Design And Optimization Of EHA Speed Control System

Aircraft actuation system is not only an important research direction of aircraft technology, but also the key part of the driving and control system of aircraft. With the improvement of the speed and comprehensive performance, there is a higher requirement for actuation system of aircraft. The Electro Hydrostatic Actuator (EHA) is a complicated system which is integrated with the electromechanical, hydraulic and control. Its advantages of excellent reliability, maintainability and efficiency help it get more and more attention, and EHA is becoming the focus of aircraft actuation system research. At present, the domestic research on aircraft EHA actuator is still in its infancy stage; therefore, a basic research is carried out on its key technology of speed control system in this paper.The specific research contents and research results are as follows:(1) At first, the basic structure of EHA and the particularity of its brushless motor with high speed and high voltage (270V) are introduced and the appropriate mode of motor speed control is selected according to its working principle. The realization of the principle and the working process of the speed control of the motor is analyzed and discussed comprehensively, and basic steps for design and optimization of the speed control system are shown.(2) According to the working principle of EHA motor speed control system, the block diagram of closed-loop control of motor speed control system and hydraulic pump, actuating cylinder is established. The design requirement of speed regulation system in EHA is analyzed, and the optimization object is optimized. After mathematical model of the system is analyzed, an appropriate controller is designed. The electric current loop and speed loop with PID controller with variable parameter are set to realize double closed-loop feedback control of motor speed control system in this paper.(3) The methods of PID controller design and basic principle of Genetic Algorithm (GA), Particle Swarm Algorithm (PSA) are introduced. The feasible region based on the PID parameters optimization of mathematical model of speed control system is calculated. Taking the ITAE (Integral of Time-weighted Absolute Error) index of the motor output speed in the model as the optimization index, the parameters of PID regulator are optimized by improved Genetic Algorithm and Particle Swarm Algorithm using Matlab software. The parameters of the PID regulator are tested as sample under different load conditions, and the variable parameters of the PID regulator are adjusted by fitting equation, and the speed control system is with good response and disturbance rejection performance under different load conditions.(4) Combined with the actual situation, DSP chip is used as the controller of motor control system, and the hardware of the control system are designed. The realization of digital PID regulation and the generation of PWM signal based on DSP are introduced.In this paper, the problem of design and optimization of aircraft EHA speed control system is researched to achieve the minimum output speed adjustment time as main optimization goal, following as far as possible to reduce motor speed overshoot as the optimization criterion. After the algorithm optimization, many group of optimal PID regulator parameters are found, and the adaptive adjustment of the PID regulator parameters is realized by fitting equation, which makes EHA have a better responsiveness and robustness performance.