ADRC for variable valve timing system of gasoline engine

The response and disturbance rejection ability of the electro-hydraulic variable valve timing(VVT)system make great influence on the performance of gasoline engine. It is a challenge for the classical linear controller because of the nonlinear behavior of the system including the mechanical wear, oil pressure, oil temperature and engine speed. The feedforward controller and liner ADRC are proposed in this paper based on active disturbance rejection concept. In the control framework which is simplified through using bandwidth-parameterization technique, the disturbance and unmeasured dynamics associated with VVT processes are treated as an additional state variable, which is then estimated and compensated for in real time. This reduces VVT system to an approximately linear, time-invariant process. A simulation platform of VVT system, based on AMESim/Simulink, is set up to test the performance of ADRC. The results demonstrate good dynamic performance in the circumstance of external disturbance and internal unmeasured dynamics.