On Key Technologies Of Distributed Engine Control System

The next revolutionary change in aero-engine control systems will be the physical distribution of control functions,namely the Distributed Engine Control(DEC)system.The concept of distributed control of aeroengines originates from industrial automation,which features the utilization of advanced data bus,smart sensors and actuators.The implementation of the DEC system facilitates the application of advanced control modes and control algorithms such as active control,model-based control,and brings a series of advantages such as weight reduction,modularization,and high reliability.This paper carries out research on key technologies of aero-engine distributed control system,including ○1 the distributed architecture and bus communication scheme,○2 distributed system stability analysis and control algorithm design,and ○3 distributed hardware in-loop simulation.Firstly,a distributed architecture which is based on processor nodes is proposed.The processor nodes are in charge of the signal processing and the local close-loop control of actuators,which effectively reduces the calculation load of electronic controller and improves the modularity of the system.Based on the architecture,a bus communication scheme is designed based on Time-Triggered Controller Area Network(TTCAN)protocol and its bus load is evaluated.The evaluation result shows that the transmission rate between 250kbit/s and 1Mbit/s meets the needs of signal transmission.Subquently,Validation of the bus communication scheme is performed using True Time toolbox.The simulation result shows that the transmission delay of the TTCAN protocol is up-bounded,which effectively avoids the transmission uncertainty caused by the arbitration mechanism.Secondly,the transmission delay and packet dropout caused by serial data bus are analyzed,and the mathematical description of the distributed system is obtained using the time-delay system approach,which takes the delay and packet dropout into account simultaneously.Based on the description,the stability criterion and control algorithm design method of distributed system are presented: ○1 The maximum delay and the number of packet dropout allowed by the system are calculated.Results show that the stability criterion presented in this paper is reliable and can be used to analyze the tolerance degree of distributed systems for delay and packet dropout;○2 The the guaranteed cost control and regional poles assignment techniques are proposed to design control gain matrices with both strong delay/dropout robustness and satisfactory dynamic performance;○3 Then the above work is extended to the case of engine deterioration.Theoretical calculations and simulation results show the robustness against delay and packet dropout are not affected significantly by the engine degradation.Finally,the automatic code generation technology is utilized to realize the rapid prototyping of the hardware-in-the-loop(HIL)simulation platform,whereby the control logic of the electronic controller and the real-time and reliability of the information interaction are validated.The verification experiment results show that: ○1 The TTCAN node designed synchronizes with the time master node accurately and start broadcasting messages within 16 bus time units after the specified time window is activated,of which the real-time performance complies with the TTCAN protocol;○2 In the case of bus communication,the engine works safely and reliably through all power conditionas.The result of the HIL simulation is consistent with the digital simulation.Since all the software components of the HIL platform are automatic generated,the bugs are effectively avoided,which lays a solid foundation for further development of the distributed engine control system.