Siemens Module B3 ユーザーズマニュアル

 

 

 

 

 

 

 

   

 

 

 

 

T I A  Training Document 

Page 23 of 64 

  Module 

 

 

The figure below shows the performance of the P-controller: 

 

 

Time 

System 
Deviation 

             
Setpoint

  
Actual  
Value 

Controlled 
Variable

 

 

 

 

 

 

 

 

 

 

 

The advantages of this controller type are, on the one hand, its simplicity (the electronic 

implementation can, in the simplest case, consist of merely a resistor); on the other hand, in its 

prompt reaction in comparison to other controller types.  The main disadvantage of a P-controller is 

its lasting system deviation.  The setpoint is never completely reached, even over long periods of 

time.  This disadvantage as well as a reaction speed that is not yet ideal can be minimized only 

insufficiently by using a larger proportional factor, since otherwise, the controller will overshoot; that 

is, it will overreact so to speak. In the worst case, the controller oscillates continuously, whereby the 

controlled variable is moved by the controller itself away from the setpoint -instead of by the 

disturbance variable.   

The problem of continuous system deviation is best solved by the integral action controller. 

Preface     Fundamentals     Discontinuous Action Controller     Controller Block (S)FB41     Setting the System     Appendix 

B3 

Issued: 02/2008                                                                                                                                     Control Engineering with STEP 7