【作者】 王平；

【导师】 谷立臣；

【作者基本信息】 长安大学 ， 机械电子工程， 2018， 硕士

【摘要】 液压设备以其传动平稳、能容量大、调速方便及对复杂作业工况适应性强等优点,被广泛应用于宇宙航行、海洋开发、工程机械等诸多领域。由于液压传动的能量利用率不高,致使液压设备整机效率较低,因此随着电机变频调速技术的发展,高效率和节能效果显著的变转速液压系统,在许多工程实际中得到了广泛应用。但变转速液压系统带来高效率和节能的同时,也存在的控制精度低、响应速度慢和低速稳定性差等问题,这限制了其在更多工业领域中的应用。因此,研究如何改善提高变转速(尤其是低速段)液压系统的控制性能具有重要实际意义。从实际工程应用的效果看,常规的PID反馈控制由于算法成熟、稳定性好、简单易实现等优点,因此在工业过程控制、航空航天控制等诸多领域中应用最广。在实际测控系统中,由于变频环境下的电磁干扰,测量信号总会混杂多种干扰成分,如电磁干扰、高频噪声等,而直接将混有干扰的反馈信号用于反馈控制,会影响系统的控制性能,甚至不能正常工作。针对此问题,本文采用理论分析、仿真分析和实验验证相结合的方法,针对变转速泵控马达液压系统测控平台中的电磁干扰问题,提出对系统反馈的压力和流量信号的时频域特性分别进行滤波处理,滤波后的信号再作为PID控制器的反馈输入的方法,为提升系统控制性能提供实用方法。论文的主要研究内容如下:(1)根据数字滤波器的设计原理及方法,以巴特沃斯低通数字滤波器和零相位数字滤波器为例,在MATLAB软件中通过编程完成了对二者的程序设计,通过滤波仿真对比分析得到了二者的滤波特性。仿真结果表明:巴特沃斯低通数字滤波器是非零相位滤波器,能够有效滤除高频干扰成分,但存在相位滞后;零相位数字滤波器能实现零相位滤波。(2)以变转速泵控马达液压系统为物理模型,建立各子系统数学模型,推导系统全局数学模型,并据此在Simulink中搭建系统仿真模型。通过流量闭环控制仿真实验,对比分析流量反馈信号未滤波处理、非零相位滤波处理和零相位滤波处理三种情况下,系统流量的动态响应、控制精度及鲁棒性。仿真结果表明:对反馈信号零相位滤波处理比巴特沃斯低通数字滤波器具有更好的控制精度和鲁棒性。(3)以变转速泵控马达液压系统为实验基础,设计了闭环控制反馈信号滤波实验程序和对比实验。通过LabVIEW软件和MATLAB软件联合编程,完成了反馈信号零相位滤波程序的设计,实现了对LabVIEW软件编程的二次开发。分别设计了压力、流量闭环控制反馈信号未滤波、非零相位滤波、零相位滤波三种情况下的对比实验,实验结果表明:反馈信号未滤波处理虽然能达到稳态,但存在很大波动;反馈信号非零相位滤波处理具有稳态误差,控制精度低;反馈信号零相位滤波处理不仅能达到稳态,且波动很小,具有更好的控制精度和鲁棒性。更多还原

【Abstract】 Hydraulic equipment is widely used in space navigation,ocean development,engineering machinery and many other fields because of its advantages of stable transmission,large capacity,convenient speed adjustment and strong adaptability to complex working conditions.Due to the low energy utilization of hydraulic transmission,the efficiency of the machine is low too.With the development of the variable frequency speed regulation technology,variable speed hydraulic system with remarkable energy saving effect has been widely used in many engineering practices.However,the high efficiency and energy saving brought by variable speed hydraulic system,the problem of low control precision,slow response speed and low speed stability also limits its application in more industrial fields.Therefore,the study of how to improve the control performance of hydraulic system has important practical significance.From the point of view of practical engineering application,the conventional PID feedback control is widely used in industrial process control,aerospace control and other fields due to the advantages of mature algorithm,good stability and easy implementation.In the actual measurement and control system,because of the environment and other external interference,the measurement signal will always be mixed with a variety of interference components,such as electromagnetic interference,high-frequency noise,which affects the control performance of the system.In view of this problem,this article uses the method of theoretical analysis,simulation analysis and experimental verification,based on the measurement and control platform of the hydraulic system of the variable speed pump-control motor,a new method of filtering the feedback signal and filtering the signal into the feedback input of the PID controller is put forward,which can be used to improve the control performance of the system.The main research contents of the thesis are as follows:(1)According to the design principle and method of digital filter,taking Butterworth Lowpass digital filter and zero phase digital filter as example,the design and realization of the two are accomplished by programming in MATLAB,and the filtering characteristics are obtained by simple filtering simulation,The simulation results show that the Butterworth Low-pass digital filter is a non-zero phase distortion digital filtering,which can filter out the high frequency interference component,but has phase lag,while the zero phase digital filter can realize zero phase distortion digital filtering.(2)With variable speed pump-controlled motor hydraulic system physical model,the mathematical model of each subsystem is established,and the global mathematical model is deduced,and then the system simulation model is built on the basis of Simulink.Through the simulation experiment of flow closed loop control,the dynamic response,control precision and robustness of the system flow are compared and analyzed in three cases,such as the filter processing of flow feedback signal,non-zero phase distortion digital filtering processing and zero phase distortion digital filtering processing.The simulation results show that: the feedback signal zero phase distortion digital filtering has better control precision and robustness.(3)Based on the experimental basis of variable speed pump-control motor hydraulic system,a closed-loop control feedback signal filtering experiment program and contrast experiment are designed.By using LabVIEW and MATLAB,the design of the feedback signal zero phase distortion digital filtering program is completed.The contrast experiments of pressure,flow closed loop control feedback signal don’t filter,non-zero phase distortion digital filtering and zero phase distortion digital filtering were designed,and the result shows that,although the filtering process can achieve steady state,there is a great fluctuation,and the feedback signal is not zero phase distortion digital filtering processing has steady state error and low control precision.The feedback signal zero phase distortion digital filtering can not only achieve steady state,but also has a little fluctuation,and has better control precision and robustness.更多还原