Research On Frequency Domain Design Method Of PID Control For Aeroengines

At present, aero-engine control systems are mainly using the PID controller, the controllerparameters are mainly tuned by time domain method. However, that is always a difficult problem totune the control parameters in the control system design process. Since the research on usingfrequency response analysis for the control parameters tunning of the aero-engine PID control systemis not much in our country, in this paper, the PID controller frequency domain design method for theaero-engine was researched.For some non-linear component model of turbo engine, the method to build up linear modelthrough identication of their frequency response was studied. The linear models of fuel amount-highpressure shaft speed, fuel amount-low pressure shaft speed and exhaust nozzle area-pressure ratio inthe envelope were built up, then accuracy was proved by means of step response.For the aero-engine shaft-speed and pressure ratio PI control system, which actuator wasincluded, the optimal tuning method was proposed considering the gain margin, phase margin andtime domain indices. The optional region of controller parameters which satisfied the requiredstability margin was obtained. In the resultant region, the parameters were optimized in terms of thetime domain performance indices. The optimal control parameters of different intermediate stateoperating points in the envelope were acquired. Simulations demonstrated that the tuned parametershad fine control results.The variation laws of aero-engine stability margin, phase crossover frequency, gain crossoverfrequency, closed-loop bandwidth in the envelope were analysed, then a PID tuning method withexact gain and phase margins was proposed. The gain and phase margins were obtained bytwo-dimensional interpolation in different operating conditions in the envelope. PI controllerparameters of shaft-speed system and pressure ratio system were tuned. Simulations illustrated theeffectiveness of the method.The frequency domain design method of robust PID controllers was proposed. Based on theextended edge theorem for time-delay systems, the stability region intersection of the edge systems ofthe uncertain systems class can be determined as the robust controller parameters set. Simulations ofthe non-linear model showed the benefit of the presented method, the robustness of the control systemwas improved.