S7-200 PLC的PID自整定算法剖析

经典PID控制器的设计根据被控对象的数学模型,选择调节器的形式,如模型为确知的传递函数,用根轨迹法或频率响应法来确定PID参数,如对象模型不确知,往往用试凑法来整定控制器参数。对复杂多变的现场,这费时费力,且整定的控制器性能有限。S7-200 PLC已经支持PID自整定功能,对其所用继电反馈算法予以剖析,讨论其特点。

During designing of classical PID controller,should set adjustor by maths module.If the module is a known transfer function,can set PID parameters by root locus method or frequency-response method.If the maths module is indeterminate, can generally get controller parameters by cut-and-try method,but which will spend so much time,and get a poor result that the controller cann＇t adapt itself,perfectly.Now,S7-200 PLC can automaticlly adjust parameters of PID by relay feedback method.This paper analyses character of the method in detail.