Integral Control

Navigation:  Library > Signal > Control > PID Control >

Integral Control

Previous pageReturn to chapter overviewNext page

With integral action, the controller output is proportional to the amount of time the error is present. Integral action eliminates offset that remains when proportional control is used.

 

controller output = (1/Ti)*int(error)

 

where the parameter Ti is called the integral time. Integral action is also know as reset and the parameter Ti as reset time.

 

Integral action gives the controller a large gain at low frequencies that results in eliminating offset. Integrals give information concerning the past. That is why integrals are always late. Integrals provide stability but have a tendency to get stuck in the past. In most controllers the proportional and integral action are combined. The output of the combined proportional and integral action (in s-domain) is then:

PI_Equation

with E equal to SP - PV.