Abstract
Aeroengines are prone to failure due to their large range of working envelopes and bad working environments. Fault diagnosis and a fault-tolerant control strategy for aeroengines and control systems are important means to improve the reliability of aeroengine. In this article, the turbofan engine is taken as the research object, and the fault diagnosis and fault-tolerant control of an aeroengine control system are studied. First, based on the principle of component-level modeling and the algorithm of the extended Kalman filter, an adaptive turbofan model is established, and the adaptive effect of the model in the range of the full envelopment is verified by digital simulation. Next, based on the analytical redundancy provided by the adaptive model, sensor fault diagnosis and fault-tolerant control are studied. The low-voltage speed closed-loop control and EPR closed-loop control are designed, and the sensor fault-tolerant control based on analytic redundancy and the switching control rate is studied. The simulation results show that the filter based on the adaptive model can accurately locate and diagnose the sensor faults, and the sensor fault-tolerance based on the analytic redundancy and switching control rate can be effective fault tolerance for the sensor faults. Finally, as a hardware platform, this article selects MC203 VxWorks as an embedded system, the adaptive model for a turbofan engine as the research object, and has carried on the fault diagnosis and fault-tolerant control in the loop simulation experiment research; the experimental results show that the adaptive model can provide accurate analytical redundancy, and the real-time and fault tolerance of sensor fault effect is better.
Highlights
The aeroengine is known as the heart of the aircraft and plays an important role in the aviation industry [1]
The schematic diagram of fault-tolerant control based on analytical redundancy is shown in Figure 2; taking the high-voltage speed sensor as an example, if it does not fail, the sensor value of the real engine is used for PID control
The analytical redundancy, that is, the estimated value corresponding to the adaptive model, is used to replace the error value of the high-voltage speed sensor as the feedback signal for closed-loop control, so as to isolate the failed sensor and ensure the stability of the system
Summary
The aeroengine is known as the heart of the aircraft and plays an important role in the aviation industry [1]. The engine control system works in the harsh environment of high temperature and strong vibration, and the controller, sensor, and actuator are prone to failure [2]. Relevant factors have been considered in the process of processing and manufacturing, various faults may still occur, among which sensor faults account for more than four fifths of the total faults [3]. The improvement of safety requires fault diagnosis and fault-tolerant control, because when a fault occurs, the fault diagnosis can isolate it by finding the location of the fault. The fault-tolerant control system adopts appropriate means according to the type of fault, such as channel switching or adjusting the control law, so as to make the engine work normally or safely and minimize the impact of the fault
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