Closed‐loop combustion control of homogeneous charge compression ignition (HCCI) engine dynamics

Abstract

Homogeneous charge compression ignition (HCCI) is a hybrid of the spark ignition and compression ignition engine concepts. As in a spark ignition engine, a homogeneous fuel-air mixture is created in the inlet system. During the compression stroke the temperature of the mixture increases and reaches the point of auto ignition, just as in a compression ignition engine (or diesel). One challenge with HCCI engines is the need for good timing control of the combustion. Auto ignition of a homogeneous mixture is very sensitive to operating condition. Even small variations of the load can change the timing from too early to too late combustion. Thus a fast combustion timing control is necessary since it sets the performance limitation of the load control. As measurement for combustion timing feedback, the crank angle of 50% burnt has been used. This paper performs a comparative study of different cylinder-pressure based methods for estimating the crank angle of 50% burnt, CA50. The estimates are compared in terms of accuracy, robustness and feasibility for cycle-to-cycle real-time control. Dynamic models of CA50 are estimated using system identification as a means to find models relevant to engine control.

Double-Wiebe function: An approach for single-zone HCCI engine modeling

“…A key characteristic of HCCI is the rapid burning of the fuel/air mixture because of autoignition occurring almost simultaneously around the cylinder. Results from numerous researches on HCCI combustion have been published [1][2][3][4][5][6][7][8][9][10][11][12][13][14] in recent years. HCCI engines have been shown to achieve extremely low levels of nitrogen oxide emissions (NO x ) without catalytic converters.…”

Modeling of HCCI engine combustion for control analysis

“…There are several alternatives how to calculate the combustion timing and in this paper the combustion timing is calculated as the crank angle where 50% of the energy has been release, α 50 , [6]. The timing effects on α 50 were studied by varying the corresponding variables from a nominal operating condition of T in = 373 K, Q in = 1400 J, w = 1200 rpm, and R f = 0.93 vol% as described in Table II.…”

“…As soon as one cylinder passed exhaust valve opening, pressure data were transferred from the AD card to the control program. When new pressure data was available in the data acqusition system, a simplified rate of heat release calculation based on pressure, [6], was performed and thereafter combustion timing was calculated. The two fuels have different autoignition temperatures, a property that was used to change the combustion timing.…”

Closed-loop control of HCCI combustion for DME using external EGR and rebreathed EGR to reduce pressure-rise rate with combustion-phasing retard

“…5 shows, this study designs the closed-loop control system for feedback control of HCCI combustion using LabVIEW program due to its flexible and scalable design. Since practical and reliable variables are necessary for the fast response closed-loop control [31][32][33], one input variable of (fuel/air-equivalence ratio (/)) and two output variables (50% burn point (CA50) and heat-release efficiency (g hr )) were selected as the suitable variables for feedback control based on a recent study of the authors [34]. Here the heat-release efficiency used in this study is the ratio of the cumulative heat release during the period from the start of LTHR to the end of HTHR (Q hr ) to the lower heating value of the fuel supplied in the gas phase (Q LHV ), as shown in Eq.…”