Control method and system of hydrogen fuel unmanned aerial vehicle stack based on current step adjustment

Abstract

The invention relates to the technical field of hydrogen fuel cell stacks, in particular to a control method and system of a hydrogen fuel unmanned aerial vehicle stack based on current step adjustment. According to the system, by optimizing the control strategy and system design of the hydrogen fuel cell, the cruising ability of the hydrogen fuel unmanned aerial vehicle is improved, the service life of a galvanic pile is prolonged, meanwhile, the system complexity is reduced, and stable operation is ensured. The system is mainly composed of the following key components: a master control MCU, a DC / DC converter, a hydrogen fuel cell, a hydrogen cylinder, a standby lithium battery, a flight control system and a motor. Compared with the prior art, a current step type adjusting strategy is adopted, potential instability or too low potential caused by frequent current change is effectively avoided, and therefore the performance and durability of the electric pile are remarkably improved. Meanwhile, the system optimizes a thermal management mechanism, ensures that the galvanic pile operates in an optimal temperature range, and further prolongs the service life of the galvanic pile.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen fuel cell stacks, and in particular to a control method and system for a hydrogen fuel UAV stack based on current step regulation. Background Art

[0002] With the continuous development of hydrogen fuel cell technology, its application in the field of drones has gradually attracted attention. Hydrogen fuel cells have the advantages of high energy density and long endurance, and are considered to be an important development direction for future drone power systems. However, in the existing technology, there are still some problems with the control method of hydrogen fuel drone stacks. For example, frequent changes in current can cause dynamic fluctuations in many aspects such as the internal reaction rate, water management, gas supply, polarization effect, and mechanical stability of the fuel cell, thereby causing potential instability. Traditional control strategies are difficult to effectively deal with this potential instability or low potential phenomenon, which not only affects the performance and durability of the stack, but may also increase the complexity of the system.

[0003] In order to ensure the stability of the potential of the fuel cell stack during operation, proper potential regulation is particularly important. Studies have shown that the consistency of the potential of each cell in the operation of the proton exchange membrane fuel cell stack is crucial to improving the overall performance. Especially under dynamic conditions of variable load, the uniformity of the cell potential will change with the change of the current step amplitude and the current change frequency. By accurately adjusting these two parameters, the uniform change of the single cell potential can be effectively maintained, thereby ensuring the stability of the potential. This provides an important theoretical basis and optimization direction for the potential balance of the stack.

[0004] In addition, the efficiency and service life of hydrogen fuel cell stacks are also limited by the thermal management system. High temperatures will accelerate the aging of materials inside the stack, including catalysts, proton exchange membranes, and electrodes; while in low temperature environments, the overall temperature of the stack is low and the electrochemical reaction rate slows down. At the same time, the existing system is insufficient in adapting to different types of hydrogen fuel cell stacks, drone flight control systems, and motor operation requirements, limiting the widespread application of hydrogen fuel cell drones.

[0005] Based on the above situation, developing a strategy that can achieve both current step control and effective thermal management is crucial to significantly improve the service life of the fuel cell stack. At the same time, designing a universal system that can be widely adapted to different types of fuel cell stacks and flight control systems is the key to achieving technological breakthroughs. Summary of the invention

[0006] The purpose of the present invention is to propose a control method and system for a hydrogen fuel UAV stack based on current step regulation in response to the problems existing in the background technology. The invention aims to effectively solve the problems of complexity, compatibility and stack attenuation existing in the prior art through innovative control strategies and system architecture, thereby significantly improving the comprehensive performance and application value of hydrogen fuel cell UAVs.

[0007] The technical solution of the present invention, the first aspect of the present invention provides a control method and system for a hydrogen fuel UAV battery stack based on current step regulation, a control system for a hydrogen fuel UAV battery stack based on current step regulation, comprising a main control MCU, a DC / DC converter, a hydrogen fuel cell, a hydrogen cylinder, a backup lithium battery, a flight control system and a motor; The main control MCU is used to collect various data of system operation in real time and control various parts of the system based on the collected data; The DC / DC converter obtains the current output of the hydrogen fuel cell stack in constant current mode according to the current regulation instruction provided by the main control MCU, and transmits it to the flight control system; The hydrogen fuel cell and hydrogen tank together constitute the main power source of the system, providing continuous and stable power for the flight control system and motor; The backup lithium battery provides power to the system when the hydrogen fuel cell output power is insufficient or in the initial stage of system startup; at the same time, it outputs a stable voltage to the flight control system and motor.

[0008] Furthermore, the main MCU controls the hydrogen supply, exhaust emissions and thermal management of the hydrogen fuel cell; it also controls the current step regulation of the DC / DC converter and the voltage maintenance of the backup lithium battery.

[0009] Furthermore, the data collected by the main control MCU includes temperature, air pressure, Hall current, voltage, external switch status and fan speed.

[0010] Furthermore, the input and output voltage range of the DC / DC converter is between 10V and 130V.

[0011] The second aspect of the present invention provides a method for controlling a hydrogen fuel UAV stack based on current step regulation, and uses the above system to control the UAV, including the following specific steps: S1, connect the lithium battery power supply, open the hydrogen cylinder valve, and trigger the external switch of the main control MCU; S2, the main control MCU controls the intake valve and exhaust valve to open, and starts the cooling fan to perform power-on purge to remove the residual gas inside the battery stack; S3. After the purge is completed, the air inlet valve is kept open, the exhaust valve is opened at a fixed time, and the environment and stack operation data are collected in real time; the environment and stack data in step S3 specifically include: ambient temperature, stack temperature, fan speed, stack output current and voltage, lithium battery charge or discharge current, lithium battery voltage, hydrogen bottle pressure, and external switch status; S4: When the drone starts, the main control MCU adjusts the fan PWM signal according to the ambient temperature and output current, maintains the battery stack in the optimal temperature range, and dynamically adjusts the duty cycle; S5. The current required by the drone is evenly distributed to the two battery stacks, and the current is adjusted in steps through the DC / DC converter; S6. After the drone lands and stops, turn off the external switch to trigger the shutdown and purge signal. The main control MCU controls the air intake valve and exhaust valve to open, and the cooling fan runs steadily to remove residual gas. S7, after the shutdown and purge is completed, the main control MCU controls the cooling fan to rotate at full speed to remove the residual moisture in the stack; S8. After completing the shutdown, purging and drying processes, close the hydrogen bottle valve and the lithium battery switch to end the system operation.

[0012] Furthermore, once the external switch is detected to be closed in step S1, the main control MCU pin is grounded, which triggers the power-on purge process of the battery stack.

[0013] Furthermore, in step S2, the intake valve and the exhaust valve of the fuel cell stack are opened, and a PWM signal with a duty cycle of 42% is output to drive the fuel cell stack cooling fan.

[0014] Furthermore, in step S5, the actual output current of the battery stack is accurately monitored and adjusted through the dual feedback mechanism of the processor; when the current increases, the first feedback mechanism of the processor is responsible for real-time monitoring and accumulating the amplitude of the current step; when the accumulated step amplitude reaches the set value, the second feedback mechanism is activated, and the system gradually increases the output current of the battery stack at a set rate through the DC / DC converter.

[0015] Furthermore, when the current needs to be reduced, the system will gradually reduce the output current of the battery stack at a set rate.

[0016] Furthermore, after the external switch is manually turned off in step S6, the 3.3V voltage of the pin of the main control MCU sends a shutdown purge signal for the hydrogen fuel cell stack; the system executes steps S7-S8 until the system ends operation.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: (1) The present invention adopts a step current regulation strategy and a dual feedback mechanism, which can effectively suppress the fluctuation and too low potential of the battery stack caused by frequent current changes, and significantly reduce the poisoning reaction of the catalyst inside the battery stack and the accumulation of electrochemical stress. After testing, under the condition of a current density of 175A / cm², the attenuation of a 2kW battery stack after 100 hours of operation in simulated drone conditions using the method of the present invention was significantly reduced by 56.5% compared with the traditional method. This result shows that the present invention has significant advantages in improving the durability and voltage stability of the battery stack, and can effectively delay the attenuation of the battery stack performance.

[0018] (2) The present invention is based on the three-dimensional fitting surface of ambient temperature and output current, combined with the PI adjustment algorithm, to accurately control the PWM signal duty cycle of the stack fan to ensure that the stack temperature is always maintained within the optimal reaction temperature range. This dynamic temperature management strategy monitors the deviation between the center point temperature of the stack and the preset optimal reaction temperature in real time, calculates the corresponding PWM duty cycle using the PI algorithm, and dynamically adjusts the fan speed, thereby effectively suppressing temperature fluctuations. This precise temperature control method not only optimizes the operating efficiency of the stack under different operating conditions, but also significantly reduces the problems of decreased catalyst activity and intensified side reactions inside the stack caused by abnormal temperature, thereby extending the service life of the stack.

[0019] (3) The high-power DC / DC converter used in the present invention has an input and output voltage range of 10~130V, which can adapt to fuel cells and flight control systems with various voltage configurations. This wide voltage range design significantly improves the compatibility and flexibility of the system, enabling it to adapt to different models of hydrogen fuel cell fuel cells and diverse flight control system requirements. In addition, the system also has good scalability and can be customized according to actual application scenarios, further enhancing its application value in the field of hydrogen fuel cell drones.

[0020] (4) The overall system operation process of the present invention is highly simplified and extremely user-friendly. After completing the assembly of the power system package, the user only needs to turn on the lithium battery power switch, the hydrogen bottle valve and the control panel switch in sequence, and the system can enter the working state, realizing the rapid startup and operation of the drone. This startup process fully considers the convenience and safety of operation, ensuring that the user completes the system activation in the shortest time, while avoiding the risks that may be caused by complex operating steps. During the shutdown process, the system also follows the principles of simplicity and efficiency. The user only needs to turn off the control panel switch, the hydrogen bottle valve and the lithium battery switch in reverse order to complete the safe shutdown of the system. This shutdown process is not only easy to operate, but also ensures the stability of the system during the shutdown process through a reasonable sequence design, avoiding safety hazards caused by sudden power outages or hydrogen supply interruptions.

[0021] (5) During the startup and shutdown process, the system performs a purge process to remove residual gas and moisture inside the stack. The startup purge ensures that the stack is in a clean and stable state before startup, while the shutdown purge prevents safety risks and stack damage caused by residual gas and moisture. In addition, the full rotation of the cooling fan after shutdown further ensures that the inside of the stack is dry, ready for the next startup, and enhances the safety and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the control method and system structure of the hydrogen fuel UAV battery stack based on current step regulation Figure 2 A control method and system flow chart for a hydrogen fuel UAV stack based on current step regulation Figure 3 The figure shows the change of the cooling fan duty cycle under different ambient temperatures and stack current conditions. DETAILED DESCRIPTION

[0023] Example 1

[0024] like Figure 1 As shown, the present invention proposes a control system for a hydrogen fuel UAV stack based on current step regulation, including a main control MCU, a DC / DC converter, a hydrogen fuel cell, a hydrogen cylinder, a backup lithium battery, a flight control system and a motor.

[0025] The main control MCU, as the central nervous system of the system, is responsible for real-time collection of key data of system operation and accurate control of various components based on these data. Specifically, its control functions cover hydrogen supply, exhaust gas emission and thermal management of hydrogen fuel cell stacks; current step regulation of high-power DC / DC converters; and voltage maintenance of backup lithium batteries.

[0026] The DC / DC converter plays a vital role in the system. Based on the current regulation instructions provided by the main control MCU, it accurately obtains the current output of the hydrogen fuel cell stack in constant current mode and stably transmits it to the flight control system. Its input and output voltage range is wide, ranging from 10V to 130V, which enables it to effectively connect the hydrogen fuel cell stack and the flight control system, acting as a power conversion bridge between the two, and has good adaptability and is compatible with various models of hydrogen fuel cell stacks and flight control systems.

[0027] The hydrogen fuel cell and hydrogen cylinder together constitute the main power source of the system, providing continuous and stable power support for the flight control system and motor, ensuring the efficient operation of the system.

[0028] The backup lithium battery plays a dual role in the system: on the one hand, it provides the necessary power supplement for the system under special circumstances such as insufficient output power of the hydrogen fuel cell or in the initial stage of system startup; on the other hand, it can also output a stable voltage for the flight control system and the motor to ensure the reliable operation of the system under various working conditions.

[0029] The control process of the system, such as Figure 2 As shown, when starting, first turn on the lithium battery power switch and the hydrogen cylinder valve, then the system enters the operating state and starts to monitor key operating parameters in real time, including but not limited to temperature, air pressure, Hall current, voltage, and external switch status. Once the switch is detected to be closed, that is, the control board processor pin is connected to 3.3V voltage, the system triggers the power-on purge process of the stack. This process involves opening the intake valve and exhaust valve of the stack and outputting a PWM signal with a duty cycle of 42% to drive the stack cooling fan.

[0030] After the power-on purge process is completed, the system will start the high-power DC / DC converter, which obtains current from the battery stack in constant current mode and controls the timing of the exhaust valve opening. At the same time, the system will dynamically adjust the duty cycle of the fan PWM signal according to the real-time monitored current and temperature data to optimize the heat dissipation effect. In constant current mode, the current value obtained by the high-power DC / DC converter from the battery stack will be distributed according to the power demand of the drone. Specifically, the required total current will be evenly distributed to the two hydrogen fuel cell stacks. The system adopts a step current regulation strategy and accurately monitors and adjusts the actual output current of the battery stack through the dual feedback mechanism of the processor. In the case of increasing current, the first feedback mechanism of the processor is responsible for real-time monitoring and accumulating the amplitude of the current step. When the accumulated step amplitude reaches 3A, the second feedback mechanism is activated, and the system gradually increases the output current of the battery stack at a rate of 3A / s through the DC / DC converter. On the contrary, when the current needs to be reduced, the system will gradually reduce the output current of the battery stack at a rate of 10A / s. After the drone is used, turn off the switch first. When the switch is detected to be disconnected, that is, the control board processor pin is grounded, the system will execute the shutdown purge process of the battery stack. This process first opens the intake valve and exhaust valve, and sets the duty cycle of the fan PWM signal to 42%. After the purge is completed, the system will close all solenoid valves and make the fan rotate at high speed for 10 seconds, and then end the system operation.

[0031] Example 2

[0032] The present invention proposes a control method for a hydrogen fuel UAV stack based on current step regulation, comprising the following steps: (1) Connect the lithium battery power supply, open the hydrogen cylinder valve, and trigger the external switch of the control circuit board to prepare for system startup.

[0033] (2) The STM32H7 microcontroller controls the opening of the intake valve and the exhaust valve, and starts the cooling fan to perform power-on purge to remove residual gas inside the fuel cell stack.

[0034] (3) After the purge is completed, keep the intake valve open, open the exhaust valve regularly, and collect environmental and stack operation data in real time to provide support for subsequent control.

[0035] (4) When the drone starts, the STM32H7 microcontroller adjusts the fan PWM signal according to the ambient temperature and output current, maintains the battery stack in the optimal temperature range, and dynamically adjusts the duty cycle to ensure stable operation.

[0036] (5) The system evenly distributes the current required by the drone to the two battery stacks and adjusts the current in steps through the DC / DC converter to ensure stable output of the battery stack and avoid potential fluctuations.

[0037] (6) After the drone lands and stops, turn off the external switch to trigger the shutdown and purge signal. The STM32H7 microcontroller controls the opening of the intake valve and exhaust valve, and the cooling fan runs steadily to remove residual gas.

[0038] (7) After the shutdown and purge are completed, the STM32H7 microcontroller controls the cooling fan to rotate at full speed to remove residual moisture in the stack and ensure that the inside of the stack is dry.

[0039] (8) After completing the shutdown, purging and drying processes, close the hydrogen cylinder valve and the lithium battery switch to end system operation.

[0040] Furthermore, in step (1), the switching of the level state of the designated pin of the processor (STM32H7 single-chip microcomputer chip) on the circuit board is realized by controlling the closing and opening of the external switch. When the pin level is switched to 3.3V, the signal is defined as the power-on purge instruction of the hydrogen fuel cell stack, thereby triggering the system initialization purge process.

[0041] Furthermore, in step (2), the STM32H7 single-chip microcomputer is the core processor of the control circuit board, which precisely controls the opening of the intake valve and exhaust valve of the hydrogen fuel cell stack by enabling the corresponding driver chip, and drives the cooling fan to start through the PWM signal to perform the power-on purge process. This process is intended to remove the residual gas inside the fuel cell stack to ensure that the fuel cell stack is in a clean and stable state before starting.

[0042] Furthermore, after the stack purge is completed in step (3), the intake valve is kept open and the exhaust valve is opened regularly to maintain the gas circulation inside the stack. The operating data collected by the system in real time include the ambient temperature, the center temperature of the stack, the output current, the output voltage, and the output current and voltage of the lithium battery. At the same time, the current required for the operation of the drone is monitored to provide real-time data support for subsequent operation control.

[0043] Furthermore, in step (4), when the UAV is started and powered by the hydrogen fuel cell stack and the lithium battery, the STM32H7 single-chip microcomputer selects a preset duty cycle as the PWM signal of the stack fan on the three-dimensional fitting surface according to the ambient temperature and the stack output current, so as to accurately control the stack temperature within the optimal reaction temperature range under the current. At the same time, the system uses a proportional-integral (PI) regulator to dynamically adjust the duty cycle of the fan PWM signal according to the deviation between the real-time measured stack center temperature and the preset optimal reaction temperature. When the stack center temperature is higher or lower than the optimal reaction temperature, the system automatically increases or decreases the duty cycle of the fan PWM signal to maintain the stability of the stack temperature.

[0044] Further, in step (5), the system first distributes the required total current evenly to the two hydrogen fuel cell stacks according to the power demand of the UAV. This allocation strategy is intended to set a clear and balanced current demand target for each stack, thereby ensuring that the two stacks can work together during operation and avoiding performance differences caused by uneven current distribution. Subsequently, the system accurately adjusts the output current of each hydrogen fuel cell stack through a DC / DC converter to ensure that the output current of the stack can accurately match the actual power demand of the UAV. To achieve this goal, the system adopts a step current regulation strategy to dynamically monitor and adjust the actual output current of the stack through the dual feedback mechanism of the processor. Specifically, taking the current increase as an example, the first feedback mechanism of the processor is responsible for real-time monitoring and accumulating the current change value. When the accumulated change value reaches the step amplitude set by the second feedback mechanism (for example, 3 amperes), the second feedback mechanism is triggered, and the accumulated time in this process is the step cycle (for example, 1 second). The system gradually increases the output current of the stack at a set rate (3A / s) through the DC / DC converter. Similarly, when the current needs to be reduced, the system gradually reduces the output current of the battery stack at another rate (10A / s).

[0045] Furthermore, in step (6), after the drone completes landing and is in a stable state, the operator will turn off the external switch on the control circuit board. The external switch will give a low-level signal to the microcontroller when the switch is closed, and the closure of the switch will trigger the system purge program. This step will trigger the pin of the processor STM32H7 microcontroller chip to be grounded, thereby sending a shutdown purge signal for the hydrogen fuel cell stack. This signal is a key instruction to start the shutdown purge process, which is intended to remove hydrogen and water that may remain inside the stack, prevent potential safety risks, and prepare for the next startup of the stack. In this way, the system can ensure the safety and reliability of the drone and its hydrogen fuel cell stack when it is shut down.

[0046] Furthermore, after the shutdown and purging in step (7) is completed, the STM32H7 single-chip microcomputer chip uses a PWM signal to make the stack cooling fan fully rotate, further removing the residual moisture in the stack, ensuring that the inside of the stack is dry and ready for the next startup.

[0047] The following uses a specific case to introduce the solution of the present invention in detail: Assume that the target current requirement for a single battery stack during the flight of the drone is , after a feedback system, we get the function .according to The value is fed back for the second time to obtain the actual output current value of the battery stack ,in For a step wave signal that satisfies the requirement of increasing S1 amperes every T1 seconds or decreasing S2 amperes every T2 seconds, the update formula is:

[0048] First level feedback The accumulated current change value is equal to the actual output current value of the battery stack. When the error is greater than S1 or less than -S2, the second feedback function is triggered. The core processor used in this system is the STM32H7 single-chip microcomputer chip, and its feedback operation time is set to 10 milliseconds. Therefore, The update formula is

[0049] In summary, the periods T1 and T2 of the current step are determined by the first feedback function The current step amplitudes S1 and S2 are determined by the second feedback function In practical applications, the step sizes S1 and S2, and the time intervals T1 and T2 can be adjusted according to the characteristics of different battery stacks. Subsequently, the actual output current value of the battery stack is transmitted to the high-power DC / DC converter through CAN bus communication. After receiving the CAN signal, the DC / DC converter will obtain the corresponding output current value from the battery stack accordingly. The specific experimental steps are as follows: First, collect flight power change data of a 25kg-class UAV during takeoff, hovering, flight according to the route, return, and landing. Analyze the collected power data, clarify the power characteristics and change rules of each flight stage, and set the working mode of the programmable electronic load meter accordingly so that its power change can accurately simulate the actual flight power change of the UAV. Each operation time is 1 hour. During this process, the power output of the electronic load meter is monitored in real time to ensure that it is consistent with the UAV flight power change to meet the experimental requirements; Table 1 compares the voltage attenuation of the traditional method and the current step regulation method at a current density of 175A / cm² after the 2 kW stack has been running for 100 hours. Among them, the traditional method refers to the common control method in which the current of the stack is not adjusted and the current changes in real time with the load. The comparison results are based on the difference between the voltage after the stack is running and the initial voltage when it is not running, which is used to evaluate the impact of the two methods on the performance of the stack. The results show that the voltage of the traditional method decayed by 8.5% after 100 hours of operation, while the voltage decay of the current step regulation method was only 3.8%, and the attenuation was significantly reduced by 56.5%. Table 1 Comparison of attenuation of 2kW stack after 100 hours of operation

[0050] Changes in fan speed and ambient temperature can lead to significantly different operating temperatures of the stack. In the experiment, the fan speed was precisely adjusted by manually adjusting the duty cycle of the fan's PWM control signal, thereby achieving effective control of the stack's operating temperature. At the same time, the operating temperature and voltage data of the stack at different fan speeds were recorded in real time to analyze the relationship between fan speed and stack performance. Table 2 lists the output voltage values ​​of a 2kW stack at different operating temperatures when the current density is 200A / cm². The results show that there are significant differences in the output voltage of the stack at different temperatures, which fully demonstrates that the operating temperature has a significant impact on the stack performance. Therefore, effective thermal management of the stack is the key to ensuring its efficient and stable operation.

[0051] Table 2 Output voltage of 2kW stack at different operating temperatures

[0052] In order to achieve the best operating state of the battery stack, it is necessary to test and determine the duty cycle of the cooling fan PWM control signal required to maintain the optimal operating temperature of the battery stack under various combinations of ambient temperature and battery stack output current. Under four ambient temperature conditions of 10°C, 20°C, 32°C and 35°C, manually adjust the fan's PWM (pulse width modulation) control signal duty cycle to change the fan speed to adjust the operating temperature of the battery stack. At the same time, monitor and record the potential changes of the battery stack to determine the highest operating temperature range for the battery stack potential at each ambient temperature, and accurately record the duty cycle value of the fan PWM control signal at this time to provide key data support for subsequent thermal management. The following table shows the test results for the 2kW battery stack used in the system.

[0053] Table 3 2kW battery stack test results

[0054] Based on the data in the table, the following Figure 3The three-dimensional surface graph shown in the figure clearly depicts the relationship between ambient temperature, stack current and cooling fan duty cycle. The parameters represented by each axis in the figure are as follows: The X-axis (horizontal axis) indicates the ambient temperature, and the measurement range is set between 0 and 35 degrees Celsius. The Y-axis (front-to-back axis) indicates the stack current, and the measurement range is set between 0 and 80 amperes. The Z-axis (vertical axis) indicates the duty cycle of the cooling fan, and the measurement range is set between 40% and 48%. During the operation of the system, the corresponding duty cycle value can be accurately found in the three-dimensional graph through the real-time collection of ambient temperature and stack output current data. During the operation of the system, the corresponding cooling fan PWM signal duty cycle value can be accurately found according to the pre-constructed three-dimensional graph by collecting ambient temperature and stack output current data in real time. At the same time, the system needs to dynamically adjust the duty cycle of the fan PWM signal according to the deviation between the real-time measured stack center point temperature and the preset optimal reaction temperature to ensure that the stack always operates within the optimal temperature range, thereby maintaining its efficient and stable operation.

[0055] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto, and various changes can be made within the knowledge scope of technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A control system for a hydrogen fuel UAV stack based on current step regulation, characterized in that: Including main control MCU, DC / DC converter, hydrogen fuel cell, hydrogen cylinder, backup lithium battery, flight control system and motor; The main control MCU is used to collect various data of system operation in real time and control various parts of the system based on the collected data; The DC / DC converter obtains the current output of the hydrogen fuel cell stack in constant current mode according to the current regulation instruction provided by the main control MCU, and transmits it to the flight control system; The hydrogen fuel cell and hydrogen tank together constitute the main power source of the system, providing continuous and stable power for the flight control system and motor; The backup lithium battery provides power to the system when the hydrogen fuel cell output power is insufficient or in the initial stage of system startup; at the same time, it outputs a stable voltage to the flight control system and motor.

2. The control system of the hydrogen fuel UAV stack based on current step regulation according to claim 1 is characterized in that: The main MCU controls the hydrogen supply, exhaust emissions and thermal management of the hydrogen fuel cell; it also controls the current step regulation of the DC / DC converter and the voltage maintenance of the backup lithium battery.

3. The control system of the hydrogen fuel UAV stack based on current step regulation according to claim 1 is characterized in that: The data collected by the main MCU includes temperature, air pressure, Hall current, voltage, external switch status and fan speed.

4. The control system of the hydrogen fuel UAV stack based on current step regulation according to claim 1 is characterized in that: The input and output voltage range of the DC / DC converter is between 10V and 130V.

5. A control method for a hydrogen fuel UAV stack based on current step regulation, using the system described in any one of claims 1 to 4 to control the UAV, characterized in that: The specific steps include: S1, connect the lithium battery power supply, open the hydrogen cylinder valve, and trigger the external switch of the main control MCU; S2, the main control MCU controls the intake valve and exhaust valve to open, and starts the cooling fan to perform power-on purge to remove the residual gas inside the battery stack; S3. After the purge is completed, the intake valve is kept open, the exhaust valve is opened regularly, and the environment and stack operation data are collected in real time; S4: When the drone starts, the main control MCU adjusts the fan PWM signal according to the ambient temperature and output current, maintains the battery stack in the optimal temperature range, and dynamically adjusts the duty cycle; S5. The current required by the drone is evenly distributed to the two battery stacks, and the current is adjusted in steps through the DC / DC converter; S6. After the drone lands and stops, turn off the external switch to trigger the shutdown and purge signal. The main control MCU controls the air intake valve and exhaust valve to open, and the cooling fan runs steadily to remove residual gas. S7, after the shutdown and purge is completed, the main control MCU controls the cooling fan to rotate at full speed to remove the residual moisture in the stack; S8. After completing the shutdown, purging and drying processes, close the hydrogen bottle valve and the lithium battery switch to end the system operation.

6. The control method of the hydrogen fuel UAV stack based on current step regulation according to claim 5 is characterized in that: Once the external switch is detected to be closed in step S1, the main control MCU pin is grounded, which triggers the power-on purge process of the battery stack.

7. The control method of the hydrogen fuel UAV stack based on current step regulation according to claim 5 is characterized in that: In step S2, the intake valve and exhaust valve of the fuel cell stack are opened, and a PWM signal with a duty cycle of 42% is output to drive the fuel cell stack cooling fan.

8. The control method of the hydrogen fuel UAV stack based on current step regulation according to claim 5 is characterized in that: In step S5, the actual output current of the battery stack is accurately monitored and adjusted through the dual feedback mechanism of the processor; when the current increases, the first feedback mechanism of the processor is responsible for real-time monitoring and accumulating the amplitude of the current step; When the cumulative step amplitude reaches the set value, the second feedback mechanism is activated, and the system gradually increases the output current of the battery stack at a set rate through the DC / DC converter.

9. The control method of the hydrogen fuel UAV stack based on current step regulation according to claim 8 is characterized in that: When the current needs to be reduced, the system will gradually reduce the output current of the battery stack at a set rate.

10. The control method of the hydrogen fuel UAV stack based on current step regulation according to claim 5 is characterized in that: After the external switch is manually turned off in step S6, the pin of the main control MCU is connected to a 3.3V voltage, and a shutdown purge signal of the hydrogen fuel cell stack is issued; the system executes steps S7-S8 until the system ends operation.

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