A temperature control method and device for a fuel cell stack

Abstract

The present invention discloses a temperature control method and device for a fuel cell stack. When applying temperature control to the fuel cell stack, by obtaining the power to be output by the fuel cell stack, the coolant inlet temperature, the minimum single-cell voltage, and the air outlet temperature of the radiator, the minimum opening degree of the temperature control valve is obtained according to the power to be output and the heat dissipation temperature, preventing excessive opening from causing uneven temperature inside the stack. At the same time, based on the feedforward control method, the first feedforward speed of the water pump is obtained according to the power to be output and the coolant inlet temperature, and the first feedforward speed is compensated according to the minimum single-cell voltage to obtain the first target speed of the water pump, preventing unreasonable setting of the water pump speed and causing too low single-cell voltage due to uneven temperature. By adjusting the temperature control valve to the minimum opening degree and controlling the water pump to operate at the first target speed, the temperature inside the stack can be made as uniform as possible, thereby improving the uniformity of the temperature inside the fuel cell stack.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell stack temperature control, and particularly to a temperature control method and device for a fuel cell stack. Background Art

[0002] With the increasingly fierce competition in the automotive field, various enterprises and universities have begun to engage in the research of automotive hydrogen fuel cell stacks. The key component of the fuel cell stack system is the stack, which needs to operate within a specific temperature range to achieve the highest efficiency. If the stack temperature is too low or too high, it will not only reduce the stack working efficiency, but even cause permanent damage to the stack itself. Precise control of the working temperature inside the stack is crucial for the efficiency and lifespan of the fuel cell stack system. To ensure that the fuel cell stack operates within a specific temperature range and meets the power requirements of the whole vehicle, the fuel cell stack system needs to precisely control the stack temperature through a thermal management system to enable normal reactions inside the stack.

[0003] Currently, the stack temperature control of the fuel cell stack is implemented based on the coolant outlet temperature from the stack. Based on the coolant outlet temperature from the stack, the opening degree of the temperature control valve and the rotation speed of the radiator fan are controlled. The higher the coolant outlet temperature from the stack, the larger the opening degree of the temperature control valve and the higher the rotation speed of the radiator fan, to avoid excessive coolant outlet temperature from the stack and damage to the stack. This control method cannot achieve balanced temperature control inside the fuel cell stack, resulting in uneven temperature inside the stack and the situation of low single-cell voltage.

[0004] Therefore, how to improve the uniformity of the temperature inside the fuel cell stack is a technical problem that needs to be solved urgently at present. Summary of the Invention

[0005] A temperature control method and device for a fuel cell stack of the present invention improve the uniformity of the temperature inside the fuel cell stack.

[0006] The embodiments of the present invention provide the following solutions:

[0007] In a first aspect, the embodiments of the present invention provide a temperature control method for a fuel cell stack, which is applied to a temperature control system of the fuel cell stack for temperature control. The temperature control system includes a water pump and a temperature control valve that connect the coolant inlet and the coolant outlet, and a radiator that connects the coolant inlet and the temperature control valve. The method includes:

[0008] Obtain the operating parameters of the fuel cell stack, where the operating parameters at least include the power to be output, the coolant inlet temperature, the lowest single-cell voltage, and the outlet temperature of the radiator.

[0009] Obtain the minimum opening degree of the temperature control valve according to the power to be output and the heat dissipation temperature, where the heat dissipation temperature is the temperature difference between the coolant inlet temperature and the outlet temperature.

[0010] Obtain the first feedforward speed of the water pump according to the to-be-output power and the coolant inlet temperature;

[0011] Compensate the first feedforward speed according to the lowest single-chip voltage to obtain the first target speed of the water pump;

[0012] Adjust the temperature control valve to the minimum opening degree and control the water pump to operate at the first target speed.

[0013] In an optional embodiment, the operating parameters further include the rated speed of the water pump and the PID output speed S p , let the rated speed of the water pump be S e , the PID output speed be S p , and the first feedforward speed be S q ; The compensating the first feedforward speed according to the lowest single-chip voltage to obtain the first target speed of the water pump includes:

[0014] If the lowest single-chip voltage is not greater than the preset voltage range, according to the formula S c = S e -(S q + S p ), obtain the water pump compensation speed S c ;

[0015] If the lowest single-chip voltage is within the preset voltage range and aS e -(S q + S p ) > 0, according to the formula S c = aS e -(S q + S p ), obtain the water pump compensation speed S c , where a is a preset coefficient;

[0016] If the lowest single-chip voltage is greater than the preset voltage range, or aS e -(S q + S p ) ≤ 0, set the water pump compensation speed S c to 0;

[0017] Obtain the first target speed according to the sum of the water pump compensation speed and the first feedforward speed.

[0018] In an alternative embodiment, the operating parameters further include the coolant outlet temperature and the temperature error data of the coolant entering the fuel cell stack; before adjusting the temperature control valve to the minimum opening and controlling the water pump to operate at the first target speed, the method further includes:

[0019] When the coolant inlet temperature reaches a preset target temperature, input the coolant temperature difference into a PID controller to obtain the adjusted speed of the water pump, and obtain an updated first target speed based on the sum of the adjusted speed of the water pump and the initial first target speed;

[0020] Update the minimum opening according to the historical cycle error and the current cycle error of the temperature error data.

[0021] In an alternative embodiment, the updating the minimum opening according to the historical cycle error and the current cycle error of the temperature error data includes:

[0022] According to the formula K = K p ×(e k -e k-1 ) + K I ×e k + K D ×(e k - 2e k-1 + e k-2 ), obtain the adjusted opening K, where e k is the current cycle error, e k-1 is the error of the previous cycle of the current cycle error, e k-2 is the error of the previous cycle of e k-1 , K p is the proportionality coefficient, K I is the integral coefficient, K D is the differential coefficient;

[0023] Obtain the updated minimum opening based on the sum of the adjusted opening and the initial minimum opening.

[0024] In an alternative embodiment, the operating parameters further include the valve opening of the temperature control valve; after adjusting the temperature control valve to the minimum opening and controlling the water pump to operate at the target speed, the method further includes:

[0025] When the outlet air temperature is not less than the first set threshold and the valve opening is greater than the second set threshold, obtain a second target speed according to a preset second feedforward speed and a speed correction model;

[0026] Control the fan of the radiator to operate at the second target speed.

[0027] In an alternative embodiment, obtaining the second target speed according to the preset second feedforward speed and the speed correction model includes:

[0028] Looking up the corresponding speed value in a preset look-up table according to the power to be output to obtain the second feedforward speed, where the preset look-up table is a corresponding relationship table of the fan speed following the increase of the power to be output;

[0029] Inputting the correction parameter into the speed correction model to obtain a corrected speed, where the correction parameter at least includes one of the valve opening, the air outlet temperature, and the vehicle driving speed;

[0030] Obtaining the second target speed according to the sum of the second feedforward speed and the corrected speed.

[0031] In an alternative embodiment, the correction parameter includes the valve opening and the stack temperature. Inputting the correction parameter into the speed correction model to obtain a corrected speed includes:

[0032] If the valve opening is not within the preset opening range, configuring the corrected speed output by the speed correction model to change correspondingly with the valve opening;

[0033] If the valve opening is within the preset opening range, adjusting the valve opening of the temperature control valve according to the stack temperature until the valve opening is not within the preset opening range, and determining the output result of the speed correction model as the corrected speed.

[0034] In a second aspect, an embodiment of the present invention further provides a temperature control device for a fuel cell stack, which is applied to a temperature control system of the fuel cell stack for temperature control. The temperature control system includes a water pump and a temperature control valve connecting a coolant inlet and a coolant outlet, and a radiator connecting the coolant inlet and the temperature control valve. The device includes:

[0035] An acquisition module, configured to acquire the operating parameters of the fuel cell stack, where the operating parameters at least include the power to be output, the coolant inlet temperature, the minimum single-cell voltage, and the air outlet temperature of the radiator;

[0036] A first acquisition module, configured to obtain the minimum opening of the temperature control valve according to the power to be output and the heat dissipation temperature, where the heat dissipation temperature is the temperature difference between the coolant inlet temperature and the air outlet temperature;

[0037] A second acquisition module, configured to obtain the first feedforward speed of the water pump according to the power to be output and the coolant inlet temperature;

[0038] A third acquisition module, configured to compensate and process the first feedforward rotational speed according to the lowest single-chip voltage to obtain a first target rotational speed of the water pump;

[0039] A first control module, configured to adjust the temperature control valve to the minimum opening degree and control the water pump to operate at the first target rotational speed.

[0040] In a third aspect, an embodiment of the present invention further provides an electronic device, including a processor and a memory, the memory is coupled to the processor, the memory stores instructions, and when the instructions are executed by the processor, the electronic device executes the steps of the method according to any one of the first aspect.

[0041] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the steps of the method according to any one of the first aspect are implemented.

[0042] Compared with the prior art, a temperature control method and device of a fuel cell stack of the present invention have the following advantages:

[0043] When the temperature control method of the present invention is applied to a fuel cell stack for temperature control, by obtaining the power to be output, the coolant inlet temperature, the lowest single-chip voltage of the fuel cell stack, and the outlet temperature of the radiator, the minimum opening degree of the temperature control valve is obtained according to the power to be output and the heat dissipation temperature, preventing the opening degree from being too large and causing uneven temperature inside the stack. At the same time, based on the feedforward control method, the first feedforward rotational speed of the water pump is obtained according to the power to be output and the coolant inlet temperature, and the first feedforward rotational speed is compensated and processed according to the lowest single-chip voltage to obtain the first target rotational speed of the water pump, preventing the rotational speed of the water pump from being set unreasonably and causing the single-chip voltage to be too low due to uneven temperature. By adjusting the temperature control valve to the minimum opening degree and controlling the water pump to operate at the first target rotational speed, the temperature inside the stack can be made as uniform as possible, thereby improving the uniformity of the temperature inside the fuel cell stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present specification or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present specification. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0045] Figure 1 It is a schematic structural diagram of a temperature control system provided by an embodiment of the present invention;

[0046] Figure 2 It is a flowchart of a temperature control method of a fuel cell stack provided by an embodiment of the present invention;

[0047] Figure 3 It is the control logic diagram of the water pump provided by the embodiment of the present invention;

[0048] Figure 4 It is the control logic diagram of the temperature control valve provided by the embodiment of the present invention;

[0049] Figure 5 It is the control logic diagram of the fan provided by the embodiment of the present invention;

[0050] Figure 6 It is the structural schematic diagram of a temperature control device for a fuel cell stack provided by the embodiment of the present invention.

[0051] Explanation of reference numerals: 1 - fuel cell stack, 2 - water pump, 3 - temperature control valve, 4 - radiator, 5 - heater, 6 - outlet temperature sensor, 7 - inlet temperature sensor. Detailed implementation manners

[0052] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope protected by the embodiments of the present invention.

[0053] Please refer to Figure 1, for the temperature control of the fuel cell stack 1, it is currently mostly implemented based on a temperature control system. The direction indicated by the arrow in the figure is the flow path of the coolant. The temperature control system includes a water pump 2 and a temperature control valve 3 that connect the coolant inlet and the coolant outlet. The outlet of the coolant outlet is connected to the inlet of the water pump 2, the outlet of the water pump 2 is connected to the inlet of the temperature control valve 3. The temperature control valve 3 is a three-way structure. The first outlet of the temperature control valve 3 is connected to the coolant outlet to form a small circulation water path of the fuel cell stack 1. When the coolant temperature of the fuel cell stack 1 is relatively low, the temperature control valve 3 directly outputs the coolant to the fuel cell stack 1, and the coolant only circulates through the small circulation water path. The second outlet of the temperature control valve 3 is connected to the inlet of the radiator 4, and the outlet of the radiator 4 is connected to the coolant inlet to form a large circulation water path of the fuel cell stack 1. When the coolant temperature of the fuel cell stack 1 gradually rises, the coolant flow rate at the second outlet of the temperature control valve 3 gradually increases accordingly to dissipate heat through the large circulation water path. To monitor the cooling state of the fuel cell stack 1 in real time, an outlet temperature sensor 6 is installed at the coolant outlet, and an inlet temperature sensor 7 is installed at the coolant inlet to collect the temperatures of the coolant entering and leaving the stack respectively, and monitor the temperature inside the stack in real time. The temperature control system also includes a heater 5 (or called PTC, Positive Temperature Coefficient), which is used to heat the coolant in a low-temperature environment so that the fuel cell stack 1 operates at the target temperature. Since the heater 5 is used for the cold start condition of the fuel cell stack 1 and does not work at room temperature, the control of the heater 5 is not involved in the present invention.

[0054] Regarding the control of the temperature control valve, the existing control logic is to control the opening degree of the temperature control valve according to the coolant temperature out of the stack. When the coolant temperature out of the stack reaches the initial opening temperature of the temperature control valve (60 °C), the temperature control valve opens, and the fan of the radiator starts to work. The coolant after passing through the large circulation coolant circuit enters the stack. This control method will cause the coolant temperature entering the stack to drop suddenly. However, at this time, the coolant temperature out of the stack is still at a relatively high value. If the opening degree of the temperature control valve is controlled according to the coolant temperature out of the stack, the opening degree of the temperature control valve will continue to increase, resulting in a larger temperature difference between the coolant entering and leaving the stack, causing uneven temperature inside the stack, and possibly a situation where the voltage of a single fuel cell inside the stack is low.

[0055] Regarding the control of the water pump, the existing control logic is to control the water pump speed according to the coolant temperature. During the cold start process of the fuel cell stack, as the output power of the fuel cell stack increases, the stack temperature gradually rises, and the temperature difference between the coolant entering and leaving the stack is relatively large. The water pump speed increases. The overall control strategy does not consider the influence of temperature on the fuel cell stack; at the same time, during the cold start process, at this time, the actual temperatures of the coolant entering and leaving the stack are relatively low (below 40 °C), and there is no need for the water pump to operate at a high speed for heat dissipation, resulting in unnecessary power consumption.

[0056] Based on the deficiencies of the prior art, an embodiment of the present invention provides a method for controlling the temperature of a fuel cell stack. The following will specifically elaborate on how to implement this solution to improve the uniformity of the internal temperature of the fuel cell stack. Please refer to Figure 2 , Figure 2 which is a flowchart of a method for controlling the temperature of a fuel cell stack provided by an embodiment of the present invention. The method includes:

[0057] S11. Obtain the operating parameters of the fuel cell stack, where the operating parameters at least include the power to be output, the coolant inlet temperature, the minimum single-cell voltage, and the outlet temperature of the radiator.

[0058] Specifically, the power to be output (or the VCU required power) characterizes the power magnitude that the fuel cell stack needs to output externally in a control cycle. When the fuel cell stack is used to output electrical energy to a vehicle, it can be determined based on the required power issued by the voltage control unit (VCU, Vehicular Communication Unit) on the vehicle. The coolant inlet temperature characterizes the temperature when the coolant enters the fuel cell stack and can be obtained based on the acquisition by the inlet temperature sensor. The fuel cell stack is composed of multiple single-cell fuel cells. The minimum single-cell voltage characterizes the lowest voltage among all single-cell fuel cells and can be obtained by calculating after collecting each single-cell voltage. For example, the information of the single-cell voltage of the fuel cell stack sent by the cell voltage monitor (CVM) is collected in real time through the CAN (Controller Area Network) communication method, and then compared, and the minimum value among them is determined as the minimum single-cell voltage. The radiator dissipates heat through its built-in fan, and the outlet temperature characterizes the temperature at the outlet position of the radiator. After obtaining the operating parameters of the fuel cell stack, step S12 is entered.

[0059] S12. Obtain the minimum opening degree of the temperature control valve according to the power to be output and the heat dissipation temperature, where the heat dissipation temperature is the temperature difference between the coolant inlet temperature and the outlet temperature.

[0060] Specifically, after the fuel cell stack is started, when the coolant inlet temperature does not reach the temperature control valve opening temperature (for example, 40 °C), the temperature control valve enable signal is 0, and all the coolant flows in the small circulation loop; when the coolant inlet temperature to the stack reaches the temperature control valve opening temperature, the temperature control valve enable signal is set to 1. After the temperature control valve enable signal is set to 1, its minimum opening is determined. The heat dissipation temperature characterizes the cooling capacity of the system. Calibration experiments can be carried out based on the power to be output and the heat dissipation temperature to generate a two-dimensional data table including the minimum opening. The rows and columns of the two-dimensional data table represent the distributions of the heat dissipation temperature and the power to be output respectively, and the data corresponding to the rows and columns is the minimum opening of the temperature control valve. The minimum opening characterizes the minimum flow rate output by the temperature control valve during the temperature control process. After obtaining the power to be output and the heat dissipation temperature, the corresponding minimum opening is obtained by looking up the table. It can be understood that the higher the power to be output, the larger the minimum opening of the temperature control valve; the smaller the heat dissipation temperature, it indicates that the cooling capacity of the system needs to be improved, and the larger the minimum opening of the temperature control valve. After obtaining the minimum opening, step S13 is entered.

[0061] S13. Obtain the first feedforward speed of the water pump according to the power to be output and the coolant inlet temperature.

[0062] Specifically, since there is a lag in regulating the temperature of the fuel cell stack through the coolant, the adverse effect can be reduced by means of feedforward control. The first feedforward speed characterizes the corresponding speed of the water pump under feedforward control. Similarly, calibration experiments can be carried out based on the power to be output, the coolant inlet temperature and the first feedforward speed to generate a two-dimensional data table including the first feedforward speed. According to the current values of the power to be output and the coolant inlet temperature, the first feedforward speed is determined by looking up the table. It should be noted that when the fuel cell stack is started in the cold state, although the power to be output increases, the coolant inlet temperature to the stack is relatively low, and the first feedforward speed obtained by looking up the table is relatively low, which can avoid excessive heat dissipation caused by too high a water pump speed when the coolant inlet temperature to the stack is relatively low, resulting in a longer time for the fuel cell stack to reach the operating temperature range (60 - 80 °C), and reducing the power generation efficiency of the fuel cell stack. At the same time, the higher the power to be output, the higher the first feedforward speed; the higher the coolant inlet temperature to the stack, the higher the first feedforward speed. When the power to be output is relatively high, but the coolant inlet temperature is low, the obtained coolant inlet temperature is relatively low, avoiding excessive heat dissipation capacity caused by too high a water pump speed, resulting in the fuel cell stack temperature not reaching the operating range in time, affecting the operating efficiency of the fuel cell stack, increasing the power consumption of the water pump. After obtaining the first feedforward speed of the water pump, step S14 is entered.

[0063] S14. Compensate and process the first feedforward speed according to the lowest single-cell voltage to obtain the first target speed of the water pump.

[0064] Specifically, the first target speed is the working speed of the water pump to ensure uniform temperature of the fuel cell stack. The compensation coefficient can be determined based on the voltage value of the lowest single-chip voltage, for example, by a one-dimensional table lookup; then the first target speed is obtained based on the product of the compensation coefficient and the first feedforward speed. The compensation coefficient is determined by calibration experiments or the experience of technicians, and can improve the uniformity of the internal temperature of the fuel cell stack. Of course, a calibration experiment can also be performed based on the lowest single-chip voltage and the first feedforward speed to generate a two-dimensional data table containing the first target speed, and the first target speed can be determined by looking up the table according to the current values of the lowest single-chip voltage and the first feedforward speed.

[0065] In actual application, since the water pump speed has a great influence on the cooling of the fuel cell stack, the conventional compensation method may cause the first target speed to be determined inaccurately. Based on this, in a specific implementation, the operating parameters also include the water pump rated speed and the PID output speed S p , assuming the rated speed of the pump is S e , PID output speed is S p , the first feedforward speed is S q , where the PID output speed can be obtained through the output result of the PID controller. The enabling condition of the PID (proportion, proportion, differentiation) closed-loop algorithm of the water pump is that the temperature of the coolant entering the stack reaches the preset target temperature (for example, 50°C). The temperature difference of the coolant entering and leaving the stack is used as the feedback quantity. The target value of the coolant temperature entering and leaving the stack is obtained according to the calibration of the output power to be output. The temperature difference of the coolant entering and leaving the stack represents the heat dissipation capacity corresponding to the operation of the water pump. The first feedforward speed is compensated according to the minimum single-chip voltage to obtain the first target speed of the water pump, including:

[0066] If the minimum single-chip voltage is not greater than the preset voltage range, it means that the minimum single-chip voltage is small, and the temperature imbalance of the fuel cell stack has a greater impact. It is necessary to maximize the heat dissipation and minimize the temperature difference in and out of the stack to avoid the situation where the single-chip fuel voltage is too low due to excessive temperature difference. According to the formula S c =S e -(S q +S p ), obtain the water pump compensation speed S c .

[0067] If the lowest single chip voltage is within the preset voltage range and aS e -(S q +S p )>0, it means that the stack has the risk of low single-chip voltage, and the water pump needs to run at a higher speed, such as 50% of the rated speed, to ensure half of the heat dissipation capacity and keep the temperature difference between the inlet and outlet of the stack within a certain range. According to the formula Sc = aS e - (S q + S p ) to obtain the pump compensation speed S c , where a is a preset coefficient, which can be set through a calibration experiment. For example, a is set to 0.5.

[0068] If the lowest single-cell voltage is greater than the preset voltage range, or aS e - (S q + S p ) ≤ 0, it indicates that the fuel cell stack has no risk of low single-cell voltage temporarily and no speed compensation is required. Then, the pump compensation speed S c is set to 0.

[0069] The pump compensation speed represents the speed compensation value determined based on the lowest single-cell voltage. After determining the pump compensation speed, the first target speed is obtained according to the sum of the pump compensation speed and the first feedforward speed. After obtaining the first target speed, step S15 is entered.

[0070] S15: Adjust the temperature control valve to the minimum opening degree and control the pump to operate at the first target speed.

[0071] Specifically, the adjustment of the temperature control valve can be implemented based on the corresponding adjustment instruction to adjust the temperature control valve to the minimum opening degree; the operation of the pump can be implemented based on the corresponding drive instruction to make the pump operate at the first target speed.

[0072] In practical applications, since the temperature control error is related to the temperature control accuracy of the fuel cell stack, if the temperature control error is not considered, there will be a problem of inaccurate control. Based on this, in a specific embodiment, the operating parameters further include the coolant outlet temperature and the temperature error data of the coolant entering the fuel cell stack; before adjusting the temperature control valve to the minimum opening degree and controlling the pump to operate at the first target speed, the method further includes:

[0073] When the coolant inlet temperature reaches the preset target temperature, the coolant temperature difference is input to the PID controller to obtain the pump adjustment speed, and the updated first target speed is obtained according to the sum of the pump adjustment speed and the initial first target speed. The coolant temperature difference is the temperature difference between the coolant outlet temperature and the coolant inlet temperature.

[0074] Specifically, please refer to Figure 3, the first target speed = the first feedforward speed + the water pump adjustment speed + the water pump compensation speed. The water pump compensation speed is determined by the lowest single-chip voltage; the power to be output is output to the feedforward controller and the target value calculation module of the coolant temperature difference. The feedforward controller obtains the first feedforward speed based on the power to be output and the coolant inlet temperature; the water pump PID controller outputs the water pump adjustment speed based on the output result of the target value calculation module and the control error of the stack temperature. Summing up the three speeds can obtain the first target speed of the water pump. The summation result can also be input into the speed limit module. When the summation result is greater than the extreme value in the speed limit module, the corresponding extreme value is determined as the first target speed; when the summation result is not greater than the extreme value in the speed limit module, the summation result is determined as the first target speed.

[0075] Since the temperature control error is related to the control accuracy of the temperature control valve, if the temperature control error is not considered, there is a problem of inaccurate setting of the minimum opening. Based on this, the minimum opening is updated according to the historical cycle error and the current cycle error of the temperature error data. Please refer to Figure 4 , in the control strategy of the temperature control valve, an incremental PID controller can be set to update the minimum opening of the next adjustment cycle based on the historical cycle error and the current cycle error. The incremental PID is used to perform closed-loop control on the temperature control valve. Since the coolant inlet temperature into the stack changes more sensitively than the outlet temperature, the coolant inlet temperature drops rapidly when the temperature control valve opens, which can better reflect the heat dissipation capacity of the thermal management subsystem. Therefore, it is used as the feedback quantity. In addition, compared with the traditional PID, the incremental PID algorithm improves integral saturation, reduces overshoot, and improves dynamic performance. The algorithm does not require accumulation and is only related to the recent deviation values, reducing the operation load of the controller.

[0076] In a specific implementation, updating the minimum opening according to the historical cycle error and the current cycle error of the temperature error data includes:

[0077] According to the formula K = K p ×(e k -e k-1 ) + K I ×e k + K D ×(e k -2e k-1 + e k-2 ), the adjustment opening K is obtained, where e k is the current cycle error, e k-1 is the error of the previous cycle of the current cycle error, e k-2 is the error of the previous cycle of e k-1 , K p is the proportionality coefficient, K I is the integral coefficient, K Dis the differential coefficient; the updated minimum opening degree is obtained based on the sum of the adjustment opening degree and the initial minimum opening degree.

[0078] Specifically, while restricting the temperature control valve to adjust to the minimum opening degree, the incremental PID algorithm is used to perform closed-loop control on the temperature control valve to update its adjustment opening degree; the temperature error data represents the difference between the actual measured value of the coolant inlet temperature and the target value of the coolant inlet temperature, which can be calibrated by looking up a table according to the power to be output. The proportional coefficient, integral coefficient, and differential coefficient can be determined through calibration experiments to improve the control accuracy of the minimum opening degree of the temperature control valve. Since it is based on the errors of the last three adjustment cycles, the load of system operation can be reduced.

[0079] After regulating the temperature control valve and the water pump based on the above method, the temperature uniformity in the fuel cell stack can be effectively improved. However, as an important component in the temperature control system, if the control accuracy of the radiator is not improved after the coolant undergoes a large circulation, it will also have an adverse impact on the temperature uniformity in the fuel cell stack. The existing control strategy is to control the fan speed in the radiator according to the coolant outlet temperature. When the temperature control valve is initially opened, the coolant inlet temperature drops suddenly, and the coolant outlet temperature is still at a relatively high value. Since the fan speed is controlled according to the coolant outlet temperature, the speed continues to increase, resulting in an increase in the temperature difference between the coolant inlet and outlet of the stack, leading to uneven temperature inside the stack and possibly a situation where the single-cell voltage of the stack is low.

[0080] To solve the above problems, in a specific implementation, the operating parameters further include the valve opening degree of the temperature control valve; after adjusting the temperature control valve to the minimum opening degree and controlling the water pump to operate at the target speed, the method further includes:

[0081] When the outlet air temperature is not less than the first set threshold and the valve opening degree is greater than the second set threshold, the second target speed is obtained according to the preset second feedforward speed and the speed correction model; control the fan of the radiator to operate at the second target speed.

[0082] Specifically, when the outlet temperature is less than 40°C and the opening degree of the temperature control valve is not greater than 30% of the total opening degree, the fan does not operate; when the outlet temperature is not less than the first set threshold and the valve opening degree is greater than the second set threshold, it indicates that the fan needs to be turned on for cooling. Then, query the one-dimensional data table to obtain the second feedforward speed. The one-dimensional data table is a corresponding relationship table between the power to be output and the fan speed. The greater the power to be output, the higher the corresponding second feedforward speed. Among them, the first set threshold and the second set threshold can be determined according to actual needs. For example, the first set threshold is set to 45°C, and the second set threshold is set to 30% of the total opening degree of the temperature control valve. The speed correction model is a model that corrects based on the deviation between the actual temperature and the target temperature of the fuel cell stack. When the temperature deviation is too large, the correction value output by the speed correction model is larger, and vice versa. The second target speed can be determined based on the sum of the second feedforward speed and the output result of the model, and then the fan operation can be controlled based on the second target speed.

[0083] In a specific implementation manner, obtaining the second target speed according to the preset second feedforward speed and the speed correction model includes:

[0084] Find the corresponding speed value in the preset comparison table according to the power to be output to obtain the second feedforward speed, where the preset comparison table is a corresponding relationship table in which the fan speed increases with the increase of the power to be output; input the correction parameter into the speed correction model to obtain the corrected speed, where the correction parameter includes at least one of the valve opening degree, the outlet temperature, and the vehicle driving speed; obtain the second target speed according to the sum of the second feedforward speed and the corrected speed.

[0085] Specifically, the corresponding corrected speed can be obtained through the correction parameter. For example, when the correction parameter is the valve opening degree, determine the opening degree corrected speed according to the valve opening degree. If the valve opening degree is greater than the opening degree threshold, the opening degree corrected speed increases with the increase of the valve opening degree; if the valve opening degree is not greater than the opening degree threshold, the opening degree corrected speed decreases with the decrease of the valve opening degree. Similarly, when the correction parameter is the outlet temperature, determine the temperature corrected speed according to the outlet temperature; when the correction parameter is the vehicle driving speed, determine the vehicle speed corrected speed according to the vehicle driving speed. Calculate the second target speed according to the formula: Second target speed = Second feedforward speed + Opening degree corrected speed + Temperature corrected speed + Vehicle speed corrected speed.

[0086] Please refer to Figure 5 , the second feedforward speed can input the power to be output to the feedforward controller, and obtain the second feedforward speed based on the output result of the feedforward controller; obtain the temperature deviation based on the measured value and the actual value of the outlet temperature of the radiator, and correct the fan speed based on this temperature deviation; perform compensation based on the vehicle speed and the ambient temperature where the fuel cell stack is located to obtain the corresponding compensation value, and obtain the second target speed based on the summation result of the second feedforward speed and all compensation values, and output it to the fan controller to control the running speed of the fan.

[0087] In practical applications, since the opening degree of the temperature control valve and the fan speed are both sensitive to the temperature uniformity inside the fuel cell stack, if they are adjusted simultaneously, abnormal temperature fluctuations may occur. Based on this, in a specific embodiment, the correction parameters include the valve opening degree and the stack temperature. Inputting the correction parameters into the speed correction model to obtain the corrected speed includes:

[0088] If the valve opening degree is not within the preset opening degree range, the corrected speed output by the speed correction model is configured to change correspondingly following the valve opening degree; if the valve opening degree is within the preset opening degree range, the valve opening degree of the temperature control valve is adjusted according to the stack temperature until the valve opening degree is not within the preset opening degree range, and the output result of the speed correction model is determined as the corrected speed.

[0089] Specifically, when the valve opening degree is not within the preset opening degree range, it indicates that the cooling method emphasizes the large cycle or the small cycle. Implementing the corrected speed to change correspondingly following the valve opening degree will not cause a large impact on temperature fluctuations. Then, the corrected speed output by the speed correction model is configured to change correspondingly following the valve opening degree. Among them, the preset opening degree range can be set to 40%-70% of the total opening degree of the temperature control valve. When the valve opening degree is greater than 70%, the fan speed will only follow and increase in gear; when the opening degree of the temperature control valve is less than 40%, the fan will only follow and decrease in gear. When the valve opening degree is within the preset opening degree range, it indicates that there are both large cycles and small cycles in the cooling cycle. Adjusting the valve opening degree of the temperature control valve and the fan speed simultaneously will cause large fluctuations in the temperature inside the fuel cell stack. Then, the temperature of the fuel cell stack is adjusted by adjusting the valve opening degree of the temperature control valve. When the adjustment ability of the temperature control valve reaches a certain limit (greater than 70% or less than 40%), the fan will perform a closed-loop speed correction to avoid abnormal temperature fluctuations caused by the simultaneous change of the valve opening degree of the temperature control valve and the fan speed.

[0090] It should be noted that since the fan speed has a large operating range, there is a close correlation with the temperature uniformity. Based on this, the control method of the present invention further includes: obtaining the fan correction speed calculation setting period by calibrating and looking up a table according to the power to be output, to avoid frequent changes in the fan speed due to the temperature fluctuation of the radiator. Setting a delay time for the adjustment period of the fan speed according to the change amount of the power to be output, to avoid the situation that when the system runs to the high-power load reduction, the power to be output decreases, resulting in a sharp decrease in the fan speed. However, at this time, the temperature at the outlet of the radiator is relatively high, which cannot meet the heat dissipation requirements of the fuel cell system. It is also possible to obtain the fan speed change period by two-dimensional looking up a table according to the power to be output and the difference between the power to be output and the actual power of the system. Adjusting the fan speed change period in the low-power section to prevent frequent changes in the speed from causing temperature fluctuations in the fuel cell stack and reducing the power generation efficiency.

[0091] Next, the embodiments of the present invention will comprehensively elaborate on the control timing of the water pump, the temperature control valve, and the fan when the fuel cell system is applied to vehicle driving:

[0092] After the fuel cell system is started, the water pump is started first. The FCCU (Fuel Cell Control Unit) sends the water pump enable signal to 1 and sends the target speed of the water pump according to the target current of the fuel cell stack and the temperature difference between the inlet and outlet of the fuel cell stack, so that the coolant circulates in the fuel cell stack and makes the internal temperature of the fuel cell stack uniform.

[0093] When the coolant inlet temperature is greater than 40°C, the temperature control valve is opened. The FCCU sends the temperature control valve enable signal to 1 and closed-loop controls the opening of the temperature control valve according to the inlet temperature of the fuel cell stack.

[0094] Decouple the control of the fan and the temperature control valve. First, control the temperature control valve to adjust the temperature of the fuel cell stack. When the opening of the temperature control valve reaches a certain value, then turn on the fan for adjustment.

[0095] When the fan outlet temperature is less than 40°C and the opening of the temperature control valve is not greater than 30%, the fan enable signal is 0 and it does not work.

[0096] When the fan outlet temperature is not less than 45°C and the opening of the temperature control valve is greater than 30%, the fan enable signal is set to 1 and it starts to work.

[0097] During the operation of the fuel cell stack, the temperature control valve, the water pump and the fan are regulated in real time based on the above strategy to ensure the uniformity of the internal temperature of the fuel cell stack.

[0098] When the fuel cell system shuts down, the system power is reduced. After the shutdown purge is completed, when the fan outlet temperature is less than 40°C and the opening of the temperature control valve is not greater than 30%, the fan enable signal is set to 0, the fan target speed is 0, and the fan is turned off.

[0099] When the coolant inlet temperature is less than 40°C, the temperature control valve enable signal is set to 0, the temperature control valve target opening is set to 0, and the temperature control valve is closed. When the coolant outlet temperature of the fuel cell stack is less than 40°C, the water pump enable signal is set to 0, the water pump target speed is set to 0, and the water pump is closed; the shutdown of the fuel cell system is completed.

[0100] Based on the same inventive concept as the control method, an embodiment of the present invention further provides a temperature control device for a fuel cell stack, which is applied to a temperature control system of a fuel cell stack for temperature control. The temperature control system includes a water pump and a temperature control valve connecting the coolant inlet and the coolant outlet, and a radiator connecting the coolant inlet and the temperature control valve; please refer to Figure 6 , the device includes:

[0101] An acquisition module 601, configured to acquire the operating parameters of the fuel cell stack, where the operating parameters at least include the power to be output, the coolant inlet temperature, the lowest single-cell voltage, and the outlet temperature of the radiator;

[0102] The first acquisition module 602 is configured to obtain the minimum opening degree of the temperature control valve according to the to-be-output power and the heat dissipation temperature, where the heat dissipation temperature is the temperature difference between the coolant inlet temperature and the air outlet temperature;

[0103] The second acquisition module 603 is configured to obtain the first feedforward speed of the water pump according to the to-be-output power and the coolant inlet temperature;

[0104] The third acquisition module 604 is configured to perform a compensation process on the first feedforward speed according to the lowest single-chip voltage to obtain the first target speed of the water pump;

[0105] The first control module 605 is configured to adjust the temperature control valve to the minimum opening degree and control the water pump to operate at the first target speed.

[0106] In an optional embodiment, the operating parameters further include the rated speed of the water pump and the PID output speed S p , assuming the rated speed of the water pump is S e , and the PID output speed is S p , the third acquisition module includes:

[0107] The first acquisition sub-module is configured to, when the lowest single-chip voltage is not greater than the preset voltage range, according to the formula S c =S e -(S q +S p ), obtain the water pump compensation speed S c ;

[0108] The second acquisition sub-module is configured to, when the lowest single-chip voltage is within the preset voltage range and aS e -(S q +S p )>0, according to the formula S c =aS e -(S q +S p ), obtain the water pump compensation speed S c , where a is a preset coefficient;

[0109] The setting sub-module is configured to, when the lowest single-chip voltage is greater than the preset voltage range, or aS e -(S q +S p )≤0, set the water pump compensation speed S c to 0;

[0110] The third acquisition sub-module is configured to obtain the first target speed according to the sum of the water pump compensation speed and the first feedforward speed.

[0111] In an alternative embodiment, the operating parameters further include the coolant outlet temperature and the temperature error data of the coolant entering the fuel cell stack; the device further includes:

[0112] A fourth obtaining module, configured to, when the coolant inlet temperature reaches a preset target temperature, input the coolant temperature difference into a PID controller to obtain a regulated pump speed, and obtain an updated first target speed according to the sum of the regulated pump speed and the initial first target speed;

[0113] An updating module, configured to update the minimum opening according to the historical cycle error and the current cycle error of the temperature error data.

[0114] In an alternative embodiment, the updating module includes:

[0115] A fourth obtaining sub-module, configured to obtain a regulated opening K according to the formula K = K p ×(e k -e k-1 ) + K I ×e k +K D ×(e k -2e k-1 +e k-2 ), where e k is the current cycle error, e k-1 is the previous cycle error of the current cycle error, e k-2 is the previous cycle error of e k-1 , K p is the proportionality coefficient, K I is the integral coefficient, and K D is the differential coefficient;

[0116] A fifth obtaining sub-module, configured to obtain an updated minimum opening according to the sum of the regulated opening and the initial minimum opening.

[0117] In an alternative embodiment, the operating parameters further include the valve opening of the temperature control valve; the device further includes:

[0118] A fifth obtaining module, configured to, when the air outlet temperature is not less than a first set threshold and the valve opening is greater than a second set threshold, obtain a second target speed according to a preset second feedforward speed and a speed correction model;

[0119] A second control module, configured to control the fan of the radiator to operate at the second target speed.

[0120] In an alternative embodiment, the fifth obtaining module includes:

[0121] The sixth acquisition sub-module is configured to look up a corresponding rotational speed value in a preset comparison table according to the to-be-output power to obtain the second feedforward rotational speed, where the preset comparison table is a corresponding relationship table of the fan rotational speed following the increase of the to-be-output power;

[0122] The seventh acquisition sub-module is configured to input a correction parameter into the rotational speed correction model to obtain a corrected rotational speed, where the correction parameter includes at least one of the valve opening degree, the air outlet temperature, and the vehicle driving speed;

[0123] The eighth acquisition sub-module is configured to obtain the second target rotational speed according to the sum of the rotational speeds of the second feedforward rotational speed and the corrected rotational speed.

[0124] In an optional embodiment, the correction parameter includes the valve opening degree and the stack temperature, and the seventh acquisition sub-module includes:

[0125] An output unit, configured to, when the valve opening degree is not within a preset opening degree range, configure the corrected rotational speed output by the rotational speed correction model to change correspondingly following the valve opening degree;

[0126] A determination unit, configured to, when the valve opening degree is within the preset opening degree range, adjust the valve opening degree of the temperature control valve according to the stack temperature, and when the valve opening degree is not within the preset opening degree range, determine the output result of the rotational speed correction model as the corrected rotational speed.

[0127] Based on the same inventive concept as the control method, an embodiment of the present invention further provides an electronic device, including a processor and a memory, the memory is coupled to the processor, the memory stores instructions, and when the instructions are executed by the processor, the electronic device executes the steps of any one of the control methods.

[0128] Based on the same inventive concept as the control method, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the steps of any one of the control methods are implemented.

[0129] The technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0130] When performing temperature control applied to a fuel cell stack, by obtaining the power to be output by the fuel cell stack, the coolant inlet temperature, the minimum single-cell voltage, and the air outlet temperature of the radiator, the minimum opening degree of the temperature control valve is obtained based on the power to be output and the heat dissipation temperature, preventing excessive opening from causing uneven temperature inside the stack. At the same time, based on the feedforward control method, the first feedforward speed of the water pump is obtained according to the power to be output and the coolant inlet temperature, and the first feedforward speed is compensated according to the minimum single-cell voltage to obtain the first target speed of the water pump, preventing unreasonable setting of the water pump speed and causing too low single-cell voltage due to uneven temperature. When the temperature control valve is adjusted to the minimum opening degree and the water pump is controlled to operate at the first target speed, the temperature inside the stack can be made as uniform as possible, thereby improving the uniformity of the temperature inside the fuel cell stack.

[0131] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0132] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (modules, systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded computer, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0133] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0134] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus, causing a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process, such that the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one process or a plurality of processes and / or blocks Figure 1 one process or a plurality of processes and / or blocks Figure 1 steps for implementing the functions specified in one block or a plurality of blocks.

[0135] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made by those skilled in the art once they learn of the basic inventive concept. Therefore, the appended claims are intended to be construed to cover the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0136] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A temperature control method for a fuel cell stack, characterized in that The temperature control system applied to the fuel cell stack performs temperature control. The temperature control system includes a water pump and a temperature control valve that connect the coolant inlet and the coolant outlet, and a radiator that connects the coolant inlet and the temperature control valve. The method includes: Obtain the operating parameters of the fuel cell stack, where the operating parameters at least include the power to be output, the coolant inlet temperature, the minimum single-cell voltage, and the air outlet temperature of the radiator; Obtain the minimum opening degree of the temperature control valve according to the power to be output and the heat dissipation temperature, where the heat dissipation temperature is the temperature difference between the coolant inlet temperature and the air outlet temperature; Obtain the first feedforward speed of the water pump according to the power to be output and the coolant inlet temperature; Perform compensation processing on the first feedforward speed according to the minimum single-cell voltage to obtain the first target speed of the water pump; Adjust the temperature control valve to the minimum opening degree and control the water pump to operate at the first target speed; The operating parameters further include the rated speed of the water pump and the PID output speed S p , and let the rated speed of the water pump be S e , the PID output speed be S p , and the first feedforward speed be S q ; The compensation processing of the first feedforward speed according to the lowest single-chip voltage to obtain the first target speed of the water pump includes: If the lowest single-chip voltage is not greater than the preset voltage range, according to the formula S c = S e -(S q + S p ), the pump compensation speed S c ; If the lowest single-chip voltage is within the preset voltage range, and aS e -(S q +S p ) > 0, according to the formula S c = aS e -(S q +S p ), the pump compensation speed S c is obtained, where a is a preset coefficient; If the lowest single-chip voltage is greater than the preset voltage range, or aS e -(S q +S p ) ≤ 0, set the pump compensation speed S c to 0; Obtain the first target speed according to the sum of the compensation speed of the water pump and the first feedforward speed.

2. The temperature control method of the fuel cell stack according to claim 1, wherein The operating parameters further include the coolant outlet temperature and the temperature error data of the coolant entering the fuel cell stack; Before adjusting the temperature control valve to the minimum opening degree and controlling the water pump to operate at the first target speed, the method further includes: When the coolant inlet temperature reaches the preset target temperature, input the coolant temperature difference into the PID controller to obtain the water pump adjustment speed, and obtain the updated first target speed according to the sum of the water pump adjustment speed and the initial first target speed; Update the minimum opening degree according to the historical cycle error and the current cycle error of the temperature error data.

3. The temperature control method of the fuel cell stack according to claim 2, characterized in that, The updating the minimum opening degree according to the historical cycle error and the current cycle error of the temperature error data includes: According to the formula K = K p ×(e k - e k-1 ) + K I ×e k + K D ×(e k - 2e k-1 + e k-2 ), the adjusted opening K is obtained, where e k is the current cycle error, e k-1 is the previous cycle error of the current cycle error, e k-2 is the previous cycle error of e k-1 , K p is the proportionality coefficient, K I is the integral coefficient, K D is the differential coefficient; Obtain the updated minimum opening degree according to the sum of the adjustment opening degree and the initial minimum opening degree.

4. The temperature control method of the fuel cell stack according to claim 1, characterized in that The operating parameters further include the valve opening degree of the temperature control valve. After adjusting the temperature control valve to the minimum opening degree and controlling the water pump to operate at the target speed, the method further includes: When the air outlet temperature is not less than the first set threshold and the valve opening degree is greater than the second set threshold, obtain the second target speed according to the preset second feedforward speed and the speed correction model; Control the fan of the radiator to operate at the second target speed.

5. The temperature control method of the fuel cell stack according to claim 4, wherein The obtaining the second target speed according to the preset second feedforward speed and the speed correction model includes: Look up the corresponding speed value in the preset look-up table according to the power to be output to obtain the second feedforward speed, where the preset look-up table is a corresponding relationship table in which the fan speed increases with the increase of the power to be output; Input the correction parameter into the speed correction model to obtain the correction speed, where the correction parameter at least includes one of the valve opening degree, the air outlet temperature, and the vehicle driving speed; Obtain the second target speed according to the sum of the second feedforward speed and the correction speed.

6. The temperature control method of the fuel cell stack according to claim 5, wherein, The correction parameters include the valve opening and the stack temperature. Inputting the correction parameters into the rotational speed correction model to obtain a corrected rotational speed includes: If the valve opening is not within a preset opening range, configure the corrected rotational speed output by the rotational speed correction model to change correspondingly following the valve opening; If the valve opening is within the preset opening range, adjust the valve opening of the temperature control valve according to the stack temperature until the valve opening is not within the preset opening range, and determine the output result of the rotational speed correction model as the corrected rotational speed.

7. A temperature control device for a fuel cell stack, characterized in that Adopt the temperature control method of the fuel cell stack according to any one of claims 1-6 to perform temperature control in the temperature control system of the fuel cell stack. The temperature control system includes a water pump and a temperature control valve connecting the coolant inlet and the coolant outlet, and a radiator connecting the coolant inlet and the temperature control valve; the device includes: An acquisition module, configured to acquire the operating parameters of the fuel cell stack, where the operating parameters at least include the power to be output, the coolant inlet temperature, the minimum single-cell voltage, and the outlet temperature of the radiator; A first obtaining module, configured to obtain the minimum opening of the temperature control valve according to the power to be output and the heat dissipation temperature, where the heat dissipation temperature is the temperature difference between the coolant inlet temperature and the outlet temperature; A second obtaining module, configured to obtain the first feedforward rotational speed of the water pump according to the power to be output and the coolant inlet temperature; A third obtaining module, configured to perform a compensation process on the first feedforward rotational speed according to the minimum single-cell voltage to obtain the first target rotational speed of the water pump; A first control module, configured to adjust the temperature control valve to the minimum opening and control the water pump to operate at the first target rotational speed.

8. An electronic device, characterized in that, It includes a processor and a memory. The memory is coupled to the processor. The memory stores instructions, and when the instructions are executed by the processor, the electronic device executes the steps of the method according to any one of claims 1-6.

9. A computer-readable storage medium, on which a computer program is stored, characterized in that, When the program is executed by the processor, it implements the steps of the method according to any one of claims 1-6.

Images