阅读说明：本技术 具有可配置燃料电池电力系统的uav (UAV with configurable fuel cell power system ) 是由 A·P·凯利 M·C·斯克拉斯 R·E·维尔德 G·M·罗森 I·M·弗雷泽 于 2020-04-23 设计创作，主要内容包括：本公开涉及一种无人驾驶飞行器系统。一些示例性实施方式可包括：至少一个有效载荷(30)附连到其上的安装框架(110)；可在预定配置中操作的多个燃料电池堆(50),该多个堆(50)中的每个都在单独封装中；被配置为向多个堆供应氢气的一个或多个储罐(60)；被配置为接收从多个堆(50)生成的输出功率的推进系统(70,80)；以及被配置为以预定配置耦合多个堆的电力控制器(40)。(The present disclosure relates to an unmanned aerial vehicle system. Some exemplary embodiments may include: a mounting frame (110) to which at least one payload (30) is attached; a plurality of fuel cell stacks (50) operable in a predetermined configuration, each of the plurality of stacks (50) being in a separate package; one or more tanks (60) configured to supply hydrogen to the plurality of stacks; a propulsion system (70, 80) configured to receive output power generated from a plurality of stacks (50); and a power controller (40) configured to couple the plurality of stacks in a predetermined configuration.)

1. An unmanned aerial vehicle comprising:

a mounting frame to which at least the payload is attached;

a plurality of fuel cell stacks operable in a predetermined configuration, each of the plurality of stacks being in a separate package;

one or more storage tanks configured to supply hydrogen to the plurality of stacks;

a propulsion system configured to receive output power generated from the plurality of stacks; and

a power controller configured to couple the plurality of stacks in the predetermined configuration.

2. The unmanned aerial vehicle of claim 1, wherein each of the stacks is configured to generate the same amount of power and have the same level of efficiency.

3. The unmanned aerial vehicle of claim 2, wherein the plurality of stacks are distributed around the frame such that a center of mass of the vehicle is balanced and a manner in which the vehicle flies is affected.

4. The unmanned aerial vehicle of claim 1, wherein the predetermined configuration comprises the plurality of stacks arranged in series.

5. The unmanned aerial vehicle of claim 4, wherein the plurality of stacks is two stacks, and wherein the series arrangement doubles the power output to the propulsion system.

6. The unmanned aerial vehicle of claim 5, wherein the power doubling is based on the output voltage of the two stacks being doubled to a value between 44.4 volts and 50.0 volts, and on the current through each of the two stacks being the same as if the each stack were operating independently.

7. The unmanned aerial vehicle of claim 1, wherein the predetermined configuration comprises the plurality of stacks arranged in parallel.

8. The unmanned aerial vehicle of claim 7, wherein the plurality of stacks is two stacks, and wherein the parallel arrangement doubles the power output to the propulsion system.

9. The unmanned aerial vehicle of claim 8, wherein the power doubling is based on the output voltage of each of the two stacks being the same as if each stack were operating independently, and on output current doubling from the two stacks.

10. The unmanned aerial vehicle of claim 9, wherein the power controller is further configured to balance the current from each of the two stacks.

11. The unmanned aerial vehicle of claim 1, wherein the propulsion system comprises one or more motors and one or more rotors.

12. The unmanned aerial vehicle of claim 11, wherein the power controller is further configured to detect a fault in one of the plurality of stacks and to continue operation of the other stacks such that the propulsion system can safely land the vehicle.

13. The unmanned aerial vehicle of claim 3, wherein the plurality of stacks, the one or more storage tanks, and the power controller are attached to the frame.

14. The unmanned aerial vehicle of claim 13, wherein the power controller is further configured to adjust the center of mass of the aircraft by adjusting a position or orientation of at least one of the plurality of stacks, at least one of the one or more storage tanks, or the payload via the frame.

15. The unmanned aerial vehicle of claim 1, further comprising:

a communication signal configured to interconnect the plurality of stacks, the one or more storage tanks, and the power controller,

wherein the communication signals are isolated with respect to each of the plurality of stacks such that a common ground exists.

16. The unmanned aerial vehicle of claim 12, wherein the power controller is further configured to remotely control via a device on the ground or locally control via a direct connection onboard the vehicle to breach a safety threshold associated with power cell overheating such that the payload has a non-negligible probability of non-destructive landing due to a safe setting of the payload in preference to survival of the stacks and/or motors of the vehicle.

17. The unmanned aerial vehicle of claim 16, further comprising:

a spare storage battery is arranged on the base station,

wherein the probability is increased via use of the backup battery in response to detecting the fault.

18. The unmanned aerial vehicle of claim 14, wherein the adjustment of the orientation comprises at least one of a rotation, a tip-over, and a tilt of the at least one stack, the at least one tank, or the payload.

19. An unmanned aerial vehicle comprising:

a mounting frame configured to mount a payload;

a plurality of fuel cell stacks operable in a predetermined configuration, each of the plurality of stacks being in a separate package;

the mounting frame configured to reposition each stack to one of at least two positions;

one or more fuel tanks configured to supply hydrogen to the plurality of stacks;

a propulsion system configured to receive output power generated from the plurality of stacks;

a power controller configured to couple the plurality of stacks in the predetermined configuration; and

wherein the position of the fuel cell stack is adjusted to balance the aircraft relative to the payload.

20. The unmanned aerial vehicle of claim 19, further comprising:

the mounting frame is configured to reposition each fuel tank to one of at least two positions,

wherein the positions of at least one fuel cell stack and fuel storage tank are adjusted to balance the aircraft relative to the payload.

Technical Field

The present disclosure relates generally to configurable systems for assembling Fuel Cell Power Modules (FCPM) for Unmanned Aerial Vehicles (UAVs). Further disclosed is a method to obtain center of gravity (CoG) flexibility and control when integrating a fuel cell stack onto a UAV.

Background

UAVs, also known as drones, are gaining popularity in applications such as photography, surveillance, farm maintenance (e.g., pest control), atmospheric research, fire control, wildlife monitoring, package delivery, and military purposes. UAVs generally fall into two categories, multi-rotor UAVs for commercial applications generally and fixed-wing UAVs for military applications. UAVs are equipped with navigation systems. The payload in the UAV varies depending on the end application and may include cameras, surveillance equipment, remote sensing devices, pesticides contained in suitable containers capable of spraying, fire retardants, packages for shipping, and the like. UAVs are typically smaller than manned aircraft and may weigh between a few grams and tens of kilograms, for example.

UAVs require power to provide propulsion and to power auxiliary functions (e.g., operating payload such as image or video capture, signal telemetry, etc.) or other onboard systems. For many applications, the computing power required on board an aircraft to provide the necessary functionality may represent a significant power requirement. This is particularly true in autonomous UAVs, where the onboard control system may make decisions regarding the flight path and deployment of auxiliary functions. Although the aircraft itself is unmanned, the UAV may be remotely piloted and may still be under some form of human control.

Some UAVs use primary batteries to provide power, although it is now more common to use secondary (rechargeable) batteries, such as lithium ion batteries. When power is supplied only by the battery, the flight time of the UAV may be limited because of the power requirements of the propulsion and other onboard systems. In recent years, photovoltaic panels have been used to extend the flight path of UAVs. However, the power generation capacity of a photovoltaic panel depends on the ambient weather conditions and the time of day, and therefore, a photovoltaic panel may not be suitable for use in all situations. Furthermore, the power generation capability of photovoltaic panels may not be suitable for applications where either high power (speed) propulsion is required, or the onboard systems of UAVs providing their functionality are particularly heavy or require a large amount of electrical power. The flight time and range of a UAV are generally a function of the payload (weight) and the energy available from the power source (watt-hours). Other power sources include jet engines fueled by fuels such as gasoline and jet fuel for fixed wing military applications, and fuel cells fueled by hydrogen and other fuels such as propane, gasoline, diesel, and jet fuel. UAVs are typically returned to the origin, that is to say to a parent station or base, after flight to charge or refill the power source.

Fuel cells are an attractive power source for UAVs, can exceed the power supplied by batteries, and can extend flight time (or range) in many cases. Fuel cells are electrochemical energy conversion devices that convert an external source of fuel into an electrical current. Many fuel cells use hydrogen as a fuel and oxygen (typically from air) as an oxidant. The by-product of such a fuel cell is water, making the fuel cell a power generation device with very little impact on the environment. For more and more applications, fuel cells are more efficient than traditional means of generating electricity (such as burning fossil fuels) and portable power storage (such as lithium ion batteries).

Even with the advantages of using a fuel cell, in some cases the power level supplied by one FCPM may not be sufficient to meet a particular application. However, as the demand for power output from the FCPM increases, the size of the stack becomes unwieldy. For example, it is very difficult in practice to package a single bulk fuel cell stack such that it can be mounted on a UAV. Another problem with known UAV power methods is that when the power supply fails in flight, the mission and/or payload will be at great risk of damage from the fall. The positioning and orientation of the different components mounted to the UAV frame may also cause CoG and/or weight balance issues.

Disclosure of Invention

The present disclosure illustrates various aspects of Unmanned Aerial Vehicles (UAVs), including but not limited to those set forth in the appended claims.

Various aspects of methods, systems, and apparatus for mounting frames, including but not limited to payloads,

a plurality of fuel cell stacks operable in a predetermined configuration, each of the plurality of fuel cell stacks in a separate package;

one or more tanks configured to supply hydrogen to the plurality of stacks;

a propulsion system configured to receive output power generated from the plurality of stacks;

a power controller configured to couple the plurality of stacks in a predetermined configuration; and the number of the first and second groups,

wherein the predetermined configuration includes a plurality of stacks arranged in one of parallel and series.

Various aspects of methods, systems, and apparatus for mounting frames, including but not limited to unmanned aerial vehicles having

A mounting frame configured to mount a payload;

a plurality of fuel cell stacks operable in a predetermined configuration, each of the plurality of fuel cell stacks in a separate package;

a mounting frame configured to reposition each stack to one of at least two positions;

one or more fuel tanks configured to supply hydrogen to the plurality of stacks;

a propulsion system configured to receive output power generated from the plurality of stacks;

a power controller configured to couple the plurality of stacks in a predetermined configuration, wherein the predetermined configuration includes the plurality of stacks arranged in one of parallel and series; and wherein the position of the fuel cell stack is adjusted to balance the aircraft relative to the payload.

Various aspects of methods, systems, and apparatus for a modular power supply for powering components of a UAV to which signal and power lines may be connected are disclosed herein. Two or more Fuel Cell Power Modules (FCPMs) may be connected in series or parallel, doubling the power output and allowing an end user to have a single communication port.

The power controller may be configured to communicate with the fuel cell stack and other component(s) of the UAV. The controller may be configured to control at least one of the hydrogen gas supply, the inert gas supply, the electrical load, and the auxiliary power supply.

In some cases, the power supply is a hybrid version, where a combination of power supplies may be used. For example, when using a fuel cell, any peak power demand (such as during takeoff) can be supplemented using a battery. Fuel cells are an attractive power source for UAVs, can exceed the power supplied by batteries, and can extend flight time (or range) in many cases. Fuel cells are electrochemical energy conversion devices that convert an external source of fuel into an electrical current. Many fuel cells use hydrogen as a fuel and oxygen (typically from air) as an oxidant. The by-product of such a fuel cell is water, making the fuel cell a power generation device with very little impact on the environment. For more and more applications, fuel cells are more efficient than traditional means of generating electricity (such as burning fossil fuels) and portable power storage (such as lithium ion batteries).

Even with the advantages of using a fuel cell, in some cases the power level supplied by one FCPM may not be sufficient to meet a particular application. However, as the demand for power output from the FCPM increases, the size of the stack becomes unwieldy. For example, it is very difficult in practice to package a single bulk fuel cell stack such that it can be mounted on a UAV. Another problem with known UAV power methods is that when the power supply fails in flight, the mission and/or payload will be at great risk of damage from the fall. The positioning and orientation of the different components mounted to the UAV frame may also cause CoG and/or weight balance issues.

Additional features and advantages of the disclosure will be set forth in part in the description which follows and in part will be apparent to those having ordinary skill in the art upon examination of the following detailed description taken in conjunction with the accompanying drawings or may be learned from practice of the disclosure. The advantages of the disclosure may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

Drawings

The foregoing aspects and many of the attendant advantages of this disclosure will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

fig. 1 schematically illustrates a UAV configured to operate via a plurality of modular fuel cell stacks in accordance with one or more embodiments.

Fig. 2 shows a representation of a UAV powered by two Fuel Cell Power Modules (FCPMs) in accordance with one or more embodiments.

Fig. 3 illustrates another representation of a UAV powered by two FCPMs in accordance with one or more embodiments.

Fig. 4 illustrates another representation of a UAV powered by two FCPMs in accordance with one or more embodiments.

Fig. 5A-5B illustrate series and parallel configurations, respectively, of two FCPMs in accordance with one or more embodiments.

The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the disclosure. All reference numerals, codes and call letters in the drawings and appendix are incorporated herein by reference as if fully set forth herein. The failure to number an element in the figure does not imply a disclaimer of any rights. Unnumbered references may also be identified in the drawings by alphabetic characters.

Detailed Description

The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which some disclosed aspects may be practiced. These embodiments, also referred to herein as "examples" or "options," are described in sufficient detail to enable those skilled in the art to practice the disclosed methods and apparatus. The embodiments may be combined, other embodiments may be utilized, or structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims and their legal equivalents.

Certain aspects of the present disclosure are described below for the purpose of illustrating the use of multiple fuel cells to power a UAV. These fuel cells may be arranged in series or parallel configurations depending on the particular use case. Various modifications may be made, and the scope of the disclosure is not limited to the exemplary aspects described.

A schematic diagram of an exemplary UAV100 is shown in fig. 1. UAV100 may include several components, such as fuel cell power source 90, which in turn includes a plurality of fuel cell stack modules 50 (connected in series or parallel). The plurality of fuel cell stack modules 50 may each include a fuel cell stack 54 and one or more fans 52.

A plurality of fuel cell stack modules 50 may be coupled to one or more fuel cell power controllers 40. Power controller 40 may interface communication signals and power with each of modules 50. The power controller 40 may further be in communication with one or more storage tanks 60 (e.g., to control a pump, line pressure, or otherwise adjust the flow of compressed hydrogen from the storage tanks). UAV100 may include other components such as one or more motors 70, one or more motor rotors 80, one or more motor controllers 20, and payload 30. The power controller 40 may feed power from the module 50 to the motor 70 directly or indirectly via the motor controller 20.

UAV100 in fig. 2-4 may be a helicopter and include one or more propulsion systems coupled to frame 110 by one or more struts 130, which may also be referred to as arms or limbs of the UAV. Each propulsion system may include a motor 70 configured to drive a respective rotor 80. The number of propulsion systems in UAV100 may vary depending on the aerodynamic design, payload, and desired flight time.

The fuel cell power supply 90 may be removably coupled to the frame 110 and electrically coupled to the fuel cell power supply controller 40 via a suitable electrical adapter or plug 92. The struts may provide mechanical support, but may also provide conduits to carry signals (e.g., cables) that provide electrical and control communication between the module 50, the power controller 40, the motor controller 20, and each of the propulsion systems. Rotor 80 provides thrust and lift to UAV 100. Exemplary UAV100 may also include a plurality of leg members 140 to support the UAV during landing and to protect payload 30 during landing.

The hydrogen feed to the fuel cell power supply 90 may be supplied by a hydrogen supply 60 (e.g., a tank or cylinder) that is removably mounted on a saddle that may be mechanically coupled to the frame 110. The hydrogen gas supply 60 may also be removably mounted to the frame 110 using brackets, straps, or the like. The hydrogen supply 60 may include a hydrogen connection assembly that can mate with the first end of the hydrogen supply conduit using a quick connect/disconnect fitting, magnetic coupling, or the like. The hydrogen connection assembly may include at least one of a pressure regulator, solenoid valve, shut-off valve, and pressure relief valve to ensure that hydrogen is delivered to the power supply 90 at a desired flow rate and pressure. The hydrogen supply 60 may be configured to store compressed hydrogen at a pressure below 700 bar.

In some exemplary embodiments, for UAV100, a selection is made between series and parallel configurations based on the efficiency of fuel cell stack module 50. In some exemplary embodiments, the efficiency is based on the power output of module 50. In some exemplary embodiments, providing 25 volts (V) to the propulsion system (referred to as 6s) operates the motor 70 more efficiently than providing 50 volts (referred to as 12s) to the propulsion system.

The components including the hydrogen connecting assembly may be electrically actuated by a signal from the motor controller 20 or from the power controller 40. A second end of the hydrogen supply conduit opposite the first end is capable of mating with the fuel cell connection assembly 91. The fuel cell connection assembly 91 may include at least one of a pressure regulator, solenoid valve, shut-off valve, and pressure relief valve to ensure that hydrogen gas is delivered to the fuel cell power source 90 at a desired flow rate and pressure. The components included in the fuel cell connection assembly 91 may be electrically actuated by signals from the controller 20 or the power supply controller 40.

In some embodiments, payload 30 may include one or more cameras and may be removably coupled to fuel cell power supply 90 or frame 110 (fig. 2-4). The payload 30 is capable of communicating with at least one of the controller 20, the controller 40, and the fuel cell power source 90.

The controller 20 may be configured to control at least one of the propulsion system, the operation of the payload 30, and an auxiliary power source, such as a rechargeable battery, which may be configured to store excess power generated by the fuel cell power source 90. The controller 40 may be configured to control at least one of the propulsion system, the operation of the fuel cell power supply 90, the operation of the hydrogen gas supply 60, the operation of the payload 30, and an auxiliary power source, such as a rechargeable battery.

In some exemplary embodiments, an auxiliary power source, such as a backup battery 35, may be removably coupled to the frame 110. In some embodiments, backup battery 35 is sized to provide a predetermined amount of peak power (e.g., over a known period of time, such as recovery from a strong wind). In some exemplary embodiments, backup battery 35 is a lithium polymer battery.

The auxiliary power source may also be used to power at least one of payload 30 and other component(s) of UAV100 during transient power periods, such as at takeoff, or when the power generated by fuel cell power source 90 is below expectations. The auxiliary power source may also include a super capacitor and a primary battery. Exemplary systems and methods for operating a device that powers a load (such as UAV 100) using a fuel cell power source and an auxiliary power source are disclosed in commonly owned U.S. patent No. 9,356,470 and U.S. patent publication No. 209040285, both of which are incorporated herein by reference in their entirety.

The fuel cell power source 90 may be provided in relation to the fuel cell power source controller 40, in which case the controller 20 may be able to communicate with the fuel cell power source controller 40 in a bi-directional manner. Alternatively, the fuel cell power controller 40 may be used to control components in the fuel cell connection assembly 91 and the hydrogen connection assembly instead of the controller 20. UAV100 may return to the origin after flight, that is, to a parent station or base (not shown) after flight to charge or refill the power source.

In some exemplary embodiments, two or more fuel cell stack modules 50 are linked in series or parallel via a configuration facilitated by power controller 40. By having the modules 50 powered in series, the power output (e.g., to the propulsion system) can be doubled while doubling the power supply voltage, for example, from 25V or approximately 25V to between 44.4V and 50V from modules 50-1 and 50-2 (although this example is not intended to be limiting as any suitable voltage byproduct of a series configuration of any suitable number of modules 50 may be used). In these or other embodiments, the doubling may occur while keeping the current through each of the two or more modules 50 (e.g., modules 50-1, 50-2) the same as if each module were operating independently.

In UAV embodiments in which two or more modules 50 are arranged in parallel, power doubling may be based on the output voltage of each of the two or more modules 50 being the same, as if each stack were operating independently, and on output current doubling from the two or more modules 50. In UAV embodiments in which modules 50 are connected in parallel, a greater total output current may be achieved than provided by one single module 50. The parallel configuration of modules 50 within UAV100 may also benefit by providing redundancy, enhancing reliability, avoiding PCB thermal issues, and increasing system efficiency. In some exemplary embodiments, power controller 40 may be configured to balance the current from each of modules 50. That is, some example embodiments of the modules 50 in a parallel configuration may be performed such that the load current is shared, e.g., to prevent one of the modules 50 from turning off before the desired current is delivered. Some example embodiments may use a control loop to actively balance the output current from the modules 50 to compensate between the modules 50. To achieve this, some embodiments may monitor both voltage and temperature via a control loop.

In some exemplary embodiments, the power controller 40 of the UAV100 may be configured to detect a failure or malfunction of one of the modules 50 and to continue operation of one or more other modules 50 such that the propulsion system (i.e., the motor(s) 70 and the rotor(s) 80) can safely land the UAV100 (e.g., without damaging the payload 30 and/or any other components of the UAV 100). In some exemplary embodiments, the power controller 40 of the UAV100 may be further remotely configured or controlled via ground means to breach a safety threshold related to fuel cell overheating, such that upon detection of a fault, the payload 30 has a greater probability of non-destructive landing due to the safety setting of the payload 30 being prioritized over the survival of any other components (e.g., the motor 70, the module 50, etc.) on the UAV 100. In some exemplary embodiments, using the backup battery 35 to at least temporarily power the propulsion system(s) may increase the probability of a safe landing in response to detecting a fault.

The fuel cell power source 90 may include a plurality of fuel cell stack modules 50 (e.g., 50-1 and 50-2, as shown in fig. 2). In some exemplary embodiments, each of the fuel cell stack modules 50 may be independently packaged and separately positioned around UAV 100. In other embodiments, the fuel cell stack modules 50 may be packaged together within the fuel cell power supply 90. As shown in fig. 2, fuel cell power source 90 (which includes module 50) may be located above hydrogen supply 60, with reference to a fixed location of UAV100 on the ground. Alternatively, the fuel cell power supply 90 may be located below the hydrogen gas supply 60 (fig. 3). Alternatively, the fuel cell power supply 90 and the hydrogen gas supply 60 may be mounted adjacent to each other (fig. 4).

Each of the fuel cell stack modules 50 may output a maximum continuous power of about 650 watts (W) or about 800 watts, depending on the total power requirements of the UAV100, although any maximum continuous power output value is contemplated by the present disclosure. In some exemplary embodiments, the maximum peak power output from each of the modules 50 may be temporarily (e.g., about 30 seconds or less) about 1000W or about 1400W. In some exemplary embodiments, the power modules 50 may be identical to one another. For example, module 50-1 may be the same as each of modules 50-2, if used. In this or another example, each of the modules 50 may be configured to generate the same amount of power and have the same level of efficiency. In some exemplary embodiments, module 50-1 may produce a different maximum continuous power output than any other module 50 (e.g., module 50-2). For example, a 650W module may be configured in series with an 800W module. In another example, a 650W module may be configured in parallel with an 800W module.

In some exemplary embodiments, a double-headed arrow representing two-way communication may depict a signal. These signals may convey communication data, such as commands and controls (e.g., status) to/from controller 40 for each of fuel cell stack 54, hydrogen supply 60 (e.g., current fill level, pressure level in the piping, etc.), motor 70, motor controller 20, fan 52, and/or payload 30.

In some exemplary embodiments, the fuel cell stack modules 50 may be connected only in series. For reasons related to being in a series configuration, the communication signals of each of the modules 50 may be isolated from the power controller 40. In a parallel configuration, some or more of the same signals will not need to be isolated; instead, these signals may be multiplexed up to the controller 40.

In some exemplary embodiments, when fuel cell stack modules 50 are linked in series, UAV100 may be prevented from spurious grounding in the middle rail (mid-rail). That is, some embodiments may have connected the positive terminal of the fuel cell stack module 50-2 to the negative terminal of the fuel cell stack module 50-1, and in this configuration, the ground of the module 50-1 becomes the power source for the module 50-2. Thus, presently disclosed is a method of electrically isolating communication signals via optical coupling techniques in combination with an analog-to-digital converter (ADC). Further disclosed are methods for decoupling signals using isolation transformers (which are relatively heavy), simple opto-isolators, hall effect sensors, or series-connected capacitors. Some embodiments may create a common ground/earth ground within the isolation barrier. In some exemplary embodiments, the communication signals are isolated with respect to each of the modules 50. The disclosed embodiments thus overcome the problem of connecting modules 50 and/or controllers 40, whereby direct connections would otherwise appear to be spurious grounds in the middle rail.

The total power output required from the power supply 90 may depend on the quality and/or function of the payload 30. In some embodiments, each of the fuel cell stack modules 50 may be an open cathode Proton Exchange Membrane Fuel Cell (PEMFC) stack module. Multiple hydrogen supplies 60 may be employed depending on the required time of flight and the mass budget available to the fuel supply for a given mass of payload 30. Payload 30 may be coupled to frame 110. In fig. 4, UAV100 includes a single fuel cell power source 90, which may include a plurality of individually packaged fuel cell stacks 54 (connected in series or parallel) and a plurality of fans 52.

In some exemplary embodiments, one or more components of UAV100 (e.g., fuel cell stack module 50, hydrogen supply 60, payload 30, power controller 40, motor controller 20, and battery 35) may be attached to frame 110. In some exemplary embodiments, the manual pre-flight mechanical arrangement, power controller 40, or another controller may be configured to adjust the center of gravity (CoG) of UAV100 by adjusting the position or orientation of one or more components via frame 110.

Although used to illustrate some different possible mounting configurations, the depictions of fig. 2-4 are not intended to be limiting, as any configuration or orientation of the various components of UAV100 is contemplated. And controllers 20 and 40 may be mounted at any suitable location on frame 110 to obtain an optimal CoG for the flight characteristics of UAV 100. For example, the components may be mounted in a distributed manner around the frame 110, or at least some of the components may be merged together. In some exemplary embodiments, UAV100 may have modules 50 distributed around frame 110 such that the center of mass of the aircraft is balanced and the manner of flight of the aircraft is controllably influenced. In some exemplary embodiments, the mounting placement and orientation of the components of UAV100 may flexibly control the weight balance of the UAV as a whole. The mounting placement and orientation of these components may also be aerodynamically designed to minimize drag. With respect to orientation, the present disclosure refers to rotating, flipping, or tilting one or more of the components of UAV 100. In embodiments where multiple hydrogen supplies 60 are used, the supplies 60 may be repositioned to balance weight distribution (i.e., including CoG considerations relative to other components of the UAV 100). In these or other embodiments, the framework 110 may allow both manual and automatic reconfiguration. That is, the power controller 40 or another component of the UAV100 may control the positioning and orientation of the supply 60, the power controller 40, the motor controller 20, the payload 30, and each fuel cell stack module 50.

The power output as a function of the accumulated service time from the fuel cell stack module 50 depends on various factors such as ambient temperature, humidity, and the number of starts/stops. To ensure reliable operation of the fuel cell power supply 90, it is desirable to check the condition (health) of the fuel cell stack module 50, for example, using a ground station to adjust the stack 54 or to replace one or more of the fuel cell stack modules 50 when the UAV100 returns to an mother base. In particular, for long duration flights, it may be desirable to adjust the stack 54 prior to takeoff. In the present disclosure, the adjustment of the stack 54 may include adjustment of one or more fuel cells comprising the stack.

Fig. 5A-5B illustrate series and parallel configurations of two fuel cell power modules, respectively. These exemplary embodiments are not intended to be limiting in number as three or more power modules may be connected in a series or parallel configuration. In fig. 5A, a fuel cell stack module 50-1 is connected in series with a fuel cell stack module 50-2, particularly by (i) connecting its positive terminal to the "power" terminal of a resistive load, (ii) connecting its negative terminal to the positive terminal of the fuel cell stack module 50-2, and (iii) connecting the negative terminal of the fuel cell stack module 50-2 to the "ground" terminal of the resistive load. In contrast, fig. 5B depicts the fuel cell stack module 50-1 being connected in parallel with the fuel cell stack module 50-2, particularly by (i) connecting its positive terminal to the "power" terminal of the resistive load and the positive terminal of the fuel cell stack module 50-2, and (ii) connecting its negative terminal to the "ground" terminal of the resistive load and the negative terminal of the fuel cell stack module 50-2. In these and/or other embodiments, the resistive load may be motor controller 20, motor 70, payload 70, and/or any electrical function associated with payload 30.

While the method and fuel cell power system have been described in terms of what are presently considered to be the most practical and preferred embodiments, it is to be understood that the disclosure is not necessarily limited to the disclosed embodiments. The disclosure is intended to cover various modifications and similar arrangements included within the spirit and scope of the claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structures. The present disclosure includes any and all embodiments of the following claims.

It should also be understood that various changes may be made without departing from the essence of the present disclosure. Such changes are also implicitly included in the description. They still fall within the scope of the present disclosure. It should be understood that the present disclosure is intended to produce patents which are both independent and integral systems and which cover many aspects of the present disclosure in both method and apparatus modes. In addition, each of the various elements of the disclosure and claims may also be implemented in various ways. The present disclosure should be understood to encompass each such variation, whether a variation of an embodiment of any apparatus embodiment, method or process embodiment, or even merely a variation of any element of these.

In particular, it should be understood that as the disclosure relates to elements of the disclosure, the words for each element may be expressed by equivalent apparatus terms or method terms even if only the function or result is the same. Such equivalent, broader, or even more generic terms should be considered to be encompassed in the description of each element or action. Such terms may be substituted where desired to clarify the broad coverage implied by the present disclosure.

It should be understood that all actions may be expressed as a means for taking that action or as an element which causes that action. Similarly, each physical component disclosed should be understood to encompass a disclosure of the action facilitated by that physical component.

Throughout this application, the word "may" is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). The words "include", "including" and "containing" and the like mean including but not limited to. As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. As used herein, the term "number" refers to one or an integer greater than one (i.e., a plurality). As used herein, the statement that two or more parts or components are "coupled" means that the parts are joined or operated together either directly or indirectly (i.e., through one or more intermediate parts or components), so long as a link occurs. As used herein, "directly coupled" means that two elements are in direct contact with each other. As used herein, "fixedly coupled" or "fixed" means that two components are coupled so as to move as a unit while maintaining a constant orientation relative to each other. As used herein, the word "unitary" refers to a component being created as a single piece or unit. That is, a component that includes pieces that are created separately and then coupled together as a unit is not a "unitary" component or body. As used herein, the statement that two or more parts or components "engage" one another means that the parts exert a force on one another either directly or through one or more intermediate parts or components.

Also, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description and not of limitation. Directional phrases used herein, such as, but not limited to, upper, top, bottom, lower, left, right, upper, lower, front, rear, and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein.

Further, as to each term used, it should be understood that unless its utilization in this application is inconsistent with such interpretation, it should be understood that each term incorporates the definition of a common dictionary and all definitions, alternative terms, and synonyms, incorporated by reference herein, are embedded in at least one of the art dictionary recognized by the artisan and the landen house webster unabridged dictionary (latest version).

To the extent that no claim at issue is actually drawn by the applicant to literally encompass any particular embodiment, and to the extent that such coverage is otherwise applicable, applicants should not be read as intending in any way to or actually foregoing such coverage, as applicants may not foresee all possibilities at all; those skilled in the art should not be reasonably expected to draft a claim that would literally encompass such alternative embodiments.

Furthermore, the transitional phrase "comprising" is used in accordance with conventional claim interpretation to maintain the "open" claims herein. Thus, unless the context requires otherwise, it should be understood that the term "comprise" or variations such as "comprises" or "comprising" are intended to imply the inclusion of a stated element or step or group of elements or steps but not the exclusion of any other element or step or group of elements or steps. Such terms should be interpreted in their broadest form so as to provide the applicant with the broadest coverage legally permissible.