Research On Fast Tracking Control Strategy Of Speed And Torque For Engine-dynamometer System

Engine performance test,calibration of parameters in ECU,and vehicle dynamic simulation are inseparable from engine-dynamometer test benches.At present,test benches controlled under traditional PID have some problems such as insufficient transient control performance and long tuning period.Therefore,it is an urgent need for industry to develop an advanced algorithm that can improve benches'transient speed/torque response performance with simple parameter scheduling and adaptive ability.In this paper,control algorithms for speed loop and torque loop in engine-dynamometer bench were developed and then validated in a GDI engine model with a calibrating accuracy of 95%.The specific research work is summarized as follows:1.A model reference adaptive control method based on disturbance compensation was designed for the speed loop.Firstly,the dynamical equation of dynamometer was modeled and then Extend State Observer?ESO?was designed to simplify the system into an integeral part by observing and compensating disturbance from inside and outside the system.Secondly,a Model Reference Adaptive Control?MRAC?feedback was developed based on Lyapunov function for the system compensated by ESO,which simplifies the tuning of feedback control parameters.Finally,Recursive Least Square?RLS?was adopted to identify the inertia of dynamometerJ_d so that ₀b of ESO can be adjusted online.The combination of ESO,MRAC and RLS greatly simplifies the tuning process of controller,with only one paremeter _o?needs tuning.Simulation results show that the mean absolute error of relative percentage error of transient speed control is 1.103%.2.A control method based on MAP reconstruction and ADRC feedback was designed for the torque loop.Firstly,a polynomial model of engine torque was established,and 8 working points for parameter identification were selected based on D-Optimal theory,and the identified polynomial model was then used to generate initial MAP to reduce burden of MAP reconstruction.Secondly,the driving characteristic MAP is reconstructed based on the stochastic gradient descent method,and the inverse and monotonicity correction were carried out to get feedforward control MAP.Finally,the model from throttle to engine torque is established,and the ADRC feedback law is designed.Simulation results show that the absolute of torque tracking error is 1.62N·m under the ETC suburban condition.3.HIL test enviromen was built with bottom driver developed and integrated with control algorithm,and HIL test was carried out to validate the real-time performance of the control algorithms proppsed in this paper.In summary,the control methods proposed in this paper can effectively improve the speed and torque tracking performance of engine-dynamometer bench,which has a good adaptability with control parameters easy to adjust.