A Two-Stage Augmented Extended Kalman Filter as an Observer for Sensorless Valve Control in Camless Internal Combustion Engines

Camless internal combustion engines offer improvements over traditional engines in terms of improved torque performance and fuel economy, lower emissions, and pumping losses. Theoretically, their control flexibility provides electromagnetic valve actuators with the highest potential for improving efficiency. Sensorless control is one of the most important issues when implementing this new technology. The main contribution of this paper is a proposed observer comprising an augmented extended Kalman filter (EKF) and another EKF, which results in a sensorless control. The observer estimates the inductance of the actuator, which may vary. The proposed combination achieves a numerically efficient estimation. The proposed state observation structure avoids bulky and complicated measurement systems, which is an important advancement for real world applications. The introduced method is general and can be applied to problems in which it is not feasible or affordable to obtain position and velocity measurements. The current is measured, the position and the velocity of the electromagnetic valve are estimated with a robust method. The effectiveness of the proposed method is demonstrated using measured data acquired from an experimental setup based on an innovative electromagnetic valve actuator. A detailed comparative analysis of the arithmetic operations of the algorithm is also reported.