Control of HCCI During Engine Transients by Aid of Variable Valve Timings Through the Use of Model Based Non-Linear Compensation 2005-01-0131
One of the main challenges with the Homogeneous Charge Compression Ignition, HCCI, combustion system is to control the Start Of Combustion, SOC, for varying load and external conditions. A method to achieve this on a cycle-by-cycle basis is to vary the valve timing based on a feedback signal from the SOC of previous cycles. The control can be achieved with two basic valve-timing strategies named the Overlap- and the IVC-method. The Overlap-method works by trapping of residuals while the IVC-method affects the effective compression ratio.
In an earlier paper it has been shown that if the two methods are incorporated into one controller, SOC can be controlled in a relatively large operating window although the transient performance was not sufficient. The reason is that the simple PI-controller cannot be made fast enough to cope with the transients without magnifying the cycle-to-cycle variations of the combustion into instability. In this work a model based control system that features a non-linear compensation, based on the inverse of the non-linear function from valve timings to ignition delay, is suggested and evaluated. The results show good transient performance. Control performance from engine tests is reported.
A combined engine and control simulation system is used for the development of the control strategies. The simulations are accomplished with a commercial cycle simulation code linked with a commercial control simulation code. The simulations are iteratively verified against engine test data. Engine tests are conducted on a single cylinder engine equipped with a hydraulic valve system.
Citation: Agrell, F., Ångström, H., Eriksson, B., Wikander, J. et al., "Control of HCCI During Engine Transients by Aid of Variable Valve Timings Through the Use of Model Based Non-Linear Compensation," SAE Technical Paper 2005-01-0131, 2005, https://doi.org/10.4271/2005-01-0131. Download Citation
Fredrik Agrell, Hans-Erik Ångström, Bengt Eriksson, Jan Wikander, Johan Linderyd
SCANIA CV AB/ KTH
SAE 2005 World Congress & Exhibition
Homogeneous Charge Compression Ignition (HCCI) Combustion on CD-ROM from the SAE 2005 World Congress-SP-1982CD, Homogeneous Charge Compression Ignition (HCCI) Combustion 2005-SP-1963, SAE 2005 Transactions Journal of Engines-V114-3