Study on Layered Close Loop Control of 4-Stroke Gasoline HCCI Engine Equipped with 4VVAS 2008-01-0791

Homogeneous Charge Compression Ignition (HCCI) has the potential of reducing fuel consumption as well as NOx emissions. However, it is still confronted with problems in real-time control system and control strategy for the application of HCCI, which are studied in detail in this paper.

A CAN-bus-based distributed HCCI control system was designed to implement a layered close loop control for HCCI gasoline engine equipped with 4VVAS. Meanwhile, a layered management strategy was developed to achieve high real-time control as well as to simplify the couplings between the inputs and the outputs. The entire control system was stratified into three layers, which are responsible for load (IMEP) management; combustion phase (CA50) control and mechanical system control respectively, each with its own specified close loop control strategy. The system is outstanding for its explicit configuration, easy actualization and robust performance.

After investigating the general valve control influence, the strategy combining classical PID and feed forward control strategy was proposed to realize effective control of IMEP and CA50 respectively. Meanwhile, an HCCI/SI mode transition control strategy, which is based on managing hybrid heat release curve, was studied. Experimental results show that it is possible to realize a real-time control with the layered management over HCCI operation

In order to evaluate and verify the HCCI control strategy, a virtual HCCI vehicle simulating platform was established, on which engine operation simulation and road simulation were combined. The results of simulation show that the layered control structure and control strategy can meet demands of real-time control on HCCI combustion in NEDC driving cycle.