Auto-tuner Design For High Pressure Common Rail Pressure Control System

For the high-pressure common rail system,the working process is complicated and it is difficult to establish the accurate model.The design and setting process of pressure controller is complex for high pressure common rail.In practical application,PID control is still the main control core of most control systems.Many PID controller tuning methods often rely on artificial experience,and the tuning method by object model is difficult to establish accurate model for many complex objects.In order to improve the design convenience and reliability of PID control system,it is necessary to study the auto-tuning of PID control system.Therefore,this paper carries on the auto-tuner PID control system design for high-pressure common rail system.First of all,through the research of automatic setting technology,this paper establishes the relay feedback control system with hysteresis for common rail and the integrator with relay feedback control for common rail system.Obtaining the response signal and make a comparison.From the results,it can be seen that using the integrated relay feedback system can effectively improve the signal-to-noise ratio of the signal and enhance the system identifiability.Secondly,on the basis of getting common rail relay feedback signal,two methods based on fast Fourier transform and frequency sampling filter model are applied to extract the characteristic frequency respectively,and Monte Carlo simulation is carried out for the reliability and accuracy of the extraction.The comparison results show that the extraction results based on frequency sampling filter model are more accurate.Finally,the controller is designed according to the extracted characteristic frequency.This paper is based on two controllers design methods which are the expected open-loop transfer function and the closed-loop performance.The control system based on the expected closed-loop function tuning has better speediness and disturbance rejection performance.Finally,the automatic setting design of the common rail pressure control system is completed,and the control system structure is optimized to improve the performance of the control system.