Application Study On Air-path Control Algorithm Of Diesel Engine Based On Sliding Mode Control

In-cylinder condition and fuel parameters are the key factors which determined the in-cylinder combustion. The fuel parameters control is instantaneous and precise for the modern common-rail diesel engine. Thus, in-cylinder condition control is an important way to improve in-cylinder combustion condition, and do benefit to the application of the advanced combustion modes and switch control of combustion modes. The gas condition of intake manifold at the inlet valve closing time determined the in-cylinder gas condition before combustion. Thus a good control of intake pressure, temperature and composition of inducted flow by complex air-path actuating mechanism offered a great research value to the control of diesel engine combustion and combustion modes switch.A boost diesel engine simulation model equipped with EGR and VGT system, and an alternative combustion mode diesel engine simulation model equipped with throttle valve, EGR and VGT system are established by GT-Power based on the 4H diesel engine bench. Boost pressure and mass flow rate are chosen to be system outputs, and an improved Super-Twisting controller is designed for the conventional engine model based on second sliding mode algorithm. Similarly, the intake and exhaust pressure, oxygen mass fraction of inducted flow are chosen to be system outputs, and two sliding mode controller are designed for the alternative combustion mode engine model based on integral sliding mode and model reference sliding mode control algorithm. The performance of the designed controller is evaluated by co-simulation using GT-Power and MATLAB/Simulink. At last, the process of combustion modes switch of the alternative combustion mode diesel engine running low temperature combustion and conventional compression ignition combustion mode is simulated by the co-simulation platform based on sliding mode control.The result unveiled that, compared with the separated PI algorithm the sliding mode control strategy has significant merits, such as good steady and transient tracking performance, strong anti-interference and robustness, and designed parameters are not sensitive to the variation of operating point, smooth switch control and so on. This innovative control strategy can provide a reference method for cooperative control of multiple parameters of the complex and advanced air-path system and the switch control between the multiple combustion modes.