Lightweight Design And Rectified Load Characteristics Analysis Of Gasoline Generator For UAVs

Due to the advantages of high efficiency,long battery,and high payload,the centralized oil-electric hybrid drone is an important development direction.As the core of the power system,the operating characteristics of the gasoline generator have seriously affected the flight and working of the drone.This thesis systematically studies the lightweight design method of the gasoline,and analyzes the operating characteristics in the non-controlled rectifier-load condition.A gasoline generator with high torque density is designed,and its electromagnetic and thermal characteristics are obtained under uncontrolled rectification load.The research content for the gasoline generator in this thesis can be divided into the following parts:Firstly,according to the application conditions and application fields,the rated speed and output power of the generator are determined.Combined with the topology and electromagnetic scheme of the popular motors with the same applications,the structure and main dimensions of the generators are determined.With the key parameters of cogging torque and stator vibration acceleration as the optimization targets,the three pole-slot combine of the16-poles 24-slots,18-poles 24-slots and 20-poles 24-slots are compared,and the 20-poles24-slots is considered as optimal.According to the installation method,the matching design of the shell structure is carried out,and the internal air fluid field in the generator is analyzed by using the software of CFX,to optimize the position of ventilation holes.Secondly,based on the finite element model,the electromagnetic characteristics of the generator are simulated for no-load and load conditions,and the main losses,such as,stator core iron loss,rotor core iron loss,and permanent magnet eddy current loss,are calculated.The obtained losses are considered as the heat sources,and the temperature distribution of the generator in the no-load and load conditions is calculated by Motor-CAD,to further determine the permanent magnet material and winding insulation grade.Then,the electromagnetic and thermal characteristics of the generator will be affected by the quadrature-axis and direct-axis armature reaction,therefore,the losses and temperature characteristics are analyzed in the with quadrature-axis and direct-axis current(including no load,half load with the current of 57.5 A,and full load with the current of 115 A).Based on the original circuit,the corresponding components of quadrature-axis direct-axis armature reaction are decomposed,and the air-gap flux density,losses and temperature distribution in the two conditions are analyzed.The results show that the quadrature-axis armature reaction causes the overall temperature to rise,while the direct-axis armature reaction causes the overall temperature except coils to decrease.Finally,the limit loss method is applied,and the electromagnetic and thermal characteristics of the generator in the overloaded conditions are analyzed.The limit losses and the transient temperature curves of the main region are obtained,which provides reliable data support for overload operation of the designed gasoline generator.