Load responsive adaptive control method for fuel cell power systems and its application to unmanned aerial vehicles

Abstract

The application discloses a load response type adaptive control method of a fuel cell power system and an unmanned aerial vehicle applying the same. An electric energy output end of a fuel cell stack is connected with an input end of a DC-DC converter, and an output end of the DC-DC converter is connected with a power supply input end of a charging battery and an external load in parallel. The load response type adaptive control method at least comprises the following control process: energy management control: a look-up table relationship between a charging battery bus voltage and an SoC is established in advance, the SoC of the charging battery corresponding to the charging battery bus voltage is obtained through a look-up table method based on the real-time detected charging battery bus voltage, and the fuel cell system controller adaptively adjusts and sets the requested output power of the fuel cell stack based on the change of the SoC. The application can change the pull load power of the fuel cell with the change of the load, so as to achieve the adaptive adjustment of the output power of the fuel cell system.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell application control, and specifically relates to a load-response adaptive control method for a fuel cell power system. This invention also relates to a drone that applies this load-response adaptive control method. Background Technology

[0002] Current innovation directions in the field of hydrogen-powered drone research typically treat fuel cell power (usually hydrogen fuel cells, which this application refers to as "hydrogen power") technology and pure lithium battery technology as two opposing routes.

[0003] Although hydrogen-powered drones have significant advantages over purely rechargeable battery-powered drones in terms of long endurance and environmental friendliness, current research in the field of hydrogen-powered drones mainly focuses on overall integration and the corresponding power system layout, power energy management and control, with less research on safety and intelligence. In particular, there is very little research on load-following power control methods for hydrogen-powered systems.

[0004] Therefore, this application seeks a technical solution to achieve load-following power control of hydrogen power systems. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a load-response adaptive control method for a fuel cell power system and its application in a drone, which enables the fuel cell's load power to change with the load, thereby achieving adaptive adjustment of the stack system's output power.

[0006] The technical solution adopted in this invention is as follows:

[0007] A load-response adaptive control method for a fuel cell power system, the fuel cell power system comprising a fuel cell stack, a fuel cell system controller, and a rechargeable battery, all connected to a reductant input line, an oxidant input line, and a cooling medium input line respectively; the power output terminal of the fuel cell stack is connected to the input terminal of a DC-DC converter, and the output terminal of the DC-DC converter is connected in parallel with the power input terminal of the rechargeable battery and the external load.

[0008] The load-response adaptive control method includes at least the following control process:

[0009] Energy management control: A lookup table relationship between the charging battery bus voltage and the SoC is established in advance. Based on the real-time detected charging battery bus voltage, the SoC of the corresponding charging battery under the bus voltage is obtained by the lookup table method. The fuel cell system controller adaptively adjusts the stack's requested output power based on the changes in the SoC.

[0010] Preferably, when the fuel cell power system is operating, the bus voltage of the charging battery decreases when the power consumed by the external load is higher than the output power of the fuel cell; and increases when the power consumed by the external load is lower than the output power of the fuel cell. During the energy management and control process, the correspondence between the output power and the bus voltage of the charging battery is used to adaptively adjust the requested output power of the fuel cell stack according to the power consumption of the external load.

[0011] Preferably, the adaptive adjustment employs the following control process:

[0012] First, complete the initialization: set the power control enable signal EMS_En to 0, and the system is in a powered-off state; set the requested output power setting value EMS_Pwr to 0;

[0013] The real-time changes of the SoC are obtained by detecting the charging battery bus voltage in real time, and the requested output power setting value EMS_Pwr is set based on the real-time changes of the SoC.

[0014] Preferably, the power control enable signal EMS_En is stored in the fuel cell system controller (i.e., the FuelCell Control Unit, often simply referred to as "FCU"), and an external input variable determines whether the power control enable signal EMS_En is set to 0 or 1 (the "0" and "1" are the values ​​of the power control enable signal EMS_En); wherein, the external input variable includes at least one of the following external input variables:

[0015] The unlock status of the external load;

[0016] SoC for rechargeable batteries;

[0017] Self-test status of the fuel cell stack;

[0018] Self-test status of external load;

[0019] Fault status of external load;

[0020] Fault status of the fuel cell stack.

[0021] Preferably, when the external load is in an unlocked state (ST2 > 0) and the current SoC is less than the lower threshold of the SoC (e.g., SOC), Min If the power control enable signal EMS_En is 1, then the power control enable signal will be set to 1.

[0022] When the external load is unlocked (ST2 > 0), and when the SoC is at the lower threshold and the higher threshold of the SoC (e.g., SOC) MaxBetween these two points, the power control enable signal EMS_En will be maintained at 1 or 0 based on the state of the fuel cell power system at the previous moment;

[0023] When the SoC is above the SoC higher threshold or the external load is in an unlocked state (ST2=0), it remains in the initialization state and the power control enable signal EMS_En is set to 0.

[0024] More preferably, the following formula is used to determine whether to set the power control enable signal EMS_En to 0 or 1:

[0025] ;

[0026] In the formula, ST2 is the unlock status code of the external load, CST1 is the self-test status of the fuel cell power system, CST2 is the self-test status code of the external load, ER1 is the fault status code of the fuel cell power system (i.e., the fault status code of the fuel cell stack), ER2 is the fault status of the external load, SOC is the SoC of the rechargeable battery, and SOC0 is the SoC threshold constant for starting the fuel cell power system; where,

[0027] When ST2=0, it means the external load is not unlocked; when ST2=1, it means the external load is unlocked.

[0028] When CST1=0, it means that the fuel cell power system self-test has failed; when CST1=1, it means that the fuel cell power system self-test has passed.

[0029] When CST2=0, it means that the external load self-test failed; when CST2=1, it means that the external load self-test passed.

[0030] When ER1=0, it means that the fuel cell power system is fault-free; when ER1=1, it means that the fuel cell power system has a warning fault; when ER1=2 or 3, it means that the fuel cell power system has a shutdown fault.

[0031] When ER2=0, it means that the external load is fault-free; when ER2=1, it means that the external load has a warning fault; when ER2=2 or 3, it means that the external load has a shutdown fault.

[0032] It is also important to note that, firstly, when the control switch (usually a manual air switch) connecting the fuel cell power system to the charging battery changes from the open state to the closed state, the fuel cell power system changes from the de-energized state to the energized state. The energized fuel cell power system does not immediately begin operation; instead, it needs to determine whether certain parameters meet the conditions for starting the fuel cell power system. After processing these parameters, the system outputs a start-up enable or disable command via the EMS_En signal. The EMS_En signal output is a Boolean value with only two possible values: 0 and 1. 0 indicates disable, preventing start-up; 1 indicates enable, executing the start-up command.

[0033] Secondly, the function of the EMS_En signal is to control the start-up and shutdown of the fuel cell power system. When EMS_En=0, if the fuel cell power system has not started, it will prevent the fuel cell power system from starting. If the fuel cell power system is already running, it will execute the shutdown procedure. When EMS_En=1, if the fuel cell power system has not started, it will execute the start-up procedure. If the fuel cell power system is already running, it will continue to run.

[0034] It is also important to note that when EMS_En=1, the fuel cell power system will only execute the startup procedure from the standby state (also known as the power-on shutdown state) and enter the idle state (i.e., the minimum stack output power point). If the value of EMS_Pwr is lower than the power output of the stack at the idle point, it will continue to operate at the idle point until EMS_En=0, at which point the shutdown procedure will be executed to shut down the fuel cell power system. Only when EMS_En=1 and the value of EMS_Pwr is greater than the power at the idle point (i.e., the minimum stack output power point) will the fuel cell power system enter the dynamic load state and respond to the request value of EMS_Pwr to change the output power of the stack accordingly.

[0035] For example, when the external load is a drone, the sufficient but not necessary condition for EMS_En=1 in this solution is that the drone is unlocked and the SoC is lower than SOC0. The necessary and sufficient condition for EMS_En=1 is that the drone is unlocked, the SoC is lower than SOC0, the fuel cell power system self-test is passed, the drone self-test is passed, the drone fault status is no fault or only warning fault, and the stack fault status is no fault or only warning fault. When the load is other instances, the necessary condition for EMS_En=1 can be set to the load being powered on.

[0036] Preferably, the requested output power setting value EMS_Pwr is set based on the real-time changes of the SoC, combined with the status of the fuel cell power system and the change in the charging battery bus voltage ΔU.

[0037] More preferably, the formula for calculating the requested output power setting value EMS_Pwr is as follows:

[0038] ;

[0039] In the formula, The requested output power of the fuel cell stack, calculated in the previous step, is a variable and its unit is kW; The currently calculated requested output power of the fuel cell stack, i.e., the requested output power setpoint EMS_Pwr, is a variable, and its unit is kW; P idle P represents the valley power of the fuel cell stack, which is the lower limit of the fuel cell's power output. rate P is the rated power of the fuel cell stack, which is a constant and its unit is kW; peak Δp is the peak power of the battery stack, a constant, and its unit is kW; Δp is the output power increment, a constant, and its unit is kW; SOC is the SoC of the rechargeable battery, a variable, and its unit is %. Ultra SOC Max SOC Min and SOC Med All are constants, expressed as a percentage, where SOC Ultra The highest threshold for SoC, SOC Max For a higher threshold of SoC, SOC Med For SoC medium threshold, SOC Min ST1 represents the lower threshold of the SoC; ST1 is the status code of the fuel cell power system, which is a variable; X1 represents the state of the system when it maintains a stable power output P0 (also known as the minimum output power P0) with the minimum load current I0, which is a constant; X2 represents the operating state of the fuel cell stack when the output power is higher than P0, which is a constant (it should be noted that the minimum output power P0 = the peak power P of the fuel cell stack). idle ); ΔU is the rate of change of the rechargeable battery bus voltage, in V / s, and is a variable, namely the change of the rechargeable battery bus voltage; β1 and β2 refer to two different bus voltage changes, both of which are constants, and their units are both V / s; ST2 is the unlock status code of the external load, which is a variable; Y1 indicates that the external load is in an unlocked state, which is a constant.

[0040] Preferably, the system further includes the following control process:

[0041] Requested output power control: The calculated requested output power of the fuel cell stack is limited based on the upper and lower limits of the fuel cell's power output and the current input temperature of the cooling medium. The calculation formula used is as follows:

[0042] ;

[0043] In the formula, P out The actual output power of the fuel cell stack after water temperature limiting treatment is the requested output power. Request output power for the fuel cell stack after upper and lower limit processing; The requested output power of the fuel cell stack, calculated so far, is EMS_Pwr; P peak P represents the peak power of the fuel cell stack, which is a constant and its unit is kW. idle P1 is the peak power of the fuel cell stack, which is the lower limit of the fuel cell's power output. It is a constant and its unit is kW. P2 is the limit power, which is a constant and its unit is kW. T is the current input temperature of the cooling medium, which is a variable and its unit is °C. T1 is the input temperature limit threshold of the cooling medium, which is a constant and its unit is °C. ST1 is the status code of the fuel cell power system, which is a variable. X1 is the state of the system when it maintains a stable power output of P0 with the minimum load current I0, which is a constant. X3 is the state of the fuel cell stack starting the DC-DC converter, which is the state of the FCU issuing a DC-DC start command to the DC-DC converter, which is a constant. X4 is the state of the fuel cell stack receiving a shutdown command, which is the state of the power control enable signal EMS_En changing from a value of 1 to a value of 0, which is a constant.

[0044] Preferably, the system further includes the following control process:

[0045] Requested power response speed processing control: The requested output power value obtained after completing the requested output power control is subjected to linear load variation processing; the calculation formula used is as follows:

[0046] ;

[0047] In the formula, ΔP out ΔP1 is the output power change value, a variable, with the unit kW / s; ΔP2 is the output power change threshold, a constant, with the unit kW / s; T is the current cooling medium input temperature, a variable, with the unit ℃; T2 is the suitable cooling medium input temperature value required by the fuel cell stack, a constant, with the unit ℃.

[0048] It is important to note that the above calculation formula limits the rate at which the fuel cell stack responds to the requested power setpoint based on different fuel cell stack inlet water temperatures. This rate limitation is due to a physical characteristic inherent in both the fuel cell stack and the DC-DC converter (hereinafter referred to as DC-DC). The fuel cell stack has a relatively soft power output characteristic, meaning it cannot instantly reach a large power setpoint. When the load power setpoint is large, an excessively fast load rate may cause aging or damage to the PEM film inside the fuel cell stack, leading to a sharp decrease in stack lifespan. Therefore, rate limitation can protect the fuel cell stack to some extent. For the DC-DC, since the fuel cell stack's output current ultimately flows to the DC-DC input terminal, excessively high load power and a too-fast load rate may cause a sharp increase in the input current, leading to a rapid increase in heat generation in some power devices within the DC-DC, potentially damaging the DC-DC in severe cases.

[0049] On the other hand, the fundamental reason for setting different loading rates based on the feed water temperature of the fuel cell stack in this application is that it is determined by the physical characteristics of the catalyst inside the fuel cell stack. That is, the Pt catalyst attached to the PEM film has different activities at different temperatures. When the feed water temperature is low, the activity of the Pt catalyst is low, which in turn makes the electrochemical reaction rate inside the fuel cell stack slower. If the output power of the fuel cell stack is too high at this time (when the output power is high, the current is also correspondingly high), it may cause irreversible damage to the catalyst (essentially, the catalyst activity is low, the chemical reaction is incomplete, and under the influence of high current, the incompletely reacted oxygen molecules will promote the oxidation of the catalyst). Therefore, when the feed water temperature is low, the loading rate is deliberately slowed down. Slowing down the loading rate is essentially to slow down the change in power value of the output power over time, giving the electrochemical reaction sufficient reaction time.

[0050] Preferably, in a drone, the drone's power system employs the load-response adaptive control method for fuel cell power systems as described above, wherein...

[0051] The fuel cell system controller is bidirectionally connected to the UAV; the fuel cell power system preferably also includes a DC-AC converter, the power output terminal of the fuel cell stack is connected to the input terminal of the DC-AC converter, and the output terminal of the DC-AC converter is used to connect other external loads.

[0052] The main working principle and advantages of this invention are as follows:

[0053] First, this application proposes an Energy Management (EMS) algorithm, which calculates the System-on-Chips (SoC) of the rechargeable battery based on the detected bus voltage using a lookup table algorithm. Then, it uses this SoC as the injection amount for adaptive power adjustment. The basic principle of this adaptive power adjustment algorithm is: when the power consumed by the external load (including DC and AC terminals) is higher than the output power of the fuel cell, the bus voltage of the rechargeable battery decreases, and vice versa. Based on this fundamental physical law, the load power of the fuel cell can change with the load, thus achieving adaptive power adjustment of the stack system's output power.

[0054] Preferably, since the rechargeable battery used in this system is a small-capacity, high-charge-discharge-rate lithium battery, it can alleviate the soft power response curve of the fuel cell by utilizing the characteristics of rapid charging and discharging when the external load changes drastically, without increasing the burden on the overall weight and volume of the stack.

[0055] It should be noted that the inverted triangle “∨” operator in all formulas involved in this application represents the logical relationship of “or”, and the upright triangle “∧” operator represents the logical relationship of “and”. The content following the comma “,” in all formulas involved in this application is the parameter condition that needs to be satisfied when the line is true. Since these are all common knowledge to those skilled in the art, in order to save space, this application will not elaborate on the various conditions represented by the formulas.

[0056] This application further proposes a requested power Ramp algorithm, which uses the system requested power calculated by the EMS algorithm module to further limit the power output of the fuel cell based on the upper and lower limits of the fuel cell's power output and the current inlet water temperature of the fuel cell. This algorithm can effectively prevent the requested power calculated by the EMS algorithm from exceeding the power limit supported by the fuel cell, and can also prevent the following phenomena from occurring: when the inlet water temperature does not reach the rated operating water temperature of the fuel cell, the fuel cell may experience water blockage or low catalyst activity due to excessive requested power, which may lead to excessive voltage range of individual stack cells or excessively low average voltage of individual stack cells.

[0057] This application further proposes a requested power response speed processing algorithm, which performs linear load variation on the requested power value obtained after processing by the requested power Ramp algorithm, and sets a reasonable linear load increase and decrease slope. This algorithm can effectively avoid step-like jumps in the requested power of the fuel cell, thereby preventing phenomena such as underpower, anode-cathode gas pressure imbalance, or even runaway caused by the lag in the response of the fuel (e.g., H2) and oxidant (e.g., O2). This design adopts a linear slope load variation algorithm, which can make the power response of the fuel cell under rapid load variation conditions (sudden power increase or decrease) have a uniform adjustment range and buffer time, thereby making the power response of the stack stable and reliable. Attached Figure Description

[0058] Figure 1(a) is a schematic diagram of the electrical connection structure between the fuel cell power system and the drone (integrated as a "hydrogen-powered drone") in a specific embodiment of the present invention; Figure 1(b) is a schematic diagram of the electrical connection structure between the fuel cell power system and the drone (integrated as a "hydrogen-powered drone") in a specific embodiment of the present invention.

[0059] Figure 2 The lithium battery bus voltage U is pre-established under the specific embodiments of the present invention. DC A lookup table diagram relating to the SoC;

[0060] Figure 3 This is a schematic diagram of the control flow steps of the load-response adaptive control method for a fuel cell power system according to a specific embodiment of the present invention;

[0061] Figure 4 This is a schematic diagram illustrating the process of performing the request power Ramp algorithm under a specific embodiment of the present invention;

[0062] Figure 5 This is a schematic diagram illustrating the process of the request power response speed processing algorithm under a specific embodiment of the present invention;

[0063] Figure 6 These are field test photos of a prototype of a 25kg-class hydrogen-powered drone (equipped with a hydrogen power pack with a rated power of 5kW, including a lithium battery with a capacity of 0.3kW·h and a charge / discharge rate of 60C) under a specific embodiment of the present invention.

[0064] Figure 7 This is the scripture Figure 6 Key operational data of the fuel cell powertrain (FCS) after the test;

[0065] Figure 8 This is the scripture Figure 6 A screenshot of the lithium battery bus voltage data interface in the UAV flight control operation log after the test. Detailed Implementation

[0066] This invention discloses a load-response adaptive control method for a fuel cell power system. The fuel cell power system includes a fuel cell stack connected to a reductant input line, an oxidant input line, and a cooling medium input line, a fuel cell system controller, and a rechargeable battery. The power output terminal of the fuel cell stack is connected to the input terminal of a DC-DC converter, and the output terminal of the DC-DC converter is connected in parallel with the power input terminals of the rechargeable battery and the external load. The load-response adaptive control method includes at least the following control process:

[0067] Energy management control: A lookup table relationship between the charging battery bus voltage and the SoC is established in advance. Based on the real-time detected charging battery bus voltage, the SoC of the corresponding charging battery under the bus voltage is obtained by the lookup table method. The fuel cell system controller adaptively adjusts the stack's requested output power based on the changes in the SoC.

[0068] This invention also discloses a drone. The drone's power system adopts the load-response adaptive control method of the fuel cell power system described above. The fuel cell system controller is bidirectionally connected to the drone. The fuel cell power system preferably also includes a DC-AC converter. The power output terminal of the fuel cell stack is connected to the input terminal of the DC-AC converter, and the output terminal of the DC-AC converter is used to connect to other external loads.

[0069] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0070] Based on the technical solution proposed in this application, and referring to Figures 1(a) and 1(b), the fuel cell power system includes a fuel cell stack (specifically, a water-cooled silicon-based fuel cell stack is used in this embodiment; please refer to the “water-cooled silicon-based fuel cell stack” marked in Figure 1(a)), a fuel cell system controller, and a rechargeable battery, all connected to a reductant input line, an oxidant input line, and a cooling medium input line, respectively; wherein, the state management and control method of the fuel cell power system includes: the power output terminal of the fuel cell stack is connected to the input terminal of a DC-DC converter, and the output terminal of the DC-DC converter (see the “DCDC” marked in the figure) is connected in parallel with the rechargeable battery (specifically, a lithium battery is used in this embodiment; please refer to the “lithium battery” marked in the figure, which is charged by the DCCDC output terminal) and the power input terminal of the external load; the fuel cell system controller (see the… The FCU (as shown in the figure) is bidirectionally connected to the external load. Based on the operating conditions of the external load and the operating status of the fuel cell power system, multiple status codes are defined, and each status code is matched with its corresponding control command. These control commands control the operation of the reductant input pipeline, oxidant input pipeline, cooling medium input pipeline, and the electrical connection circuit between the fuel cell stack and the external load. Specifically, in this embodiment, the external load is a drone, which is equipped with a flight control module (see Figure 1(a) marked "flight control") that is bidirectionally connected to the FCU, and an ESC module (serving as the power input for the drone) connected to the DC-DC output. Furthermore, in this embodiment, the FCU is also communicatively connected to the INAC host computer, and the flight control module is also connected to a remote control handle via wireless communication.

[0071] In this embodiment, the reducing agent is hydrogen, the oxidizing agent is oxygen or air, and the cooling medium is deionized water. Of course, in other embodiments, other known and suitable materials can also be used as the reducing agent, other known and suitable materials can also be used as the oxidizing agent, and other known and suitable materials can also be used as the cooling medium (e.g., antifreeze). The state management and control method of the fuel cell power system proposed in this embodiment can also be applied to other external loads with similar requirements. This application does not impose a unique limitation on its implementation.

[0072] Based on the technical solutions proposed in this application as described above, in order to further illustrate the specific implementation process of this application, the following describes a specific implementation scheme when the state management control method of the fuel cell power system is applied to an unmanned aerial vehicle (UAV) as an external load:

[0073] In this embodiment, the drone is specifically a 25kg-class drone; the rechargeable battery is specifically a ternary lithium battery, please refer to "lithium battery" marked in Figure 1(a) or "12S ternary lithium battery" marked in Figure 1(b); the operating parameters of the fuel cell power system include at least the average voltage of a single stack cell and / or the voltage difference of a single stack cell and / or the reducing agent delivery pressure, temperature and / or the oxidant delivery pressure, temperature and / or the cooling medium delivery pressure, temperature and / or the DC-DC converter operating status feedback, and the communication status feedback.

[0074] In this embodiment, the power input terminal of the UAV is equipped with a power-on switch connected to the low-voltage control input terminal of the fuel cell power system and the bus terminal of the rechargeable battery. In this embodiment, the power-on switch is preferably a manually controlled switch. When it is open, no electrical circuit is formed between the UAV and the fuel cell and the rechargeable battery (a ternary lithium battery is specifically used in this embodiment). When it is closed, electrical circuits are formed between the UAV and the fuel cell and the rechargeable battery respectively. Referring to Figure 1, more specifically, in this embodiment, the power-on switch is a 150A rated current air switch connected to the lithium battery on the left side of Figure 1(b) (marked as "150A air switch" in Figure 1(b)). During operation, the operator needs to manually operate the switch to open and close it. Its working principle is that when the power-on switch is open, no electrical circuit is formed between the lithium battery and the UAV and the fuel cell power pack BOP. Therefore, the overall hydrogen-powered UAV system, including the UAV and the fuel cell power pack BOP, is in a non-powered state. Conversely, when the power-on switch is closed, electrical circuits are formed between the UAV and the fuel cell power pack and the rechargeable battery respectively. Therefore, the overall hydrogen-powered UAV system is in a powered-on state.

[0075] It should be further explained that, in this embodiment, the power-on principle of the drone is as follows: after the lithium battery is connected to the drone's flight controller, ESC, and other BOPs (Balance of Plant) and forms an electrical circuit, the drone's flight controller will execute its own self-test program. The control program of the flight controller is independent of the control program of the fuel cell power pack (FCU, i.e., Fuel Cell Control Unit, see "FCU" marked in Figure 1). The two are only connected by a CAN communication line for information exchange, enabling them to work together. In addition, the drone can only work normally after the lithium battery is connected to both the drone's ESC and the flight controller. That is, only after both are powered can the drone execute takeoff, landing, and other commands according to the control handle.

[0076] In this embodiment, the reducing agent input line is equipped with several switching valves connected to the fuel cell system controller for controlling the input pressure and / or flow rate of the reducing agent, as well as the discharge of moisture from the line; the oxidant input line is connected to a blower, which is driven by a blower controller connected to the fuel cell system controller for controlling the input pressure and / or flow rate of the oxidant; the cooling medium input line is equipped with a cooling medium circulation pump (i.e., the "water pump" marked in Figure 1(b)) connected to the fuel cell system controller for controlling the input pressure and / or flow rate of the cooling medium; preferably, a circulation line is formed between the cooling medium input line and its output line, and a liquid cooling device is provided on the circulation line, with a controllable valve connected to the fuel cell system controller above the liquid cooling device. Multiple cooling fans are used to control the temperature of the cooling medium. Please refer to Figure 1(b) for further details. In this embodiment, the fuel cell power system is equipped with 6 cooling fans, namely "Fan 1", "Fan 2", "Fan 3", "Fan 4", "Fan 5" and "Fan 6" as marked in Figure 1(b). In this embodiment, the blower, FCU, each cooling fan and the cooling medium delivery pump, etc., are all powered by the output of the DC-DC converter (see "DCDC" as marked in the figure). Of course, in order to achieve a stable output of the power supply voltage required by the controlled components connected to it, a transformer (also known as a voltage regulator) structure will be further set up, such as the "30V-90V input 24V-16A output" specification transformer and the "24V input 48V 8A output" specification transformer shown in Figure 1(b).

[0077] Referring also to Figure 1(b), the fuel cell power pack FCU ​​chip has multiple signal pins, specifically including "Hydrogen Inlet Pressure" (i.e., the hydrogen input pressure signal of the fuel cell stack), "Air Inlet Pressure" (i.e., the air input pressure signal of the fuel cell stack), "Water Inlet Pressure" (i.e., the cooling water input pressure signal of the fuel cell stack), "Water Outlet Pressure" (i.e., the cooling water discharge pressure signal of the fuel cell stack), "Hydrogen Tank Pressure" (i.e., the hydrogen tank pressure signal supplying hydrogen), "Hydrogen Pipeline Pressure" (i.e., the pipeline pressure connecting the hydrogen tank and the hydrogen inlet of the fuel cell stack), and "Water Inlet Temperature" (i.e., the cooling water input temperature signal of the fuel cell stack). The following signals are used to control the BOP (Balance of Plant) of the fuel cell power pack: "Water Outlet Temperature" (i.e., the cooling water outlet temperature signal of the fuel cell stack), "Air Inlet Temperature" (i.e., the air input temperature signal of the fuel cell stack), "Hydrogen Inlet Temperature" (i.e., the hydrogen input temperature signal of the fuel cell stack), "Drain Valve" drive signal, "Proportional Valve" drive signal (this proportional valve is set in the hydrogen inlet pipeline), "Water Pump" drive signal, "Fan 1-Fan 6" drive signal, and "Blower Controller" drive signal. These are conventional technical means for fuel cell stack control, so the specific drive process will not be described in detail in this application.

[0078] Preferably, in this embodiment, the fuel cell system controller is equipped with a CAN-to-pulse module (connected between the blower, cooling fan, and FCU), enabling the cooling fan and blower controlled by PWM waves to have CAN communication control effects. Specifically, the fuel cell system controller (FCU) provides the required speed value for the cooling fan and / or blower based on the operating status of the fuel cell power system (such as the temperature of the circulating coolant in the hydrogen fuel cell, the inlet air pressure, etc.). Then, based on this required speed value, it calculates the corresponding required PWM duty cycle according to the MAP diagram of the cooling fan or blower. The fuel cell system controller then sends this PWM duty cycle as a set value to the CAN-to-pulse module via CAN communication. The CAN-to-pulse module outputs a corresponding PWM waveform based on the obtained PWM duty cycle set value and sends it to the cooling fan or blower. Subsequently, the cooling fan... The fan or blower can respond to initial temperature or pressure control requirements, controlling the stack temperature or air inlet pressure of the hydrogen power pack (i.e., hydrogen fuel cell) within the target range. Simultaneously, in this embodiment, the CAN-to-pulse module generates a vital heartbeat signal, preferably in the form of a time-cycled cumulative count within the range of 0-255, and transmits this vital heartbeat signal to the FCU via CAN communication. The FCU can determine whether the CAN-to-pulse module is faulty based on the state of this vital heartbeat signal. The judgment logic is similar to: if the FCU does not receive the CAN-to-pulse vital heartbeat signal at a certain moment or the vital heartbeat signal value is disordered, then the CAN-to-pulse module is faulty, thereby triggering the predetermined fault protection function in the FCU to provide appropriate protection for the hydrogen power pack, thus enabling monitoring of the control status of the cooling fan or blower.

[0079] It should be further explained that, in this embodiment, the purpose of setting up the CAN to pulse module is twofold: firstly, to reduce the wiring harness in the overall system of the hydrogen-powered UAV; secondly, to increase control accuracy and make the control function more stable and reliable by using CAN communication for control; and thirdly, to provide PWM pulse drive signals to the cooling fan and / or blower through the CAN to pulse module.

[0080] Preferably, in order to achieve a more flexible and diverse power supply for the load, in this embodiment, the fuel cell power system further includes a DC-AC converter (not shown in Figure 1). The power output terminal of the fuel cell stack is connected to the input terminal of the DC-AC converter, and the output terminal of the DC-AC converter is used to connect to other drones or other external loads.

[0081] Preferably, in this embodiment, the fuel cell stack is also equipped with a fuel cell stack monitoring instrument (i.e., "CVM" marked in Figure 1(b), which stands for Cell Voltage Monitoring). Its function is to monitor the voltage of each cell in the fuel cell stack and transmit the voltage values ​​of each cell to the FCU via CAN communication. It should be further explained that since the fuel cell stack is composed of dozens or hundreds of individual cells stacked together, monitoring the voltage of each individual cell during the operation of the fuel cell stack can help to understand the current operating status of the stack. Furthermore, the voltage range of the individual cells (i.e., the voltage difference between the individual cell with the highest voltage value and the individual cell with the lowest voltage value) can reflect the voltage consistency of the current fuel cell stack, thereby predicting whether the fuel cell stack will experience a fault or has already experienced a fault (such as PEM membrane perforation, water blockage in the electrode flow channels, etc.).

[0082] Based on the technical solution of this application, in this specific embodiment, the lithium battery bus voltage U DC (i.e., the voltage at the parallel connection of the DCDC output, lithium battery, and drone power input), FCS status code, drone status code output by the drone flight controller, and rate of change of the lithium battery bus voltage; the algorithm's output variables include: enable switch quantity and requested power value. The mathematical model of this algorithm can be simplified to the following form. It is worth noting that the sampling calculation period used in the control program is 10ms.

[0083] ·U DC Convert to SoC (where, Figure 2 The x-axis "Row breakpoints" in the figure is U DC (The unit is V, and the vertical axis "Table data" represents SoC, with the unit being %).

[0084] pass Figure 2 The table lookup relationship is shown, and EMS_En is calculated according to the following formula:

[0085] ;

[0086] In the formula, EN is the value of EMS_En, and SOC0 is specifically set to 98% (the SoC threshold constant for starting the fuel cell power system).

[0087] Further refer to Figure 3 The specific control flow steps shown are used to calculate P. out :

[0088] It is particularly important to note that when calculating P... outTo prevent voltage detection noise from causing overshoot oscillations in power calculations, a 200ms hold mechanism was added when judging ΔU. That is, if ΔU > 0.05V / s is held for 200ms, then P is executed. out Similarly, if ΔU < -0.05V / s is maintained for 200ms, then P is executed. out -∑Δp.

[0089] ;

[0090] The constants in the formula are set as follows:

[0091] P rate =4.3kW, P peak =5.49kW, Δp=0.5kW, SOC Ultra =90%, SOC Max =80%, SOC Min =40%, SOC Med =60%, X1=21, X2=22; β1=0.05V / s and β2=-0.05V / s; Y1=1.

[0092] Please refer to the above for further details. Figure 4 The specific process of the requested power Ramp algorithm shown below and Figure 5 The specific process of the requested power response speed processing algorithm shown below involves the following control process:

[0093] • Demand power anti-saturation treatment:

[0094] ;

[0095] In the formula, P idle =1.15kW, P peak =5.49kW;

[0096] • Temperature-based power limiting:

[0097] ;

[0098] In the formula, P1=4.05kW, T1=57℃, X3=14, X3=31.

[0099] • Power change rate limiting processing:

[0100] ;

[0101] In the formula, ΔP1 = 0.15 kW / s and ΔP2 = 0.1 kW / s.

[0102] Based on the mathematical model set above, the control model of FCS is built in Matlab, compiled and integrated into control code, and then applied to... Figure 6 The corresponding tests were conducted on the 25kg hydrogen-powered drone prototype shown. According to the test data, it can be verified that the load-response adaptive power control algorithm using the above mathematical model has advantages such as fast response, strong robustness, and the FCS power output can achieve a response speed of milliseconds to follow the changes in drone load.

[0103] Based on the prototype's test data, the effectiveness and rationality of the above load-response adaptive power control algorithm are deduced:

[0104] Please refer to the screenshots of the fuel cell power pack system (FCS) operation data and the drone's flight control operation logs respectively. Figure 7 and Figure 8 As shown:

[0105] in, Figure 7 This embodiment mainly demonstrates the key operational data of the fuel cell power system during the entire process of the hydrogen-powered drone going from being locked on the ground to being unlocked on the ground, and then taking off and hovering in the air.

[0106] Specifically: Figure 7 There are a total of 6 curves, which are displayed in 6 regions. These 6 curves share the same horizontal axis (the horizontal axis represents time, in seconds). From top to bottom, the curves in these 6 regions represent the fuel cell system status code, the fuel cell system cooling water temperature at the inlet, the fuel cell stack output current (also known as the load current), the fuel cell stack output power, the voltage range of a single cell in the fuel cell system, and the average voltage of a single cell in the fuel cell system. Each of the 6 curves in these 6 regions has its own vertical axis. The status code has no unit, the inlet water temperature is in °C, the load current is in A, the output power is in kW, the voltage range of a single cell is in mV, and the average voltage of a single cell is in mV.

[0107] Depend on Figure 7The six data curves shown demonstrate that, throughout the entire flight of the UAV in this embodiment, the status codes of the fuel cell system can transition in an orderly manner according to the predetermined program of the control program; the inlet water temperature increases with the increase of the fuel cell system's operating time, and achieves basically stable and controllable fluctuations near the final target temperature value; the output current and output power of the fuel cell stack also gradually increase with the flight state of the hydrogen-powered UAV, maintaining stable power output while the UAV is hovering in the air, and reducing power output to 0kW when the UAV lands; the voltage difference of a single cell of the fuel cell stack and the average voltage of the fuel cell stack also remain basically stable throughout the entire flight, indicating that the fuel cell stack is operating in a relatively good manner.

[0108] Figure 8 This primarily demonstrates the lithium battery bus voltage (corresponding to) in the flight control operation log of the hydrogen-powered drone during the entire process of the drone going from being locked on the ground, to being unlocked on the ground, and then taking off and hovering in the air. Figure 8 The vertical axis is the data in units of V.

[0109] from Figure 8 The lithium battery bus voltage data curve shows that during the initial takeoff phase of the drone, the high power consumption of the drone and the low output power of the fuel cell system led to increased energy consumption of the lithium battery, resulting in a decrease in the lithium battery bus voltage. During the hovering phase, the fuel cell system adjusted its power output according to the lithium battery bus voltage, and after several fluctuations, it maintained a relatively stable and normal voltage level. During the drone's descent, the fuel cell system detected the descent signal from the drone's flight control and reduced its power output, causing a temporary decrease in the lithium battery bus voltage. After the drone landed, with zero power consumption, the fuel cell system's output power was entirely used to charge the lithium battery, causing a temporary increase in the lithium battery bus voltage. Finally, the fuel cell system detected that the lithium battery bus voltage was at a high threshold and that the drone had successfully landed, triggering a shutdown command and ceasing power output.

[0110] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0111] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A load-response adaptive control method for a fuel cell power system, characterized in that, The fuel cell power system includes a fuel cell stack, a fuel cell system controller, and a rechargeable battery, all connected to a reducing agent input line, an oxidant input line, and a cooling medium input line, respectively. The power output terminal of the fuel cell stack is connected to the input terminal of a DC-DC converter, and the output terminal of the DC-DC converter is connected in parallel with the power input terminal of the rechargeable battery and the external load. The load-response adaptive control method includes at least the following control process: Energy management control: A lookup table relationship between the charging battery bus voltage and the SoC is established in advance. Based on the real-time detected charging battery bus voltage, the SoC of the corresponding charging battery under the bus voltage is obtained by the lookup table method. The fuel cell system controller adaptively adjusts the stack's requested output power based on the changes in the SoC.

2. The load-response adaptive control method for a fuel cell power system according to claim 1, characterized in that, When the fuel cell power system is in operation, the bus voltage of the charging battery decreases when the power consumed by the external load is higher than the output power of the fuel cell; and increases when the power consumed by the external load is lower than the output power of the fuel cell. In the energy management and control process, the correspondence between the output power and the bus voltage of the charging battery is used to adaptively adjust the requested output power of the fuel cell stack according to the power consumption of the external load.

3. The load-response adaptive control method for a fuel cell power system according to claim 1 or 2, characterized in that, The adaptive adjustment employs the following control process: First, complete the initialization: set the power control enable signal EMS_En to 0, and the system is in a powered-off state; set the requested output power setting value EMS_Pwr to 0; The real-time changes of the SoC are obtained by detecting the charging battery bus voltage in real time, and the requested output power setting value EMS_Pwr is set based on the real-time changes of the SoC.

4. The load-response adaptive control method for a fuel cell power system according to claim 3, characterized in that, The power control enable signal EMS_En is stored in the fuel cell system controller, and its setting to 0 or 1 is determined by an external input variable; wherein, the external input variable includes at least one of the following external input variables: The unlock status of the external load; SoC for rechargeable batteries; Self-test status of the fuel cell stack; Self-test status of external load; Fault status of external load; Fault status of the fuel cell stack.

5. The load-response adaptive control method for a fuel cell power system according to claim 4, characterized in that, When the external load is in an unlocked state (ST2 is greater than 0) and the current SoC is less than the lower threshold of the SoC, the power control enable signal EMS_En is set to 1; When the external load is in the unlocked state (ST2 is greater than 0), and when the SoC is between the lower threshold and the higher threshold of the SoC, the power control enable signal EMS_En will be maintained at 1 or 0 according to the state of the fuel cell power system at the previous moment. When the SoC is higher than the higher threshold of the SoC or the external load is in an unlocked state (ST2=0), the fuel cell power system is kept in the initialization state and the power control enable signal EMS_En is set to 0.

6. The load-response adaptive control method for a fuel cell power system according to claim 3, characterized in that, Based on the real-time changes in the SoC and the status of the fuel cell power system, the requested output power setpoint EMS_Pwr is set.

7. The load-response adaptive control method for a fuel cell power system according to claim 6, characterized in that, Based on the real-time changes in the SoC, combined with the state of the fuel cell power system and the change in the charging battery bus voltage ΔU, the requested output power setpoint EMS_Pwr is set; the calculation formula for the requested output power setpoint EMS_Pwr is as follows: ； In the formula, The requested output power of the fuel cell stack, calculated in the previous step, is a variable and its unit is kW; The currently calculated requested output power of the fuel cell stack, i.e., the requested output power setpoint EMS_Pwr, is a variable, and its unit is kW; P idle P represents the peak power of the fuel cell stack, which is the lower limit of the fuel cell's power output. It is a constant and its unit is kW. rate P is the rated power of the fuel cell stack, which is a constant and its unit is kW; peak Δp is the peak power of the battery stack, a constant, and its unit is kW; Δp is the output power increment, a constant, and its unit is kW; SOC is the SoC of the rechargeable battery, a variable, and its unit is %. Ultra SOC Max SOC Min and SOC Med All are constants, expressed as a percentage, where SOC Ultra The highest threshold for SoC, SOC Max For a higher threshold of SoC, SOC Med For SoC medium threshold, SOC Min ST1 is the lower threshold of SoC; X1 is the status code of the fuel cell power system, which is a variable; X2 is the state of the system when it maintains a stable power output P0 with the minimum load current I0, which is a constant; X2 is the operating state of the stack when the output power is higher than P0, which is a constant; ΔU is the rate of change of the charging battery bus voltage, in V / s, which is a variable, i.e., the change of the charging battery bus voltage; β1 and β2 refer to two different bus voltage changes, both of which are constants, and their units are both V / s; ST2 is the unlock status code of the external load, which is a variable; Y1 is the state of the external load being unlocked, which is a constant.

8. The load-response adaptive control method for a fuel cell power system according to claim 1, characterized in that, It also includes the following control processes: Requested output power control: The calculated requested output power of the fuel cell stack is limited based on the upper and lower limits of the fuel cell's power output and the current input temperature of the cooling medium. The calculation formula used is as follows: ； In the formula, P out The actual output power of the fuel cell stack after water temperature limiting treatment is the requested output power. Request output power for the fuel cell stack after upper and lower limit processing; The requested output power of the fuel cell stack, calculated so far, is EMS_Pwr; P peak P represents the peak power of the fuel cell stack, which is a constant and its unit is kW. idle P1 is the peak power of the fuel cell stack, which is the lower limit of the fuel cell's power output. It is a constant and its unit is kW. P2 is the limit power, which is a constant and its unit is kW. T is the current input temperature of the cooling medium, which is a variable and its unit is °C. T1 is the input temperature limit threshold of the cooling medium, which is a constant and its unit is °C. ST1 is the status code of the fuel cell power system, which is a variable. X1 is the state of the system when it maintains a stable power output of P0 with the minimum load current I0, which is a constant. X3 is the state of the fuel cell stack starting the DC-DC converter, which is the state of the FCU issuing a DC-DC start command to the DC-DC converter, which is a constant. X4 is the state of the fuel cell stack receiving a shutdown command, which is the state of the power control enable signal EMS_En changing from a value of 1 to a value of 0, which is a constant.

9. The load-response adaptive control method for a fuel cell power system according to claim 1 or 8, characterized in that, It also includes the following control processes: Requested power response speed processing control: The requested output power value obtained after completing the requested output power control is subjected to linear load variation processing; the calculation formula used is as follows: In the formula, ΔP out ΔP1 is the output power change value, a variable, with the unit kW / s; ΔP2 is the output power change threshold, a constant, with the unit kW / s; T is the current cooling medium input temperature, a variable, with the unit ℃; T2 is the suitable cooling medium input temperature value required by the fuel cell stack, a constant, with the unit ℃.

10. A drone, characterized in that, The UAV power system adopts the load-response adaptive control method for fuel cell power systems as described in any one of claims 1-9, wherein, The fuel cell system controller is bidirectionally connected to the UAV flight control system; the fuel cell power system preferably also includes a DC-AC converter, the power output terminal of the fuel cell stack is connected to the input terminal of the DC-AC converter, and the output terminal of the DC-AC converter is used to connect to other external loads.

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