Vertical take-off and landing aircraft with tandem tilting wings and hybrid power control method of vertical take-off and landing aircraft

Abstract

The invention discloses a vertical take-off and landing aircraft with tandem tilting wings and a hybrid power control method of the vertical take-off and landing aircraft, and belongs to the technical field of advanced air traffic. The aircraft comprises a tandem tilting wing structure, wherein a plurality of power units are distributed on a front wing and a rear wing and integrally tilt together with the units; the hybrid power system is integrated in the fuselage and comprises a hydrogen fuel cell system matched with cruise steady-state power and a lithium battery system matched with take-off and landing transient peak power; and the energy management controller is in signal connection with the hybrid power system and the tilt angle sensor, and is configured to dynamically adjust the power output ratio of the hydrogen fuel cell to the lithium battery in response to the wing tilt angle change. According to the invention, the power system and the tandem tilting wing configuration are deeply cooperated, so that the breakthrough improvement of the flight range is realized, the millisecond-level power response and safety redundancy in the transition flight stage are ensured, and the service life of the lithium battery is obviously prolonged through shallow charging and shallow discharging management of the lithium battery.

Description

Technical Field

[0001] This invention relates to the field of advanced air mobility technology, specifically to a tandem tiltwing vertical takeoff and landing aircraft and its hybrid power control method. Background Technology

[0002] Electric vertical takeoff and landing (eVTOL) aircraft, with their runway-free, environmentally friendly, and low-noise characteristics, are considered core transportation tools for realizing the UAM (Universal Aircraft Operation) vision, suitable for various scenarios such as passenger transport, logistics, and emergency rescue. However, existing eVTOL technologies generally suffer from significant technical bottlenecks in the selection of power systems, which restricts the feasibility and economics of their large-scale commercial application.

[0003] I. Limitations of Pure Battery Power Solutions

[0004] Currently, the vast majority of eVTOL designs rely primarily on lithium-ion batteries as their sole power source. Although lithium-ion battery technology has made significant progress over the past decade, its energy density remains fundamentally, even orders of magnitude, lower than that of traditional aviation fuel. Currently, the energy density of a single advanced lithium-ion battery cell is approximately 300 Wh / kg, while aviation kerosene boasts an energy density as high as 12,000 Wh / kg. This vast difference in physical properties directly leads to a series of insurmountable challenges for pure battery eVTOL: First, there is a severe constraint on range and payload. The energy density of the battery system is a core parameter determining the aircraft's range and payload. To achieve the minimum effective range required for commercial operation, the battery pack's mass will occupy a significant portion of the aircraft's maximum takeoff mass, typically as high as 30% to 40%. This greatly reduces the commercial payload space available for passengers or cargo, significantly diminishing the aircraft's operational economics.

[0005] Secondly, battery life is drastically reduced under high-rate discharge. Vertical takeoff and landing (VTOL) aircraft have extremely uneven power demands across their mission profiles. During vertical takeoff, hovering, and vertical landing, all rotors need to output lift far exceeding the aircraft's own weight. This requires the propulsion system to output instantaneous, enormous peak power, which translates to batteries requiring extremely high discharge rates (C-rates), reaching 6C to 15C or even higher. Such stringent discharge conditions drastically accelerate the irreversible degradation of the electrochemical materials inside the battery, leading to a significant reduction in cycle life and persistently high total life-cycle operating costs.

[0006] Third, there is an inherent contradiction between charging time and operational efficiency. Urban air mobility scenarios require aircraft to have high-frequency turnaround capabilities. However, after completing a mission, the remaining battery power is limited, and energy replenishment is necessary. While high-rate fast charging can shorten ground waiting time, it will further accelerate battery aging. Battery swapping, on the other hand, requires huge investments in ground infrastructure and the storage of a large number of expensive spare battery packs, which also increases operational complexity and cost.

[0007] II. Challenges of Pure Hydrogen Fuel Cell Solutions To fundamentally overcome the range limitations of pure battery solutions, the industry has turned its attention to hydrogen fuel cell technology, which boasts extremely high energy density. Hydrogen's mass energy density is more than three times that of aviation kerosene and more than one hundred times that of lithium-ion batteries, making it widely recognized as an ideal energy source for achieving long-range, zero-carbon-emission flight. However, using a proton exchange membrane fuel cell (PEMFC) system directly as the sole power source for eVTOL also faces inherent and insurmountable technical challenges: First, its transient response capability is severely inadequate. The power output response speed of the PEMFC system is limited by its internal electrochemical reaction rate, gas diffusion process, and the dynamic adjustment capability of auxiliary systems, and its power response time is typically on the order of seconds or even longer. This response speed is far from meeting the millisecond-level peak power requirements of eVTOL during vertical takeoff and landing, responding to sudden gust interference, or performing emergency evasive maneuvers, posing an unacceptable and serious threat to flight safety.

[0008] Secondly, its power density is relatively low. Although the PEMFC system has an extremely high energy density, its power density is still significantly lower than that of high-power lithium-ion batteries. This means that to independently support the high peak power required for vertical takeoff and landing, the fuel cell system would have to be too large and heavy, thus negating its advantage in energy density.

[0009] III. Aerodynamic Complexity of Tilted Wing Configuration In terms of aerodynamic layout, tilt-wing configurations are becoming the design trend for future eVTOLs due to their combination of vertical takeoff and landing capabilities and high-speed cruise performance of fixed-wing aircraft. Among them, the tandem configuration has advantages such as high aerodynamic efficiency, compact structure, and large fuselage space. However, the power system management under this configuration is more complex. How to achieve efficient energy distribution in different flight phases such as takeoff and landing, tilt transition, and cruise is a problem that urgently needs to be solved by current technology.

[0010] Specifically, during the transition phase, the aircraft operates at low speeds, and the wings need to gradually tilt. At this time, the wings are typically at a large angle of attack, and the powerful slipstream generated by the rotor creates a strong aerodynamic coupling effect with the wing surface. This complex flow environment can easily lead to airflow separation in certain areas of the wing, or even a deep stall, causing drastic changes in the aircraft's attitude and posing a severe challenge to stability and controllability. Simultaneously, the transition phase is an energy-intensive process with a complex and variable power demand curve. The aircraft needs to overcome enormous aerodynamic drag to accelerate while maintaining sufficient lift. This process places extremely high demands on the dynamic response capability and power output control precision of the propulsion system.

[0011] In summary, neither existing technologies, whether pure battery solutions or pure hydrogen fuel cell solutions, can independently and perfectly resolve the core technological contradictions in urban air mobility operations. Pure battery solutions are constrained by energy density limitations, making it difficult to balance range and payload; pure fuel cell solutions are limited by transient response characteristics, failing to meet the safety requirements of vertical takeoff and landing (VTOL) and transition phases. For tiltrotor configurations that combine efficient cruise and VTOL capabilities, especially the more aerodynamically complex tandem biplane configuration, existing technologies neither provide an energy architecture solution that simultaneously addresses the contradiction between long range and high peak power demands, nor a control strategy that matches and coordinates this energy architecture with the unique power demand curve of the tiltrotor's transition phase. Therefore, a novel, systematic, and comprehensive solution is urgently needed. This solution must not only provide long range and high payload capacity but also ensure rapid and reliable power response capabilities in all flight phases, especially VTOL and critical transition phases. Furthermore, it must deeply optimize the aircraft's overall aerodynamic layout, structural integration efficiency, and life-cycle economics. Summary of the Invention

[0012] The purpose of this invention is to overcome the shortcomings of the prior art and provide a tandem tiltwing vertical takeoff and landing (VTOL) aircraft and its hybrid power control method. This invention systematically solves the problems of short range and limited payload caused by the physical bottleneck of energy density in pure battery power schemes, and the problem that pure hydrogen fuel cell schemes cannot meet the peak power safety requirements of VTOL and transition flight phases due to transient response lag. In particular, it addresses the unique technical challenges of severe aerodynamic coupling, stall risk, and drastic dynamic changes in power demand in the transition flight phase of tandem tiltwing configurations. By deeply co-designing the hybrid power system of hydrogen fuel cells and lithium batteries with the overall aerodynamic layout of the aircraft, the energy management strategy is linked in real time with the wing tilt angle and flight phase. This achieves a breakthrough improvement in range and payload while ensuring millisecond-level power response and flight safety across the entire flight profile, especially during the transition phase. Furthermore, the intelligent management of shallow charging and discharging of lithium batteries significantly extends their cycle life and reduces the total life cycle operating cost. Ultimately, this provides a systematic technical solution for advanced air mobility that combines long range, high safety, and excellent economy.

[0013] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a tandem tiltwing vertical takeoff and landing aircraft, comprising: A tandem tiltwing configuration includes a front wing and a rear wing. Multiple power units are distributed on both the front wing and the rear wing. Each power unit includes a rotor and a motor that drives the rotor. The front wing and the rear wing, together with the power units fixed thereon, tilt as a whole. A hybrid power system, integrated within the aircraft fuselage, includes a hydrogen fuel cell system as the primary energy source and a lithium battery system as peak power compensation. The rated power of the hydrogen fuel cell system matches the steady-state power requirement of the aircraft during the cruise phase, and the peak discharge power of the lithium battery system matches the transient peak power requirement of the aircraft during the vertical takeoff and landing phase. An energy management controller is connected to the tilt angle sensor signals of the hybrid power system and the tandem tilt wing configuration, and is configured to dynamically adjust the power output ratio of the hydrogen fuel cell system and the lithium battery system in response to changes in the tilt angle of the forewing and / or the aft wing.

[0014] Furthermore, the number of power units is 12, which are evenly and symmetrically distributed along the span of the forewing and the aftwing; the rotor is a variable collective pitch rotor.

[0015] Furthermore, the energy management controller is configured to execute the following power allocation strategy tied to the flight phase: During vertical takeoff and vertical landing, the tilt angle of the fore wing and the rear wing is 90°, the lithium battery system undertakes 60%-70% of the total power demand, and the hydrogen fuel cell system undertakes 30%-40% of the total power demand. During the tilt transition phase, the tilt angles of the front wing and the rear wing continuously change from 90° to 0°, the power proportion of the hydrogen fuel cell system linearly increases from 30% to 90%, and the power proportion of the lithium battery system linearly decreases from 70% to 10%. During the deceleration transition phase, the tilt angles of the front wing and the rear wing continuously change from 0° to 90°, the power ratio of the hydrogen fuel cell system decreases linearly from 90% to 40%, and the power ratio of the lithium battery system increases linearly from 10% to 60%. During the cruise phase, the tilt angle of the front wing and the rear wing is 0°, the hydrogen fuel cell system undertakes 100% of the total power demand, and the lithium battery system is in standby or charging state.

[0016] Furthermore, it also includes a high-voltage DC power distribution network, wherein the hydrogen fuel cell system and the lithium battery system are connected in parallel to a common DC bus via a bidirectional DC / DC converter; the power distribution network includes a solid-state power controller network for performing power distribution and fault isolation.

[0017] Furthermore, it also includes a liquid hydrogen storage tank, which is a load-bearing component integrated with the fuselage structure. The inner liner of the liquid hydrogen storage tank is made of aluminum alloy that can withstand temperatures up to -253°C, and the outer shell is made of carbon fiber composite material. There is a vacuum insulation layer between the inner and outer shells.

[0018] Furthermore, the maximum takeoff weight of the aircraft is not less than 1,000 kilograms.

[0019] Furthermore, the cruising speed of the aircraft is no less than 300 km / h.

[0020] Secondly, the present invention provides a hybrid power control method for the above-mentioned tandem tiltwing vertical takeoff and landing aircraft, comprising the following steps: Obtain the current flight phase information and current wing tilt angle information of the aircraft; Based on the current flight phase information and the current wing tilt angle information, determine the target power distribution ratio; Based on the target power distribution ratio, control the hydrogen fuel cell system to output a first power and control the lithium battery system to output a second power. Specifically, when the wing tilt angle is greater than the first angle threshold, the second power is greater than the first power; when the wing tilt angle is less than the second angle threshold, the first power is greater than the second power, and the lithium battery system enters standby or charging mode.

[0021] Furthermore, the flight phase information includes the vertical takeoff phase, tilt transition phase, cruise phase, deceleration transition phase, and vertical landing phase; the control method further includes: During the vertical takeoff and vertical landing phases, the lithium battery system is controlled to discharge at a discharge rate of 5C to 8C. During the cruise phase, the hydrogen fuel cell system is controlled to recharge the lithium battery system, maintaining the state of charge of the lithium battery system within a healthy range of 70% to 85%.

[0022] Furthermore, it also includes: real-time monitoring of the aircraft's real-time power requirements; When a sudden gust of wind or an emergency go-around command is detected, the lithium battery system is controlled to output peak power within 100 milliseconds to compensate for the power response delay of the hydrogen fuel cell system.

[0023] Beneficial effects Compared with existing technologies, this invention achieves the following beneficial effects by deeply integrating the hydrogen fuel cell and lithium battery hybrid power system with the tandem tilt-wing aerodynamic layout, particularly by enabling the energy management strategy to dynamically adjust the power distribution ratio in response to changes in the wing tilt angle: 1. Breakthrough Enhancement in Range and Mission Capability: This invention utilizes liquid hydrogen, with its extremely high energy density, as the primary energy source, fundamentally overcoming the physical bottleneck of energy density in lithium batteries. By precisely matching the lithium battery system capacity to the transient energy consumption during vertical takeoff and landing, and precisely matching the rated power of the fuel cell system to the steady-state power required for cruise, over-design of the power system is avoided. Simulation results show that, under the same takeoff mass and mission profile, compared to a pure lithium battery power scheme, this invention increases the mission range from 188 kilometers to over 300 kilometers, an improvement of more than 60%.

[0024] 2. Synergistic Optimization of Peak Power Response and Flight Safety: This invention resolves the contradiction between the transient response lag of hydrogen fuel cells and the millisecond-level power demands during vertical takeoff and landing (VTOL) phases through a peak power compensation architecture design for the lithium battery system. By dynamically allocating power based on wing tilt angle and providing peak compensation in emergency situations, the aircraft maintains ample and reliable instantaneous power during critical flight moments with the most demanding power response requirements, such as tilt transitions, gust disturbances, and emergency go-arounds. Simulation results show that when encountering a 15 m / s vertical gust during approach, the system can complete power compensation response within 40 milliseconds, with power output exceeding the peak demand by 8 kW, and the aircraft's attitude quickly returns to stability. At the end of the mission, the lithium battery retains a safety redundancy of over 22% state of charge, sufficient to support a complete go-around procedure. This effect is unattainable by pure lithium battery solutions (where the state of charge returns to zero at mission end) and pure fuel cell solutions (with response speeds in the milliseconds).

[0025] 3. Significant Improvements in Battery Life and Lifecycle Economics: This invention employs a power distribution strategy tied to the flight phase, allowing the lithium battery to discharge at a high rate of 5C-8C only during the short periods of vertical takeoff and landing. During the cruise phase, which lasts for tens of minutes, the battery remains in standby mode or is recharged at a low rate by the fuel cell, maintaining a healthy state of charge (SOC) of 70%-85%. This operating mode is expected to extend the cycle life of the lithium battery by 3 to 5 times compared to pure battery solutions. Simultaneously, the fuel cell bears 100% steady-state load during the cruise phase, avoiding membrane electrode performance degradation caused by frequent load changes. The cost of battery replacement and investment in ground charging infrastructure are significantly reduced throughout the lifecycle, laying an economic foundation for large-scale commercial operation.

[0026] 4. Deep Synergy Between Aerodynamic Layout and Power System: Addressing the unique aerodynamic coupling and stall risks inherent in tandem tilt-wing configurations during the transition phase, this invention achieves closed-loop synergy through the structural characteristics of the wing and its fixed power unit tilting as a whole, and the control characteristics of power distribution responding to changes in the tilt angle. On one hand, the rotor slipstream effectively suppresses airflow separation at high angles of attack, delaying stall. On the other hand, the energy management controller precisely adjusts the output ratio of the fuel cell and lithium battery based on the real-time tilt angle, dynamically matching the power output curve with the power demand curve during the transition phase. Simulations show that power fluctuations throughout the tilt transition are controlled within ±5kW, avoiding attitude disturbances caused by power supply lag or fluctuations.

[0027] 5. Significantly Enhanced System Redundancy and Fault Tolerance: This invention constructs a highly robust power distribution and fault isolation system through a distributed propulsion layout (12 independent power units) and a solid-state power controller network architecture. In the event of a single or multiple power unit failure, the flight control system can quickly adjust the power output of the remaining normal units to maintain flight controllability; the solid-state power controller network can isolate faulty branches within microseconds, preventing fault propagation. This redundancy design, combined with the dual-energy backup characteristics of the hybrid power system, makes the safety margin of this invention's aircraft in power system failure modes significantly superior to existing single-energy, low-rotor configurations, providing the highest level of safety assurance for commercial operations in densely populated urban environments. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the overall structure of the tandem tiltwing vertical takeoff and landing aircraft according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the arrangement of the aircraft's internal seats, hydrogen fuel cells, lithium batteries, and liquid hydrogen storage tanks according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the aircraft described in the embodiments of the present invention in vertical take-off and landing, tilt transition, and level flight states; Figure 4 This is a schematic diagram of signal and energy transmission in the hybrid power system described in an embodiment of the present invention; Figure 5 This is a schematic diagram of the electrical architecture of the hybrid power system described in an embodiment of the present invention; Figure 6 This is a simulation comparison diagram of power distribution and battery state of charge between the embodiments of the present invention and a pure lithium battery; In the diagram, 10-fuselage, 20-forward wing, 21-forward wing stabilizer, 30-rear wing, 31-rear wing stabilizer, 32-rear winglet, 40-V-tail, 50-power unit, 60-variable collective pitch rotor, 101-seat, 102-lithium battery, 103-hydrogen fuel cell, 104-liquid hydrogen storage tank. Detailed Implementation

[0030] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0031] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] Example 1 This embodiment provides a tandem tiltwing vertical takeoff and landing aircraft, such as... Figure 1 As shown, the aircraft adopts a tandem biplane configuration, mainly comprising a fuselage 10, a front wing 20, a rear wing 30, and a V-tail 40. The front wing 20 is connected to the fuselage 10 via a front wing stabilizer 21, and the rear wing 30 is connected to the fuselage 10 via a rear wing stabilizer 31. Symmetrical winglets 32 are also provided at the ends of the rear wing 30 away from the fuselage. Multiple power units 50 are symmetrically arranged on the front wing 20 and rear wing 30 via pylons. As a preferred example, the number of power units 50 is 12, evenly and symmetrically distributed along the spanwise direction of the front wing 20 and rear wing 30. Each power unit 50 consists of a high-efficiency permanent magnet synchronous motor and a variable collective pitch rotor 60. All power units 50 are driven by an electric tilting mechanism connected to the wings, enabling continuous and controllable tilting from vertically upward (90 degrees) to horizontally forward (0 degrees). Crucially, the fore wing 20 and rear wing 30, along with their fixed power units 50, tilt as a single unit. The wing tilting can be electrically, hydraulically, or hybridly driven. This integrated wing-propeller tilting design ensures that the rotor slipstream consistently acts on the wing surface during complex transitional flight phases. Utilizing the slipstream washing effect (power-enhancing effect), it effectively suppresses airflow separation at high angles of attack, delaying stall and significantly improving the aircraft's handling stability and safety during transitional phases. Understandably, the number of power units can be adjusted according to the aircraft's tonnage and wing loading requirements, such as within the range of 8 to 16.

[0033] Reference Figure 2The aircraft has a compact internal structure. Within the fuselage 10, along its length, are arranged a seat 101 (for manned configuration) or cargo bay, a lithium battery 102, a hydrogen fuel cell 103, and a liquid hydrogen storage tank 104. The liquid hydrogen storage tank 104 is an integrated load-bearing component with the fuselage structure. The liquid hydrogen storage tank 104 can adopt spherical, multi-lobed, or other irregular shapes to adapt to different fuselage configurations. The liquid hydrogen storage tank 104 has a double-walled structure. Its inner liner is made of 5083 aluminum alloy resistant to temperatures as low as -253°C, used to directly contain liquid hydrogen. The outer shell is made of carbon fiber composite material, such as a reinforced grating structure made of T800 grade carbon fiber / epoxy resin composite material. This serves not only as the outer wall of the liquid hydrogen storage tank but also as the main load-bearing frame of the fuselage. The space between the inner and outer shells is evacuated to a high vacuum and filled with multiple layers of insulation material to achieve optimal insulation. This integrated design eliminates the need for a separate, bulky liquid hydrogen storage tank, contributing to the overall lightweight design and center of gravity stability of the aircraft.

[0034] Reference Figure 4 and Figure 5 The core of the aircraft in this invention lies in the hybrid power system integrated within the aircraft fuselage. This system includes a hydrogen fuel cell system as the primary energy source and a lithium battery system for peak power compensation. The hydrogen fuel cell system employs a proton exchange membrane fuel cell (PEMFC) stack, and its rated output power is precisely matched and optimized according to the power requirements of the aircraft during its most efficient cruise phase. For example, in this embodiment, it is matched to a steady-state power requirement of 40kW during the cruise phase. In this invention embodiment, the hydrogen fuel cell system also includes a centrifugal air compressor, a hydrogen supply and circulation module, and related auxiliary systems. This hydrogen fuel cell system serves as the core for providing basic load and continuous energy, providing a stable and uninterrupted power supply for long-duration cruise flight and the onboard avionics system. The lithium battery system uses a special lithium-ion battery pack with high discharge rate and high power density. Its total capacity and peak power are precisely designed according to the peak power requirements of extreme conditions such as vertical takeoff and landing, transitional flight, and emergency maneuvers. For example, in this embodiment, the total capacity of the lithium battery is 12kWh, and the peak discharge power can reach 360kW to match the transient peak power requirement of 90-100kW during the vertical takeoff and landing phase. The core function of this lithium battery system is to provide enormous instantaneous power on a millisecond timescale, perfectly compensating for the shortcomings of hydrogen fuel cell systems in dynamic response and ensuring absolute flight safety.

[0035] The entire hybrid power system employs a high-voltage direct current (HVDC) power distribution network architecture. The hydrogen fuel cell system and the lithium battery system are connected in parallel to a common HVDC bus with a rated voltage of 800V via their respective dedicated bidirectional DC / DC converters. Power from the DC bus is precisely distributed to the motor controllers / inverters of the twelve power units through a distributed network (i.e., a solid-state power controller network) consisting of multiple solid-state power controllers, thereby driving the motors. Figure 5 As shown, the front wing is equipped with motors 1, 2, 3, 4, 5, and 6, totaling six motors; the rear wing is equipped with motors 7, 8, 9, 10, 11, and 12, totaling six motors. Solid-state power controller networks are used for power distribution and fault isolation. Utilizing semiconductor devices (such as SiC MOSFETs) for switching, they offer significant advantages such as arc-free operation, fast response (microseconds), long lifespan, light weight, and software-programmable control, greatly improving the reliability, safety, and intelligence of electrical systems.

[0036] The aircraft in this embodiment of the invention also includes an energy management controller, which is connected to the tilt sensor signals of the hybrid power system and the tandem tiltwing configuration. The tilt sensor monitors the tilt angle of the forewing 20 and / or the aft wing 30 in real time and sends the angle information to the energy management controller. The energy management controller is configured to dynamically adjust the power output ratio between the hydrogen fuel cell system and the lithium battery system in response to changes in the tilt angle of the forewing and / or the aft wing.

[0037] Specifically, the energy management controller executes a power allocation strategy tied to the flight phase, which has been validated in simulation optimization. For example... Figure 3 The diagram illustrates a tiltrotor aircraft in vertical takeoff and landing, tilt transition, and level flight (cruise) states. The tilt angles of the front and rear wings can be differentially adjusted to reduce control surface deflection and lower trim drag. (Refer to...) Figure 3 Based on Table 1 below, this strategy can be described as follows: Table 1 Power allocation strategies under typical mission profiles

[0038] During vertical takeoff and landing, the tilt angles of the canard and aft wings are 90°. The lithium-ion battery system handles 60% to 70% of the total power demand, while the hydrogen fuel cell system handles 30% to 40%. At this stage, the lithium-ion battery leverages its high power density to provide the large power required for takeoff and landing, while the hydrogen fuel cell operates at its base power to avoid startup shock.

[0039] During the tilt transition phase, the tilt angles of the forewing and aftwing continuously change from 90° to 0° (takeoff transition). The power share of the hydrogen fuel cell system increases linearly from 30% to 90%, while the power share of the lithium battery system decreases linearly from 70% to 10%. This smooth transition ensures the continuity of power output and avoids flight attitude disturbances caused by sudden power changes.

[0040] During the deceleration transition phase, the tilt angles of the front and rear wings continuously change from 0° to 90° (landing transition). The power share of the hydrogen fuel cell system decreases linearly from 90% to 40%, while the power share of the lithium battery system increases linearly from 10% to 60%. At this time, the lithium battery system performs dynamic power compensation.

[0041] During high-efficiency cruise or ground standby, with the front and rear wings tilted at 0°, the hydrogen fuel cell system handles 100% of the total power demand, while the lithium battery system is in standby or charging mode. At this time, the hydrogen fuel cell, with its high energy density, provides the aircraft with sustained range, while the lithium battery rests or is recharged to maintain its health.

[0042] The above power allocation strategy ensures that the two energy sources complement each other at different stages of flight, meeting peak power requirements while protecting battery life.

[0043] Example 2 This invention also provides a hybrid power control method for the aforementioned aircraft, which can be automatically executed by an energy management controller. (See reference...) Figure 4 The method for controlling the signal flow includes the following steps: First, obtain the aircraft's current flight phase information and current wing tilt angle information; Then, based on the current flight phase information and the current wing tilt angle information, the target power distribution ratio is determined; Finally, based on the target power allocation ratio, the hydrogen fuel cell system is controlled to output the first power, and the lithium battery system is controlled to output the second power.

[0044] Specifically, when the wing tilt angle is greater than the first angle threshold (e.g., close to 90°), the second power is greater than the first power; when the wing tilt angle is less than the second angle threshold (e.g., close to 0°), the first power is greater than the second power, and the lithium battery system enters standby or charging mode.

[0045] Furthermore, the flight phase information includes the vertical takeoff phase, tilt transition phase, cruise phase, deceleration transition phase, and vertical landing phase. During the vertical takeoff and vertical landing phases, the lithium battery system is controlled to discharge at a rate of 5C to 8C to meet instantaneous high power demands. During the cruise phase, the hydrogen fuel cell system is controlled to supplement the lithium battery system, maintaining the lithium battery system's state of charge in the range of 70% to 85%. This shallow charge and discharge operating mode can significantly extend the cycle life of the lithium battery.

[0046] Furthermore, the method includes real-time monitoring of the aircraft's power requirements. Upon detecting a sudden gust of wind or an emergency go-around command, the lithium-ion battery system is controlled to output peak power within 100 milliseconds to compensate for the power response delay of the hydrogen fuel cell system. This ensures the aircraft's safety under extreme operating conditions.

[0047] Simulation verification: To verify the technical effectiveness of the solution described in the embodiments of the present invention, a high-fidelity system-level simulation model was constructed. Under the same aerodynamic layout, mission profile, and payload conditions, a comparative simulation was conducted between the pure lithium battery power scheme and the hybrid power scheme described in the embodiments of the present invention. In the simulation, the maximum takeoff weight of the aircraft was not less than 1000 kg, and the cruise speed was not less than 300 km / h. The mission profile included: vertical takeoff (power approximately 90 kW) → tilt transition (dynamic power change) → cruise (40 kW) → deceleration transition → vertical landing.

[0048] Simulation results are as follows Figure 6 As shown. From the simulation results, we can obtain: 1. The pure lithium battery solution is powered by the battery throughout the entire process. The battery discharges at 6C during takeoff and continuously discharges at 1C during cruise. The solution described in this embodiment of the invention uses a fuel cell to bear the entire 40kW steady-state load during cruise. The lithium battery only intervenes during takeoff, landing, and transition. The rate of change of fuel cell output power is actively limited to within 5kW / s, avoiding sudden voltage drop in the stack and damage to the membrane electrode.

[0049] 2. In the pure lithium battery solution, the battery state of charge (SOC) returns to zero (100% depth of discharge) at the end of the mission. In the embodiment of this invention, the lithium battery SOC drops from 85% to 65% during takeoff, is slowly charged by the fuel cell at 5kW during cruise, and recovers to 80%. After discharge during landing, the SOC ends at 22%. This 22% remaining charge constitutes a critical safety redundancy, sufficient to support a complete go-around procedure.

[0050] 3. Under the same takeoff weight of 1200kg and energy mass constraints, the pure lithium battery solution has a maximum cruise time of 75 minutes and a range of 188 kilometers; the solution described in this embodiment has a maximum cruise time of 120 minutes and a range of 300 kilometers, representing a range increase of over 60%. If the 169kg reduction in power system mass is used entirely to increase payload, additional passengers or cargo can be carried, such as two passengers or 150kg of cargo.

[0051] 4. The simulation scenario involved a 15m / s vertical gust during the approach phase, causing the aircraft's instantaneous power demand to jump from 55kW to 92kW. The system described in this embodiment of the invention completed a power compensation response within 40 milliseconds, exceeding the peak demand by 8kW, and the aircraft's attitude quickly returned to stability. In contrast, the pure lithium battery solution, due to its low SOC, increased internal resistance, and severe voltage drop, experienced limited power output, resulting in an 8-meter drop in altitude and triggering an alarm.

[0052] The simulation data above fully demonstrates the significant advantages of the hybrid power system described in this invention in terms of range, safety, and battery life.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the embodiments of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A tandem tilt-wing vertical takeoff and landing aircraft, characterized in that, include: A tandem tiltwing configuration includes a front wing and a rear wing. Multiple power units are distributed on both the front wing and the rear wing. Each power unit includes a rotor and a motor that drives the rotor. The front wing and the rear wing, together with the power units fixed thereon, tilt as a whole. A hybrid power system, integrated within the aircraft fuselage, includes a hydrogen fuel cell system as the primary energy source and a lithium battery system as peak power compensation. The rated power of the hydrogen fuel cell system matches the steady-state power requirement of the aircraft during the cruise phase, and the peak discharge power of the lithium battery system matches the transient peak power requirement of the aircraft during the vertical takeoff and landing phase. An energy management controller is connected to the tilt angle sensor signals of the hybrid power system and the tandem tilt wing configuration, and is configured to dynamically adjust the power output ratio of the hydrogen fuel cell system and the lithium battery system in response to changes in the tilt angle of the forewing and / or the aft wing.

2. The tandem tiltwing vertical takeoff and landing aircraft according to claim 1, characterized in that, The number of power units is 12, which are evenly and symmetrically distributed along the span of the front wing and the rear wing; the rotor is a variable collective pitch rotor.

3. The tandem tiltwing vertical takeoff and landing aircraft according to claim 1, characterized in that, The energy management controller is configured to execute the following power allocation strategy tied to the flight phase: During vertical takeoff and vertical landing, the tilt angle of the fore wing and the rear wing is 90°, the lithium battery system undertakes 60%-70% of the total power demand, and the hydrogen fuel cell system undertakes 30%-40% of the total power demand. During the tilt transition phase, the tilt angles of the forewing and the aftwing continuously change from 90° to 0°, the power proportion of the hydrogen fuel cell system linearly increases from 30% to 90%, and the power proportion of the lithium battery system linearly decreases from 70% to 10%. During the deceleration transition phase, the tilt angles of the front wing and the rear wing continuously change from 0° to 90°, the power ratio of the hydrogen fuel cell system decreases linearly from 90% to 40%, and the power ratio of the lithium battery system increases linearly from 10% to 60%. During the cruise phase, the tilt angle of the front wing and the rear wing is 0°, the hydrogen fuel cell system undertakes 100% of the total power demand, and the lithium battery system is in standby or charging state.

4. The tandem tiltwing vertical takeoff and landing aircraft according to claim 1, characterized in that, It also includes a high-voltage DC power distribution network, wherein the hydrogen fuel cell system and the lithium battery system are connected in parallel to a common DC bus via a bidirectional DC / DC converter; the power distribution network includes a solid-state power controller network for performing power distribution and fault isolation.

5. The tandem tiltwing vertical takeoff and landing aircraft according to claim 1, characterized in that, It also includes a liquid hydrogen storage tank, which is a load-bearing component integrated with the fuselage structure. The inner liner of the liquid hydrogen storage tank is made of aluminum alloy that can withstand -253°C, and the outer shell is made of carbon fiber composite material. There is a vacuum insulation layer between the inner and outer shells.

6. The tandem tiltwing vertical takeoff and landing aircraft according to claim 1, characterized in that, The maximum takeoff weight of the aircraft is no less than 1,000 kilograms.

7. The tandem tiltwing vertical takeoff and landing aircraft according to claim 1, characterized in that, The aircraft's cruising speed is no less than 300 km / h.

8. A hybrid power control method for a tandem tiltwing vertical takeoff and landing aircraft according to any one of claims 1 to 7, characterized in that, Includes the following steps: Obtain the current flight phase information and current wing tilt angle information of the aircraft; Based on the current flight phase information and the current wing tilt angle information, determine the target power distribution ratio; Based on the target power distribution ratio, control the hydrogen fuel cell system to output a first power and control the lithium battery system to output a second power. Specifically, when the wing tilt angle is greater than the first angle threshold, the second power is greater than the first power; when the wing tilt angle is less than the second angle threshold, the first power is greater than the second power, and the lithium battery system enters standby or charging mode.

9. The control method according to claim 8, characterized in that, The flight phase information includes the vertical takeoff phase, tilt transition phase, cruise phase, deceleration transition phase, and vertical landing phase; the control method further includes: During the vertical takeoff and vertical landing phases, the lithium battery system is controlled to discharge at a discharge rate of 5C to 8C. During the cruise phase, the hydrogen fuel cell system is controlled to recharge the lithium battery system, maintaining the state of charge of the lithium battery system within a healthy range of 70% to 85%.

10. The control method according to claim 8, characterized in that, Also includes: Real-time monitoring of the aircraft's real-time power requirements; When a sudden gust of wind or an emergency go-around command is detected, the lithium battery system is controlled to output peak power within 100 milliseconds to compensate for the power response delay of the hydrogen fuel cell system.

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