Robust control for an electromagnetic actuator for a camless engine

The increase of the effective efficiency of the internal combustion engines is important for the fuel consumption reduction and the CO2 emission reduction. The variable engine valve trains are important for the gas exchanges and influence directly the effective efficiency of the internal combustion engine. With the increased electrifications of the vehicles, variable valve train based on electricity driven actuators presents interest for investigation for gasoline engines for vehicular application. This article presents an innovative application of an electromagnetic actuator for a future variable engine valve train. The actuators are designed for small gasoline engine. The design of a high performing and dynamic electromechanical system leads to a nonlinear behavior of the actuator. The nonlinearities that have to be faced come from the magnetic laws and the mechanical friction. In the final control strategy, it is proposed to compensate them both with nonlinear feedforward actions and with a linear robust feedback controller, which is able to reject all what cannot be predicted. An experimental test bench is built for the correlation of the control model with experimental measures. Control strategies are developed and the performance indicators of the actuators are evaluated. The robust controller method uses CRONE system control methodology. The investigations show that very good dynamic performances of the controller are obtained.