Control of recompression HCCI with a three region switching controller

Homogeneous charge compression ignition (HCCI) presents new challenges in combustion phasing control due to the lack of direct ignition trigger. In addition, recompression HCCI possesses cycle-to-cycle coupling through trapping a large portion of the exhaust gas in the cylinder. This paper examines the change in the cycle-to-cycle coupling around different operating points in recompression HCCI and show that there are three qualitative types of temperature dynamics: smooth decaying when combustion phasing is early, oscillatory when phasing is late, and strongly converging with moderate combustion phasing. As a result, a three region switching linear model that combines three linearized models can capture the qualitative change in system characteristics. Based on this model, a three region switching controller is designed and shown in experiments that it can track a wide range of desired combustion phasing and improve the variance of combustion phasing over open-loop operations. In the last part of this paper, two semi-definite programming (SDP) formulations are presented to prove the stability of the switching control/model framework. (C) 2012 Elsevier Ltd. All rights reserved