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Camless internal combustion engines offer improvements over traditional engines in terms of increased torque performance and fuel economy and of decreased emissions and pumping losses. The main goal of this project is to replace the camshaft system with electromagnetic actuators to control the intake and exhaust valves of internal combustion engines. Theoretically, electromagnetic valve actuators provide, with their control flexibility, the highest potential for improved efficiency. Sensorless control is one of the most important issues in implementations of this new technology. The main contribution of this paper is the proposal of a hysteresis hybrid observer to be applied for achieving a sensorless control. This observer consists of a combination of an extended Kalman filter with a hybrid automation. The proposed state-observation structure avoids bulky and complicated measurement systems, which is an important advancement for real-world applications. The introduced method is quite general and could be applied to other problems in which it is not feasible or affordable to obtain position and velocity measurements. In fact, in application with synchronous machines, such kind of an observer can represent a general approach to obtain a sensorless control. The proposed hysteresis strategy not only avoids chattering problems when the velocity is close to zero but also allows the use of unobservable sets and sets in which the observability level is too low to guarantee sufficient variation in the Kalman gains. The proposed structure consists of two models, each model containing two embedded switching conditions. The current is measured, and the position and the velocity of the electromagnetic valve are estimated. The effectiveness of the proposed method is demonstrated using measured data acquired from an experimental setup based on an innovative electromagnetic valve actuator.
Date of Publication: Nov.-Dec. 2012