Research On Aviation Main Driving System Based On High Energy Density Electric Machine

In recent years,with the continuous advancement of China’s low-altitude airspace reform and the continuous support of new energy industry,the electric aircraft industry has ushered in a new development opportunity.At present,hybrid electric aircrafts and all-electric electric aircraft have been designed and developed by several countries and research institutes,while the test flight experiments were completed and industry promotion is under way.For all-electric electric aircraft,the main drive system is the most critical core technology,which is the heart and brain of electric aircraft.Electric aircraft requires high efficiency,small size,light weight,high fault tolerance,long endurance and high output torque,so how to design and develop the high performance aviation main drive system is the key.Firstly,according to the structure characteristics of the power system,six structures of the main driving system of electric aircraft were given and the whole electric topology was analyzed emphatically.In order to improve the lightweight of the main drive system,the design characteristics of high performance main drive motor and inverter were analyzed respectively.This paper gives a brief analysis of the flight process of the all-electric plane and gives the physical characteristics of the actual flight environment.The preliminary design and basic function analysis of the main drive system of all-electric aircraft were completed.Secondly,for the main drive motor of electric aircraft,the method of increasing force energy density and the method of improving the energy density were analyzed and based on the conventional method the main size,permanent magnet and winding of permanent magnet motor were designed.The core loss,copper loss and mechanical loss analysis of high energy density permanent magnet motor were completed.This paper focused on the iron consumption calculation of inverter harmonic,and studied the influence rule of different sizes on iron consumption.Based on the finite element method,the electromagnetic simulation analysis of the main drive permanent magnet motor was completed and genetic algorithm was used to optimize the initial electromagnetic scheme.Based on the basic theory of temperature field and heat transfer,this paper gives the basic solution process and two kinds of numerical solutions for electromagnetic-temperature unilateral coupling and electromagnetic-temperature bilateral coupling of permanent magnet motor.The electromagnetic-temperature simulation analysis of the main drive permanent magnet motor for electric aircraft was carried out.Then,the mathematical model of permanent magnet motor control was established and the overall control strategy was given.The theoretical derivation of coordinate transformation was completed,and the principle of 7-section SVPWM was analyzed emphatically,where the sequence and action time of six sector switches in the voltage space vector were given.Based on vector control theory,the vector control simulation analysis of permanent magnet motor based on SVPWM technology was completed.The hardware schematic diagrams of the main drive inverter circuit such as intelligent power module,control drive module,power conversion module and detection module were given and the real-time monitoring of the main drive motor of electric aircraft was completed by using the rotary transformer.The software flow chart of the main drive inverter was completed,including the design of main program and interrupt subroutine.Finally,the development of the high power energy density permanent magnet motor was completed,in which the rated power density of the electric machine is 8.96kW·N·m/kg~2 and the maximum energy density of the electric machine is 15.9kW·N·m/kg~2.Two kinds of test platform of main propulsion systems were described and the method of anti-electric potential measurement and the experimental method for permanent magnet motor propeller system were presented.The experimental data of the main drive motor were measured and the experimental data were analyzed briefly.The experimental data showed that the developed aviation main drive permanent magnet motor has a high energy density.