| Moving towards the more electric aircraft is the trend of the future aircraft industry.In the future more electric aircraft landing gears,the traditional hydraulic retraction/extension system will be gradually replaced by the more electric retraction/extension system.Based on the background that aircraft manufacturers still have not reached consensus on future more electric aircraft landing gear retraction/extension system solutions,research on more electric landing gear retraction/extension system solutions and electrical characteristics of the more electric aircraft landing gear retraction/extension faults is of great significance for the design and refit of more electric aircraft landing gears in China in the future.This paper mainly studies the best landing gear retraction/extension system solution which is applicable for the more electric aircraft in the future,the stability of this solution under large input voltage disturbances caused by power faults and its electrical characteristics in case of typical retraction/extension faults.Firstly,the working principles of distributed hydraulic retraction/extension system,electro-hydrostatic retraction/extension system and electromechanical retraction/extension system are studied,and relative fault tree analysis is carried out.By comparing the characteristics of these systems,the electromechanical retraction/extension system of landing gear is determined to be the research object.The retraction/extension system of main landing gear BRW-1 which is the result of an engineering project in my lab is selected as the reference object.The simulation software for complex system,AMEsim,is used to simulate the BRW-1 retraction/extension system,and the motor power of the electromechanical actuating landing gear retraction/extension system is derived.Combing what the more electric aircraft requests of motors with the specific characteristics of different motors,the motor type is determined to be a brushless DC motor,and the brushless DC motor is modeled and simulated by Matlab/Simulink.Then,based on the research on the characteristics of the power system of more electric aircraft and the characteristics of brushless DC motor based on closed-loop control,the stability optimization method that a double-stage LC filter is utilized to strengthen the stability of the DC load system under large input voltage disturbances caused by power faults is proposed.Brayton-moser theorem is used to analyze the stability of the system with double-stage LC filter under large power disturbances.The stability criteria of the system are derived in this way and Matlab/Simulink is used to verify the results.Finally,the fault modes of the motor and gearbox of the electromechanical actuating landing gear retraction/extension system are analyzed,the methods of injecting the fault modes into the motor model are studied,and the electrical characteristics of the fault are obtained through simulation.Through the fast Fourier transform analysis of the electrical characteristics of these faults,the diagnosis basis of the faults is obtained.These studies on the electrical characteristics of retraction/extension faults have a high degree of practicability,which helps to speed up product design and refit progress and reduce R&D costs. |
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