Research On Control System Design And Experiment Of A Micro Turboprop Engine With Variable Pitch

As a non-conventional aero-engine,micro turbine engine is widely used in the fields of unmanned aerial vehicle,cruise missile and aircraft model.The micro turboprop engine rig test system with fuel flow and adjustable pitch angle is an ideal platform for the research of aero-engine modeling,multivariable control and advanced control.The pitch-changing mechanism of traditional engines with normal or large thrust is complex and relatively costly.The limited installation space of micro-turboprop engines restricts the use of the mechanism.Therefore,micro turboprop engines on sale all have fixed pitch angle.In this paper,an experimental bench for micro turboprop engine with variable pitch propeller is established,and the controller design,modeling and control system of the engine are also studied.An experimental platform of micro turboprop engine based on SPT10 micro turbine engine is built and the pitch-changing mechanism is designed to realize the free regulation of pitch angle.An electronic controller of the engine is developed independently based on the original controller.The micro turboprop engine can start reliably by utilizing the controller.Furthermore,the basic dual variable control of the engine by fuel and pitch angle is realized in the normal operation of the engine.The engine power is controlled by adjusting fuel flow in open loop and the pitch angle is used as the control variable to control the propeller speed unchanged in a closed-loop way.The test results show that the control system can keep propeller speed constant while fuel input changes and the error of propeller speed is less than 1.37%.In order to reduce the risk of research on advanced control on micro turboprop engine with variable pitch platform,a hardware-in-the-loop simulation system is designed and the hardware and software realization of the system is introduced.In order to improve the simulation confidence of hardware-in-the-loop simulation system,an improved dynamic coefficient modeling method is proposed to establish a mathematical model of the micro turboprop engine based on test data.On the basis of the core engine speed model,a method is proposed that the output power of the engine is designed as a function of the propeller speed and the core engine speed.Then the propeller speed model can be obtained by iteration with the rotor dynamics method.According to the test,the error between the model and the test data is less than 8%,and the model has significant real-time performance.A method of variable speed control system for turboprop engine is presented in this paper.Firstly,the relationship among fuel consumption,power and rotary speed of each operating point in the steady state characteristic diagram of turboprop engine is analyzed.The operating line is figured out in the steady state characteristic diagram,which is the design basis of Engine Thrust Management System(ETMS).Secondly,the reference model sliding mode multivariable control is used to design the control law to follow the speed instructions given by ETMS.Finally,the optimization of the minimum fuel consumption operating line is realized,and the control system designed is applied to the numerical model of micro turboprop engine.The simulation results show that compared with the constant speed control system,the system can reduce the specific fuel consumption by 2.37% on average.Furthermore,the method can enable the pilot to manipulate the turboprop aircraft by using only one throttle lever,which can greatly reduce the pilot operation burden.