Research On Several Key Technologies Of Solar Powered UAV’s Energy Manager

The power scheme of solar powered unmanned aerial vehicle(UAV)has the advantages of renewable energy,environmental protection,and long flight duration,making it one of the important innovations and research directions in the development of advanced aircraft equipment.The energy manager is a core regulatory component in the energy system of solar powered UAVs,and its working process is closely related to the environment and flight conditions of the aircraft.Therefore,research on the energy manager of solar powered UAVs cannot be solely based on hardware circuit design,but also needs to consider the coupling effects of external environment and flight behavior on the operation of the energy system,and exploring methods to extend the flight endurance from the perspective of energy optimization,among many other issues.On the basis of a deep understanding of the special status and research significance of the energy manager for solar powered UAVs,this paper conducts research from the aspects of coupling parameter sensitivity,power converter,energy optimization strategy,and ground semi physical simulation.1)In order to quantitatively analyze the energy coupling characteristics of solar powered UAVs,the Sobol sensitivity method was used to obtain the parameter sensitivity of power generation and consumption in the energy system to the external environment and flight behavior.This sensitivity result serves as a quantitative basis for considering the coupling effect of the energy system.According to the sensitivity results,it can be seen that the power generation exhibits high sensitivity to the flight altitude,time,and attitude angle;The power consumption exhibits high sensitivity to flight speed and pitch angle,while showing low sensitivity to flight altitude.2)A study was conducted on a three port converter for solar powered UAVs to meet the application requirements of three different types of solar powered UAVs: low-voltage power supply,high-voltage power supply,and distributed power supply.A type of three port converter based on pulsing cell structure is proposed for low-voltage power supply applications,which has the advantages of diverse topology forms and fewer components.The circuit only contains three switches and one inductor,with an operating efficiency of over 96%;A high gain coupled inductor three port converter is proposed for high-voltage power supply applications.This topology only includes three switches and one coupled inductor,with a boost ratio of 10 and an operating efficiency of over 94%;A distributed power supply structure for solar powered UAVs was constructed using multiple three-port converters for distributed power supply applications.A power coordination control strategy for distributed three-port converters was proposed,which achieved the utilization of power generation for photovoltaic cells with "more generation,more supply,less generation,and less supply",as well as the balance of remaining battery power with "more energy,more discharge;less energy,less discharge".3)A motion-power optimization based energy optimization strategy is proposed to meet the extended endurance requirements of solar powered UAVs,based on the coupling characteristics of flight motion and power variation.Decompose the flight process into three states: daytime horizontal motion,daytime vertical motion,and nighttime horizontal motion.Taking the task of increasing power generation and tracking as the optimization objective for daytime horizontal motion,dynamic weight coefficients are constructed to achieve a balance between the two sub objectives;Taking high energy storage power allocation as the optimization objective for daytime vertical motion;The optimization goal for nighttime horizontal movement is to reduce power consumption.Finally,the multi stage optimization objectives of the entire flight process are synthesized,and the Gaussian pseudospectral method is used to transform the continuous optimization problem of the flight state into a discrete nonlinear programming problem of the flight trajectory for solution.Comparing the conventional trajectory with the optimized trajectory,the battery SOC under the optimized trajectory increased by 15.5%,and the flight duration was extended by 1 hour and 13 minutes.4)A ground flight test system for solar powered UAV energy managers based on NI/Labview semi physical simulation is proposed to provide a fast test condition for system power changes during flight.The system simulates virtual parts such as external spatiotemporal environment,drone motion,motors and propellers,energy optimization strategies,etc.by loading Simulink dynamic link library files of mathematical models in NI/Labview,and designs a visual state interface;By simulating real-time flight processes such as takeoff,level flight,climb,and descent,a dynamic power change curve during flight is formed.The operation of photovoltaic simulators and load simulators is linked to the curve to simulate the output/input power characteristics of photovoltaic cells and electrical loads on unmanned aerial vehicles;The power converter,as the test equipment,is connected to the photovoltaic simulator,load simulator,and battery to form the hardware physical part of the test platform.The efficiency of the power converter during operation is>95%,and the voltage error rate is<1%.