The highly pulsated flow output of an engine causes a nonlinear dynamic behavior of a variable geometry turbocharger (VGT). A method, namely active control turbocharger with a passive actuator, was previously developed to recover more energy than the steady-state-based conventional methods. An accurate transient model is required to optimize and improve the control system performance. This paper focuses on the formulation of the unified control-oriented model of the VGT turbine and passive actuator. The bond graph framework is utilized to build a unified system consisting of three principal parts, which are the VGT turbine, the intake air path, and the passive actuator. The simulation results were then benchmarked with the experimental data by varying two tune-able parameters of the actuator. The model has shown agreeable results showing a similar pattern while being changed from one to another condition with the errors of less than 6.5% of cycle-averaged power for PCT cases. In summary, the model has shown its capability to replicate the VGT system behavior with the passive actuator and its possibility to be applied in the optimization process of the system performance.
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