[0056] The present invention will be further described in detail below in conjunction with the drawings.
[0057] The present invention is a long-endurance UAV hybrid power system based on the following design principles:
[0058] 1. The long-endurance flight system must first solve the contradiction that the aircraft cannot take off due to the over-load of the long-endurance. For example, a pure fuel flight power system or a pure battery flight power system, when a long flight of 20 hours is required, the overweight load prevents the aircraft from taking off.
[0059] 2. The long-endurance flight system should also solve the problem that the efficiency of the existing technology of the hybrid system is lower than that of the pure oil power system. The principle is as follows: the efficiency from the engine to the generator is 0.9, and the power generation efficiency of the generator is 0.8. To the rectifier, the efficiency is 0.95, and the total efficiency is: 0.9*0.8*0.95=0.684;
[0060] In summary, the long-endurance UAV hybrid power system of the present invention should solve the light load problem and high efficiency problem.
[0061] One of the methods of the present invention to solve the light load problem is to use a motor with a very good power/weight ratio and relatively small weight. Since the UAV is not a maneuverable aircraft during long endurance, the flight overload changes little within the flight envelope, that is to say, the power change is small within the range of maintaining level flight and the energy consumption is relatively stable. Long-endurance electric drones can use motors with excellent power/weight ratios within a certain range of steady speeds. When using oil-electric hybrid power, the engine used for power generation can be a special fuel engine. This kind of engine runs at the highest efficiency, has a very narrow constant speed range, and has the lowest fuel consumption, which is very conducive to long endurance.
[0062] The second method of the present invention to solve the light load problem is to use an engine with the lowest fuel consumption. When using oil-electric hybrid power, the engine used for power generation can be a special fuel engine. This kind of engine runs at the highest efficiency, has a very narrow constant speed range, and has the lowest fuel consumption, which is very conducive to long endurance.
[0063] The third method of the present invention to solve the light load problem is to make full use of the short-term overload capacity of the DC motor when the plane takes off, and reduce the weight of the take-off energy storage lithium battery assembly. When the UAV takes off, the power of the motor driving the propeller is obviously required to be greater than that of the horizontal flight. The power characteristic curve of a DC motor shows that the motor power is the product of voltage and current. When the input voltage increases, the electrode power increases and the speed increases. The increase in the tensile force produced by the increase in the speed of the propeller is proportional to the square of the speed. The high-efficiency designed DC motors have the ability to increase the overload by about 100% in a short time, and the DC motors with overload and high power allow a short time for about 2-4 minutes, until the overheating stops. The take-off time of the drone is only 10-20 seconds, and the entire overload operation process is less than 30 seconds. In this way, the UAV can use small and light motor power suitable for level flight, while also satisfying the short-term high power during takeoff, which is a very obvious feature.
[0064] The fourth method of the present invention to solve the light load problem is to solve that the power required by the motor during takeoff is greater than the output power of the generator. The energy storage battery used in the UAV's oil-electric hybrid power system is also a necessary link in flight. by figure 1 with figure 2 It can be seen that the discharge characteristics of energy storage lithium batteries are exactly the characteristics of the high take-off power of UAVs that meet our needs. The electrical energy consumed during takeoff is the sum of the electrical energy that the energy-storage lithium battery has been charged before takeoff, and the electrical energy generated by the fuel generator. Obviously, a smaller power motor can be used, which reduces the total weight of the aircraft and saves fuel consumption. The battery power consumed by takeoff can be recharged during the mission of the drone.
[0065] Then takeoff energy = part of the battery power + generator power supply
[0066] One of the methods of the present invention to solve the problem of high efficiency is the restart function of the power generation system. The power generation system is turned off under certain conditions and restarted under certain conditions to save power consumption. For example, when flying at a high altitude, that is, when the flight altitude is greater than 4500 meters, the fuel engine power generation system has stopped working properly at this time. The energy storage battery source of the UAV is also the energy used to drive the propeller when the drone is flying at an altitude greater than 4500 meters. All the electrical energy consumed during the flight from 4500 meters to 6000 meters altitude should be supplied by energy storage lithium batteries.
[0067] The second method of the present invention to solve the problem of high efficiency is to recharge the energy storage lithium battery assembly when the aircraft is in a normal flight state. The recharging function of the energy storage lithium battery assembly of the present invention is divided into two stages. The first stage is the stage from takeoff to level flight. Before takeoff, the electric energy of the airborne battery is most completed on the ground, and a large amount of energy is consumed during takeoff. When it enters the level flight state, the flight control system controls the power generation system to recharge the battery pack, thereby supplementing the energy loss consumed by the energy-storage lithium battery components during takeoff; the second stage is the aircraft flying from a high altitude to In normal flight conditions, when the aircraft descends above 4500 meters, the onboard power generation control system automatically restarts the power generation system according to the set procedure, recharges the energy storage battery, and drives the propeller to keep the drone flying. The power generation capacity of the power generation system is the sum of the electrical energy required to maintain the normal flight of the aircraft and recharge the energy storage battery. The energy of the battery before takeoff is already sufficient on the ground. The power of the onboard battery after being charged on the ground. The electric energy maintains the electric energy for 4 drone takeoffs and landings. The total amount of energy storage batteries is determined by the total electrical energy required to fly from 4500 meters to over 6000 meters and complete the mission. In this system, the power generation system is fully and reasonably designed, and the total amount of optimized electric motors and energy storage batteries are their interrelated weight factors.
[0068] Based on the above invention principle,
[0069] A long-endurance UAV oil-electric hybrid power system, refer to figure 1 As shown, including flight altimeter, environmental sensor, flight control system, power generation control system, restart system, power generation system, rectifier, battery pack, energy storage lithium battery assembly and thrust propeller motor, among them, the flight altimeter and environmental sensors are used Based on the current location of the sensor and environmental information, environmental sensors include air temperature and humidity sensors, air viscosity sensors, wind speed sensors, etc., and send the collected signals to the flight control system, which controls the drone in various flight systems It includes take-off subsystem, normal flight subsystem, charging subsystem, high-altitude flight subsystem, and flight control system that controls the UAV to switch between the above-mentioned multiple subsystems; the power generation control system is controlled by the flight control system output command Specifically, the power generation control system controls whether the restart system restarts the power generation system, refer to Picture 8 As shown, the power generation system includes an engine, a generator, and a rectifier. The above-mentioned engine is a low fuel consumption fuel engine with a constant speed of 4 strokes; the generator adopts a generator with a power generation restart module and is controlled by the restart system control, the rectifier By connecting the battery pack with the balance charger, those skilled in the art can know that the battery pack is part of the energy storage lithium battery assembly, and the energy storage lithium battery assembly can be controlled by the flight control system to output electric power, and the energy storage lithium battery assembly controls the thrust propeller And UAV system electricity (including electricity for sensors, indicator lights, etc.), because the thrust propeller motor is powered by the energy storage lithium battery component, the thrust propeller motor is a DC motor.
[0070] Reference figure 2 As shown, figure 2 It is a schematic diagram of the overall control method of the system. The flight altimeter outputs the current altitude signal to the flight control system. The flight control system switches the flight state of the aircraft. The take-off subsystem includes an overload judgment unit. The overload judgment unit detects the need for thrust propeller motors. Electric energy, when the thrust propeller motor needs power greater than the maximum output power of the charging subsystem or the energy storage lithium battery component, it is judged to be overloaded, otherwise it is not overloaded. When it is not overloaded, the drone is in normal flight and the power generation control system controls the power generation system Power is supplied to the thrust propeller motor, at this time in the normal flight subsystem; when overloaded, in the overloaded flight, the power generation control system controls the power generation system and the energy storage lithium battery assembly to simultaneously supply power to the thrust propeller motor to meet the requirements of the UAV. Takeoff energy = part of battery power + generator power supply. In the normal flight state, the flight control system switches to the normal flight subsystem. The flight control system judges whether the energy storage lithium battery component is fully charged. When the power is not full, the power generation system controls the balance charger to charge the energy storage lithium battery pack ; When the flight control system switches to the high-altitude flight subsystem, the flight control system controls the power generation system to stop working. At this time, the power generation control system controls the power generation system to supply power to the thrust propeller motors; and when the UAV drops from a high altitude to a normal At altitude, the flight control system controls the restart system to restart the power generation system and switch from the high altitude flight subsystem to the normal flight subsystem.
[0071] In order to explain the above principles more clearly, each flight state is divided into Figure 3 to Figure 7.
[0072] Reference image 3 Shown is the flight state diagram of the take-off subsystem. The principle is that the flight altimeter detects the current flight state of the UAV in real time, and the flight control system switches the flight state to the take-off subsystem. At this time, the thrust propeller motor needs to be Determine whether it is overloaded. When overloaded, the thrust propeller motor is powered by the energy storage lithium battery assembly and the power generation system at the same time. During takeoff, the power of the electric motor driving the propeller is obviously required to be greater than in level flight. According to the power characteristic curve of the thrust propeller motor, the motor power is the product of voltage and current. When the input voltage increases, the electrode power increases and the speed increases. The increase in the tensile force produced by the increase in the speed of the propeller is proportional to the square of the speed. The generator has the ability to increase the short-term power by about 100% when the overload is overloaded. The DC motor overload and high-power short-term allowable time is about 2-4 minutes, until the overheating stops. The take-off time of the drone is only 10-20 seconds, and the entire overload operation process is less than 30 seconds. In this way, the drone can use a small and light generator suitable for level flight. In addition, the energy storage lithium battery component provides at least twice the electrical energy provided by the power generation system during the takeoff of the aircraft. This can meet the requirement of 3-4 times that of level flight during takeoff.
[0073] Reference Figure 4 Shown is the normal flight subsystem flight state diagram. When the UAV completes take-off, it enters the normal state, so the normal flight subsystem starts. At this time, according to the signal feedback of the normal flight subsystem, the flight control system is controlled by the power generation system Powering the thrust propeller, the UAV is not a maneuverable aircraft during the long endurance, and the flight overload changes little within the flight envelope, that is to say, the power change is very small during the long endurance of the level flight, and the energy consumption is relatively It is stable, therefore, the thrust propeller motor adopts a thrust propeller motor with a very good power/weight ratio within a certain constant speed range, which is very conducive to long endurance.
[0074] Reference Figure 5 As shown, in the normal flight state, the battery pack includes a power collection module and a power judgment module for the battery to determine whether the energy storage lithium battery assembly is fully charged. When the power is not full, a balance charger connected to the power generation system is used to store the energy. The lithium battery components are charged to ensure that the energy storage lithium battery components remain fully charged at all times during level flight.
[0075] Reference Image 6 with Figure 7 As shown, when the flight altimeter detects that the UAV exceeds 4500 meters (which can be set according to the specific address position), the high-altitude flight subsystem is activated. Because the environment is not conducive to the operation of the power generation system at this time, the energy storage lithium battery The components are powered, and there is a restart system to control the power generation system to stop working, reducing energy consumption. When the drone descends below 4500 meters, the restart system restarts the power generation system and returns to normal flight status at this time.
[0076] A control method of a long-endurance UAV oil-electric hybrid power system includes the following steps:
[0077] S1. Charge the energy storage lithium battery components before takeoff; after the onboard battery is fully charged, it can maintain the electrical energy for at least 4 UAV takeoffs and landings.
[0078] S2. When it is detected that the UAV is in the take-off state, the power generation system and the energy storage lithium battery assembly are controlled to work at the same time through the flight control system to provide electrical energy during takeoff; the energy storage lithium battery assembly provides electrical energy during takeoff of the aircraft The power generation system provides at least twice the electrical energy; the electrical energy provided by the power generation system includes the limit overload electrical energy of the power generation system during the takeoff of the aircraft;
[0079] S3. When the drone is in a normal flight state after taking off, the flight control system simultaneously controls the power generation system to provide the power required by the thrust propeller and charge the energy storage lithium battery components;
[0080] S4. When the UAV rises from a normal flight state to a high altitude, the flight control system controls the power generation system to stop working, and the energy storage lithium battery component provides the power during flight;
[0081] S5. When the drone descends from a large altitude to a normal altitude, the flight control system controls the restart of the power generation system, and the power generation system again supplies power to the thrust propeller motor and the energy storage lithium battery assembly.
[0082] The flight control system includes a charging module for the battery, and the charging module includes a power collection module and a power judgment module for detecting the current power of the energy storage lithium battery assembly;
[0083] In step S3, when the power determination module determines that the current power is not full, the battery is charged through the charging subsystem;
[0084] In step S5, when the power judgment module determines that the energy storage lithium battery assembly is insufficient, the flight control system controls the drone to descend from a large altitude to a normal altitude.
[0085] This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contribution as needed, but as long as the rights of the present invention All requirements are protected by patent law.
