Fuel cell hybrid vehicle and power battery soc feedback calibration method thereof

Abstract

The application provides a fuel cell hybrid vehicle and a power battery SOC feedback calibration method thereof, and belongs to the technical field of vehicle SOC calibration. In order to meet the demand of calibrating the power battery SOC of the fuel cell hybrid vehicle in the driving state, the application formulates the allowed calibration judgment interval and the calibration interval based on the trend that the voltage of the power battery changes with the SOC at the end of charging. When the fuel cell hybrid vehicle is in the driving process, if the maximum single battery voltage of the power battery is in the allowed calibration judgment interval, the feedback current is too large and the duration is relatively long, the charging of the power battery is limited. If the maximum single battery voltage of the power battery is in the calibration interval and lasts for a period of time, and the maximum single battery voltage of the power battery exceeds the set voltage, it indicates that the single battery voltage of the power battery suddenly changes with the SOC, at this time, the detected feedback current is small and lasts for a period of time, so the SOC of the power battery can be accurately set to 100%.

Description

Technical Field

[0001] This invention provides a fuel cell hybrid vehicle and its power battery SOC feedback calibration method, belonging to the field of vehicle SOC calibration technology. Background Technology

[0002] Fuel cell hybrid vehicles use fuel cells and power batteries as their power source. For fuel cell hybrid vehicles, the state of charge (SOC) of the power battery is one of the important parameters provided by the battery management system (BMS), and it is also the basis for the control strategies formulated by control units such as the vehicle controller (VCU), fuel cell control unit (FCU), and motor controller (MCU).

[0003] Currently, fuel cell hybrid vehicles typically use low-end static correction and high-end plug-in charging full-charge correction to calibrate the State of Charge (SOC). Low-end static correction requires obtaining open-circuit voltage through sufficient static time and then using a lookup table to correct the SOC. Alternatively, it involves obtaining dynamic voltage, current ratio, and temperature parameters from laboratory test data and then using a lookup table to correct the SOC. However, fuel cell hybrid vehicles operate in hybrid mode for extended periods, meaning they are constantly in motion, making low-end static correction less likely to be triggered. Furthermore, low-end static correction requires extensive laboratory testing to obtain data, resulting in a large workload, long testing cycles, and difficulty in simulating real-world application scenarios in the laboratory, thus compromising the practical application effectiveness of the test data.

[0004] Furthermore, due to the complex operating conditions of fuel cell hybrid vehicles, the probability of the BMS triggering full-charge correction based on the high-end charging gun is low when the vehicle is not externally charged for extended periods. In particular, relying solely on the traditional method of calculating SOC based on ampere-hour integrals is prone to cumulative errors. When the SOC calculated by the BMS differs significantly from the actual remaining charge of the battery, continuing to control charging and discharging based on the BMS-calculated SOC can easily lead to overcharging and over-discharging of the battery. Overcharging and over-discharging not only affect battery lifespan but can also damage the battery and even pose a safety hazard to the entire vehicle when overcharged; conversely, over-discharging can cause the vehicle to lose power and break down during driving, impacting the driving experience.

[0005] In summary, for fuel cell hybrid vehicles, using low-end static correction and high-end plug-in charging full-charge correction to calibrate the SOC is too dependent on the overall vehicle operating conditions, making it difficult to meet the SOC calibration requirements of the vehicle while it is in motion. Summary of the Invention

[0006] The purpose of this invention is to provide a power battery SOC feedback calibration method for fuel cell hybrid vehicles, which solves the problem that using low-end static correction and high-end plug-in charging full-charge correction is insufficient to meet the power battery SOC calibration requirements of fuel cell hybrid vehicles in driving conditions; the purpose of this invention is also to provide a fuel cell hybrid vehicle that can achieve power battery SOC calibration in driving conditions.

[0007] To achieve the above objectives, the present invention provides a method for SOC feedback calibration of a power battery in a fuel cell hybrid vehicle, comprising the following steps:

[0008] S1. When the fuel cell hybrid vehicle is in driving mode, the maximum single cell voltage of the power battery is judged based on the real-time acquired maximum single cell voltage. If the maximum single cell voltage is within the pre-set allowable calibration judgment range, the first feedback current of the fuel cell charging the power battery is judged. If the first feedback current is greater than the first set current, or the first feedback current is greater than the first set current and the duration of the first feedback current being greater than the first set current reaches the first set time, the charging power of the fuel cell to the power battery is reduced.

[0009] If the maximum single cell voltage is within a pre-set calibration range, and the maximum single cell voltage remains within the calibration range for a second set time, then the maximum single cell voltage of the power battery is reacquired, and the reacquired maximum single cell voltage of the power battery is judged; the lower threshold of the calibration judgment range is greater than the upper threshold of the calibration range.

[0010] S2. If the maximum single cell voltage of the power battery is reacquired and is greater than the set voltage, the second feedback current of the fuel cell charging the power battery is reacquired and judged. If the second feedback current is less than the second set current and the duration of the second feedback current being less than the second set current reaches the third set time, the SOC of the power battery is set to 100%; the set voltage is greater than the upper limit threshold of the calibration range.

[0011] The judgment interval and calibration interval for allowing calibration mentioned in step S1 are obtained by the following method:

[0012] The OCV-SOC curve of the power battery during the charging process of the fuel cell is calibrated, and then the judgment range and calibration range that allow calibration are determined based on the OCV-SOC curve of the power battery.

[0013] To meet the requirement of calibrating the State of Charge (SOC) of the power battery in fuel cell hybrid vehicles during driving, this invention establishes a judgment range and a calibration range based on the voltage change trend of the power battery with SOC at the end of charging. When the fuel cell hybrid vehicle is in operation, the individual cell voltages and feedback currents of the power battery are collected for judgment. If the maximum individual cell voltage of the power battery is within the judgment range of allowable calibration, and the feedback current is excessively large and lasts for a long time, it indicates the influence of polarization voltage, which can easily lead to miscalibration; therefore, charging of the power battery is restricted. If the maximum individual cell voltage of the power battery is within the calibration range and persists for a period of time, it indicates that the power battery is in the stage where the individual cell voltage does not change significantly with SOC at the end of charging. Furthermore, if the detected maximum individual cell voltage of the power battery exceeds the set voltage, it indicates a sudden change in the trend of the individual cell voltage changing with SOC, and the power battery is about to reach full charge. At this time, the detected feedback current is small and lasts for a period of time, avoiding overcharging of the power battery; therefore, the SOC of the power battery can be accurately set to 100%.

[0014] In the above method, when the fuel cell hybrid vehicle is in driving mode, the cumulative discharge of the power battery is also judged; if the cumulative discharge is greater than the set threshold, steps S1 and S2 are executed.

[0015] To avoid frequent calibration of the power battery's SOC during driving, a threshold is set to judge the cumulative discharge amount. This allows the power battery SOC feedback calibration method of the present invention to be executed only after the power battery has been working for a period of time, thus reducing the processing load of the controller.

[0016] In the above method, the cumulative discharge amount is the amount of electricity output by the power battery of the fuel cell hybrid vehicle during this driving process.

[0017] Using the cumulative discharge amount during a single trip for judgment can effectively reduce the processing load on the controller.

[0018] In the above method, the cumulative discharge amount is the cumulative amount of electricity output by the power battery from the end of the last feedback calibration of the power battery SOC of the fuel hybrid vehicle to the current moment.

[0019] The cumulative discharge amount from the end of the last feedback calibration to the current moment is used for judgment, so that the power battery can perform SOC feedback calibration under the condition of uniform discharge, and the processing volume is small.

[0020] In the above method, in step S2, the SOC of the power battery is set to 100% using a smooth transition method.

[0021] By adopting a smooth transition approach, drivers are less likely to experience concerns about battery malfunction when there are significant changes in SOC, thus enhancing the driving experience.

[0022] The present invention also provides a fuel cell hybrid vehicle, including a controller, wherein the controller executes instructions to realize a method for SOC feedback calibration of the power battery of the fuel cell hybrid vehicle, the method comprising the following steps:

[0023] S1. When the fuel cell hybrid vehicle is in driving mode, the maximum single cell voltage of the power battery is judged based on the real-time acquired maximum single cell voltage. If the maximum single cell voltage is within the pre-set allowable calibration judgment range, the first feedback current of the fuel cell charging the power battery is judged. If the first feedback current is greater than the first set current, or the first feedback current is greater than the first set current and the duration of the first feedback current being greater than the first set current reaches the first set time, the charging power of the fuel cell to the power battery is reduced.

[0024] If the maximum single cell voltage is within a pre-set calibration range, and the maximum single cell voltage remains within the calibration range for a second set time, then the maximum single cell voltage of the power battery is reacquired, and the reacquired maximum single cell voltage of the power battery is judged; the lower threshold of the calibration judgment range is greater than the upper threshold of the calibration range.

[0025] S2. If the maximum single cell voltage of the power battery is reacquired and is greater than the set voltage, the second feedback current for the fuel cell to charge the power battery is reacquired. If the second feedback current is less than the second set current and the duration of the second feedback current being less than the second set current reaches the third set time, the SOC of the power battery is set to 100%; the set voltage is greater than the upper limit threshold of the calibration range.

[0026] The judgment interval and calibration interval for allowing calibration mentioned in step S1 are obtained by the following method:

[0027] The OCV-SOC curve of the power battery during the charging process of the fuel cell is calibrated, and then the judgment range and calibration range that allow calibration are determined based on the OCV-SOC curve of the power battery.

[0028] The fuel cell hybrid vehicle of this invention establishes a judgment range and a calibration range for permissible calibration based on the trend of voltage change with SOC at the end of charging. When the fuel cell hybrid vehicle is in operation, the individual cell voltages and feedback currents of the power battery are collected for judgment. If the maximum individual cell voltage of the power battery is within the permissible calibration judgment range, and the feedback current is excessively large and lasts for a long time, it indicates the influence of polarization voltage, which can easily lead to miscalibration, thus limiting the charging of the power battery. If the maximum individual cell voltage of the power battery is within the calibration range and persists for a period of time, it indicates that the power battery is in the stage where the individual cell voltage change with SOC is not significant at the end of charging. Furthermore, if the detected maximum individual cell voltage of the power battery exceeds the set voltage, it indicates a sudden change in the trend of individual cell voltage change with SOC, and the power battery is about to reach full charge. At this time, the detected feedback current is small and lasts for a period of time, avoiding overcharging of the power battery. Therefore, the SOC of the power battery can be accurately set to 100%, realizing the power battery SOC feedback calibration function during driving.

[0029] In the aforementioned vehicles, when the fuel cell hybrid vehicle is in operation, the cumulative discharge of the power battery is also judged; if the cumulative discharge exceeds a set threshold, steps S1 and S2 are executed.

[0030] To avoid frequent calibration of the power battery's SOC during driving, a threshold is set to judge the cumulative discharge amount. This allows the power battery SOC feedback calibration method of the present invention to be executed only after the power battery has been working for a period of time, thus reducing the processing load of the controller (i.e., the battery management system).

[0031] In the aforementioned vehicles, the cumulative discharge amount refers to the amount of electricity output by the power battery of the fuel cell hybrid vehicle from the start of this driving process to the current moment.

[0032] Using the cumulative discharge amount during a single trip for judgment can effectively reduce the processing load on the controller.

[0033] In the aforementioned vehicles, the cumulative discharge amount is the cumulative amount of electricity output by the power battery from the end of the last feedback calibration of the power battery SOC to the current moment.

[0034] The cumulative discharge amount from the end of the last feedback calibration to the current moment is used for judgment, so that the power battery can perform SOC feedback calibration under the condition of uniform discharge, and the processing volume is small.

[0035] In the aforementioned vehicle, in step S2, the SOC of the power battery is set to 100% using a smooth transition method.

[0036] By adopting a smooth transition approach, drivers are less likely to experience concerns about battery malfunction when there are significant changes in SOC, thus enhancing the driving experience. Attached Figure Description

[0037] Figure 1 This is a structural block diagram of the battery system of a fuel cell hybrid vehicle in an embodiment of the method of the present invention;

[0038] Figure 2 This is a flowchart illustrating the startup process of the SOC feedback calibration method for the power battery of a fuel cell hybrid vehicle in an embodiment of the present invention.

[0039] Figure 3 This is a flowchart of the SOC feedback calibration method for the power battery of a fuel cell hybrid vehicle in an embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram of the OCV-SOC curve of the lithium iron phosphate power battery during charging in an embodiment of the method of the present invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0042] Method Implementation Examples:

[0043] To facilitate understanding of the SOC feedback calibration method for the power battery of the fuel cell hybrid vehicle (hereinafter referred to as the SOC feedback calibration method) of the present invention, a brief introduction to the system structure of the fuel cell hybrid vehicle is given first. Figure 1 As shown, a fuel cell hybrid vehicle includes a fuel cell system, a power battery system, a load, and a high-voltage switchgear. The fuel cell system includes a fuel cell, a fuel cell control unit (FCU), and an auxiliary DC-DC converter. The power battery system includes a power battery and a battery management system (BMS). The fuel cell is electrically connected to the high-voltage switchgear via the auxiliary DC-DC converter. The power battery is electrically connected to the auxiliary DC-DC converter of the fuel cell system via the high-voltage switchgear. The high-voltage switchgear is electrically connected to the load.

[0044] Then, through, as Figure 2 The startup procedure shown illustrates the startup conditions for the SOC feedback calibration method. This startup procedure includes the following steps:

[0045] 1) When the system is powered on, the Battery Management System (BMS) collects basic information such as the voltage, current, and temperature of the power battery. After confirming that there are no faults in the vehicle, it enters normal working state.

[0046] 2) The Battery Management System (BMS) determines the vehicle status based on vehicle signals, such as ON signal and charging signal, to confirm whether the vehicle is in driving condition.

[0047] The SOC feedback calibration method can be performed when the vehicle is in operation. To avoid frequent SOC feedback calibration during driving, which would increase the computational load on the Battery Management System (BMS), one of the following two methods can be used to determine whether to perform the SOC feedback calibration method based on the cumulative discharge of the power battery.

[0048] Judgment Method 1: After the start of this trip, the Battery Management System (BMS) calculates the cumulative discharge amount Q0 of the power battery during this trip using the ampere-hour integration method based on the collected voltage, current and other information. The BMS only executes the SOC feedback calibration method when the cumulative discharge amount Q0 of the power battery during this trip reaches the set threshold Q.

[0049] Judgment Method 2: Starting from the (n-1)th execution of the SOC feedback calibration method by the Battery Management System (BMS), calculate the cumulative discharge amount Q1 of the power battery. If the cumulative discharge amount Q1 reaches the set threshold Q, then execute the nth SOC feedback calibration method. If the cumulative discharge amount Q1 has not reached the set threshold Q by the end of the driving process, then store the cumulative discharge amount Q1 in non-volatile memory as the initial value for calculating the cumulative discharge amount during subsequent driving processes. This process continues until the cumulative discharge amount reaches the set threshold Q, at which point the nth SOC feedback calibration method is executed. After the nth SOC feedback calibration method is completed, the power battery has completed a full charge correction, and the cumulative discharge amount is cleared and stored.

[0050] Taking lithium iron phosphate (LFP) batteries as an example, at the end of the charging process (e.g., when the State of Charge (SOC) reaches 90%), the voltage of each individual cell does not show a significant trend with SOC. However, as the SOC approaches full charge, the voltage of each cell undergoes a more pronounced abrupt change with increasing SOC. Based on the characteristics of power batteries, such as... Figure 3 As shown, the SOC feedback calibration method for the power battery of the fuel cell hybrid vehicle of the present invention includes:

[0051] The Battery Management System (BMS) assesses the real-time voltage of individual battery cells. To eliminate the impact of polarization voltage introduced by continuous high-current feedback, it first determines whether the maximum single-cell voltage of the battery is within a pre-set allowable calibration range. If the maximum single-cell voltage is within this range, it then checks whether the feedback current from the fuel cell charging the battery exceeds a first set current I1. If the feedback current exceeds I1, the BMS proactively sends a request to the Fuel Cell Control Unit (FCU) to reduce the charging power from the fuel cell to the battery, thereby lowering the maximum single-cell voltage until it enters the calibration range, at which point SOC calibration is performed.

[0052] To avoid misjudgment, the duration of feedback current exceeding the first set current I1 is recorded. Only when the duration of feedback current exceeding the first set current I1 exceeds the first set time T1 is it considered that the continuous large current feedback has caused the polarization voltage to be affected. At this time, the battery management system (BMS) does not perform power battery SOC feedback calibration, but actively sends a request to the fuel cell control unit (FCU) to reduce the charging power of the fuel cell to the power battery, thereby reducing the maximum single cell voltage of the power battery. Only when it enters the calibration range is the SOC calibration judgment performed.

[0053] By calibrating the OCV-SOC curve of the power battery during the charging process of the fuel cell, the allowable calibration range can be determined based on the OCV-SOC curve. The OCV-SOC curve of the lithium iron phosphate power battery during charging is shown below. Figure 4 As shown in the figure, the section from point K1 to point K2 represents the final stage of charging, where the polarization voltage is reduced by decreasing the charging current. Therefore, when the voltage of a single cell exceeds the voltage value corresponding to point K1, the power battery can be considered to be in the final stage of charging, with a large charging current and the influence of polarization voltage. Therefore, in this embodiment, the allowable calibration range is set to 3.6V~3.65V.

[0054] If the maximum single-cell voltage of the power battery is not within the preset allowable calibration range, then it is determined whether the maximum single-cell voltage of the power battery is within the preset calibration range. If the maximum single-cell voltage of the power battery is within the preset calibration range, the duration is recorded. If the duration of the maximum single-cell voltage of the power battery being within the calibration range reaches a second preset time T2, then the Battery Management System (BMS) collects the single-cell voltage of the power battery again and makes a judgment on the maximum single-cell voltage of the power battery.

[0055] By calibrating the OCV-SOC curve of the power battery during the charging process of the fuel cell, a calibration range can be determined based on the OCV-SOC curve. The OCV-SOC curve of a lithium iron phosphate power battery during charging is shown below. Figure 4 As shown in the prior art, the power battery is considered to be fully charged when the voltage of a single cell exceeds the voltage corresponding to point K3 in the figure. In this scenario, the SOC calibration of the power battery is reduced to 100%. However, fuel cell hybrid vehicles basically do not have a plug-in full-charge scenario. Dynamic calibration is usually performed by regenerative charging during driving. Figure 4 The portion between points K2 and K3 represents the stage where the power battery reaches full charge under trickle charging conditions. Moreover, the time it takes for the voltage of a single cell in the power battery to rise from 3.6V to 3.65V is relatively short. To avoid overcharging, in this embodiment, the calibration range is set to 3.55V~3.6V.

[0056] If the maximum single-cell voltage of the power battery is greater than the set voltage at this time, the SOC of the power battery will be set to 100%.

[0057] To ensure the battery remains relatively stable when the maximum single-cell voltage exceeds the set voltage, the feedback current from the fuel cell charging the battery can be re-acquired when the maximum single-cell voltage exceeds the set voltage. If the feedback current from the fuel cell charging the battery is less than the second set current, the duration is timed. If the duration of the feedback current being less than the second set current reaches a third set time, the battery is considered to be fully charged, and the SOC of the battery is set to 100%.

[0058] By calibrating the OCV-SOC curve of the power battery during the charging process of the fuel cell, the set voltage is determined based on the OCV-SOC curve. In this embodiment, the set voltage is 3.65V.

[0059] When the battery management system (BMS) sets the state of charge (SOC) of the power battery to 100%, it performs a gradual correction through a smooth transition and displays the result on the vehicle's instrument panel.

[0060] Once the Battery Management System (BMS) completes the SOC feedback calibration of the power battery under driving conditions, it restores the limitation on the charging power of the power battery to avoid overcharging.

[0061] By employing this invention, fuel cell hybrid vehicles can be freed from the reliance on low-end static calibration and high-end plug-in charging full-charge calibration. The SOC of the power battery can also be corrected while driving, avoiding the problems of accumulated SOC error and inaccurate SOC display caused by long-term non-full-charge calibration of fuel cell hybrid vehicles. This improves the safety of fuel cell hybrid vehicles in driving conditions and the driving experience of the driver.

[0062] Vehicle Example:

[0063] This invention provides a fuel cell hybrid vehicle, such as... Figure 1As shown, the system includes a fuel cell system, a power battery system, a load, and a high-voltage switchgear. The fuel cell system includes a fuel cell, a fuel cell control unit (FCU), and an auxiliary DC-DC converter. The power battery system includes a power battery and a battery management system (BMS). The fuel cell is electrically connected to the high-voltage switchgear via the auxiliary DC-DC converter, the power battery is electrically connected to the auxiliary DC-DC converter of the fuel cell system via the high-voltage switchgear, and the high-voltage switchgear is electrically connected to the load.

[0064] The implementation method of the battery management system (BMS) execution instructions for fuel cell hybrid vehicles includes a method for SOC feedback calibration of the power battery. The implementation of this method has been clearly described in the method embodiment and will not be repeated here.

Claims

1. A method for SOC feedback calibration of a power battery in a fuel cell hybrid vehicle, characterized in that, Includes the following steps: S1. When the fuel cell hybrid vehicle is in driving mode, the maximum single cell voltage of the power battery is judged based on the real-time acquired maximum single cell voltage. If the maximum single cell voltage is within the pre-set allowable calibration judgment range, the first feedback current of the fuel cell charging the power battery is judged. If the first feedback current is greater than the first set current, or the first feedback current is greater than the first set current and the duration of the first feedback current being greater than the first set current reaches the first set time, it is determined that there is the influence of polarization voltage, and the charging power of the fuel cell to the power battery is reduced. If the maximum single cell voltage is within a pre-set calibration range, and the maximum single cell voltage remains within the calibration range for a second set time, then the maximum single cell voltage of the power battery is reacquired, and the reacquired maximum single cell voltage of the power battery is judged; the lower threshold of the calibration judgment range is greater than the upper threshold of the calibration range. S2. If the maximum single cell voltage of the power battery is reacquired and is greater than the set voltage, the second feedback current of the fuel cell charging the power battery is reacquired and judged. If the second feedback current is less than the second set current and the duration of the second feedback current being less than the second set current reaches the third set time, the SOC of the power battery is set to 100%; the set voltage is greater than the upper limit threshold of the calibration range. The judgment interval and calibration interval for allowing calibration mentioned in step S1 are obtained by the following method: The OCV-SOC curve of the power battery during the charging process of the fuel cell is calibrated, and then the judgment range and calibration range that allow calibration are determined based on the OCV-SOC curve of the power battery.

2. The method for SOC feedback calibration of a power battery in a fuel cell hybrid vehicle according to claim 1, characterized in that, When the fuel cell hybrid vehicle is in operation, the cumulative discharge of the power battery is also judged; if the cumulative discharge is greater than the set threshold, steps S1 and S2 are executed.

3. The method for SOC feedback calibration of a power battery in a fuel cell hybrid vehicle according to claim 2, characterized in that, The cumulative discharge amount refers to the amount of electricity output by the power battery of the fuel cell hybrid vehicle during this driving process.

4. The method for SOC feedback calibration of a power battery in a fuel cell hybrid vehicle according to claim 2, characterized in that, The cumulative discharge amount is the total amount of electricity output by the power battery from the end of the last feedback calibration of the power battery SOC of the fuel hybrid vehicle to the current moment.

5. The method for SOC feedback calibration of a power battery in a fuel cell hybrid vehicle according to claim 1, characterized in that, In step S2, a smooth transition method is used to set the SOC of the power battery to 100%.

6. A fuel cell hybrid vehicle, comprising a controller, characterized in that, The controller executes instructions to implement a method for SOC feedback calibration of the power battery in a fuel cell hybrid vehicle. This method includes the following steps: S1. When the fuel cell hybrid vehicle is in driving mode, the maximum single cell voltage of the power battery is judged based on the real-time acquired maximum single cell voltage. If the maximum single cell voltage is within the pre-set allowable calibration judgment range, the first feedback current of the fuel cell charging the power battery is judged. If the first feedback current is greater than the first set current, or the first feedback current is greater than the first set current and the duration of the first feedback current being greater than the first set current reaches the first set time, it is determined that there is the influence of polarization voltage, and the charging power of the fuel cell to the power battery is reduced. If the maximum single cell voltage is within a pre-set calibration range, and the maximum single cell voltage remains within the calibration range for a second set time, then the maximum single cell voltage of the power battery is reacquired, and the reacquired maximum single cell voltage of the power battery is judged; the lower threshold of the calibration judgment range is greater than the upper threshold of the calibration range. S2. If the maximum single cell voltage of the power battery is reacquired and is greater than the set voltage, the second feedback current for the fuel cell to charge the power battery is reacquired. If the second feedback current is less than the second set current and the duration of the second feedback current being less than the second set current reaches the third set time, the SOC of the power battery is set to 100%; the set voltage is greater than the upper limit threshold of the calibration range. The judgment interval and calibration interval for allowing calibration mentioned in step S1 are obtained by the following method: The OCV-SOC curve of the power battery during the charging process of the fuel cell is calibrated, and then the judgment range and calibration range that allow calibration are determined based on the OCV-SOC curve of the power battery.

7. The fuel cell hybrid vehicle according to claim 6, characterized in that, When the fuel cell hybrid vehicle is in operation, the cumulative discharge of the power battery is also judged; if the cumulative discharge is greater than the set threshold, steps S1 and S2 are executed.

8. The fuel cell hybrid vehicle according to claim 7, characterized in that, The cumulative discharge amount refers to the amount of electricity output by the power battery of the fuel cell hybrid vehicle from the start of this driving process to the current moment.

9. The fuel cell hybrid vehicle according to claim 7, characterized in that, The cumulative discharge amount is the total amount of electricity output by the power battery from the end of the last feedback calibration of the power battery SOC of the fuel hybrid vehicle to the current moment.

10. The fuel cell hybrid vehicle according to claim 6, characterized in that, In step S2, a smooth transition method is used to set the SOC of the power battery to 100%.

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