Relaxed Ziegler-Nichols closed loop tuning of PI controllers
Journal article, Peer reviewed
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Original versionHauge, F. & Lie, B. Relaxed Ziegler-Nichols closed loop tuning of PI controllers. Modeling, Identification and Control 2013, 34(2):83-97 10.4173/mic.2013.2.4
A modification of the PI setting of the Ziegler-Nichols closed loop tuningmethod is proposed. The modification is based on a combination of the Skogestad SIMCtuning formulas for ´´integrator plus time-delay´´ processes with the Ziegler-Nichols tuning formulas assuming that the process is modeled as an ´´integrator plus time-delay´´ process. The resulting PI settings provide improved stability margins compared with those obtained with the original Ziegler-Nichols PI settings. Compared with the well-known Tyreus-Luyben PI settings, the proposed PI settings give improved disturbance compensation. For processes with zero or a negligible time-delay, but with some lags in the form of time-constants, tuning based on ultimate gain and ultimate period may give poor results. Successful PI settings for such processes are proposed.