Torque balance control for light-duty diesel engines using an individual cylinder IMEP estimation model with a single cylinder pressure sensor

- Our paper presents the torque balance controller using an IMEP estimation model.
- The IMEP estimation model estimates the IMEP of individual cylinder using only a single cylinder pressure sensor.
- The torque balance control algorithm is designed by model reference adaptive control scheme.

A closed-loop control for torque balance using a cylinder pressure sensor can improve drivability and can suppress noise from light-duty diesel engines. However, the closed-loop control requires cylinder pressure sensor cost and computational time about pressure data. This paper proposes a torque balance control algorithm using a torque estimation model to solve these problems. The proposed algorithm consists of an indicated mean effective pressure (IMEP) estimation model and model reference controller. The estimation model estimates the IMEP of each cylinder. IMEP represents the indicated torque from the combustion of each cylinder that generates the crankshaft rotational dynamics. An IMEP estimation model is developed for all four cylinders based on the relationship of IMEP and crankshaft rotation. The proposed model also contains compensation parameters to solve dispersion and inequality problems of crankshaft acceleration. The proposed estimation algorithm only requires crankshaft acceleration and a single cylinder pressure sensor. This algorithm significantly reduces the cost required for four-cylinder torque control and is more suitable for real-time torque balance control because the IMEP computational time for other cylinders can be eliminated. The estimated IMEP by model is then controlled for real-time torque control which controls the IMEP of the individual cylinder for torque balance. The torque balance control algorithm is designed by a model reference adaptive control scheme and controller stability is derived by Lyapunov stability theorem. The IMEP estimation algorithm and torque balance controller were embedded and validated in a real-time engine management system. In conclusion, torque balance control can use estimated IMEP to reduce the IMEP variation of each cylinder.