Design And Verification Of Electronic Control Unit For Micro Turbojet Engine

As a light-weight aero-engine,the micro turbojet engine is widely used in the power systems of unmanned reconnaissance aircraft,cruise missiles,target drone and many other aircraft.The matching control system is the key component to ensure its stable operation.Therefore,taking the control research of micro turbojet engine as the starting point and the production engineering application as the ultimate goal,a complete control system for a certain type of micro turbojet engine has been developed and tested on the ground.The main work accomplished is as follows.(1)Establish the design goal and overall scheme of the control system.The weight of the engine used in this paper is 780 g,the maximum thrust is 6 da N,and the maximum rotation speed is 160000 RPM.In order to achieve the design goals of light weight,high reliability,easy operation,rich sensor signals and strong expansibility,the distributed controller based on LIN bus communication is determined as the design framework of the control system.The control system includes the main controller,the auxiliary controller,the panel controller and the measurement and control system.The data interaction among these controllers is realized on LIN bus.(2)The hardware of controller are designed according to the characteristics of actuator and sensor.The actuators of the engine include starting motor,fuel valve,igniter and fuel pump.The sensors of the engine include rotation speed sensor,exhaust temperature sensor,atmospheric temperature and humidity sensor,atmospheric pressure sensor,attitude sensor,vibration sensor and bench thrust sensor.By analyzing their respective working principles and signal characteristics,the corresponding driving circuit and signal acquisition circuit are designed.A complete control system hardware scheme is synthesized and the controller is manufactured.(3)The lower computer software and upper computer software are designed.Free RTOS is adopted as the software architecture of the main controller and the auxiliary controller,and the overall function is realized through the design and distribution of tasks.By redesigning the communication protocol layer of LIN bus,the utilization rate of bus bandwidth is improved to meet the demand of high-speed communication between controllers.The upper computer software of the measurement and control system is designed based on Labview to realize the functions of measurement,control and data recording of the control system.(4)The engine starting control method is designed.The starting process of the engine is divided into six stages: motor starting,ignition,preheating,acceleration,disconnection and idling.The specific control parameters and state transition conditions of each stage are gradually determined by the engine commissioning experiment.The starting time of the engine controlled by this method is less than 35 s,and the maximum exhaust temperature is less than630℃.(5)The engine speed model and the thrust model in the static ground environment are established.The dynamic coefficient method and neural network method are used to establish the engine model through the open-loop test data.The established models are verified by two sets of data,and the results show that the modeling errors of these models established by these two methods are less than 2% and 3% respectively.(6)The engine speed control algorithm based on gain scheduling PI is designed.By selecting three design points of speed command,the corresponding controller parameters are designed at each point,and the scheduling relationship between controller parameters and speed command is established by linear interpolation.Through numerical simulation and commissioning experiment,the expected speed control performance is achieved.