Title: Optimal design of discrete-time fractional-order PID controller for idle speed control of an IC engine

Authors: Yi Yang; Haiyan Henry Zhang; Wangling Yu; Lizhe Tan

Addresses: School of Engineering Technology, Purdue University, 401 N. Grant Street, West Lafayette, Indiana 47907, USA ' School of Engineering Technology, Purdue University, 401 N. Grant Street, West Lafayette, Indiana 47907, USA ' College of Technology, Purdue University Northwest, 1401 S. US Hwy. 421, Westville, Indiana 46391, USA ' College of Engineering and Science, Purdue University Northwest, 2200 169th Street, Hammond, Indiana 46323, USA

Abstract: This paper aims at proposing a discrete-time fractional-order PID (FOPID) controller, which can stabilise the variation of the idle speed of an internal combustion engine due to the occurrence of the external load disturbance. The nonlinear idle speed dynamics is linearised to be approximated by a first order plus dead time (FOPDT) model so that the FOPID controller can be initialised by a Ziegler-Nichols type tuning rule. The initialised FOPID controller can stabilise the linearised model, but it may lose its control capability in nonlinear idle speed dynamics. Therefore, an optimisation problem is solved through genetic algorithm (GA) to minimise a cost function within a small region around the FOPID's initial parameters. The optimal discrete-time FOPID controller are compared to a conventional discrete-time PID controller. The simulation study reveals that the optimal discrete-time FOPID controller secures an excellent control performance to the nonlinear idle speed model.

Keywords: fractional-order PID; FOPID; discrete-time FOPID; idle speed control; ISC; internal combustion engine; ICE; FOPDT; Ziegler-Nichols rule; genetic algorithm.

DOI: 10.1504/IJPT.2020.108412

International Journal of Powertrains, 2020 Vol.9 No.1/2, pp.79 - 97

Received: 12 Feb 2019
Accepted: 04 Aug 2019
Published online: 13 Jul 2020 *

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