Multi-Objective Regulating And Protecting Control For Aero Engines

With the changes of the aero engine proplusion systems enviroment and the working conditions (such as speed, accelerating, decelearating, etc), the aero engine aerodynamic and thermodynamic process will change greatly, the control problems have some particularites, so the basic problems of the aero engine control should be researched.This paper makes scientific research and in-depth discussion on aero engine control as follows:First of all, the paper analyzed the control tasks, safe boundaries during working, the aero engine working conditions, and the contradiction between the shortage of the control parameter numbers and the of the controlled parameter numbers, the paper presented a multi-objective regulating and protecting control problem in aero engine, which had states constraints, outputs constratints and the functions constraints combinated the states with ouputs. And the paper expounded the multi-objective control problem is a multi-model control problem, and proposed the multi-loop control system in structure, and according to one switching strategy to control. The concept is that we can decompose the safety problem and rapid response in aero engine control. The normal control loop control the aero engine to ensure the aero engine performances. And when the aero engine works near the security boundaries, the control system switched to the protection control loop to ensure the safety problem. And through the relatively simple method to switch between the controllers, the aero engine can get balance between the rapid response and safety.Secondly, the paper analyzed the multi-loop switch strategy in aero engine. The Min/Max strategy was researched detailly. The paper analyzed the andvantage between the dynamic response performance and the safety in Min/Max switching strategy. And the paper detailed the Min/Max switching strategy's mechanism, pointed out that the Min/Max switch strategy's shortcomings. Upon completion analysis of the Min/Max switch strategy, the paper presented a modified strategy to remove the former deficiencies. The strategye is judged by real-time control targets in the course of running the state which in turn choose the engine control loop. Based on the Lyapunov function, the paper gave stability conditions of the multi-loop switching.Thirdly, this paper dealt the turbofan engine with multi-loop switching control method. The paper used the equilibrium manifold expansion model to give safe parameters'models in turbofan engine, and analyzed the dynamic characteristics. The simulations show that using the method not only can improve the dynamic performance of the engine control system, but also can guarantee the stability in some occasions.Finally, this paper used the switching control design method to ramjet control system. The paper researched the demands and the constraints in designing the control system, and gave the dynamic characterisitics of sub-systems. Controlled paremeters and the models were given, and the uncertainties were investigated. Then through some simulations, the paper showed that using the method the safety can be guaranteed, and the performance can be got. With the method, the conservatism is reduced, the dynamic performance is improved and the multi-loop controllers are regulated well.