An On-Board Calibration Scheme for Map-Based Combustion Phase Control of Spark-Ignition Engines

To improve the transient-state combustion phase control performance and adapt to the shift of engine dynamics, this paper presents an on-board calibration scheme to control the combustion phase of spark-ignition (SI) engines. First, taking a crank angle of 50% of the mass fraction burnt (CA50) as the combustion phase indicator, the relationship between CA50 and SA is studied, and the influences of two other important factors, engine speed and load, are regarded, as the parameters need calibration or update. Second, a bilinear interpolation algorithm is employed to depict the polynomial influence function of speed and load on CA50, which is also used for the CA50 control later. Then, the on-board calibration issue is converted to a parameters identification problem, and a stochastic gradient descent algorithm is utilized to identify model parameters by iterative updates, which reduces computational complexity and the use of memory space for the embedded control system. Finally, the proposed strategy is verified on a gasoline SI engine and is applied to the combustion phase control in the feedforward channel, which can significantly improve the performance at a transient-state operating condition.