Method, device and vehicle for controlling discharge of fuel cell battery

Abstract

This invention relates to the field of vehicle technology and discloses a method, apparatus, and vehicle for controlling the discharge of a fuel cell stack. The method includes: responding to a forced discharge command, determining the discharge current of the fuel cell stack based on a target discharge power through power closed-loop control, and controlling the fuel cell stack to perform a first-stage forced discharge using the discharge current; if the voltage distribution of the fuel cell stack exceeds a preset deviation range, re-determining the discharge current of the fuel cell stack based on the fuel cell stack voltage through voltage closed-loop control, and continuing to control the fuel cell stack to perform a second-stage forced discharge using the updated discharge current; and controlling the fuel cell stack to enter a third-stage resistive discharge when the voltage of the fuel cell stack drops to a resistance discharge threshold. Applying the technical solution of this invention enables safe and rapid discharge of fuel cells.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology, and more specifically to a method, apparatus, and vehicle for controlling the discharge of a fuel cell stack. Background Technology

[0002] Fuel cells are a type of highly efficient and clean energy conversion device. With their outstanding advantages such as excellent energy conversion efficiency and environmental friendliness, they have enormous application potential in transportation, distributed power generation, and portable power supplies. Forced discharge is a key control step in the operation of a fuel cell system. It mainly involves actively consuming the remaining hydrogen, oxygen, and double-layer charge within the fuel cell stack through an external load or auxiliary devices, thereby ensuring system shutdown safety or optimizing the stack's operating state.

[0003] In related technologies, the discharge current setting during forced discharge is relatively conservative, resulting in a long discharge time and difficulty in quickly removing residual active materials. Blindly increasing the current, on the other hand, can easily pull the stack voltage to the reverse polarity, causing catalyst corrosion and proton exchange membrane damage, posing safety risks. Therefore, achieving safe and rapid discharge of fuel cells is a pressing problem that needs to be solved. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this application is to provide a method, apparatus and vehicle for controlling the discharge of fuel cell stacks, which aims to achieve safe and rapid discharge of fuel cells.

[0005] In a first aspect, embodiments of this application provide a method for controlling the discharge of a fuel cell stack battery, comprising: responding to receiving a forced discharge command, determining the discharge current of the fuel cell stack battery based on the target discharge power of the fuel cell stack battery through power closed-loop control, and controlling the fuel cell stack battery to perform a first stage of forced discharge with the discharge current; the target discharge power is greater than the actual discharge power of the fuel cell stack battery when the forced discharge command is received; if the voltage distribution of the fuel cell stack battery exceeds a preset deviation range, re-determining the discharge current of the fuel cell stack battery based on the voltage of the fuel cell stack battery through voltage closed-loop control, and continuing to control the fuel cell stack battery to perform a second stage of forced discharge with the updated discharge current, so that the average cell voltage of the fuel cell stack battery is maintained at a preset average cell voltage threshold; if the voltage of the fuel cell stack battery drops to a resistance discharge threshold, controlling the fuel cell stack battery to enter a third stage of resistance discharge until the discharge is completed.

[0006] Beneficial Effects: Upon receiving a forced discharge command, a target discharge power greater than the actual discharge power is first set. Based on this target power, a power closed-loop calculation of the discharge current is performed, rapidly establishing a rising discharge current and significantly shortening the initial energy release time. As the fuel cell stack discharges continuously, reverse polarity may occur due to differences between individual cells. This application addresses this by calculating the discharge current based on a voltage closed-loop when the voltage distribution of the fuel cell stack exceeds a preset deviation range, maintaining the average individual cell voltage at a preset average individual cell voltage threshold. This ensures the stack voltage always operates above a safe threshold, completely avoiding irreversible chemical reverse polarity damage such as catalyst corrosion and proton exchange membrane perforation caused by a sudden voltage drop to zero or negative values. Finally, when the fuel cell stack voltage drops to the resistance discharge threshold, discharge is performed through a resistor, safely dissipating trace amounts of residual electrical energy and residual moisture within the stack, completing the entire forced discharge process.

[0007] In summary, this application achieves a balance between the timeliness and safety of forced discharge through three stages: power closed-loop, voltage closed-loop, and resistance discharge. It effectively suppresses the risk of reverse polarity in individual cells while enabling rapid discharge of residual active materials, thereby improving the safety and efficiency of fuel cell stack discharge.

[0008] In one possible embodiment, the voltage distribution of the fuel cell stack exceeds a preset deviation range, including: the actual minimum cell voltage is less than a preset minimum cell voltage threshold, and / or the actual average cell voltage is less than a preset average cell voltage threshold; the above-mentioned redetermining the discharge current of the fuel cell stack based on the voltage of the fuel cell stack through voltage closed-loop control includes: when the actual minimum cell voltage is less than the preset minimum cell voltage threshold and the actual average cell voltage is less than the preset average cell voltage threshold, redetermining the discharge current of the fuel cell stack based on the actual minimum cell voltage through voltage closed-loop control.

[0009] In this embodiment, during the first stage of high-power closed-loop discharge, the voltage decay of individual cells in the fuel cell stack is inconsistent, and the voltage of some cells will drop first. If only the average cell voltage is considered, the potential danger of reverse polarity due to excessively low voltage in individual cells can be easily overlooked. This application determines the actual average cell voltage and the actual lowest cell voltage, using the lowest cell voltage as the input for closed-loop calculation. This prioritizes the protection of the cells with the lowest voltage and the most vulnerable to damage, fundamentally preventing reverse polarity, catalyst corrosion, and proton exchange membrane damage, thereby improving discharge safety.

[0010] In one possible embodiment, the discharge current of the fuel cell stack is re-determined based on the voltage of the fuel cell stack through voltage closed-loop control, including: when the actual minimum single cell voltage is not lower than a preset minimum single cell voltage protection threshold and the actual average single cell voltage is less than a preset average single cell voltage threshold, performing PID calculation on the difference between the actual average single cell voltage and the preset average single cell voltage threshold of the fuel cell stack to obtain the re-determined discharge current of the fuel cell stack.

[0011] In this embodiment, during the forced discharge of the battery, if all cell voltages are safe, but the average voltage is less than the preset average cell voltage threshold, there is no need to limit the current for a single weak cell. The discharge current can be calculated based on the actual average cell voltage. Under the premise of ensuring the safety of the cells, the residual hydrogen and oxygen and double-layer charge can continue to be consumed, thus balancing the discharge speed and overall safety.

[0012] In one possible embodiment, a PID calculation is performed on the difference between the actual average cell voltage of the fuel cell stack and a preset average cell voltage threshold to obtain a redefined discharge current of the fuel cell stack. This includes: when the actual discharge current is greater than a preset current threshold, performing a PID calculation on the difference between the actual average cell voltage of the fuel cell stack and a first average cell voltage threshold to obtain a redefined discharge current of the fuel cell stack; when the actual discharge current drops to less than or equal to a preset current threshold, performing a PID calculation on the difference between the actual average cell voltage of the fuel cell stack and a second average cell voltage threshold to obtain a redefined discharge current of the fuel cell stack; wherein the first average cell voltage threshold is greater than the second average cell voltage threshold.

[0013] In this embodiment, when the discharge current drops below the preset current threshold, the reverse polarity risk is eliminated, and there is no need to maintain a high voltage. Switching to a lower second average cell voltage threshold can further reduce the overall voltage of the stack while ensuring the safety of the individual cells, thus deeply consuming the residual hydrogen, oxygen and double-layer charge inside the stack.

[0014] In one possible embodiment, the discharge current of the fuel cell stack is determined by power closed-loop control based on the target discharge power of the fuel cell stack, including: performing PID calculation on the difference between the target discharge power and the actual discharge power to determine the discharge current.

[0015] In this embodiment, the present application can accurately calculate the discharge current by performing PID closed-loop calculation based on the difference between the target discharge power and the actual discharge power.

[0016] In one possible embodiment, the discharge current of the fuel cell stack is re-determined based on the voltage of the fuel cell stack via voltage closed-loop control, including: determining the rate of change of the average cell voltage of the fuel cell stack; when the rate of change is greater than a preset rate of change threshold, subtracting the change in discharge current determined based on the rate of change from the discharge current determined based on the voltage closed-loop control to determine the discharge current of the fuel cell stack; the change in discharge current is proportional to the rate of change of the average cell voltage.

[0017] In this embodiment, during the second-stage voltage closed-loop forced discharge, if the discharge current is too large, the stack voltage will drop rapidly, which can easily lead to individual cell reverse polarity and introduce voltage change rate. By monitoring the voltage change rate, when the voltage change rate exceeds the threshold, the discharge current is reduced, thereby reducing the amount of voltage change. This avoids the control lag problem caused by the voltage closed loop relying solely on the current voltage value for adjustment, and further improves the stability and safety of the second-stage discharge process.

[0018] In one possible embodiment, the discharge current of the fuel cell is re-determined based on the voltage of the fuel cell, through voltage closed-loop control, including: determining a preset transition time for switching from power closed-loop control to voltage closed-loop control; within the preset transition time, re-determining the discharge current of the fuel cell based on a weighted value of a first current and a second current; the first current is determined based on the power closed-loop control; and the second current is determined based on the voltage closed-loop control.

[0019] In this embodiment, by setting a preset excessively low duration, the discharge current is calculated based on the weighted average of the first current and the second current within the preset excessive duration. This enables a smooth switch from power closed-loop control to voltage closed-loop control, avoiding sudden changes in discharge current and violent oscillations in stack voltage caused by hard switching of control modes. This mitigates the risk of instantaneous voltage drop in individual cells and improves the stability of the forced discharge process.

[0020] In one possible embodiment, the method further includes: if the voltage distribution at the previous moment exceeds a preset deviation range, updating the integral term of the PID algorithm at the current moment based on the integral term of the PID algorithm at the previous moment and the control error of the individual voltage.

[0021] In this embodiment, by inheriting the integral term from the previous moment and updating the integral term in combination with the individual cell error, the changes in individual cell voltage can be accurately tracked, avoiding abrupt integral changes and further preventing reverse polarity.

[0022] In one possible implementation, the integral term of the PID algorithm satisfies the following relationship:

[0023] in, This represents the integral term of the updated PID algorithm, where t represents the current time. Indicates the sampling time. This refers to the time before the current time. This represents the increment of the integral term at the current moment. The term represents the proportion at the current moment. This represents the differential term at the current moment. This represents the actual discharge current at the previous moment. This represents the increment of the integral term at the previous time step.

[0024] In this embodiment, if the voltage distribution at the previous moment exceeds the preset deviation range, it indicates that the closed-loop control algorithm needs to be switched. This application updates the integral term based on the actual discharge current at the previous moment, the proportional term at the current moment, the increment of the integral term at the current moment, the derivative term, and the increment of the integral term at the previous moment. This can achieve a smooth switch between the power closed loop and the voltage closed loop, avoiding current jumps and voltage oscillations caused by sudden changes in control mode.

[0025] In one possible embodiment, when the voltage distribution of the fuel cell stack does not exceed a preset deviation range, the integral term of the PID algorithm satisfies the following relationship:

[0026] in, This represents the integral term of the updated PID algorithm, where t represents the current time. Indicates the sampling time. This refers to the time before the current time. This represents the integral term from the previous time step. This represents the increment of the integral term at the current moment.

[0027] In this embodiment, by adding the increment of the integral term to the integral term at the previous moment, the accumulation process of continuous integration can be simulated. At each step, the integral term is updated according to the current error. As long as the error exists, the integral term will continue to change, which can eliminate steady-state error and thus improve the accuracy of the discharge current.

[0028] Secondly, embodiments of this application provide a control device for discharging a fuel cell stack battery, comprising: a first discharge module, configured to, in response to receiving a forced discharge command, determine the discharge current of the fuel cell stack battery based on the target discharge power of the fuel cell stack battery through power closed-loop control, and control the fuel cell stack battery to perform a first stage of forced discharge with the discharge current; the target discharge power is greater than the actual discharge power of the fuel cell stack battery when the forced discharge command is received; a second discharge module, configured to, when the voltage distribution of the fuel cell stack battery exceeds a preset deviation range, re-determine the discharge current of the fuel cell stack battery based on the voltage of the fuel cell stack battery through voltage closed-loop control, and continue to control the fuel cell stack battery to perform a second stage of forced discharge with the updated discharge current, so that the average cell voltage of the fuel cell stack battery is maintained at a preset average cell voltage threshold; and a third discharge module, configured to, when the voltage of the fuel cell stack battery drops to a resistance discharge threshold, control the fuel cell stack battery to enter a third stage of resistance discharge until the discharge is completed.

[0029] Thirdly, embodiments of this application provide an electronic device, including: a processor and a memory configured to store processor-executable instructions; wherein the processor is configured to execute the instructions to implement the control method for discharging a fuel cell stack described in the first aspect.

[0030] Fourthly, embodiments of this application provide a vehicle, including: a control device for discharging the fuel cell stack described in the second aspect above.

[0031] Fifthly, embodiments of this application provide a computer-readable storage medium storing instructions that, when executed by a device, enable the device to perform the control method for discharging a fuel cell stack described in the first aspect.

[0032] In a sixth aspect, this application provides a computer program product including computer instructions that, when executed on a device's processor, enable the device to perform the control method for discharging a fuel cell stack as described in the first aspect above.

[0033] It should be noted that the technical effects of any of the implementation methods in aspects two through six can be found in the technical effects of the corresponding implementation methods in aspect one, and will not be repeated here.

[0034] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the background art, the accompanying drawings used in the embodiments of this application will be described below.

[0036] Figure 1 This is a schematic diagram of the structure of a vehicle disclosed in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a control system for discharging a fuel cell stack disclosed in an embodiment of this application; Figure 3 This is a schematic flowchart of a method for controlling the discharge of a fuel cell stack disclosed in an embodiment of this application; Figure 4 This is a schematic flowchart of another control method for discharging a fuel cell stack disclosed in an embodiment of this application; Figure 5 This is a schematic flowchart of another control method for discharging a fuel cell stack disclosed in an embodiment of this application; Figure 6 This is a schematic flowchart of another control method for discharging a fuel cell stack disclosed in an embodiment of this application; Figure 7 This is a schematic flowchart of another control method for discharging a fuel cell stack disclosed in an embodiment of this application; Figure 8 This is a schematic diagram of the structure of a control device for discharging a fuel cell stack disclosed in an embodiment of this application; Figure 9 This is a schematic diagram of the structure of an electronic device disclosed in an embodiment of this application. Detailed Implementation

[0037] The terms "first," "second," etc., are used for descriptive purposes only and have no sequential or technical meaning, nor should they be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Directional terms used in this application, such as "upper," "lower," "front," "rear," "left," "right," "inner," and "outer," are merely for reference to the orientation shown in the accompanying drawings. The use of directional terms is for better and clearer explanation and understanding of this application, and does not indicate the orientation of the referred device or component in an actual application scenario.

[0038] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. "Fixed connection" refers to a connection where the relative positional relationship remains unchanged after connection. "Rotary connection" refers to a connection where the two parts can rotate relative to each other after connection. "Sliding connection" refers to a connection where the two parts can slide relative to each other after connection.

[0039] In the embodiments of this application, "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0040] The terms "parallel" and "perpendicular" are relative to the current technological level, not absolute mathematical definitions. Slight deviations are permissible; approximations of parallelism or perpendicularity are acceptable. For example, "A and B are parallel" means that A and B are parallel or approximately parallel, with the angle between them ranging from 0 to 5 degrees. Similarly, "A and B are perpendicular" means that A and B are perpendicular or approximately perpendicular, with the angle between them ranging from 85 to 95 degrees.

[0041] The term "electrical connection" refers to the flow of current or signal from one conductor to another. An electrical connection between A and B means that current or signal can flow from A to B and vice versa. This connection includes direct and indirect electrical connections. A direct electrical connection between A and B means that A and B are physically connected. An indirect electrical connection between A and B means that A and B are connected via C, where C can be at least one wire or device.

[0042] The embodiments of this application are described below with reference to the accompanying drawings.

[0043] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle disclosed in an embodiment of this application. Vehicle 1 can be, but is not limited to, a pure electric vehicle (PEV / BEV), a hybrid electric vehicle (HEV), a range-extended electric vehicle (REEV), a plug-in hybrid electric vehicle (PHEV), or a new energy vehicle.

[0044] In this embodiment of the application, the vehicle 1 includes a control system 10 for discharging the fuel cell stack battery. Through a discharge control strategy based on three stages—power closed-loop discharge, voltage closed-loop discharge, and resistance discharge—the fuel cell stack battery can be discharged quickly and safely.

[0045] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of a fuel cell battery discharge control system disclosed in an embodiment of this application. The fuel cell battery discharge control system 10 includes: a fuel cell battery 101, an air supply subsystem 102, a hydrogen supply subsystem 103, a water and heat management subsystem 104, a DC-DC converter 105, a controller 106, and a single cell voltage monitor 107.

[0046] As one possible implementation, the individual cell voltage monitor 107 is used to collect the voltage signals of each cell in the fuel cell stack 101 in real time and output them to the controller 106. Based on the collected individual cell voltages, total stack voltage, and discharge current, the controller 106 executes power closed-loop control, voltage closed-loop control, and resistance discharge strategies to discharge the fuel cell stack. The DC-DC converter 105 implements resistance discharge in the third stage. The air supply subsystem 102 and hydrogen supply subsystem 103 are used to cooperate in completing the purging operation, and the water and heat management subsystem 104 is used to regulate the stack temperature to avoid icing or local overheating during the discharge process.

[0047] The specific implementation of the controller 106 in performing power closed-loop control, voltage closed-loop control and resistance discharge strategy to discharge the fuel cell stack can be referred to the description in the following embodiments, and will not be repeated here.

[0048] In some embodiments, the fuel cell battery discharge control method of this application can be applied to the fuel cell battery discharge control system of the above embodiments, or to the controller of the fuel cell battery discharge control system of the above embodiments. This application does not impose any specific limitations on this.

[0049] Please see Figure 3 , Figure 3 This is a flowchart illustrating a method for controlling the discharge of a fuel cell stack according to an embodiment of this application, including the following steps: S301. In response to receiving a forced discharge command, based on the target discharge power of the fuel cell stack battery, the discharge current of the fuel cell stack battery is determined through power closed-loop control, and the discharge current is used to control the fuel cell stack battery to perform the first stage of forced discharge.

[0050] The target discharge power is greater than the actual discharge power of the fuel cell stack when it receives a forced discharge command.

[0051] The target discharge power is higher than the current actual power to rapidly consume hydrogen, oxygen, and double-layer charge, thereby rapidly consuming residual active materials through high power.

[0052] As one possible implementation, the controller receives a forced discharge command, sets a target discharge power higher than the current actual power, acquires the actual output power of the fuel cell stack in real time, performs PID calculation on the difference between the target discharge power and the actual discharge power, determines the discharge current, and the fuel cell stack continues to perform high-power forced discharge in the first stage with this discharge current.

[0053] In one implementation, the target discharge power is determined as follows: when the actual operating power under the current operating condition of the forced discharge process is less than 5kW, the target discharge power is 5kW; when the actual operating power under the current operating condition is greater than 5kW, the target discharge power is == the requested power generation of the fuel cell system + the increment of the forced discharge power, where the increment of the forced discharge power can be taken as 2kW.

[0054] It should be understood that if the current is relatively small during forced discharge, it will result in low discharge power, slow discharge, and incomplete removal of residual hydrogen and oxygen. This application uses higher power and a stable high current output through a power closed loop to quickly consume residual hydrogen, oxygen, and double-layer charge in the fuel cell stack, shortening the discharge time and solving the problem of slow discharge.

[0055] S302. When the voltage distribution of the fuel cell stack exceeds the preset deviation range, the discharge current of the fuel cell stack is re-determined based on the voltage of the fuel cell stack through voltage closed-loop control, and the fuel cell stack is controlled to perform a second stage of forced discharge with the updated discharge current, so as to maintain the average cell voltage of the fuel cell stack at the preset average cell voltage threshold.

[0056] The preset deviation range is the safe range for battery discharge. Exceeding this range indicates that the voltage of some individual cells is too low, posing a risk of reverse polarity.

[0057] The average monomer voltage threshold is a safe voltage; below this value, monomers are prone to reverse polarization, catalyst corrosion, and membrane damage.

[0058] One possible approach is to monitor the voltage of all individual cells in real time, calculate the voltage difference between cells, and determine that a cell is unbalanced and at risk of reverse polarity when the voltage difference exceeds a preset deviation range. The control mode is then switched from power closed-loop control to voltage closed-loop control. Using the average cell voltage threshold as the target, the discharge current is calculated via PI / PID, and the calculated discharge current is used to continuously discharge, stabilizing the average cell voltage of the stack at a safe threshold and consuming remaining energy.

[0059] It should be understood that during the first stage of high-power discharge, due to the inconsistency of individual cells, some cells are prone to voltage drop first, resulting in excessively low cell voltage or even reverse polarity. This application judges the voltage distribution and switches to voltage closed loop when the voltage distribution exceeds the preset deviation range to limit the minimum voltage, prevent cell reverse polarity, catalyst corrosion, and proton exchange membrane damage, and continue discharge under the premise of safety, taking into account both speed and safety.

[0060] S303. When the voltage of the fuel cell stack drops to the resistance discharge threshold, control the fuel cell stack to enter the third stage of resistance discharge until the discharge is completed.

[0061] As one possible approach, the actual voltage of the fuel cell stack is monitored in real time. When the actual voltage drops to the resistance discharge threshold, the controller cuts off the active regulation circuit and connects the fixed power discharge resistor. The residual electrical energy is passively consumed by the resistor until the actual voltage of the fuel cell stack approaches 0, at which point the discharge ends.

[0062] Among them, the fixed power discharge resistor is usually a DC-DC (DCDC) converter.

[0063] It should be understood that when the voltage drops to a certain level, the remaining energy of the fuel cell is very weak, and the energy consumption of current regulation is high. By disconnecting the voltage closed-loop control and using a fixed discharge resistor to consume the remaining energy, the last remaining charge and moisture can be safely exhausted, thus completing the entire forced discharge process.

[0064] Therefore, upon receiving a forced discharge command, a target discharge power greater than the actual discharge power is first set. Based on this target power, a power closed-loop calculation of the discharge current is performed, rapidly establishing a rising discharge current and significantly shortening the initial energy release time. As the fuel cell stack continues to discharge, reverse polarity may occur due to differences between individual cells. This application addresses this by calculating the discharge current based on a voltage closed-loop when the voltage distribution of the fuel cell stack exceeds a preset deviation range, maintaining the average cell voltage at a preset average cell voltage threshold. This ensures the stack voltage always operates above a safe threshold, completely avoiding irreversible chemical reverse polarity damage such as catalyst corrosion and proton exchange membrane perforation caused by a sudden voltage drop to zero or negative values. Finally, when the fuel cell stack voltage drops to the resistance discharge threshold, discharge is performed through a resistor, safely dissipating trace amounts of residual electrical energy and residual moisture within the stack, completing the entire forced discharge process.

[0065] In summary, this application achieves a balance between the timeliness and safety of forced discharge through three stages: power closed-loop, voltage closed-loop, and resistance discharge. It effectively suppresses the risk of reverse polarity in individual cells while enabling rapid discharge of residual active materials, thereby improving the safety and efficiency of fuel cell stack discharge.

[0066] In some embodiments, the voltage distribution of the fuel cell stack exceeds a preset deviation range, including: the actual minimum cell voltage is less than a preset minimum cell voltage threshold, and / or the actual average cell voltage is less than a preset average cell voltage threshold.

[0067] Therefore, the above S302 can be implemented as follows: when the actual minimum cell voltage is less than the preset minimum cell voltage threshold and the actual average cell voltage is less than the preset average cell voltage threshold, the discharge current of the fuel cell stack is re-determined based on the actual minimum cell voltage through voltage closed-loop control.

[0068] As one possible implementation, during the first-stage power closed-loop forced discharge process, the voltage of each individual cell is collected in real time. The actual minimum cell voltage and the actual average cell voltage are calculated and compared with preset minimum cell voltage thresholds and average cell voltage thresholds, respectively. When the actual minimum cell voltage is lower than the minimum cell voltage threshold and the actual average cell voltage is lower than the average cell voltage threshold, it is determined that the cell consistency of the stack has deteriorated and there is a risk of reverse polarity. The control strategy switches from power closed-loop to voltage closed-loop, using the actual minimum cell voltage as the control target. The discharge current is calculated through a PI / PID algorithm to prioritize the protection of weak cells and prevent reverse polarity and proton exchange membrane damage from the root cause.

[0069] As another possible implementation, a minimum single-cell voltage control setpoint is determined, and it is then determined whether the actual minimum single-cell voltage is less than the minimum single-cell voltage control setpoint. If so, the discharge current of the fuel cell stack is re-determined based on the actual minimum single-cell voltage through voltage closed-loop control. Using a preset average single-cell voltage threshold and a stack-wide voltage consistency threshold as both criteria for calculating the discharge current can simultaneously address the issues of single-cell over-discharge and poor voltage consistency.

[0070] The minimum single-cell voltage setting is set to the minimum single-cell voltage limit (i.e., the preset average single-cell voltage threshold). Average single-cell voltage Voltage deviation limit The larger of the two differences.

[0071] It should be understood that during the first stage of high-power closed-loop discharge, the decay of individual cells in the fuel cell stack is uneven, and the voltage of some cells will drop first. If only the average cell voltage is considered, the potential danger of reverse polarity due to excessively low voltage in individual cells can be easily overlooked. This application determines the safety of discharge by judging the actual average cell voltage and the actual lowest cell voltage, using the lowest cell voltage as the input for closed-loop calculation. It prioritizes the protection of the cells with the lowest voltage and the most vulnerable to damage, thereby preventing reverse polarity, catalyst corrosion, and proton exchange membrane damage at the source.

[0072] In some embodiments, S302 can be implemented as follows: when the actual lowest cell voltage is less than a preset lowest cell voltage threshold and the actual average cell voltage is less than a preset average cell voltage threshold, the discharge current of the fuel cell stack is redetermined based on the actual lowest cell voltage through voltage closed-loop control.

[0073] It should be understood that during the forced discharge of a battery, if the actual lowest single-cell voltage is less than the preset lowest single-cell voltage threshold, it indicates that the worst single cell is on the verge of reverse polarity. If the average voltage is still used for control, the risk of over-discharge and reverse polarity of individual cells will be ignored. In this case, the lowest single-cell voltage is used for closed-loop control to forcibly reduce the discharge current, prioritize the protection of weak cells, and avoid reverse polarity and proton exchange membrane damage from the root.

[0074] In some embodiments, S302 can also be implemented as follows: when the actual minimum cell voltage is not lower than a preset minimum cell voltage protection threshold and the actual average cell voltage is less than a preset average cell voltage threshold, PID calculation is performed on the difference between the actual average cell voltage and the preset average cell voltage threshold of the fuel cell stack to obtain the redefined discharge current of the fuel cell stack.

[0075] It should be understood that during the forced discharge of a battery, if all individual cell voltages are safe, but the average voltage is less than the preset average cell voltage threshold, there is no need to limit the current for a single weak cell. The discharge current can be calculated based on the actual average cell voltage. Under the premise of ensuring the safety of individual cells, the residual hydrogen and oxygen and double-layer charge can continue to be consumed, thus balancing the discharge speed and overall safety.

[0076] In some embodiments, during voltage closed-loop control, there may be a problem where excessive current triggers a violent forced oxygen reduction reaction at the cathode, such as... Figure 4 As shown, the above S302 may include the following steps: S401. When the actual discharge current is greater than the preset current threshold, perform PID calculation on the difference between the actual average cell voltage of the fuel cell stack and the first average cell voltage threshold to obtain the redefined discharge current of the fuel cell stack.

[0077] The actual discharge current is the discharge circuit current that the fuel cell stack is currently output in real time.

[0078] As one possible approach, the current in the fuel cell stack discharge circuit is collected in real time, and it is determined that the actual discharge current is greater than a preset current threshold. The voltage difference between the actual average cell voltage and the first average cell voltage threshold is calculated, and the voltage difference is used for PID calculation to obtain the discharge current of the fuel cell stack.

[0079] It should be understood that when the current is relatively large, the voltage drop of individual cells in the fuel cell stack is relatively large and the risk of reverse polarity is higher. Therefore, a higher first average individual cell voltage threshold is set to avoid the overall voltage dropping too quickly under the premise of high power discharge, so as to balance the discharge rate and the safety of the fuel cell stack and prevent the large current from directly pulling down the voltage and causing damage to individual cells.

[0080] S402. When the actual discharge current drops to less than or equal to the preset current threshold, perform PID calculation on the difference between the actual average cell voltage and the second average cell voltage threshold of the fuel cell stack to obtain the redefined discharge current of the fuel cell stack.

[0081] Among them, the first average cell voltage threshold is greater than the second average cell voltage threshold.

[0082] The second average cell voltage threshold is lower than the first average cell voltage threshold. After the current decreases, the voltage can be further reduced, thus deeply consuming residual charge and active material.

[0083] As one possible approach, the discharge current is continuously monitored. When the actual discharge current is less than or equal to a preset current threshold, the voltage difference between the actual average cell voltage and the second average cell voltage threshold is calculated. The voltage difference is then used for PID calculation to obtain the discharge current of the fuel cell stack.

[0084] It should be understood that when the discharge current drops below the preset current threshold, the risk of reverse polarity is eliminated, and there is no need to maintain a high voltage. Switching to a lower second average individual cell voltage threshold can further reduce the overall voltage of the stack while ensuring the safety of individual cells, and deeply consume the residual hydrogen, oxygen and double-layer charge inside the stack.

[0085] Furthermore, during the second-stage lightweight discharge process, limiting the discharge current avoids the violent forced oxygen reduction reaction at the cathode caused by excessive current, thus significantly reducing unnecessary liquid water generation during discharge. This not only reduces the difficulty of subsequent startups (especially low-temperature cold starts) but also prevents physical structural damage to the gas diffusion layer, microporous layer, and catalyst layer caused by localized liquid water accumulation and ice expansion, thereby mitigating the impact of improper discharge operations on stack lifespan from the source.

[0086] Therefore, by adjusting the average cell voltage threshold, when the discharge current is less than the preset current threshold, the average cell voltage threshold can be reduced, which can avoid the violent forced oxygen reduction reaction caused by excessive current at the cathode, thereby significantly reducing the unnecessary liquid water generation during discharge and extending the life of the core components of the fuel cell stack.

[0087] In some embodiments, when calculating the discharge current based on voltage closed-loop control, the calculated discharge current may be too large, leading to a significant voltage drop per unit time and posing a risk of reverse polarity to the fuel cell stack. For example... Figure 5 As shown, S302 above includes: S501. Determine the rate of change of the average single cell voltage of the fuel cell stack.

[0088] The rate of change of average cell voltage represents the rate at which the average cell voltage of the fuel cell stack decreases per unit time, and can reflect whether the voltage drop is fast or slow.

[0089] One possible approach is to calculate the average cell voltage of the fuel cell stack in real time, and obtain the rate of change of the average cell voltage by dividing the voltage difference at consecutive sampling times by the sampling time interval.

[0090] S502. When the rate of change is greater than the preset rate of change threshold, the discharge current of the fuel cell stack is determined by subtracting the change in discharge current determined by the rate of change from the discharge current determined by the voltage closed-loop control.

[0091] Among them, the change in discharge current is proportional to the rate of change of average cell voltage.

[0092] The preset rate of change threshold is the maximum allowable voltage drop rate. If this value is exceeded, the voltage drop rate is considered too fast, and there is a risk of reverse polarity.

[0093] As one possible implementation, the calculated average single-cell voltage change rate is compared with a preset change rate threshold. If the change rate is greater than the preset change rate threshold, the change in discharge current is calculated. The change in current is then subtracted from the original discharge current output by the voltage closed loop to obtain the corrected discharge current. The modified, smaller discharge current controls the fuel cell stack, slowing down the voltage drop and smoothly completing the second stage of forced discharge.

[0094] It should be understood that during the second-stage voltage closed-loop forced discharge, if the discharge current is too large, the stack voltage will drop rapidly, which can easily lead to individual cell reverse polarity and introduce voltage change rate. By monitoring the voltage change rate, when the voltage change rate exceeds the threshold, the discharge current is reduced, thereby reducing the amount of voltage change. This avoids the control lag problem caused by the voltage closed loop relying solely on the current voltage value for adjustment, and further improves the stability and safety of the second-stage discharge process.

[0095] In some embodiments, when switching from power closed-loop control to voltage closed-loop control, if the power closed-loop switches to voltage closed-loop control instantaneously, the discharge current will experience a step-like change, causing drastic voltage fluctuations and easily leading to individual cell voltage oscillations. For example... Figure 6 As shown, S302 above includes: S601. Determine the preset transition time for switching from power closed-loop control to voltage closed-loop control.

[0096] It should be understood that when switching from power closed-loop control to voltage closed-loop control, if the power closed-loop switches abruptly to the voltage closed-loop, the discharge current will experience a step-like change, causing drastic voltage fluctuations and easily leading to individual cell voltage oscillations. This application achieves a smooth voltage transition and improves the stability of the discharge process by setting a transition time.

[0097] As one possible approach, a preset transition time is determined based on the fuel cell stack model, number of cells, and discharge conditions. The more cells in the stack, the higher the rated power, and the more drastic the stack voltage response, the longer the required preset transition time.

[0098] S602. Within a preset transition time, the discharge current of the fuel cell stack is re-determined based on the weighted value of the first current and the second current.

[0099] The first current is determined based on the power closed loop, and the second current is determined based on the voltage closed loop.

[0100] As one possible implementation, after entering the preset transition period, the controller simultaneously runs two sets of algorithms: power closed-loop and voltage closed-loop. It determines the first current, the second current, and the weights of the two closed-loop algorithms, respectively. Based on the weights of the two closed-loop algorithms, the first current and the second current are weighted and summed to obtain the discharge current of the fuel cell stack, thereby achieving a smooth switching between the two closed-loop control algorithms.

[0101] In one implementation, the weights of the two closed-loop algorithms can be determined as follows: based on the real-time remaining transition time within a preset transition duration, the weights of the two closed-loop algorithms are determined. For example, at the start of the preset transition duration, the weight of the power closed loop is 0.9 and the weight of the voltage closed loop is 0.1; at the end, the weight of the power closed loop is 0 and the weight of the voltage closed loop is 1.

[0102] Therefore, by setting a preset excessively low duration, the discharge current can be calculated based on the weighted average of the first and second currents within the preset excessive duration. This enables a smooth transition from power closed-loop control to voltage closed-loop control, avoiding sudden changes in discharge current and severe voltage fluctuations in the stack caused by hard switching of control modes. It also mitigates the risk of instantaneous voltage drops in individual cells and improves the stability of the forced discharge process.

[0103] In some embodiments, in order to improve the accuracy of the discharge current, the method further includes: if the voltage distribution at the previous moment exceeds a preset deviation range, updating the integral term of the PID algorithm at the current moment based on the integral term of the PID algorithm at the previous moment and the control error of the individual voltage.

[0104] Among them, the control error of the individual unit voltage represents the difference between the actual voltage of the individual unit and the corresponding safe voltage threshold. It can be the difference between the actual minimum individual unit voltage and the preset minimum individual unit voltage threshold, or the difference between the actual average individual unit voltage and the preset average individual unit voltage threshold.

[0105] It should be understood that by inheriting the integral term from the previous moment and updating the integral term in combination with the individual unit error, the changes in the individual unit voltage can be accurately tracked, avoiding abrupt integral changes and further preventing reverse polarity.

[0106] As one possible implementation, the integral term of the PID algorithm satisfies the following relationship:

[0107] in, This represents the integral term of the updated PID algorithm, where t represents the current time. Indicates the sampling time. This refers to the time before the current time. This represents the increment of the integral term at the current moment. The term represents the proportion at the current moment. This represents the differential term at the current moment. This represents the actual discharge current at the previous moment. This represents the increment of the integral term at the previous time step.

[0108] It should be understood that if the voltage distribution at the previous moment exceeds the preset deviation range, it indicates that the closed-loop control algorithm needs to be switched. This application updates the integral term based on the actual discharge current at the previous moment, the proportional term at the current moment, the increment of the integral term at the current moment, the derivative term, and the increment of the integral term at the previous moment. This can achieve a smooth switch between the power closed loop and the voltage closed loop, avoiding current jumps and voltage oscillations caused by sudden changes in control mode.

[0109] As another possible implementation, provided that the voltage distribution of the fuel cell stack does not exceed a preset deviation range, the integral term of the PID algorithm satisfies the following relationship:

[0110] in, This represents the integral term of the updated PID algorithm, where t represents the current time. Indicates the sampling time. This refers to the time before the current time. This represents the integral term from the previous time step. This represents the increment of the integral term at the current moment.

[0111] It should be understood that by adding the increment of the integral term to the integral term at the previous moment, the accumulation process of continuous integration can be simulated. At each step, the integral term is updated according to the current error. As long as the error exists, the integral term will continue to change, which can eliminate steady-state error and thus improve the accuracy of the discharge current.

[0112] like Figure 7 As shown, the method for controlling the discharge of a fuel cell stack in this application may include the following steps: Determine if the system forced discharge request (forced discharge command) sent by the fuel cell controller (system) is valid. If the request is valid, close the air inlet of the fuel cell stack air system; otherwise, repeat the process. The system forced discharge request may be issued during system shutdown or a wake-up call during a low-temperature shutdown.

[0113] The system closes the air inlet of the fuel cell stack's air system and requests the next stage of arbitration-based forced discharge. This can be achieved by closing the air system inlet throttle valve, requesting that the air flow into the fuel cell stack be zero.

[0114] The power required for arbitration-mandated discharge, i.e., the power required to initiate forced discharge, is input. = Then, current loading is performed based on a power-voltage multi-objective adaptive closed-loop control strategy.

[0115] (1) Determine the difference between the requested discharge power (target discharge power) and the actual power. Specifically, when the actual operating power of the system under the current operating condition during the forced discharge process is less than 5kW, = =5kW; when the actual operating power of the system under the current operating condition is greater than 5kW. = = + ,in, To request power generation from the fuel cell system (target power generation). For forced discharge power, This represents the actual power of the system. To force the discharge power to increase incrementally, we can take 2kW, where t is the iteration calculation period.

[0116] The difference between the requested discharge power and the actual power = - = - As the input driving force, the forced discharge request current value is calculated based on the power closed-loop control strategy. The DC-DC converter executes this request current value to discharge the fuel cell stack. During the efficient discharge process, the air inside the fuel cell stack is rapidly consumed. Without additional intervention, the uniformity of air distribution decreases as the current rapidly increases, and the average and minimum voltage values ​​decrease rapidly, while the voltage consistency between individual cells also deteriorates. Therefore, this process requires simultaneous multi-target monitoring and protection of the voltage.

[0117] (2) Voltage signals are acquired using a Cell Voltage Monitor (CVM) to determine whether the minimum cell voltage, average cell voltage, and voltage deviation from the mean have exceeded limits (if the deviation from the mean or the minimum cell voltage exceeds the limit, Fvmin=0; if the average cell voltage exceeds the limit, Fvavg=0). The difference between the actual voltage value and the corresponding voltage threshold is used as the input driving force to switch to voltage closed-loop control to calculate the requested current (closed-loop adjustment is prioritized based on the difference between the actual minimum cell voltage and the threshold to protect the stack safety). During this process, the stack discharges efficiently within the multi-target safety boundary, and the voltage continuously decreases. Proceed to the next step.

[0118] (3) Determine whether the average cell voltage has been clamped to the target voltage threshold v1. If yes, proceed to the next step; otherwise, repeat the previous step. In this step, the target voltage threshold v1 corresponds to the first average cell voltage threshold mentioned above.

[0119] It should be understood that the principle of this process is that when the real-time cell voltage collected by the cell voltage monitor (CVM) is about to exceed its set threshold, the software control strategy automatically switches from the power closed-loop control process to the voltage difference closed-loop control process, thereby calculating the current request value. As the air inside the stack is continuously consumed by the reaction, in order to maintain the cell voltage ≥ the lower voltage threshold, the current will continuously decrease during this period to clamp the cell voltage near the set voltage protection threshold line.

[0120] The average voltage threshold for a single cell can be set with reference to the starting voltage point for resistor discharge in a DC-DC converter. Therefore, at this point, the stack output voltage is slightly higher than the resistor discharge threshold voltage. .

[0121] in, The average single-cell voltage threshold, V; The discharge threshold voltage for the DC-DC resistor is V; This is the voltage tolerance value, which can be taken as 10V; The average single-cell voltage threshold is used to switch the corresponding current threshold, which can be set to 1A; I is the stack output current (actual discharge current), in A; This represents the number of battery cells in the fuel cell stack.

[0122] (4) Monitor the fuel cell stack output current and determine whether the fuel cell stack output current I is less than or equal to When the current is less than or equal to the set current threshold, it can be considered that the air inside the fuel cell stack has been fully consumed. At this time, the average cell voltage threshold (average cell voltage target voltage threshold) is switched to v2 (second average cell voltage threshold). If not, voltage closed-loop control discharge continues.

[0123] Under the voltage closed-loop control function, the current will increase slightly, thereby further reducing the stack voltage. It is determined whether the stack output voltage is less than or equal to the resistor discharge cut-in threshold (equivalent to the resistor discharge threshold mentioned above). If so, the active forced discharge program is exited and resistor discharge is entered. If not, the voltage closed-loop control discharge continues until it ends.

[0124] The foregoing mainly describes the solutions provided by the embodiments of this application from a methodological perspective. To achieve the above functions, the control device or electronic device for discharging the fuel cell stack includes hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should readily recognize that, based on the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0125] Please see Figure 8 , Figure 8 This is a schematic diagram of a control device for discharging a fuel cell stack battery, as disclosed in an embodiment of this application. The control device 800 for discharging a fuel cell stack battery includes: a first discharge unit 801, a second discharge unit 802, and a third discharge unit 803.

[0126] The first discharge module 801 is used to respond to receiving a forced discharge command, determine the discharge current of the fuel cell battery based on the target discharge power of the fuel cell battery through power closed-loop control, and control the fuel cell battery to perform a first stage of forced discharge with the discharge current; the target discharge power is greater than the actual discharge power of the fuel cell battery when the forced discharge command is received.

[0127] The second discharge module 802 is used to redetermine the discharge current of the fuel cell based on the voltage of the fuel cell through voltage closed-loop control when the voltage distribution of the fuel cell exceeds the preset deviation range, and continue to control the fuel cell to perform a second stage of forced discharge with the updated discharge current so that the average cell voltage of the fuel cell is maintained at the preset average cell voltage threshold.

[0128] The third discharge module 803 is used to control the fuel cell to enter the third stage of resistance discharge when the voltage of the fuel cell drops to the resistance discharge threshold, until the discharge is completed.

[0129] In one possible embodiment, the voltage distribution of the fuel cell stack exceeds a preset deviation range, including: the actual minimum cell voltage is less than a preset minimum cell voltage threshold, and / or the actual average cell voltage is less than a preset average cell voltage threshold; the second discharge module 802 is specifically used to redetermine the discharge current of the fuel cell stack based on the actual minimum cell voltage by voltage closed-loop control when the actual minimum cell voltage is less than the preset minimum cell voltage threshold and the actual average cell voltage is less than the preset average cell voltage threshold.

[0130] In one possible embodiment, the second discharge module 802 is specifically used to perform PID calculation on the difference between the actual average cell voltage and the preset average cell voltage threshold of the fuel cell stack battery when the actual minimum cell voltage is not lower than the preset minimum cell voltage protection threshold and the actual average cell voltage is less than the preset average cell voltage threshold, so as to obtain the redetermined discharge current of the fuel cell stack battery.

[0131] In one possible embodiment, the second discharge module 802 is specifically used to perform PID calculation on the difference between the actual average cell voltage of the fuel cell stack and the first average cell voltage threshold when the actual discharge current is greater than a preset current threshold, to obtain a redefined discharge current for the fuel cell stack; and to perform PID calculation on the difference between the actual average cell voltage of the fuel cell stack and the second average cell voltage threshold when the actual discharge current drops to less than or equal to the preset current threshold, to obtain a redefined discharge current for the fuel cell stack; wherein the first average cell voltage threshold is greater than the second average cell voltage threshold.

[0132] In one possible embodiment, the first discharge module 801 is specifically used to perform PID calculation on the difference between the target discharge power and the actual discharge power to determine the discharge current.

[0133] In one possible embodiment, the second discharge module 802 is specifically used to determine the rate of change of the average cell voltage of the fuel cell stack; when the rate of change is greater than a preset rate of change threshold, the discharge current of the fuel cell stack is determined by subtracting the change in discharge current determined based on the rate of change from the discharge current determined based on the voltage closed-loop control; the change in discharge current is proportional to the rate of change of the average cell voltage.

[0134] In one possible embodiment, the second discharge module 802 is specifically used to determine a preset transition time for switching from power closed-loop control to voltage closed-loop control; within the preset transition time, the discharge current of the fuel cell stack is re-determined based on the weighted value of the first current and the second current; the first current is determined based on the power closed-loop control; the second current is determined based on the voltage closed-loop control.

[0135] In one possible embodiment, the above-mentioned device further includes: a processing module, which is used to update the integral term of the PID algorithm at the current moment based on the integral term of the PID algorithm at the previous moment and the control error of the individual voltage when the voltage distribution at the previous moment exceeds a preset deviation range.

[0136] In one possible implementation, the integral term of the PID algorithm satisfies the following relationship:

[0137] in, This represents the integral term of the updated PID algorithm, where t represents the current time. Indicates the sampling time. This refers to the time before the current time. This represents the increment of the integral term at the current moment. The term represents the proportion at the current moment. This represents the differential term at the current moment. This represents the actual discharge current at the previous moment. This represents the increment of the integral term at the previous time step.

[0138] In one possible embodiment, when the voltage distribution of the fuel cell stack does not exceed a preset deviation range, the integral term of the PID algorithm satisfies the following relationship:

[0139] in, This represents the integral term of the updated PID algorithm, where t represents the current time. Indicates the sampling time. This refers to the time before the current time. This represents the integral term from the previous time step. This represents the increment of the integral term at the current moment.

[0140] Please see Figure 9 The electronic device 900 disclosed in this application includes, but is not limited to, a processor 901 and a memory 902.

[0141] The memory 902 described above is used to store the executable instructions of the processor 901. It is understood that the processor 901 is configured to execute instructions to implement the control method for discharging the fuel cell stack in the above embodiment.

[0142] It should be noted that those skilled in the art will understand that Figure 9 The electronic device structure shown does not constitute a limitation on electronic device 900; electronic device may include, but is not limited to, other electronic devices. Figure 9 This may indicate more or fewer components, or combinations of certain components, or different component arrangements.

[0143] Processor 901 is the control center of electronic device 900. It connects various parts of the electronic device via various interfaces and lines. By running or executing software programs and / or modules stored in memory 902, and by calling data stored in memory 902, it performs various functions and processes data of electronic device 900, thereby providing overall monitoring of electronic device 900. Processor 901 may include one or more processing units. Optionally, processor 901 may integrate an application processor and a modem processor. The application processor mainly handles the operating system, user interface, and applications, while the modem processor mainly handles wireless communication. It is understood that the modem processor may not be integrated into processor 901.

[0144] The memory 902 can be used to store software programs and various data. The memory 902 may primarily include a program storage area and a data storage area. The program storage area may store the operating system, application programs required by at least one functional module (such as a determination unit, processing unit, etc.), etc. Furthermore, the memory 902 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0145] In an exemplary embodiment, a vehicle is also provided, including the aforementioned control device and electronic equipment for discharging a fuel cell stack.

[0146] In an exemplary embodiment, a computer-readable storage medium including instructions is also provided, such as a memory 902 including instructions, which can be executed by a processor 901 of an electronic device 900 to implement the methods in the above embodiments.

[0147] In practical implementation, all methods of this application can be derived from... Figure 9 The processor 901 calls the computer program stored in the memory 902 to implement the process. The specific execution process can be found in the description of the method section in the previous embodiment, and will not be repeated here.

[0148] Optionally, the computer-readable storage medium may be a non-transitory computer-readable storage medium, such as a read-only memory (ROM), random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device.

[0149] In an exemplary embodiment, this application also provides a computer program product including one or more instructions, which can be executed by the processor 901 of the electronic device 900 to perform the methods described above.

[0150] It should be noted that when one or more instructions in the computer-readable storage medium or computer program product are executed by the processor of an electronic device, they implement the various processes of the above method embodiments and achieve the same technical effect as the above method. To avoid repetition, they will not be described again here.

[0151] Through the above description of the embodiments, those skilled in the art can clearly understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0152] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another apparatus, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0153] The units described as separate components may or may not be physically separate. A component shown as a unit can be one or more physical units; that is, it can be located in one place or distributed in multiple different locations. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0154] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0155] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solutions of the embodiments of this application, essentially, or the parts that contribute to the prior art, or all or part of the technical solutions, can be embodied in the form of a software product. This software product is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0156] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Those skilled in the art can understand that implementing all or part of the processes of the above embodiments and making equivalent changes according to the claims of this application still fall within the scope of this application.

Claims

1. A method for controlling the discharge of a fuel cell stack, characterized in that, The method includes: In response to receiving a forced discharge command, based on the target discharge power of the fuel cell stack, the discharge current of the fuel cell stack is determined through power closed-loop control, and the fuel cell stack is controlled to perform a first-stage forced discharge using the discharge current; the target discharge power is greater than the actual discharge power of the fuel cell stack when the forced discharge command is received. If the voltage distribution of the fuel cell stack exceeds the preset deviation range, the discharge current of the fuel cell stack is re-determined based on the voltage of the fuel cell stack through voltage closed-loop control, and the fuel cell stack continues to be controlled to perform a second stage of forced discharge with the updated discharge current, so that the average cell voltage of the fuel cell stack is maintained at the preset average cell voltage threshold. When the voltage of the fuel cell stack drops to the resistance discharge threshold, the fuel cell stack is controlled to enter the third stage of resistance discharge until the discharge is complete.

2. The method according to claim 1, characterized in that, The voltage distribution of the fuel cell stack exceeds the preset deviation range, including: the actual minimum cell voltage is less than the preset minimum cell voltage threshold, and / or the actual average cell voltage is less than the preset average cell voltage threshold. The process of redetermining the discharge current of the fuel cell stack based on its voltage through voltage closed-loop control includes: If the actual minimum cell voltage is less than the preset minimum cell voltage threshold and the actual average cell voltage is less than the preset average cell voltage threshold, the discharge current of the fuel cell stack is re-determined based on the actual minimum cell voltage through voltage closed-loop control.

3. The method according to claim 2, characterized in that, The process of redetermining the discharge current of the fuel cell stack based on its voltage through voltage closed-loop control includes: When the actual minimum cell voltage is not lower than the preset minimum cell voltage protection threshold and the actual average cell voltage is less than the preset average cell voltage threshold, the difference between the actual average cell voltage and the preset average cell voltage threshold of the fuel cell stack is calculated using PID to obtain the redefined discharge current of the fuel cell stack.

4. The method according to claim 3, characterized in that, The step of performing PID calculation on the difference between the actual average cell voltage of the fuel cell stack and the preset average cell voltage threshold to obtain the redefined discharge current of the fuel cell stack includes: When the actual discharge current is greater than the preset current threshold, the difference between the actual average cell voltage of the fuel cell stack battery and the first average cell voltage threshold is calculated by PID to obtain the redefined discharge current of the fuel cell stack battery. When the actual discharge current drops to less than or equal to the preset current threshold, the difference between the actual average cell voltage and the second average cell voltage threshold of the fuel cell stack is calculated using PID to obtain the redefined discharge current of the fuel cell stack; the first average cell voltage threshold is greater than the second average cell voltage threshold.

5. The method according to claim 1, characterized in that, The target discharge power based on the fuel cell stack is determined by power closed-loop control, which includes: The difference between the target discharge power and the actual discharge power is used for PID calculation to determine the discharge current.

6. The method according to claim 1, characterized in that, The process of redetermining the discharge current of the fuel cell stack based on its voltage through voltage closed-loop control includes: Determine the rate of change of the average single-cell voltage of the fuel cell stack. When the rate of change is greater than a preset rate of change threshold, the discharge current of the fuel cell stack is determined by subtracting the change in discharge current determined based on the rate of change from the discharge current determined based on the voltage closed-loop control; the change in discharge current is proportional to the rate of change of the average cell voltage.

7. The method according to claim 1, characterized in that, The process of redetermining the discharge current of the fuel cell stack based on its voltage through voltage closed-loop control includes: Determine the preset transition time for switching from power closed-loop control to voltage closed-loop control; Within the preset transition time, the discharge current of the fuel cell stack is re-determined based on the weighted value of the first current and the second current; the first current is determined based on the power closed loop; and the second current is determined based on the voltage closed loop.

8. The method according to any one of claims 2-4, characterized in that, The method further includes: If the voltage distribution at the previous moment exceeds the preset deviation range, the integral term of the PID algorithm at the current moment is updated based on the integral term of the PID algorithm at the previous moment and the control error of the individual voltage.

9. The method according to claim 8, characterized in that, The integral term of the PID algorithm satisfies the following relationship: in, This represents the integral term of the updated PID algorithm, where t represents the current time. Indicates the sampling time. This refers to the time before the current time. This represents the increment of the integral term at the current moment. The term represents the proportion at the current moment. This represents the differential term at the current moment. This represents the actual discharge current at the previous moment. This represents the increment of the integral term at the previous time step.

10. The method according to claim 8, characterized in that, When the voltage distribution of the fuel cell stack does not exceed the preset deviation range, the integral term of the PID algorithm satisfies the following relationship: in, This represents the integral term of the updated PID algorithm, where t represents the current time. Indicates the sampling time. This refers to the time before the current time. This represents the integral term from the previous time step. This represents the increment of the integral term at the current moment.

11. A control device for discharging a fuel cell stack, characterized in that, include: The first discharge module is configured to, in response to receiving a forced discharge command, determine the discharge current of the fuel cell battery based on the target discharge power of the fuel cell battery through power closed-loop control, and control the fuel cell battery to perform a first-stage forced discharge using the discharge current; the target discharge power is greater than the actual discharge power of the fuel cell battery when the forced discharge command is received; The second discharge module is used to redetermine the discharge current of the fuel cell battery based on the voltage of the fuel cell battery through voltage closed-loop control when the voltage distribution of the fuel cell battery exceeds the preset deviation range, and continue to control the fuel cell battery to perform a second stage of forced discharge with the updated discharge current so that the average cell voltage of the fuel cell battery is maintained at the preset average cell voltage threshold. The third discharge module is used to control the fuel cell to enter the third stage of resistance discharge when the voltage of the fuel cell drops to the resistance discharge threshold, until the discharge is completed.

12. A vehicle, characterized in that, include: The control device for discharging fuel cell stacks as described in claim 11.

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