Research on the Control Strategy of Variable Nozzle Turbocharger for Natural Gas Engine

A variable nozzle turbocharger (VNT) was applied to a 2.2-liter L4 natural gas engine, and a VNT control system was designed to operate it. Based on VNT matching test results, a VNT control strategy was studied, in which VNT adjustment is carried out through pre-calibrated VNT handling rod position, combined with a closed-loop target boost pressure feedback using proportional-integral-derivative(PID) algorithm. Experimental results showed that the VNT control system presented in this thesis can lead to optimized performance of VNT, increase engine volumetric efficiency over a wide speed range, improve engine dynamic characteristics and upgrade economic performance.