【摘要】 PID调节是一种广泛应用的、成熟的控制方法,可以使系统获得满意的动态品质,但在对于具有较大纯滞后时间的被控对象,采用常规PID控制就很难获得良好的控制质量,这种大纯滞后系统通常采用在PID调节基础上加Smith补偿的控制方法。PLC既能用在开关量的控制,又能用于模拟量的控制,特别是以其性能稳定可靠、编程简捷方便的特点得到大量采用。尤其是新型PLC很多都有内置PID软件,如西门子S7-200小型PLC,只需一条指令就能执行PID运算公式,在内置PID软件基础上加Smith算法可以简化编程。基于此分析了采用常规PID加Smith补偿对大纯滞后系统进行控制的方法,以S7-200型PLC为例,提出了在数字控制器PLC中实现该方法的具体途径,给出了在有内置PID软件的PLC中的实现Smith补偿的具体步骤和程序编制。实验表明,采用此方法对大滞后过程进行控制,程序编制简单,并且控制效果良好。更多还原

【Abstract】 PID regulation is a widely used,mature control method,satisfactory dynamic quality can be obtained.It is difficult to obtain good control quality for the controlled object with pure lag time,using conventional PID control,the big pure time-delay systems usually adopts the PID control with Smith compensation.PLC is used to the switch quantity control,and the analog quqntity control,and widely used especially with its characteristics of performance stable,reliable and convenient programming.There are many new PLC,especially the built-in PID software,such as Siemens S7-200 PLC,only call a PID instruction can execute PID operation.The PID algorithm can simplify programming with Smith conpensation based on the built-in PID software.The method to control a large lag system is analyzed by the conventional PID with Smith compensation.In S7-200 PLC,the specific way how to achieve this method in the digital controller PLC and the specific steps and programming to the PLC are presented.Experiments show that this method is adopted to lag process control and programming simple,and control effect good.更多还原