Design And Implementation Of Hybrid-Electric Propulsion System For Tilt Rotor UAV

With the rapid development of unmanned combat system,unmanned aerial vehicles(UAVs)have become the strategic commanding points in military and civilian high-tech fields in the world.Numerous UAVs of different patterns,performance and features have been developed,and tilt-rotor UAVs have become a hot research topic in the UAV field because they possess joint advantages of vertical takeoff and landing(VTOL)ability of helicopter and long endurance of fixed wing UAVs.From the point of view of improving the flight time and efficiency of tilt rotor UAVs,a efficient hybrid-electric propulsion system with mixed advantages is designed and implemented in this paper after a comprehensively comparison of a variety of UAV power systems and configuration schemes.For the key technologies such as hybrid power layout,components selection and matching of motor and propeller,the research of hybrid-electric configuration,power testing and matching has been carried out systematically.The main contents and contributions are summarized as follows:(1)A new parallel distributed power configuration scheme with the characteristic of oil-electricity coordinationFirstly,the characteristics of basic hybrid-electric configurations are analyzed systematically and the difference in the push-weight ratio,control difficulty and energy characteristics of piston engine and brushless DC motor are compared.Then a new parallel distributed power configuration scheme with the characteristic of oil-electricity coordination is proposed for the tilt rotor UAV with distributed dynamic layout.This configuration not only has the advantages of low weight,high efficiency and flexible propulsion of parallel hybrid-electric configuration,but also can be better applied to tilt rotor UAVs.Then the design of hybrid-electric propulsion system with high effciency and long endurance has been completed on the level of structure configuration.(2)Dynamic demand analysis for different flight modes and system components selectionAiming at the multi-mode flight characteristics of the tilt rotor UAV,the dynamic demand of hybrid-electric propulsion system in different modes is analysed systematically.Starting from the platform parameters and performance indicators,the power required by the hybrid-electric propulsion system is calculated in detail when the tilt rotor UAV flies in the VTOL and fixed wing cruise mode.Through the extensive investigation of the existing power equipment in the market,the selection of power components is completed after analysis and comparison.The power system is made meet the dynamic requirements of the tilt rotor UAV in different flight modes at the propulsion components level.(3)Testing,matching and validation of hybrid-electric propulsion systemIn order to carry out the work of matching optimization and validation for the hybrid-electric propulsion system,an accurate and reliable propeller comprehensive test system is established to measure multiple performance indicators for the motor and engine loaded propeller.On this basis,propeller dynamics modeling and motor propeller matching are completed.The performance of the electric propulsion system is fully grasped,high efficiency electric propulsion subsystem meeting the requirements is achieved.Under the condition of knowing the performance of the components of the oil propulsion system,the thrust and fuel consumption characteristics of the engine loaded propeller are analyzed.The fuel efficient working area is divided for the oil propulsion subsystem.Finally,the feasibility of the hybrid-electric propulsion system is validated from the aspects of power demand,weight,navigation time,flight speed and so on.