Patent Description:
With the vigorous development of UAV industry, the UAV have been available in more types and applied in more areas. For the large and medium-sized fixed wing or compound wing UAVs whose main mission is cruise, mapping and logistics transportation, their endurance and mileage are of particular importance.

The power system of the existing UAV mostly adopts the following two power output modes: first, the built-in engine unit, which relies on the engine to drive the generator to generate electricity, and then the battery stores the electricity and supplies it to the electric motor to drive the propeller; second, the engine directly acts as the power source of the UAV, and provides power by directly driving the propeller. The first power output mode has high reliability. Even if the engine shut down, it will not affect the flight safety of the UAV. However, the power system occupies a large space, so the heat dissipation of the engine needs to be considered, and the energy utilization rate is extremely low due to multiple energy transformations. Although the second power output mode has simple structure and high energy utilization, it has no power output redundancy. Once the engine stops, the power source will be lost, affecting flight safety. Moreover, the endurance mileage of the UAV is limited by the mounted battery, which is used to power other equipment of the UAV. In case of low battery, it needs to return. <CIT> relates to a hybrid powertrain for an aircraft, which may include a drive shaft, an internal combustion engine to selectably drive the drive shaft, a propeller coupled to the drive shaft, and an electric motor having a stator and a rotor and operable to selectably drive the drive shaft. <CIT> relates to a hybrid electric propulsion system, which includes a gas turbine engine and an electric machine coupled to the gas turbine engine. <CIT> relates to an aerial platform provided with a power-assisting system. <CIT> relates to an engine provided with a powertrain, which comprises a heat engine and an output shaft, an electric motor, a battery, and a propeller propulsion system comprising a propeller and a propeller shaft. <CIT> relates to a method of operating a hybrid-electric propulsion system for an aircraft. <CIT> relates to a system, which includes a torque sensor and a hybrid power system, which includes a frame, an engine mounted on the frame, and a generator. <CIT> relates to a high-speed hybrid power UAV.

Therefore, the existing technology needs to be improved urgently.

The invention aims to provide a UAV and a UAV control method, which can ensure high energy utilization and realize power redundancy, significantly improve the flight safety of UAV, and ensure sufficient endurance and mileage.

To achieve the above purpose, the following technical scheme is provided:
The invention provides a UAV, having the features defined in claim <NUM>.

The invention also provides a UAV control method for the UAV, having the features defined in claim <NUM>.

Compared with the prior art, the invention has the following beneficial effects: the power system described in the <NUM>st example helpful in understanding the invention sets the rotor of the motor, the external power receiver and the engine output shaft to be coaxially connected, and the motor can be used as a generator to do negative work on the engine output shaft to charge the battery, or as a motor, that is, to receive the power of the battery, do positive work on the engine output shaft to realize power output. The power system control method described in the <NUM>nd example helpful in understanding the invention makes full use of the structural arrangement of the power system and determines the specific operation mode according to different working conditions of the engine. When the above power system is arranged on the above UAV, it can enable the UAV to have high energy utilization and power redundancy, thus significantly improving flight safety and ensuring sufficient endurance time and mileage.

Figure reference signs: <NUM>. Propeller; <NUM>. Engine; <NUM>. Engine body; <NUM>. Engine output shaft; <NUM>. Motor; <NUM>. Stator; <NUM>. Rotor; <NUM>. Stator connector.

In order to clarify the purpose, technical scheme, and advantages of the embodiments of the invention, the technical scheme in the embodiments of the invention will be described clearly and completely below in combination with the figures in the embodiments of the invention. Obviously, the described embodiments are part of the embodiments of the invention, not all of them. The components of the embodiments of the present invention, which are generally described and shown in the figures herein, may be arranged and designed in various types of different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed, but only represents selected embodiments of the invention. Based on the embodiments of the invention, all other embodiments obtained by those skilled in the art without creative work fall within the breadth and scope of the invention.

It should be noted that similar labels and letters indicate similar items in the following figures.

Therefore, once an item is defined in a figure, it does not need to be further defined and explained in subsequent figures.

In the description of the invention, it should be noted that the orientation or position relationship indicated by the terms "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" is based on the orientation or position relationship shown in the figures, or the orientation or position relationship that the product of the invention is customarily placed when it is used, only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, it cannot be understood as a limitation of the invention. In addition, the terms "first", "second", "third" and the like are only used to distinguish descriptions, and cannot be understood as indicating or implying relative importance. In the description of the invention, unless otherwise specified, "multiple" means two or more.

In the description of the invention, it should also be noted that, unless otherwise expressly specified and limited, the terms "arranged" and "connection" should be understood in a broad sense, for example, it can be fixedly connected, a detachably connected, or integrated. It can be mechanical connection or electrical connection. For those skilled in the art, the specific meaning of the above terms in the invention may be understood in specific circumstances.

In the description of the invention, unless otherwise clearly specified and limited, the first feature "on" or "under" the second feature may include the direct contact between the first and second features, or the contact between the first and second features that is not direct contact, but through another feature between them. Moreover, the first feature "on", "over", and "above" the second feature may include the first feature directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than the second feature. The first feature "under", "below" and "beneath" the second feature, may include the first feature directly below and obliquely below the second feature, or only indicate that the horizontal height of the first feature is smaller than that of the second feature.

The following describes in detail the embodiments of the invention, examples of which are shown in the figures, in which the same or similar labels throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the figures are exemplary and are only for the purpose of explaining the invention and cannot be understood as limitations of the invention.

The example helpful in understanding the invention aims to provide a power system for outputting power. Upon the specific implementation, the power system can be mounted to the UAV, the ship, or other mechanical equipment that needs to be equipped with the power system to realize the power drive of the corresponding mechanical equipment. Specifically, as shown in <FIG> and <FIG>, the power system includes an engine <NUM>, a motor <NUM>, and a battery. Specifically, the engine <NUM> includes an engine body <NUM> and an engine output shaft <NUM> arranged on the engine body <NUM>, and the engine body <NUM> is installed on the body of the corresponding mechanical equipment. The motor <NUM> includes a stator <NUM>, a rotor <NUM> and a stator connector <NUM> for connecting the stator <NUM> and the rotor <NUM>. Upon the specific implementation, the stator connector <NUM> is arranged on the engine body <NUM> to realize the stable arrangement of the motor <NUM>. The rotor <NUM> is coaxially arranged on the engine output shaft <NUM>. The rotor <NUM> is also used for coaxial connection with the external power receiver, that is, the rotor <NUM>, the external power receiver and the engine output shaft <NUM> are coaxially connected. The motor <NUM> in this example helpful in understanding the invention may be used as either a generator or an electric motor. When the motor <NUM> is used as an electric motor, the rotor <NUM> of the motor <NUM> does positive work on the engine output shaft <NUM>, converting electrical energy into mechanical energy, which can assist the engine <NUM> for power output. When the motor <NUM> is used as a generator, the electronic rotor <NUM> does negative work on the engine output shaft <NUM>, absorbs the output power of the engine <NUM>, converts mechanical energy into electrical energy, and realizes the power generation operation. The battery is connected to the motor <NUM>, so that when the motor <NUM> is used as an electric motor, the battery discharges to provide electric energy to the motor <NUM>. When the motor <NUM> is used as a generator, it can receive the electric energy output by the motor <NUM> for charging. Upon the specific implementation, a two-stroke engine may be selected for the engine <NUM>. The two-stroke engine is an engine that completes a working cycle between two strokes. It has no valve, which can greatly simplify the structure, reduce its own weight, and can be more conveniently and flexibly installed on mechanical equipment, reducing the weight of the whole mechanical equipment, thereby reducing energy consumption. Alternatively, the motor <NUM> is a permanent magnet synchronous motor or a permanent magnet asynchronous motor. Among them, the permanent magnet synchronous motor matches well with the two-stroke engine, and there is no conversion mechanism, so there is no conversion loss. The permanent magnet synchronous motor and two-stroke engine can work alone or together without clutch.

In order to facilitate the control over the working state of the engine <NUM> and the motor <NUM> of the power system, the power system also includes an engine controller and a motor controller. The engine controller is used to receive the control commands and output the execution signals to the engine <NUM>, so as to control the working state of the engine <NUM>. The motor controller is used to receive the control commands and output the execution signals to the motor <NUM>, so as to control the working state of the motor <NUM>. Further, the power system also includes a control board, which is used to send control commands to the engine controller or motor controller. Of course, the battery can supply power to the control board, engine controller and motor controller to ensure the smooth operation of the control system.

The power system in this example helpful in understanding the invention sets the rotor <NUM> of the motor <NUM>, the external power receiver and the engine output shaft <NUM> to be coaxially connected, and the motor <NUM> can be used as a generator to charge the battery by doing negative work on the engine output shaft <NUM>, or as an electric motor, that is, to receive the power of the battery and do positive work on the engine output shaft <NUM> to realize power output.

Based on the <NUM>st example helpful in understanding the invention, this example helpful in understanding the invention provides a power system control method for the above power system, which provides the determination process of different operation modes of the power system. Referring to <FIG>, specifically, the power system control method includes the following steps:.

In the step S10, determine the operation state of the engine <NUM> firstly. Only by ensuring that the engine <NUM> can work, then assign the work allocation between the engine <NUM> and the motor <NUM> reasonably according to the requirement. If the engine <NUM> cannot work directly, it can only enter the pure electric operation mode, in which the battery provides power, and the motor <NUM> is used as an electric motor. Specifically, in the step S10, the circumstances under which the engine <NUM> cannot work normally include but are not limited to the following: the fuel of the engine <NUM> is running out, the fuel injection nozzle of the engine <NUM> fails, and the engine <NUM> loses the rotation signal. Of course, upon the specific implementation, one or more of the above circumstances may occur to the engine <NUM>. As long as any of the above circumstances occurs, it can be determined that the engine <NUM> cannot work normally.

In the step S20, in the power assisted operation mode, the engine <NUM> outputs the maximum power. Upon the specific implementation, if the engine <NUM> can work normally, the engine <NUM> is generally used as the main power output. In such case, it is necessary to determine whether the output power of the engine <NUM> meets the needs in the step S20. If the output power of the engine <NUM> does not meet the needs and enters the power assisted operation mode at this time, it is necessary to ensure that in this operation mode, the engine <NUM>, which is the main power output, can output maximum power. On the premise that the output power of the engine <NUM> meets the needs, proceed to the step S30, that is, determine whether the engine <NUM> works in the low energy consumption range at that time, because although the output power of the engine <NUM> meets the use requirements, it is not necessarily the optimal output power rate from the perspective of energy consumption. If it is in the non-low energy consumption range, the motor <NUM> is required to participate in providing power, which is the hybrid operation mode. In the hybrid operation mode, the system will reduce the output power of the engine <NUM> as much as possible to make it work in the low energy consumption range, while increasing the output power of the motor <NUM>, it can also ensure the normal operation of mechanical equipment.

Further, the power system control method also includes a step set after the step S30:
S40: If the engine <NUM> works in the low energy consumption range, determine whether the remaining power of the battery meets the set value. If not, the power system enters the power generation operation mode, in which the output power part of the engine <NUM> is received by the motor <NUM> for charging.

That is, in the step S30, if the engine <NUM> has operated in the low energy consumption range, there is no need for the motor <NUM> to provide additional power. In such case, it can be considered to use the engine <NUM> to charge the battery, so it is necessary to determine the remaining battery power firstly. When the remaining power of the battery does not meet the set value, on the premise of ensuring the low energy consumption of the engine <NUM> as much as possible, the output power of the engine <NUM> can be appropriately increased, so that part of the output power of the engine <NUM> can be received by the motor <NUM> for charging operation, so as to ensure that the battery has sufficient power, and also ensure the normal operation of other electrical equipment. At the same time, the battery has enough power storage when entering the power assisted operation mode or hybrid operation mode subsequently. Specifically, in this example helpful in understanding the invention, the set value of the remaining power of the battery is set to <NUM>% of the full power.

The power system control method provided in this example helpful in understanding the invention makes full use of the structural arrangement of the power system in the <NUM>st example helpful in understanding the invention, and determines the specific operation mode according to the different operation conditions of the engine <NUM>, which can achieve power redundancy while ensuring high energy utilization.

Based on the <NUM>st example helpful in understanding the invention, this embodiment provides a UAV. Referring to <FIG> and <FIG>, the UAV includes the power system described in the <NUM>st example helpful in understanding the invention. Further, the UAV also includes an UAV body and a propeller <NUM> arranged on the UAV body.

Specifically, the engine body <NUM> is arranged on the UAV body to realize the stable placement of the engine <NUM> on the UAV, and the propeller <NUM> is coaxially arranged on the rotor <NUM> as an external power receiver. Specifically, the propeller <NUM> is directly locked on the rotor <NUM> by fasteners. Further, the battery of the power system is not only connected to the motor <NUM>, but also connected to other equipment on the UAV that needs power supply, so as to ensure the normal operation of the whole UAV. The control board of the power system is used to control the whole UAV overall, send corresponding control signals to the engine controller and motor controller according to the ground control signals or the UAV's own needs, and then the engine controller and motor controller control the operation of the engine <NUM> and the motor <NUM>, respectively.

This embodiment also provides a UAV control method, which can be used in the above UAV. Since the above UAV includes the power system in the <NUM>st example helpful in understanding the invention, the UAV control method provided in this embodiment naturally also includes the power system control method in the <NUM>nd example helpful in understanding the invention, that is, the power system control method in the <NUM>nd example helpful in understanding the invention is applied to the UAV with this power system, so that the UAV has pure electric operation mode, power assisted operation mode, hybrid operation mode and power generation operation mode.

The conventional UAV built-in generator set generates electric energy by driving the motor with a two-stroke engine. The chemical energy of the fuel needs to be converted into mechanical energy, which is converted into electrical energy through the engine. After the electrical energy finally returns to the battery, it also needs to be converted into mechanical energy to provide power for the UAV. The energy conversion efficiency of the engine itself is only <NUM>%, the conversion efficiency through the generator is <NUM>%, and the conversion efficiency of electric energy into shaft power is <NUM>%. The above conversion efficiency is the ideal average value. During this period, the low conversion efficiency and many conversion times result in extremely low energy utilization rate. Therefore, based on the above defects, the UAV of this embodiment adopts the power system in the <NUM>st example helpful in understanding the invention, omits the clutch, and connects the engine <NUM>, the motor <NUM> and the propeller <NUM> coaxially. At the same time, the UAV control system adopts the power system control method in the <NUM>nd example helpful in understanding the invention. Therefore, when the above power system is mounted to the UAV, it can make the UAV have high energy utilization and power redundancy, and significantly improve flight safety. Specifically, the step S10 provides the pure electric operation mode of the power system to ensure that when the extreme situation of engine <NUM> failure occurs, the UAV can return to the return point or midway forced landing point to ensure the safety of the UAV. In the step S20, for the UAV, a flying vehicle, the output power of the engine <NUM> is easily affected by altitude. In some operation environments, the maximum power output of the engine <NUM> is limited and may not meet the use needs of the UAV. In such case, it may enter the power assisted operation mode, in which the motor <NUM> assists to provide power to ensure that the overall output power of the system meets the requirements, so as to improve the speed of the UAV. For another example, when the UAV needs to fly at full speed or climb, even if the maximum power output of the engine <NUM> still cannot meet the requirements, it also needs to enter the power assisted operation mode to improve the climbing performance and speed of the UAV. Moreover, on the premise of keeping the level flight power output of the UAV unchanged, the output power of the engine <NUM> can be increased, and the motor <NUM> converts this part of the extra power into electrical energy for storage. Therefore, after the UAV is equipped with the above power system, it not only provides the UAV structure with high energy utilization and power redundancy, but also significantly improves flight safety and ensures sufficient endurance and mileage.

Of course, in some other examples helpful in understanding the invention, the above power system and power system control method may also be used on other mechanical equipment other than UAV to help the corresponding mechanical equipment achieve high energy utilization and power redundancy. For example, the above power system may be applied to the ship, and the propeller of the ship may be used as the external power receiver. The specific example helpful in understanding the invention is similar to that of the UAV, which will not be repeated here.

Based on the UAV and UAV control method provided in Embodiment <NUM>, this embodiment establishes the mathematical model of the power system for UAV, and illustrates several operation modes of UAV through the mathematical model, so as to facilitate the understanding of multiple operation modes and application scenarios of UAV control method.

Specifically, the mathematical model of the power system of UAV is: <MAT>.

Where, Pengine is the engine's shaft power; Pmotor is the shaft power of the motor; Ppropeller is the propeller's power; Pbattery-in is the input power of the battery.

Since the fuel consumption curve of the engine <NUM> is known, it is assume that the fuel consumption rate of the engine <NUM> is <NUM>/kw. h under the output power is 2200w at 5500rpm and <NUM>% throttle opening; and the fuel consumption rate is <NUM>/kw. h under the output power is 2000w at 5500rpm and <NUM>% throttle opening; then through the following calculation: <MAT> <MAT> the fuel consumption rate is reduced by <NUM>%, while the power is reduced by only <NUM>%. Therefore, in this operation mode, the reduction of throttle opening of the engine <NUM> can be controlled, and then the increase of the output power of the motor <NUM> can be controlled, so that the engine <NUM> may not work in the low energy efficiency range. The specific values of each parameter can be: Pengine= 2000w, Pmotor= 200w, Ppropeller= 2200w; Pbattery-in = 0w.

When the UAV needs to fly at full speed or climb, the output power of the engine <NUM> alone may not meet the demand, so the intervention of the motor <NUM> is required. If the UAV cruises at <NUM>/h, it needs the shaft power output of 5000w to reach the corresponding thrust, and the maximum engine shaft power is 3000W, the specific values of various parameters can be: Pengine= 3000w, Pmotor= 2000w, Ppropeller= 5000w; Pbattery-in = 0w.

When the UAV is cruising at the speed of <NUM>/h, only the shaft power output of 1500w is required, and the engine <NUM> can meet low energy consumption according to this power output. In order to meet the normal use of the battery of the UAV, the engine <NUM> will be controlled to output the power of 2000w, and the excess 500w power will be absorbed by the motor <NUM> and fed back to the battery to charge the battery. The specific values of each parameter can be: Pengine= 2000w, Pmotor= -500w, Ppropeller= 1500w; Pbattery-in = 500w.

Because the pure electric operation mode is only available when the engine <NUM> cannot work normally, that is, when the engine <NUM> fails, the UAV detects that the engine <NUM> has failed and needs to return immediately. In such case, the return power can only be provided by the motor <NUM>.

Claim 1:
A UAV, which comprises a power system for outputting power,
wherein the power system comprises:
an engine (<NUM>), which comprises an engine body (<NUM>) and an engine output shaft (<NUM>) arranged on the engine body (<NUM>);
a motor (<NUM>), which comprises a stator (<NUM>), a rotor (<NUM>) and a stator connector (<NUM>) for connecting the stator (<NUM>) and the rotor (<NUM>); the stator connector (<NUM>) is arranged on the engine body (<NUM>), and
the rotor (<NUM>) is coaxially arranged on the engine output shaft (<NUM>); the rotor (<NUM>) is used for coaxial connection with an external power receiver; and
a battery, which is connected to the motor (<NUM>), and the battery can discharge to provide electric energy to the motor (<NUM>), or receive the electric energy output by the motor (<NUM>) for charging,
wherein the UAV further comprises a UAV body and a propeller (<NUM>) arranged on the UAV body,
wherein the engine body (<NUM>) is arranged on the UAV body, and the propeller (<NUM>) is coaxially arranged on the rotor (<NUM>) as the external power receiver, and wherein
the propeller (<NUM>) is directly locked on the rotor (<NUM>) by fasteners.