Automated PI controller tuning using a phase locked loop identifier module

PID (or three term) controller tuning in industry often uses the relay experiment to find the system ultimate data followed by the use of PID coefficient calculation rules. This paper first reports a new, flexible and more accurate method of finding system frequency response data including the system ultimate data. The paper then demonstrates how this new identification module can be used in closed loop to automate PI controller tuning and achieve classical performance specifications. A new algorithm is given along with a report - a Lab VIEW implementation