Energy distribution method for long endurance unmanned aerial vehicle sofc hybrid power system

Abstract

The application discloses a kind of long voyage unmanned aerial vehicle SOFC hybrid power system energy distribution method, comprising the following specific steps: S1, obtains the power of aircraft in each flight phase, solid oxide fuel cell SOFC maximum output power, lithium battery maximum output power and lithium battery maximum allowable charging power;S2, based on the environmental data of high-altitude low-oxygen low pressure, the external environment model is obtained by calculation;S3, based on thermodynamics, dynamic equation is calculated through computer software to build SOFC system and lithium battery system model;Compared with prior art, the power output of SOFC and lithium battery is controlled, to ensure that the load change requirement can be met quickly in the whole flight process;The present application improves the overall fuel utilization rate and reduces energy waste by controlling the fuel flow and lithium battery charging and discharging state according to the energy distribution method.

Description

Technical Field

[0001] This invention relates to the fields of fuel cell green aviation and hybrid energy management, specifically to an energy distribution method for a long-endurance unmanned aerial vehicle (UAV) SOFC hybrid power system. Background Technology

[0002] Currently, traditional aviation accounts for 2% to 3% of global carbon emissions. Its high fuel consumption and large pollutant emissions pose significant challenges in the context of carbon neutrality. New energy unmanned aerial vehicles (UAVs), powered by electricity, are of great significance for achieving green, environmentally friendly, and energy-efficient aviation, and for fulfilling the "dual goals" (referring to the goals of the two major aviation development initiatives). Solid oxide fuel cell (SOFC) hybrid power systems, with their advantages of high system efficiency and low pollutant emissions, have become a research focus in the field of aviation technology and have enormous development potential.

[0003] In practical applications, SOFCs require a relatively long start-up time to reach their operating temperature (600℃), and their slow response cannot meet the demands of rapid load changes during UAV flight, such as takeoff, climb, and landing. Lithium-ion batteries, as high-power-density energy storage devices with a power density reaching 2000W / kg, can be used in conjunction with SOFCs to generate electricity to meet varying load requirements. Therefore, how to rationally allocate energy between the SOFC and lithium-ion battery systems to simultaneously meet the aircraft's rapid power response while improving overall system efficiency, the aircraft's power-to-weight ratio, flight range, and practicality has become a problem to be solved. Summary of the Invention

[0004] The purpose of this invention is to address how to rationally allocate energy between the SOFC system and the lithium battery system in order to meet the rapid power response of the aircraft's energy system, improve the overall efficiency of the system and the power-to-weight ratio of the aircraft, and increase flight range and practicality. To address this problem, an energy allocation method for a long-endurance UAV SOFC hybrid power system is proposed.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The energy distribution method for a long-endurance unmanned aerial vehicle (UAV) SOFC hybrid power system includes the following specific steps:

[0007] S1. Obtain the aircraft's power during each flight phase, the maximum output power of the solid oxide fuel cell (SOFC), the maximum output power of the lithium battery, and the maximum allowable charging power of the lithium battery.

[0008] S2. Based on high-altitude, low-oxygen, and low-pressure environmental data, an external environment model is calculated.

[0009] S3. Based on thermodynamic and kinetic equations, models of SOFC and lithium battery systems are built using computer software.

[0010] S4. Based on the external environment model, SOFC system and lithium battery system model, and combined with the power of the aircraft in each flight phase, an energy distribution strategy is constructed.

[0011] S5. Based on the energy allocation strategy, predict the power of the solid oxide fuel cell (SOFC) and the lithium battery at the next moment, and allocate energy to the hybrid power system according to the predicted power of the SOFC and the lithium battery at the next moment.

[0012] As a further preferred embodiment of the present invention, the power of the aircraft in each flight phase includes: average power during takeoff roll, power during climb, power during cruise, and power during descent.

[0013] As a further preferred embodiment of the present invention,

[0014] pass ,

[0015] in, The coefficient of friction is the ground friction factor. air density; Wing area; This represents the average speed during the ascent phase. For aircraft takeoff mass; It is the acceleration due to gravity; This represents the aircraft drag coefficient during the takeoff roll phase. The lift coefficient of the aircraft during the takeoff roll phase; Acceleration during the aircraft's takeoff roll;

[0016] The average power of the aircraft during takeoff roll was calculated. ;

[0017] pass ,

[0018] in, The angle of ascent; The lift-to-drag ratio of the aircraft during the climb phase;

[0019] Calculate the power during the climb phase ;

[0020] pass ,

[0021] in, This refers to the aircraft's cruising speed. The lift-to-drag ratio of the aircraft during the cruise phase;

[0022] Calculation of aircraft power during cruise phase ;

[0023] pass ,

[0024] in, It is the angle of descent; The lift-to-drag ratio of the aircraft during the descent phase;

[0025] Calculation of aircraft power during descent .

[0026] As a further preferred embodiment of the present invention, step S2 includes the following specific steps:

[0027] S21, Through ,

[0028] in, Altitude; The air temperature at sea level;

[0029] The ambient temperature was calculated.

[0030] S22, Through ,

[0031] in, The air pressure at sea level;

[0032] The external environmental pressure p is calculated.

[0033] As a further preferred embodiment of the present invention, step S3 includes the following specific steps:

[0034] Collect the state of charge, internal resistance, capacity, and charge / discharge rate of the lithium battery, and determine the maximum allowable current and discharge power at the charging point of the lithium battery.

[0035] The lithium battery was verified by constant current discharge and pulse discharge tests.

[0036] Based on thermodynamic and kinetic equations, complete models of SOFC and lithium battery systems are built in computer software.

[0037] As a further preferred embodiment of the present invention, the energy allocation strategy includes:

[0038] S41. Make a judgment based on the difference between the SOFC system output power and the aircraft's current load;

[0039] S42. When the difference between the SOFC system output power and the aircraft's current load is greater than zero, determine whether the predicted load change value is greater than or equal to 0; the predicted load change value is the difference between the aircraft's load at the next moment and the aircraft's current load.

[0040] S43. If the predicted load change is greater than or equal to 0;

[0041] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.8, the output power of the SOFC system is reduced by decreasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is not recharged.

[0042] When 0.4 < the state of charge (SOC) of the lithium battery < 0.8, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0043] When the state of charge (SOC) of the lithium battery is ≤0.4%, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0044] S44. If the predicted load change is less than 0;

[0045] When the state of charge (SOC) of the lithium battery is ≥ 0.8, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is not recharged.

[0046] When 0.4 < the state of charge (SOC) of the lithium battery < 0.8, the output power of the SOFC system is reduced by decreasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0047] When the state of charge (SOC) of the lithium battery is ≤0.4%, the output power of the SOFC system is reduced by decreasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0048] S45. When the difference between the SOFC system output power and the aircraft's current load is equal to 0, determine whether the predicted load change value is greater than or equal to 0.

[0049] S46. If the predicted load change is greater than or equal to 0;

[0050] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the power of the solid oxide fuel cell remains unchanged, providing power to the aircraft, and the lithium battery is not recharged.

[0051] When the state of charge (SOC) of the lithium battery is less than 0.4%, the output power of the SOFC system is increased by increasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0052] S47. If the predicted load change is less than 0;

[0053] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the power of the solid oxide fuel cell remains unchanged, providing power to the aircraft, and the lithium battery is not recharged.

[0054] When the state of charge (SOC) of the lithium battery is less than 0.4%, the power of the solid oxide fuel cell remains unchanged, providing power to the aircraft, while the lithium battery is being charged.

[0055] S48. When the difference between the SOFC system output power and the aircraft's current load is less than zero, determine whether the predicted load change value is greater than or equal to 0.

[0056] S49. If the predicted load change is greater than or equal to 0;

[0057] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the output power of the SOFC system can be increased by increasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, while the lithium battery supplements the load demand.

[0058] When the state of charge (SOC) of the lithium battery is ≤0.4%, the solid oxide fuel cell provides power to the aircraft by increasing the output power of the SOFC system, while the lithium battery is not recharged.

[0059] S410. If the predicted load change is less than 0;

[0060] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery supplements the load demand.

[0061] When the state of charge (SOC) of the lithium battery is ≤0.4%, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is not recharged.

[0062] As a further preferred embodiment of the present invention, it includes an SOFC system, a lithium battery system, and an energy distribution management system;

[0063] The SOFC system is connected in parallel with the lithium battery system to provide power for the aircraft's load.

[0064] The energy distribution management system is connected to both the SOFC system and the lithium battery system to execute energy management methods.

[0065] The energy distribution method for a long-endurance unmanned aerial vehicle (UAV) SOFC hybrid power system proposed in this invention has the following advantages compared with existing technologies:

[0066] 1. This invention can rationally allocate energy to the hybrid power system of a drone based on the specific flight mission of the drone, the maximum output power of the fuel cell, and the maximum charging and discharging power of the lithium battery.

[0067] 2. This invention ensures that the aircraft can quickly meet the load change requirements such as taxiing, climbing and landing throughout the entire flight by controlling the power output of SOFC and lithium battery.

[0068] 3. This invention improves overall fuel utilization and reduces energy waste by using energy distribution method feedback control to regulate fuel flow and lithium battery charge / discharge status.

[0069] 4. The energy distribution method for hybrid power systems provided by this invention can ensure the healthy operation of lithium batteries and improve their service life;

[0070] 5. By controlling the fuel inlet flow rate of the fuel cell and the lithium battery current, the output power of the SOFC and lithium battery can be changed, ensuring that the aircraft can quickly respond to power changes in each stage of flight and improving the aircraft's flight performance. Attached Figure Description

[0071] Figure 1 This is a schematic diagram of a direct ammonia SOFC-lithium battery hybrid power system;

[0072] Figure 2 This is a diagram illustrating the power requirements for short-range transport aircraft during flight missions.

[0073] Figure 3 This is a schematic diagram of an energy allocation strategy;

[0074] Figure 4 This is a schematic diagram of the energy allocation strategy required by an aircraft throughout its entire flight mission. Detailed Implementation

[0075] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0076] Example 1: Energy distribution method for a long-endurance unmanned aerial vehicle (UAV) SOFC hybrid power system, including the following specific steps:

[0077] S1. Obtain the aircraft's power during each flight phase, the maximum output power of the solid oxide fuel cell (SOFC), the maximum output power of the lithium battery, and the maximum allowable charging power of the lithium battery.

[0078] The aircraft's power during each flight phase includes: average power during takeoff roll, power during climb, power during cruise, and power during descent.

[0079] Determine the acceleration during the takeoff roll based on the aircraft type and throttle information. Aircraft takeoff mass ;

[0080] pass ,

[0081] In the formula, This refers to the aircraft's takeoff speed; Acceleration during the aircraft's takeoff roll;

[0082] Calculate the takeoff run distance of an aircraft .

[0083] pass ,

[0084] In the formula, The coefficient of friction is the ground friction factor. air density; Wing area; This represents the average speed during the ascent phase. For aircraft takeoff mass; It is the acceleration due to gravity; This represents the aircraft drag coefficient during the takeoff roll phase. The lift coefficient of the aircraft during the takeoff roll phase; Acceleration during the takeoff roll of an aircraft

[0085] Calculate the average power during the takeoff roll of an aircraft. .

[0086] pass ,

[0087] In the formula, The angle of ascent; This refers to the lift-to-drag ratio of the aircraft during the climb phase.

[0088] Calculate the power during the climb phase .

[0089] pass ,

[0090] In the formula, This refers to the aircraft's cruising speed. The lift-to-drag ratio of the aircraft during the cruise phase.

[0091] Calculate aircraft power during cruise phase .

[0092] pass ,

[0093] In the formula, It is the angle of descent; This refers to the lift-to-drag ratio of the aircraft during the descent phase.

[0094] Calculate the power during the descent phase .

[0095] The power requirements of the aircraft during each phase of flight are provided by both SOFC and lithium batteries.

[0096] The maximum power demand during the entire flight can be calculated using the formula. With the maximum output power of SOFC system equal.

[0097] S2. Based on high-altitude, low-oxygen, and low-pressure environmental data, an external environment model is calculated.

[0098] S21, Through ,

[0099] in, Altitude; The air temperature at sea level;

[0100] The ambient temperature was calculated.

[0101] S22, Through ,

[0102] in, The air pressure at sea level;

[0103] The external environmental pressure was calculated.

[0104] S3. Based on thermodynamic and kinetic equations, SOFC system and lithium battery system models are built using computer software.

[0105] Collect the state of charge, internal resistance, capacity, and charge / discharge rate of the lithium battery, and determine the maximum allowable current and discharge power at the charging point of the lithium battery.

[0106] The lithium battery was verified by constant current discharge and pulse discharge tests.

[0107] Based on thermodynamic and kinetic equations, complete models of SOFC and lithium battery systems are built in computer software.

[0108] S4. Based on the external environment model, SOFC system and lithium battery system model, and combined with the power of the aircraft in each flight phase, an energy distribution strategy is constructed.

[0109] like Figure 3 As shown, the energy allocation strategy includes:

[0110] ,

[0111] ,

[0112] ,

[0113] in, For the output power of the SOFC system, The current load of the aircraft. This is the difference between the OFC system output power and the aircraft's current load. To prepare for the aircraft's load in the next moment. The output power of the SOFC system at the next moment. This represents the output power of the lithium battery at the next moment. This represents the predicted load change value.

[0114] S41, Output power based on SOFC system The current load of the aircraft The difference Then, make a judgment.

[0115] S42, When the SOFC system output power The current load of the aircraft The difference When the value is greater than zero, determine the load forecast change value. Is it greater than or equal to 0; the predicted load change value For the aircraft's load in the next moment The current load of the aircraft The difference .

[0116] S43, If the load forecast change value Greater than or equal to 0.

[0117] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.8, the output power of the SOFC system is reduced by decreasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is not recharged.

[0118] When 0.4 < the state of charge (SOC) of the lithium battery < 0.8, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0119] When the state of charge (SOC) of the lithium battery is ≤0.4%, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0120] S44, If the load forecast changes... Less than 0;

[0121] When the state of charge (SOC) of the lithium battery is ≥ 0.8, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is not recharged.

[0122] When 0.4 < the state of charge (SOC) of the lithium battery < 0.8, the output power of the SOFC system is reduced by decreasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0123] When the state of charge (SOC) of the lithium battery is ≤0.4%, the output power of the SOFC system is reduced by decreasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0124] S45, When the SOFC system output power The current load of the aircraft The difference When the value equals 0, determine the load forecast change value. Is it greater than or equal to 0?

[0125] S46. If the predicted load change is greater than or equal to 0;

[0126] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the power of the solid oxide fuel cell remains unchanged, providing power to the aircraft, and the lithium battery is not recharged.

[0127] When the state of charge (SOC) of the lithium battery is less than 0.4%, the output power of the SOFC system is increased by increasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0128] S47. If the predicted load change is less than 0;

[0129] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the power of the solid oxide fuel cell remains unchanged, providing power to the aircraft, and the lithium battery is not recharged.

[0130] When the state of charge (SOC) of the lithium battery is less than 0.4%, the power of the solid oxide fuel cell remains unchanged, providing power to the aircraft, while the lithium battery is being charged.

[0131] S48, When the SOFC system output power The current load of the aircraft The difference When the value is less than zero, determine the load forecast change value. Is it greater than or equal to 0?

[0132] S49. If the load forecast changes... Greater than or equal to 0;

[0133] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the output power of the SOFC system can be increased by increasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, while the lithium battery supplements the load demand.

[0134] When the state of charge (SOC) of the lithium battery is ≤0.4%, the solid oxide fuel cell provides power to the aircraft by increasing the output power of the SOFC system, while the lithium battery is not recharged.

[0135] S410, If the load forecast change value Less than 0;

[0136] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery supplements the load demand.

[0137] When the state of charge (SOC) of the lithium battery is ≤0.4%, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is not recharged.

[0138] By analyzing and comparing the SOFC system output power with the external load demand power, and then judging the fluctuations of the external load and aircraft flight power demand at the next moment based on the predicted load change value, the state of charge (SOC) of the lithium battery is used to determine whether the lithium battery needs to be charged and discharged. Finally, based on the specific operating methods in the table above, the SOFC system and lithium battery output power at the next moment are controlled and adjusted to ultimately meet the requirements. ,in, Power required for aircraft flight; This refers to the output power of the SOFC. This refers to the output power of the lithium battery.

[0139] according to Figure 3 In addition to the steps mentioned above, there are 15 different operation modes, as shown in the table below.

[0140] Table 1: Specific operations

[0141]

[0142] S5. Based on the energy allocation strategy, predict the power of the solid oxide fuel cell (SOFC) and the lithium battery at the next moment, and allocate energy to the hybrid power system according to the predicted power of the SOFC and the lithium battery at the next moment.

[0143] Example 2: Figure 1 As shown, it includes an SOFC system, a lithium battery system, and an energy distribution management system;

[0144] The SOFC system is connected in parallel with the lithium battery system to provide power for the aircraft's load.

[0145] The energy distribution management system is connected to both the SOFC system and the lithium battery system for energy management methods.

[0146] Example 3: The full flight envelope of the BAe.146 four-engine turbofan short-range transport aircraft, manufactured by British Aerospace, was selected as the load requirement.

[0147] S1. Obtain the aircraft's power during each flight phase, the maximum output power of the solid oxide fuel cell (SOFC), the maximum output power of the lithium battery, and the maximum allowable charging power of the lithium battery.

[0148] The power requirement for the flight mission can be calculated using the formula in Example 1, such as... Figure 2 As shown.

[0149] The entire flight lasts 4000 seconds and is mainly divided into 10 phases: taxiing, takeoff, climb 1, climb 2, climb 3, continuous climb, cruise, descent, circling, and landing. The power requirements for each phase are different. The highest power requirement is for climb 3, at 223.482 kW, while the lowest power requirement is for the taxiing phase, at 28.97 kW.

[0150] S2. Based on high-altitude, low-oxygen, and low-pressure environmental data, an external environment model is calculated.

[0151] S21, Through ,

[0152] in, Altitude; The air temperature at sea level;

[0153] The ambient temperature was calculated.

[0154] S22, Through ,

[0155] in, The air pressure at sea level;

[0156] The external environmental pressure was calculated.

[0157] S3. Based on thermodynamic and kinetic equations, SOFC system and lithium battery system models are built using computer software.

[0158] Collect the state of charge, internal resistance, capacity, and charge / discharge rate of the lithium battery, and determine the maximum allowable current and discharge power at the charging point of the lithium battery.

[0159] The lithium battery was verified by constant current discharge and pulse discharge tests.

[0160] Based on thermodynamic and kinetic equations, complete models of SOFC and lithium battery systems are built in computer software.

[0161] S4. Based on the external environment model, SOFC system and lithium battery system model, and combined with the aircraft's power at each flight phase, an energy distribution strategy is constructed; such as... Figure 4 As shown.

[0162] Throughout the flight, the SOFC, as the main propulsion unit, is responsible for providing most of the load power, while the lithium battery, as an energy storage device, supplements the power when the load changes and maintains dynamic balance through charging and discharging.

[0163] During low-power flight conditions, such as the cruise phase, SOFC serves as the primary energy source to provide the power required for flight, while the SOC of the lithium battery is below 0.8%. The excess power from SOFC is then used to charge the lithium battery.

[0164] During high-performance flight conditions such as climb or landing, the power of the SOFC cannot be increased in time to meet the load changes. At this time, the lithium battery, as an energy storage device, discharges to provide the power required by the load.

[0165] When the load changes, SOFC cannot respond in time to change its power, while lithium battery power changes rapidly to meet the needs of the load change.

[0166] Specific energy allocation strategies include:

[0167] S41. Make a judgment based on the difference between the SOFC system output power and the aircraft's current load.

[0168] S42. When the difference between the SOFC system output power and the aircraft's current load is greater than zero, determine whether the load prediction change value is greater than or equal to 0; the load prediction change value is the difference between the aircraft's load at the next moment and the aircraft's current load.

[0169] S43. If the predicted load change is greater than or equal to 0;

[0170] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.8, the output power of the SOFC system is reduced by decreasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is not recharged.

[0171] When 0.4 < the state of charge (SOC) of the lithium battery < 0.8, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0172] When the state of charge (SOC) of the lithium battery is ≤0.4%, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0173] S44. If the predicted load change is less than 0;

[0174] When the state of charge (SOC) of the lithium battery is ≥ 0.8, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is not recharged.

[0175] When 0.4 < the state of charge (SOC) of the lithium battery < 0.8, the output power of the SOFC system is reduced by decreasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0176] When the state of charge (SOC) of the lithium battery is ≤0.4%, the output power of the SOFC system is reduced by decreasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0177] S45. When the difference between the SOFC system output power and the aircraft's current load is equal to 0, determine whether the predicted load change value is greater than or equal to 0.

[0178] S46. If the predicted load change is greater than or equal to 0;

[0179] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the power of the solid oxide fuel cell remains unchanged, providing power to the aircraft, and the lithium battery is not recharged.

[0180] When the state of charge (SOC) of the lithium battery is less than 0.4%, the output power of the SOFC system is increased by increasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged.

[0181] S47. If the predicted load change is less than 0;

[0182] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the power of the solid oxide fuel cell remains unchanged, providing power to the aircraft, and the lithium battery is not recharged.

[0183] When the state of charge (SOC) of the lithium battery is less than 0.4%, the power of the solid oxide fuel cell remains unchanged, providing power to the aircraft, while the lithium battery is being charged.

[0184] S48. When the difference between the SOFC system output power and the aircraft's current load is less than zero, determine whether the predicted load change value is greater than or equal to 0.

[0185] S49. If the predicted load change is greater than or equal to 0;

[0186] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the output power of the SOFC system can be increased by increasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, while the lithium battery supplements the load demand.

[0187] When the state of charge (SOC) of the lithium battery is ≤0.4%, the solid oxide fuel cell provides power to the aircraft by increasing the output power of the SOFC system, while the lithium battery is not recharged.

[0188] S410. If the predicted load change is less than 0;

[0189] When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery supplements the load demand.

[0190] When the state of charge (SOC) of the lithium battery is ≤0.4%, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is not recharged.

[0191] S5. Based on the energy allocation strategy, predict the power of the solid oxide fuel cell (SOFC) and the lithium battery at the next moment, and allocate energy to the hybrid power system according to the predicted power of the SOFC and the lithium battery at the next moment.

[0192] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. An energy distribution method for a long-endurance unmanned aerial vehicle (UAV) SOFC hybrid power system, characterized in that, The specific steps include the following: S1. Obtain the aircraft's power during each flight phase, the maximum output power of the solid oxide fuel cell (SOFC), the maximum output power of the lithium battery, and the maximum allowable charging power of the lithium battery. S2. Based on high-altitude, low-oxygen, and low-pressure environmental data, an external environment model is calculated. S3. Based on thermodynamic and kinetic equations, models of SOFC and lithium battery systems are built using computer software. S4. Based on the external environment model, SOFC system and lithium battery system model, and combined with the power of the aircraft in each flight phase, an energy distribution strategy is constructed. S5. Based on the energy allocation strategy, predict the power of the solid oxide fuel cell (SOFC) and the lithium battery at the next moment, and allocate energy to the hybrid power system according to the predicted power of the SOFC and the lithium battery at the next moment.

2. The energy distribution method for a long-endurance unmanned aerial vehicle (UAV) SOFC hybrid power system according to claim 1, characterized in that, The aircraft's power during each flight phase includes: average power during takeoff roll, power during climb, power during cruise, and power during descent.

3. The energy distribution method for a long-endurance unmanned aerial vehicle (UAV) SOFC hybrid power system according to claim 1, characterized in that, S2 includes the following specific steps: S21, Through , in, Altitude; The air temperature at sea level; The ambient temperature was calculated. S22, Through , in, The air pressure at sea level; The external environmental pressure p is calculated.

4. The energy distribution method for a long-endurance unmanned aerial vehicle (UAV) SOFC hybrid power system according to claim 1, characterized in that, S3 includes the following specific steps: Collect the state of charge, internal resistance, capacity, and charge / discharge rate of the lithium battery, and determine the maximum allowable current and discharge power at the charging point of the lithium battery. The lithium battery was verified by constant current discharge and pulse discharge tests. Based on thermodynamic and kinetic equations, complete models of SOFC and lithium battery systems are built in computer software.

5. The energy distribution method for a long-endurance unmanned aerial vehicle (UAV) SOFC hybrid power system according to any one of claims 1-4, characterized in that, The energy allocation strategy includes: S41. Make a judgment based on the difference between the SOFC system output power and the aircraft's current load; S42. When the difference between the SOFC system output power and the aircraft's current load is greater than zero, determine whether the predicted load change value is greater than or equal to 0; the predicted load change value is the difference between the aircraft's load at the next moment and the aircraft's current load. S43. If the predicted load change is greater than or equal to 0; When the state of charge (SOC) of the lithium battery is greater than or equal to 0.8, the output power of the SOFC system is reduced by decreasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is not recharged. When 0.4 < the state of charge (SOC) of the lithium battery < 0.8, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged. When the state of charge (SOC) of the lithium battery is ≤0.4%, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged. S44. If the predicted load change is less than 0; When the state of charge (SOC) of the lithium battery is ≥ 0.8, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is not recharged. When 0.4 < the state of charge (SOC) of the lithium battery < 0.8, the output power of the SOFC system is reduced by decreasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged. When the state of charge (SOC) of the lithium battery is ≤0.4%, the output power of the SOFC system is reduced by decreasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged. S45. When the difference between the SOFC system output power and the aircraft's current load is equal to 0, determine whether the predicted load change value is greater than or equal to 0. S46. If the predicted load change is greater than or equal to 0; When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the power of the solid oxide fuel cell remains unchanged, providing power to the aircraft, and the lithium battery is not recharged. When the state of charge (SOC) of the lithium battery is less than 0.4%, the output power of the SOFC system is increased by increasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, and the lithium battery is charged. S47. If the predicted load change is less than 0; When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the power of the solid oxide fuel cell remains unchanged, providing power to the aircraft, and the lithium battery is not recharged. When the state of charge (SOC) of the lithium battery is less than 0.4%, the power of the solid oxide fuel cell remains unchanged, providing power to the aircraft, while the lithium battery is being charged. S48. When the difference between the SOFC system output power and the aircraft's current load is less than zero, determine whether the predicted load change value is greater than or equal to 0. S49. If the predicted load change is greater than or equal to 0; When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the output power of the SOFC system can be increased by increasing the SOFC fuel flow rate. The solid oxide fuel cell provides power to the aircraft, while the lithium battery supplements the load demand. When the state of charge (SOC) of the lithium battery is ≤0.4%, the solid oxide fuel cell provides power to the aircraft by increasing the output power of the SOFC system, while the lithium battery is not recharged. S410. If the predicted load change is less than 0; When the state of charge (SOC) of the lithium battery is greater than or equal to 0.4%, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery supplements the load demand. When the state of charge (SOC) of the lithium battery is ≤0.4%, the SOFC fuel flow is normal, the solid oxide fuel cell provides power to the aircraft, and the lithium battery is not recharged.

6. The energy distribution method for a long-endurance unmanned aerial vehicle (UAV) SOFC hybrid power system according to claim 5, characterized in that, This includes SOFC systems, lithium battery systems, and energy distribution management systems; The SOFC system is connected in parallel with the lithium battery system to provide power for the aircraft's load. The energy distribution management system is connected to the SOFC system and the lithium battery system respectively, and is used to execute the energy distribution method according to claims 1-4.

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