Optimal trajectory operation of a cogging torque assisted motor driven valve actuator for internal combustion engines

Cogging torque assisted motor drives (CTAMD) are a novel electromechanical valve actuation (EVA) technology for internal combustion engines that have a compact size and do not require conventional valve springs. Despite using an unoptimized position trajectory, the CTAMD was shown to produce the smallest ohmic loss at 6000 RPM when compared with other EVA systems found in literature. This paper presents a minimum-energy trajectory for a CTAMD and validates its improvements. First, an ohmic loss model for the CTAMD is formulated. Next, the optimized trajectory is generated through the use of the Nelder-Mead direct search algorithm. The optimized trajectory is then tested on a previously studied experimental CTAMD setup. Finally, the results of the experiments are analyzed to determine the performance improvements and practical advantages of the optimized trajectory. The optimized trajectory enables a further reduction of ohmic loss and reduces the number of MOSFETs required to drive the CTAMD by 75%.