Discharge control method for fuel cell system and fuel cell system

Abstract

The present application provides a discharge control method for a fuel cell system, the fuel cell system comprising: a stack having a positive electrode and a negative electrode; a current sensor for detecting a current output from the positive electrode; the voltage sensor is used for detecting the voltage between the positive electrode and the negative electrode; the discharging circuit comprises a discharging resistor, one end of the discharging circuit is connected with the positive electrode, and the other end of the discharging circuit is connected with the negative electrode; a temperature sensor for detecting the temperature of the discharge resistor; and a control unit receiving a current value from the current sensor, a voltage value from the voltage sensor, and a temperature value from the temperature sensor, in which the discharge control method includes: receiving an instruction to perform a discharge operation; judging whether the temperature value is greater than a first temperature threshold; under the condition that the temperature value is smaller than or equal to the first temperature threshold value, the discharging circuit is made to execute discharging operation; and when the voltage value is smaller than or equal to the preset voltage value, the discharging circuit stops discharging operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fuel cell, and in particular, to a discharge control method for a fuel cell system and the fuel cell system. BACKGROUND

[0002] With the development of clean energy technology, fuel cell systems are widely used as power sources in many industries (e.g., electric vehicles). In a fuel cell system, electricity is generated by the reaction of hydrogen and oxygen in the air in an electric pile, and is delivered to various loads or high-voltage battery packs after being boosted by a boost DC / DC module. When an emergency situation (e.g., a failure) occurs in the fuel cell system, in order to discharge the energy in the electric pile and reduce the direct current bus voltage of the electric pile to a safe range, a discharge circuit is usually provided in the fuel cell system. For example, the national standard GB / T 18488-1 requires that the direct current bus voltage of the electric pile should be reduced to 60V or below within 3 seconds after the emergency shutdown of the fuel cell system, so a high-efficiency and reliable discharge control strategy is required.

[0003] In the prior art, a discharge circuit connected in parallel between the direct current bus of the electric pile is usually used for discharging. The discharge circuit usually includes a switch and a discharge resistor connected in series with each other, and when discharging is required, the control unit makes the switch closed, so that the energy in the electric pile is converted into heat by the discharge resistor and consumed. Therefore, the temperature of the discharge resistor will quickly rise, and if the temperature is too high, the discharge resistor may be burned out due to overheating. However, there is no temperature sensor in the existing fuel cell system for detecting the temperature of the discharge resistor. Therefore, when emergency situations occur continuously in multiple operating cycles of the fuel cell system, there is a risk of overheating of the discharge resistor, and this risk is not effectively monitored.

[0004] In addition, according to the existing discharge control strategy, the discharge circuit is only allowed to be triggered once in one operating cycle of the fuel cell system to avoid overheating of the discharge resistor. However, after the discharge circuit is triggered, the residual gas in the electric pile or the pipeline leakage may cause the voltage of the electric pile to rise again. In this case, if multiple discharges cannot be performed, it will pose a risk to the safety of the entire fuel cell system.

[0005] Therefore, it is necessary to improve the existing discharge control method for the fuel cell system and the fuel cell system. SUMMARY

[0006] The present application aims to provide a discharge control method for a fuel cell system and the fuel cell system to overcome at least one of the above technical problems.

[0007] To this end, according to an aspect of the present application, there is provided a discharge control method for a fuel cell system, the fuel cell system including: a stack having a positive electrode and a negative electrode; a current sensor configured to detect a current output from the positive electrode; a voltage sensor configured to detect a voltage between the positive electrode and the negative electrode; a discharge circuit including a discharge resistor, one end of the discharge circuit being coupled to the positive electrode, the other end of the discharge circuit being coupled to the negative electrode; a temperature sensor configured to detect a temperature of the discharge resistor; and a control unit receiving a current value from the current sensor, a voltage value from the voltage sensor, and a temperature value from the temperature sensor, wherein the discharge control method includes: receiving an instruction to perform a discharge operation; determining whether the temperature value is greater than a first temperature threshold; causing the discharge circuit to perform the discharge operation in a case where the temperature value is less than or equal to the first temperature threshold; and causing the discharge circuit to stop the discharge operation when the voltage value is less than or equal to a predetermined voltage value.

[0008] According to another aspect of the present application, there is provided a fuel cell system including: a stack having a positive electrode and a negative electrode; a current sensor configured to detect a current output from the positive electrode; a voltage sensor configured to detect a voltage between the positive electrode and the negative electrode; a discharge circuit including a discharge resistor, one end of the discharge circuit being coupled to the positive electrode, the other end of the discharge circuit being coupled to the negative electrode; a temperature sensor configured to detect a temperature of the discharge resistor; and a control unit receiving a current value from the current sensor, a voltage value from the voltage sensor, and a temperature value from the temperature sensor, wherein the control unit is configured to perform the above-described discharge control method.

[0009] According to still another aspect of the present application, there is provided a computer program product including computer instructions which, when executed by a processor, cause the processor to perform the above-described discharge control method.

[0010] In the technical solution in the present application, the temperature sensor is provided to monitor the temperature of the discharge resistor, so as to avoid the discharge resistor from overheating when performing the discharge operation at a high temperature, and to provide safer protection for the discharge resistor. In addition, the discharge resistor can perform the discharge operation multiple times in one operation cycle of the fuel cell system when the temperature of the discharge resistor is allowed. Therefore, the electrical safety of the fuel cell system in an emergency can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0011] Exemplary embodiments of this application will now be described in detail with reference to the accompanying drawings. It should be understood that the embodiments described below are for illustrative purposes only and are not intended to limit the scope of this application.

[0012] In the picture:

[0013] Figure 1 This is a schematic block diagram of a fuel cell system according to an embodiment of this application;

[0014] Figure 2 This is a schematic flowchart of a discharge control method according to an embodiment of this application. Detailed Implementation

[0015] The preferred embodiments of this application are described in detail below with reference to examples. Those skilled in the art should understand that these exemplary embodiments do not imply any limitation on this application. The exemplary embodiments of this application do not imply that the discharge control method of this application cannot include other steps, nor that the fuel cell system of this application cannot include other modules or components. Unless otherwise specified, features in the embodiments of this application can be combined with each other. It should be understood that the number, position, and order of steps of each module and component in the drawings are not intended to limit this application. The drawings are not drawn to scale, but some modules and components have been scaled for clarity.

[0016] The following reference Figures 1 to 2 This document describes exemplary embodiments of the fuel cell system and the discharge control method for the fuel cell system of this application.

[0017] like Figure 1 As shown, according to one embodiment of this application, the fuel cell system 100 includes: a fuel cell stack 10, a boost DC / DC module 20, a high-voltage battery pack 30, a control unit 40, and a load 50, wherein, in terms of circuit connection, the boost DC / DC module 20 and the load 50 are located between the fuel cell stack 10 and the high-voltage battery pack 30.

[0018] The fuel cell stack 10 typically includes multiple fuel cell units stacked together. Each fuel cell unit may include two electrode plates and a membrane electrode assembly sandwiched between the two electrode plates. Electricity is generated through an electrochemical reaction when hydrogen and air are supplied to the anode and cathode sides of each fuel cell unit, respectively. The stack 10 has a positive and a negative electrode, and the generated electricity can be boosted by a boost DC / DC module 20 and supplied to a load 50 or a high-voltage battery pack 30. The stack 10 can be a common structure in the art, and therefore will not be described in further detail herein.

[0019] When the stack 10 is normally operated, the generated electric power can power the load 50 (e.g., an electric motor of an electric vehicle) and / or the high-voltage battery pack 30. When the stack 10 is stopped, the high-voltage battery pack 30 can power the load 50.

[0020] The boost DC / DC module 20 includes a current sensor 21, a voltage sensor 22, a switch 23, and a discharge resistor 24. The current sensor 21 is configured to detect a current output from the positive electrode. The voltage sensor 22 is configured to detect a voltage between the positive electrode and the negative electrode. The switch 23 and the discharge resistor 24 are connected in series with each other to form a discharge circuit, one end of the discharge circuit is connected to the positive electrode, and the other end of the discharge circuit is connected to the negative electrode. In addition, the boost DC / DC module 20 further includes a power module 26, which can include capacitors, inductors, diodes, etc. for boost conversion. It should be noted that, in the embodiment shown, the discharge circuit is shown as part of the boost DC / DC module 20, but the present application is not limited thereto, and the discharge circuit can be provided as a separate circuit independent of the boost DC / DC module 20. Similarly, the current sensor 21 and the voltage sensor 22 can also be provided separately from the boost DC / DC module. Figure 1

[0021] According to one embodiment of the present application and as shown in FIG. 1, the fuel cell system 100 further includes a temperature sensor 25 configured to detect a temperature of the discharge resistor 24. By providing the temperature sensor 25, the temperature of the discharge resistor 24 can be monitored, and the discharge resistor 24 can be prevented from overheating when performing a discharge operation at a high temperature, and multiple discharge operations can be allowed to be performed within one operating cycle of the fuel cell system when the temperature of the discharge resistor 24 is allowed. Figure 1 As shown in FIG. 1, the fuel cell system 100 further includes a control unit 40 that receives a current value from the current sensor 21, a voltage value from the voltage sensor 22, and a temperature value from the temperature sensor 25. The control unit 40 is configured to perform a discharge control method for the fuel cell system, which will be described in detail below.

[0022] Figure 1 As shown in FIG. 1, the fuel cell system 100 further includes a control unit 40 that receives a current value from the current sensor 21, a voltage value from the voltage sensor 22, and a temperature value from the temperature sensor 25. The control unit 40 is configured to perform a discharge control method for the fuel cell system, which will be described in detail below. Figure 2

[0023] As shown in FIG. 1, the fuel cell system 100 further includes a control unit 40 that receives a current value from the current sensor 21, a voltage value from the voltage sensor 22, and a temperature value from the temperature sensor 25. The control unit 40 is configured to perform a discharge control method for the fuel cell system, which will be described in detail below. Figure 2

[0024] ​​​​At step 212, it is determined whether the temperature value from the temperature sensor 25 is greater than a first temperature threshold T1. The first temperature threshold T1 can be defined as a temperature threshold that allows the discharge resistor 24 to perform the discharge operation without being burned out.

[0025] At step 213, in the case where the temperature value from the temperature sensor 25 is less than or equal to the first temperature threshold T1, the discharge circuit is caused to perform the discharge operation, for example, by closing the switch 23. Thus, the energy remaining in the stack 10 is consumed by the discharge resistor 24 to be converted into heat.

[0026] With the discharge operation being performed, at step 214, when the voltage value between the positive electrode and the negative electrode of the stack 10 is less than or equal to a predetermined voltage value (for example, 60 volts), the discharge circuit is caused to stop the discharge operation, for example, by opening the switch 23.

[0027] In the discharge control method 200 of the present application described above, by providing the temperature sensor 25, the temperature of the discharge resistor 24 can be monitored, so as to avoid the discharge operation being performed in the case where the temperature of the discharge resistor 24 is already high, which can cause the discharge resistor 24 to be burned out due to overheating. For example, the first temperature threshold T1 can be 120 degrees, and when the current temperature of the discharge resistor 24 is greater than 120 degrees, the discharge operation can cause the discharge resistor 24 to be burned out if performed. It should be noted that the above-illustrated first temperature threshold T1 is only exemplary, and the first temperature threshold T1 can also be a value different from 120 degrees according to the specifications of the discharge resistor.

[0028] To avoid the discharge operation being performed in the case where the temperature of the discharge resistor 24 is too high and to alert the user, in the case where the temperature value of the temperature sensor 25 is greater than the first temperature threshold T1, the discharge control method 200 performs step 217: the discharge operation is prohibited from being performed and an alarm is issued so as to prompt the user to perform a treatment other than the discharge operation.

[0029] After a discharge operation, the energy consumed by the discharge resistor 24 is converted into heat to increase the temperature of the discharge resistor 24. Due to the residual reaction gas in the stack 10 or pipeline leakage, etc., the voltage of the stack 10 can be increased again. In this case, if the discharge operation is performed again in the case where the temperature of the discharge resistor 24 is already high, the discharge resistor 24 can be burned out. Thus, at step 215, after the discharge circuit is caused to stop the discharge operation, it is determined whether the temperature value of the temperature sensor 25 is greater than a second temperature threshold T2. The second temperature threshold T2 can be defined as a temperature threshold that allows the discharge resistor 24 to perform the discharge operation without being burned out. pThe temperature threshold behind which the discharge resistor 24 performs the discharge operation. For example, the second temperature threshold T2 can be 180 degrees. It should be pointed out that the second temperature threshold T2 can also be a value different from 180 degrees according to the specifications of the discharge resistor 24. In the case where the temperature of the discharge resistor 24 is greater than the second temperature threshold T2, step 217 is performed: the discharge operation is prohibited and an alarm is issued. Conversely, in the case where the temperature of the discharge resistor 24 is less than or equal to the second temperature threshold T2, it is necessary to determine whether the voltage of the stack 10 has risen and whether the discharge operation needs to be performed again. Since the rise in voltage of the stack 10 takes time, after a predetermined time interval t p The voltage of the stack is determined to be greater than a predetermined voltage V p (For example, 100 volts), as shown in step 216, and in the case where the voltage of the stack 10 is greater than the predetermined voltage V p , an instruction to perform the discharge operation is issued, as shown in step 219. Otherwise, after a predetermined time interval t p The voltage of the stack 10 is still lower than the predetermined voltage V p , the entire fuel cell system 100 can be shut down, as shown in step 218. The instruction to perform the discharge operation can be received in step 211, and then the next discharge operation is performed in a loop.

[0030] It should be pointed out that the first temperature threshold T1, the second temperature threshold T2, the predetermined voltage V p , and the predetermined time interval t p are associated with the specifications of the discharge resistor 24, the heat dissipation environment around the discharge resistor 24, and the specifications of the stack 10 and its load state, and can be obtained through experimental calibration, model calculation, etc. For example, the predetermined time interval t p may be associated with the shutdown time of the associated system of the fuel cell system 100. That is, after performing a discharge operation, the system associated with the fuel cell system 100 is shut down, and then it is determined whether the voltage of the stack 10 rises due to residual gas or pipeline leakage, thereby determining whether the discharge operation needs to be performed again. Therefore, based on this design of the present application, multiple discharge operations can be performed within one operating cycle of the fuel cell system.

[0031] Further, since the response speed of the temperature sensor 25 is slow, it is possible that the temperature of the discharge resistor 24 cannot be uploaded to the control unit 40 in real time, so there is still room for improvement in the accurate execution of the discharge operation. In view of this situation, the present application also proposes a scheme for predicting the temperature rise of the discharge resistor 24 by calculating the discharge energy carried by the discharge resistor 24. In this way, by detecting and predicting the temperature of the discharge resistor 24, more accurate and safer guarantees can be provided for performing the discharge operation.

[0032] As shown by the dashed box in FIG. 2, the discharge control method 200 further includes a step for calculating and judging the discharge energy carried by the discharge resistor 24. Specifically, at step 221, the single discharge energy E k (k is the number of discharge operations) during each discharge operation is calculated. At step 226, the single discharge energy E k during each discharge operation is summed up after each discharge operation to obtain the total discharge energy E sum carried by the discharge resistor 24. sum The total discharge energy E sum can be calculated by the following formula (1):

[0033]

[0034] where n is the total number of discharge operations. Then, at step 227, it is judged whether the total discharge energy E x is greater than the first energy threshold E sum , and if the total discharge energy E x is greater than the first energy threshold E x , step 217 is entered: the discharge operation is prohibited from being performed and an alarm is issued. The first energy threshold E x may be defined as the minimum energy value to avoid the discharge resistor 24 from being burned due to overheating. For example, the first energy threshold E p may be 50 kJ, if the discharge resistor 24 carries a total discharge energy exceeding this threshold, the discharge resistor 24 will be burned in the process of performing the discharge operation again after a predetermined time interval t x . It should be noted that the first energy threshold E x may be obtained through experimental calibration or model calculation, and may have different values according to different specifications of the discharge resistor 24. Through the above steps, the discharge energy consumed by the discharge resistor 24 and converted into heat can be calculated, and by comparison with the first energy threshold E sum , it can be judged whether it is possible to cause the discharge resistor 24 to be burned in the process of performing the discharge operation again, so as to judge whether the discharge resistor 24 is allowed to perform the next discharge operation.

[0035] It should be noted that in the process of calculating the total discharge energy E p carried by the discharge resistor 24 by using the above formula (1), only the total discharge energy consumed by the discharge resistor 24 is calculated, and the energy dissipated from the discharge resistor 24 to the surrounding environment within the predetermined time interval t k between two discharge operations is not considered, so the judgment result is conservative and is not conducive to fully exerting the discharge capacity of the discharge resistor 24.

[0036] Therefore, the discharge control method 200 of this application further includes, after each discharge operation, measuring the single discharge energy E during the performed discharge operation. k Before summing, assign the single discharge energy E to each discharge operation. k Add correction factor a k Correction factor a k Between 0 and 1, and between the predetermined time interval t between two discharge operations. p This is related to the heat dissipation of the internal discharge resistor 24. That is, during a predetermined time interval t... p Internally, the energy of a single discharge, E k Some will be lost, correction coefficient a k This is related to the lost energy. By adding a correction factor a... k This allows for a more precise calculation of the total discharge energy E carried by the discharge resistor 24 after each discharge operation. sum .

[0037] Specifically, after each discharge operation, the single discharge energy E during the performed discharge operation is... k The summation can be calculated using the following formula:

[0038]

[0039] Where n is the total number of discharge operations, k is the number of discharge operations, and a k ... a n-1 a n E is the correction factor. k E n This represents the energy of a single discharge during each discharge operation. It should be noted that the correction factor 'a'... k This refers to the predetermined time interval t between two discharge operations. p This is to define the range. For example, if a summation is performed after the nth discharge operation, a1 refers to the correction coefficient between the first and second discharge operations, a2 refers to the correction coefficient between the second and third discharge operations, and so on. n-1 This refers to the correction coefficient between the (n-1)th discharge operation and the nth discharge operation. Since the calculation is performed immediately after the nth discharge operation, the heat has not yet had time to dissipate from the discharge resistor 24, therefore a... n It can be set to 1.

[0040] Using the above formula (2), the total discharge energy E carried by the discharge resistor 24 can be calculated more accurately. sum This allows for a more accurate determination of whether the discharge resistor 24 is permitted to perform a second discharge operation.

[0041] It should be noted that in the above formula (2), the correction coefficient a k may be the same value, or different values. For example, the predetermined time interval t p may be a set of different values, and the correction coefficient a k may also be a set of different values. However, how to determine the correction coefficient a k does not affect the implementation of the inventive concept of the present application, and therefore will not be further described.

[0042] As mentioned above, within the predetermined time interval t p , the discharge resistor 24 will dissipate a portion of the energy to the surrounding environment. In this case, if the single discharge energy E k is less, it can be completely dissipated within the predetermined time interval t p , so the single discharge energy E k in the discharge operation process can be ignored in the summation of the total discharge energy E sum carried by the discharge resistor 24. In view of this situation, the discharge control method 200 of the present application can further include determining whether the single discharge energy E k in each discharge operation process is greater than a second energy threshold E k , as shown in step 222, before summing the single discharge energy E y in the discharge operation process that has been performed. The second energy threshold E y may be defined as the maximum energy value dissipated from the discharge resistor 24 within the predetermined time interval t p . For example, the second energy threshold E y may be 0.5 kJ, and if the discharge resistor 24 consumes energy less than or equal to this threshold, the discharge resistor 24 can completely dissipate the energy before performing the discharge operation again, so it has no effect on the summation of the total discharge energy E sum . It should be noted that the second energy threshold E y may be obtained by experimental calibration or model calculation, and can have different values according to the specifications of the discharge resistor 24.

[0043] Therefore, in the case where the actual discharge energy E cycle in each discharge operation process is less than or equal to the second energy threshold E y , the single discharge energy E k in the discharge operation process is set to 0, and then summed, as shown in step 225. In the case where the actual discharge energy E cycle in each discharge operation process is greater than the second energy threshold E y , the single discharge energy Ek The actual discharge energy E cycle is subtracted by the second energy threshold value E y , and then summed up, as shown in step 223. Therefore, by setting the second energy threshold value E y , the energy dissipated by the discharge resistor 24 within the predetermined time interval t p is fully considered, so that the total discharge energy E sum carried by the discharge resistor 24 can be more accurately calculated.

[0044] It should be noted that, when calculating the total discharge energy E sum carried by the discharge resistor 24 by using formula (1), the single discharge energy E k in each discharge operation process is regarded as the actual discharge energy E cycle in the discharge operation process.

[0045] In step 221, the actual discharge energy E cycle in each discharge operation process is obtained by integrating the voltage value and the current value in each discharge operation process. It should be noted that the sampling interval of the voltage value and the current value can be set according to the design accuracy requirement, the operation and storage capacity of the control unit 40, and the like.

[0046] Therefore, by summing up the single discharge energy in each discharge operation process, it can be predicted whether the discharge resistor 24 will be overheated and burned out when the temperature sensor 25 fails to timely upload the temperature change of the discharge resistor 24, so that the safety of the discharge resistor 24 can be improved, and the discharge resistor 24 can be allowed to perform multiple discharge operations within one operating cycle of the fuel cell system.

[0047] In addition, the present application also provides a computer program product comprising computer instructions, which, when executed by a processor, cause the processor to perform the discharge control method as described above. For example, the processor can be part of the control unit 40.

[0048] Based on the technical solution of the present application, the temperature sensor can be arranged to monitor the temperature of the discharge resistor, so as to avoid the discharge resistor from being overheated when performing the discharge operation at a high temperature, and the discharge resistor can be allowed to perform multiple discharge operations within one operating cycle of the fuel cell system when the temperature of the discharge resistor is allowed. In addition, in order to compensate for the defect that the temperature sensor responds slowly, the total discharge energy carried by the discharge resistor can be calculated, so as to predict the temperature change of the discharge resistor, and further improve the electrical safety of the fuel cell system.

[0049] The present application is described in detail above with reference to specific embodiments. It is obvious, however, that the above-described embodiments and examples illustrated in the drawings should be understood as exemplary only, and not as limiting the present application. Various modifications and changes can be made to the present application by those skilled in the art which do not depart from the spirit of the present application, and such modifications and changes do not depart from the scope of the present application.

Claims

1. A discharge control method (200) for a fuel cell system (100), the fuel cell system (100) comprising: a stack (10) having a positive electrode and a negative electrode; a current sensor (21) configured to detect a current output from the positive electrode; a voltage sensor (22) configured to detect a voltage between the positive electrode and the negative electrode; a discharge circuit including a discharge resistor (24), one end of the discharge circuit being coupled to the positive electrode, the other end of the discharge circuit being coupled to the negative electrode; a temperature sensor (25) configured to detect a temperature of the discharge resistor (24); and a control unit (40) receiving a current value from the current sensor (21), a voltage value from the voltage sensor (22), and a temperature value from the temperature sensor (25), wherein the discharge control method (200) comprises: receiving an instruction to perform a discharge operation (211); determining whether the temperature value is greater than a first temperature threshold (212); in a case where the temperature value is less than or equal to the first temperature threshold, causing the discharge circuit to perform the discharge operation (213); causing the discharge circuit to stop the discharge operation when the voltage value is less than or equal to a predetermined voltage value (214). The discharge control method (200) further comprises:

2. The discharge control method (200) according to claim 1, wherein in a case where the temperature value is greater than the first temperature threshold, prohibiting the discharge operation and issuing an alarm (217). The discharge control method (200) further comprises:

3. The discharge control method (200) according to claim 1, wherein after stopping the discharge operation, determining whether the temperature value is greater than a second temperature threshold (215), and in a case where the temperature value is greater than the second temperature threshold, prohibiting the discharge operation and issuing an alarm (217). The discharge control method (200) further comprises:

4. The discharge control method (200) according to claim 3, wherein in a case where the temperature value is less than or equal to the second temperature threshold, determining whether the voltage value is greater than a predetermined voltage after a predetermined time interval (216), and in a case where the voltage value is greater than the predetermined voltage, issuing an instruction to perform the discharge operation (219). The predetermined time interval is associated with a shutdown time of an associated system of the fuel cell system (100).

5. The discharge control method (200) according to claim 4, wherein The discharge control method (200) further comprises:

6. The discharge control method (200) according to claim 5, wherein calculating a single discharge energy during each discharge operation (221), and summing up the single discharge energy during the discharge operation that has been performed after each discharge operation, so as to obtain a total discharge energy (226) carried by the discharge resistor (24); determining whether the total discharge energy is greater than a first energy threshold (227), and in a case where the total discharge energy is greater than the first energy threshold, prohibiting the discharge operation and issuing an alarm (217). ​ 7. The discharge control method (200) according to claim 6, wherein The discharge control method (200) further comprises adding a correction factor (224) to the single discharge energy in each discharge operation before summing the single discharge energy in the executed discharge operations, the correction factor being associated with heat dissipation conditions of the discharge resistor (24) within the predetermined time interval.

8. The discharge control method (200) according to claim 7, wherein The discharge control method (200) further comprises: determining whether the actual discharge energy in each discharge operation is greater than a second energy threshold (222) before summing the single discharge energy in the executed discharge operations after each discharge operation; setting the single discharge energy in each discharge operation to 0 (225) in the case where the actual discharge energy in each discharge operation is less than or equal to the second energy threshold, and obtaining the single discharge energy in each discharge operation by subtracting the second energy threshold from the actual discharge energy (223) in the case where the actual discharge energy in each discharge operation is greater than the second energy threshold.

9. The discharge control method (200) according to claim 8, wherein The actual discharge energy in each discharge operation is obtained by integrating the voltage value and the current value in each discharge operation.

10. The discharge control method (200) according to claim 8, wherein The first energy threshold is defined as a minimum energy value to avoid the discharge resistor (24) from being burned due to overheating, and the second energy threshold is defined as a maximum energy value dissipated from the discharge resistor (24) within the predetermined time interval.

11. A fuel cell system (100) comprising: a stack (10) having a positive electrode and a negative electrode; a current sensor (21) configured to detect a current output from the positive electrode; a voltage sensor (22) configured to detect a voltage between the positive electrode and the negative electrode; a discharge circuit including a discharge resistor (24), one end of the discharge circuit being coupled to the positive electrode and the other end of the discharge circuit being coupled to the negative electrode; a temperature sensor (25) configured to detect a temperature of the discharge resistor (24); and a control unit (40) receiving a current value from the current sensor (21), a voltage value from the voltage sensor (22), and a temperature value from the temperature sensor (25), wherein the control unit (40) is configured to execute the discharge control method (200) according to any one of claims 1 to 10. The fuel cell system further comprises a boost DC / DC module (20), and the discharge circuit is a part of the boost DC / DC module (20).

12. The fuel cell system (100) of claim 11, wherein, 13. A computer program product comprising computer instructions which, when executed by a processor, cause the processor to perform the discharge control method according to any one of claims 1 to 10. ​

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