[0111] Therefore, this application can indirectly measure the fan speed status from the perspective of the heat sink by using the above-mentioned indirect method, that is, by calculating the change of fan speed from the perspective of the heat sink, and by combining theoretical formulas with measured data.

[0112] Based on the above embodiments, this application proposes three control logics for monitoring the actual speed of the cooling fan in a fuel cell system. In practical applications, this application can combine the above three strategies and verify and check each other, thereby effectively avoiding misjudgment and greatly enhancing the accuracy and reliability of the control strategy.

[0113] It should be noted that the above embodiments compare theoretical values ​​with measured values ​​by looking up tables, or determine whether the trend of the cooling fan speed increase or decrease is correct by the increment before and after, or indirectly calculate the change of cooling fan speed by the dimension of the heat sink, thereby determining the state of the cooling fan (first state, second state and third state). This application takes into account that the speed of the cooling fan changes continuously with the power of the fuel cell system and the surrounding environment. Therefore, the fault level is divided based on the state of the cooling fan. When the cooling fan fails, the fault information is fed back in time and an early warning is issued to avoid the fuel cell system from overheating.

[0114] In step S103, the fault level of the cooling fan is determined according to the first state, the second state and the third state, and the control strategy of the fuel cell system is matched according to the fault level, and the fuel cell system is controlled according to the control strategy.

[0115] Optionally, in some embodiments, the fault level of the cooling fan is determined based on the first state, the second state, and the third state, and the control strategy of the fuel cell system is matched according to the fault level, including: if the first state, the second state, and the third state are all normal operating states, then the fault level of the cooling fan is determined to be level 0, and the control strategy is to maintain the operating state of the fuel cell system; if the first state is a normal operating state, and the second state or the third state is an abnormal operating state, then the fault level of the cooling fan is determined to be level 1, and the control strategy is to maintain the operating state of the fuel cell system while issuing an audible alarm and / or an optical alarm; if the first state is a normal operating state, or the second state and the third state are both abnormal operating states, then the fault level of the cooling fan is determined to be level 2, and the control strategy is to limit the operating power of the fuel cell system according to a preset limiting strategy; if the first state and the second state are both abnormal operating states, and the third state is a normal operating state, or the first state and the third state are both abnormal operating states, and the second state is a normal operating state, or the first state, the second state, and the third state are all abnormal operating states, then the fault level of the cooling fan is determined to be level 3, and the control strategy is to control the fuel cell system to shut down according to a preset limiting strategy.

[0116] In this application embodiment, the acoustic alarm and / or optical alarm can be issued by the FCU. The acoustic alarm can be a horn sound or a voice broadcast of fault information, while the optical alarm can push fault information to a display screen to remind the user that the cooling fan has malfunctioned and should be investigated promptly. Furthermore, this application does not specifically limit the acoustic and optical alarm methods; those skilled in the art can set them according to actual conditions.

[0117] It should be noted that the severity of the third level in the embodiments of this application is greater than that of the second level, the severity of the second level is greater than that of the first level, and the severity of the first level is greater than level 0.

[0118] Understandably, if the cooling fan is operating normally in the first, second, and third states, then no warning needs to be issued, and the fault level is 0. If the first, second, or third state is operating normally, the fault level is 1. In this case, the control strategy is to maintain the operation of the fuel cell system while issuing a warning message to remind the user to troubleshoot the fault in a timely manner.

[0119] In some cases, the first state is the normal operating state, or the second and third states are both abnormal operating states. If the cooling fan speed is determined to be abnormal, the fault level is the second level. At this time, it is necessary to take measures to avoid risks, limit the operating power of the fuel cell system, and prevent it from shutting down due to overheating.

[0120] In other cases, the first and second states are both abnormal operating states, and the third state is a normal operating state; or, the first and third states are both abnormal operating states, and the second state is a normal operating state; or, the first, second, and third states are all abnormal operating states. In such cases, it is determined that the speed of the cooling fan is abnormal and may have a significant impact on the fuel cell system. The fault level is the third level. Therefore, in this embodiment, the fuel cell system needs to be shut down immediately to prevent it from executing a shutdown command due to overheating, which would reduce the lifespan of the entire system and other components.

[0121] The following examples illustrate the three methods provided in this application—namely, the lookup table method, the incremental method, and the indirect method—for fault classification and early warning judgment logic.

[0122] Specifically, Table 2 is a comprehensive logic judgment table for embodiments of this application. In Table 2, √ indicates normal and × indicates abnormal.

[0123] Table 2

[0124] 1 √ √ √ -- -- 2 √ √ × Level 1 Call the police 3 √ × √ Level 1 Call the police 4 √ × × Level 2 Power limiting 5 × √ √ Level 2 Power limiting 6 × × √ Level 3 Normal shutdown 7 × √ × Level 3 Normal shutdown 8 × × × Level 3 Normal shutdown

[0125] Therefore, this application can quickly determine whether the speed of the cooling fan is normal based on the logic judgment in Table 2 under the condition of negative feedback of the cooling fan, so that the FCU matches the fault level and executes the corresponding control strategy. In addition, the control method of the fuel cell system of this application can be applied to hydrogen fuel cell vehicles, especially commercial vehicles. During the testing, operation and after-sales process, it can quickly determine whether the fuel cell system overheating is caused by the failure of the cooling fan. It is also applicable to passenger vehicles.

[0126] According to the control method for a fuel cell system proposed in this application, the first state of the cooling fan is determined by acquiring the current PWM signal and the previous PWM signal of the fuel cell stack. The second state of the cooling fan is determined based on the current speed increment and the required speed increment. The third state of the cooling fan is determined based on the transient heat dissipation of the radiator. The fault level of the cooling fan is determined based on the first, second, and third states. The control strategy of the fuel cell system is matched according to the fault level, and the fuel cell system is controlled according to the control strategy. Therefore, this application effectively solves the problem of fuel cell overheating caused by the fuel cell system controller's inability to obtain cooling fan feedback signals when the cooling fan fails. It provides a solution for monitoring the cooling fan speed and handling faults during fuel cell system operation, ensuring the service life of the fuel cell system and its components.

[0127] Next, the control device for the fuel cell system proposed according to the embodiments of this application is described with reference to the accompanying drawings.

[0128] Figure 4 This is a block diagram of the control device of a fuel cell system according to an embodiment of this application.

[0129] like Figure 4 As shown, the control device 10 of the fuel cell system includes: an acquisition module 100, a determination module 200, and a control module 300.

[0130] Specifically, the acquisition module 100 is used to acquire the current pulse width modulation (PWM) signal of the fuel cell stack and the previous PWM signal, the current power increment and demand power increment of the cooling fan in the fuel cell system, and the transient heat dissipation of the radiator; the determination module 200 is used to determine the first state of the cooling fan based on the current PWM signal and the previous PWM signal, the second state of the cooling fan based on the current speed increment and the demand speed increment, and the third state of the cooling fan based on the transient heat dissipation of the radiator; the control module 300 is used to determine the fault level of the cooling fan based on the first state, the second state, and the third state, match the control strategy of the fuel cell system according to the fault level, and control the fuel cell system according to the control strategy.

[0131] Optionally, in some embodiments, the determining module 200 is specifically configured to: obtain the current voltage value and current value of the DC-DC converter corresponding to the current PWM signal, and the previous voltage value and current value of the DC-DC converter corresponding to the previous PWM signal; obtain the first theoretical power corresponding to the current PWM signal and the second theoretical power corresponding to the previous PWM signal; obtain the current power based on the product of the current voltage value and the current current value, and obtain the previous power based on the product of the previous voltage value and the previous current value; and determine the first state of the cooling fan based on the current power, the first theoretical power, the previous power, and the second theoretical power.

[0132] Optionally, in some embodiments, the determining module 200 is further configured to: calculate a first difference between the first theoretical power and the power at the current moment, and calculate a second difference between the second theoretical power and the power at the previous moment; if both the first ratio of the first difference to the power at the current moment and the second ratio of the second difference to the power at the previous moment are less than a first preset threshold, determine that the first state is a normal operating state; otherwise, determine that the first state is an abnormal operating state.

[0133] Optionally, in some embodiments, the determining module 200 is specifically used to: obtain the current power of the cooling fan, the previous power of the cooling fan, the current total power, the previous total power, the sum of the power of multiple devices at the current time, and the sum of the power of multiple devices at the previous time; calculate the first difference between the current total power and the previous total power, the second difference between the current power and the previous power, and the third difference between the sum of the power of multiple devices at the current time and the sum of the power of multiple devices at the previous time; determine the current speed increment based on the first difference, the second difference, and the third difference, and determine the second state of the cooling fan as an abnormal operating state when the current speed increment is inconsistent with the speed demand increment.

[0134] Optionally, in some embodiments, the determining module 200 is specifically used to: obtain air density, air specific heat, and the air temperature difference between the front and back sides of the radiator; obtain air mass based on the transient heat dissipated by the radiator, air specific heat, and the air temperature difference between the front and back sides of the radiator; obtain air flow rate based on air mass and air density, determine the current fan speed of the cooling fan based on the air flow rate, determine the duty cycle at the current moment based on the current fan speed, and determine the third state of the cooling fan as an abnormal operating state when the difference between the current duty cycle and the previous duty cycle is greater than a third preset threshold.

[0135] Optionally, in some embodiments, before determining the third state of the cooling fan based on the transient heat dissipation of the radiator, the determining module 200 is further configured to: obtain the specific heat of the fuel cell antifreeze, the mass of the antifreeze flowing through the radiator, and the temperature difference between the inlet and outlet water temperatures of the radiator; and obtain the transient heat dissipation based on the specific heat of the fuel cell antifreeze, the mass of the antifreeze flowing through the radiator, and the temperature difference between the inlet and outlet water temperatures of the radiator.

[0136] Optionally, in some embodiments, the control module 300 is specifically configured to: determine the fault level of the cooling fan as level 0 when the first state, the second state, and the third state are all normal operating states, and the control strategy is to maintain the operating state of the fuel cell system; determine the fault level of the cooling fan as level 1 when the first state is normal operating state and the second state or the third state is abnormal operating state, and the control strategy is to maintain the operating state of the fuel cell system while issuing an audible alarm and / or an optical alarm; determine the fault level of the cooling fan as level 2 when the first state is normal operating state, or when the second state and the third state are both abnormal operating states, and the control strategy is to limit the operating power of the fuel cell system according to a preset limiting strategy; determine the fault level of the cooling fan as level 3 when the first state and the second state are both abnormal operating states and the third state is normal operating state, or when the first state and the third state are both abnormal operating states and the second state is normal operating state, or when the first state, the second state, and the third state are all abnormal operating states, and the control strategy is to control the fuel cell system to shut down according to a preset limiting strategy.

[0137] It should be noted that the foregoing explanation of the control method embodiment for the fuel cell system also applies to the control device of the fuel cell system in this embodiment, and will not be repeated here.

[0138] The control device for a fuel cell system proposed in this application determines the first state of the cooling fan by acquiring the current PWM signal and the previous PWM signal of the fuel cell stack. It then determines the second state of the cooling fan based on the current speed increment and the required speed increment, and the third state based on the transient heat dissipation of the radiator. The fault level of the cooling fan is determined based on the first, second, and third states, and the control strategy of the fuel cell system is matched according to the fault level. The fuel cell system is then controlled according to the control strategy. Therefore, this application effectively solves the problem of fuel cell overheating caused by the fuel cell system controller's inability to obtain cooling fan feedback signals during cooling fan failure. It provides a solution for monitoring the cooling fan speed and handling faults during fuel cell system operation, ensuring the service life of the fuel cell system and its components.

[0139] Figure 5A schematic diagram of a fuel cell system provided in an embodiment of this application. The fuel cell system may include:

[0140] The memory 501, the processor 502, and the computer program stored on the memory 501 and capable of running on the processor 502.

[0141] When the processor 502 executes the program, it implements the control method of the fuel cell system provided in the above embodiments.

[0142] Furthermore, the fuel cell system also includes:

[0143] Communication interface 503 is used for communication between memory 501 and processor 502.

[0144] The memory 501 is used to store computer programs that can run on the processor 502.

[0145] The memory 501 may include high-speed RAM (Random Access Memory) memory, and may also include non-volatile memory, such as at least one disk storage.

[0146] If the memory 501, processor 502, and communication interface 503 are implemented independently, then the communication interface 503, memory 501, and processor 502 can be interconnected via a bus to complete communication between them. The bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, or an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 5 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0147] Optionally, in a specific implementation, if the memory 501, processor 502, and communication interface 503 are integrated on a single chip, then the memory 501, processor 502, and communication interface 503 can communicate with each other through an internal interface.

[0148] Processor 502 may be a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement embodiments of this application.

[0149] This application also provides a vehicle that includes the aforementioned fuel cell system.

[0150] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0151] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0152] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0153] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or more of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (FPGAs), field-programmable gate arrays (FPGAs), etc.

[0154] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0155] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A control method of a fuel cell system, characterized by, Includes the following steps: The current pulse width modulation (PWM) signal and the previous PWM signal of the fuel cell stack are obtained, as well as the current power increment and demand power increment of the cooling fan in the fuel cell system and the transient heat dissipation of the radiator. The first state of the cooling fan is determined based on the current PWM signal and the previous PWM signal, the second state of the cooling fan is determined based on the current speed increment and the required speed increment, and the third state of the cooling fan is determined based on the transient heat dissipation of the heat sink. as well as The fault level of the cooling fan is determined based on the first state, the second state, and the third state. A control strategy for the fuel cell system is then matched to the fault level, and the fuel cell system is controlled according to the control strategy. Determining the first state of the cooling fan based on the current PWM signal and the previous PWM signal includes: acquiring the current voltage and current values ​​of the DC-DC converter corresponding to the current PWM signal, and the previous voltage and current values ​​of the DC-DC converter corresponding to the previous PWM signal; acquiring the first theoretical power corresponding to the current PWM signal and the second theoretical power corresponding to the previous PWM signal; obtaining the current power by multiplying the current voltage and current values, and obtaining the previous power by multiplying the previous voltage and current values; and determining the first state of the cooling fan based on the current power, the first theoretical power, the previous power, and the second theoretical power.

2. The method of claim 1, wherein, Determining the first state of the cooling fan based on the current power, the first theoretical power, the previous power, and the second theoretical power includes: Calculate the first difference between the first theoretical power and the power at the current moment, and calculate the second difference between the second theoretical power and the power at the previous moment; If the first ratio of the first difference to the power at the current moment and the second ratio of the second difference to the power at the previous moment are both less than the first preset threshold, then the first state is determined to be a normal operating state; otherwise, the first state is determined to be an abnormal operating state.

3. The method of claim 1, wherein, Determining the second state of the cooling fan based on the current speed increment and the required speed increment includes: Get the current power of the cooling fan, the previous power of the cooling fan, the current total power, the previous total power, the sum of the power of multiple devices at the current time, and the sum of the power of multiple devices at the previous time; Calculate the first difference between the total power at the current moment and the total power at the previous moment, the second difference between the power at the current moment and the power at the previous moment, and the third difference between the sum of the power of multiple devices at the current moment and the sum of the power of multiple devices at the previous moment; The current speed increment is determined based on the first difference, the second difference, and the third difference. When the current speed increment is inconsistent with the speed demand increment, the second state of the cooling fan is determined to be an abnormal operating state.

4. The method of claim 3, wherein, The step of determining the third state of the cooling fan based on the transient heat dissipation of the heat sink includes: Obtain air density, air specific heat, and the air temperature difference between the front and back sides of the radiator; The air mass is obtained based on the transient heat dissipated by the radiator, the specific heat of the air, and the temperature difference between the front and back sides of the radiator. The airflow rate is obtained based on the air quality and air density, and the current fan speed of the cooling fan is determined based on the airflow rate. The duty cycle at the current moment is determined based on the current fan speed. When the difference between the current duty cycle and the previous duty cycle is greater than a third preset threshold, the third state of the cooling fan is determined to be an abnormal operating state.

5. The method of claim 4, wherein, Before determining the third state of the cooling fan based on the transient heat dissipation of the heat sink, the method further includes: The specific heat of the fuel cell antifreeze, the mass of the antifreeze flowing through the radiator, and the temperature difference between the inlet and outlet water temperatures of the radiator are obtained. The transient heat dissipation is obtained based on the specific heat of the fuel cell antifreeze, the mass of the antifreeze flowing through the radiator, and the temperature difference between the inlet and outlet water temperatures of the radiator.

6. The method according to claim 1, characterized in that, The step of determining the fault level of the cooling fan based on the first state, the second state, and the third state, and matching the control strategy of the fuel cell system according to the fault level, includes: If the first state, the second state, and the third state are all normal operating states, then the fault level of the cooling fan is determined to be level 0, and the control strategy is to maintain the operating state of the fuel cell system. If the first state is the normal operating state, and the second state or the third state is the abnormal operating state, then the failure level of the cooling fan is determined to be the first level, and the control strategy is to maintain the operating state of the fuel cell system while issuing an acoustic alarm and / or an optical alarm. If the first state is the normal operating state, or if both the second state and the third state are the abnormal operating states, then the fault level of the cooling fan is determined to be the second level, and the control strategy is to limit the operating power of the fuel cell system according to a preset limiting strategy. If both the first state and the second state are abnormal operating states and the third state is the normal operating state, or if both the first state and the third state are abnormal operating states and the second state is the normal operating state, or if the first state, the second state, and the third state are all abnormal operating states, then the fault level of the cooling fan is determined to be level three, and the control strategy is to control the fuel cell system to shut down according to a preset restriction strategy.

7. A control device of a fuel cell system characterized by comprising: include: The acquisition module is used to acquire the current pulse width modulation (PWM) signal of the fuel cell stack and the previous PWM signal, the current power increment and demand power increment of the cooling fan in the fuel cell system, and the transient heat dissipation of the radiator. The determination module is used to determine the first state of the cooling fan based on the current PWM signal and the previous PWM signal, determine the second state of the cooling fan based on the current speed increment and the required speed increment, and determine the third state of the cooling fan based on the transient heat dissipation of the heat sink. as well as The control module is used to determine the fault level of the cooling fan according to the first state, the second state and the third state, match the control strategy of the fuel cell system according to the fault level, and control the fuel cell system according to the control strategy. The determining module is specifically used to: obtain the current voltage value and current value of the DC converter corresponding to the current PWM signal, and the previous voltage value and current value of the DC converter corresponding to the previous PWM signal; Obtain the first theoretical power corresponding to the PWM signal at the current moment and the second theoretical power corresponding to the PWM signal at the previous moment; The power at the current moment is obtained by multiplying the voltage value at the current moment and the current value at the current moment, and the power at the previous moment is obtained by multiplying the voltage value at the previous moment and the current value at the previous moment; The first state of the cooling fan is determined based on the current power, the first theoretical power, the previous power, and the second theoretical power.

8. A fuel cell system characterized by comprising: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the control method for the fuel cell system as described in any one of claims 1-6.

9. A vehicle characterized by comprising: Including the fuel cell system as described in claim 8.

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