Modeling and identification of a current to vacuum transducer and VNT actuator

This paper describes a model for a current to vacuum transducer (CVT) in conjunction with a variable nozzle turbocharger (VNT) actuator. CVTs are commonly used in automotive applications for the control of exhaust gas recirculation valves, throttles, port deactivation devices, and variable geometry turbochargers. They are relatively cheap, however, their dynamic behavior exhibits serious nonlinearities. The model developed in this report serves to aid in the development and initial validation of control algorithms for vacuum actuated devices. The dynamics between CVT duty cycle input and VNT guide vane position are developed here from first principles and experimental data. The experimental data shown in this report were obtained from a 2.0 liter DI Diesel engine, equipped with the VNT-15 VNT from Allied Signal