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Dynamic and steady state performance comparison of line-start permanent magnet synchronous motors with interior and surface rotor magnets

Ogbuka C., Nwosu C., Agu M.

Archives of Electrical Engineering

2016

Vol. 65, nr 1

105--116

A comprehensive comparison of the dynamic and steady state performance characteristics of permanent magnet synchronous motors (PMSM) with interior and surface rotor magnets for line-start operation is presented. The dynamic model equations of the PMSM, with damper windings, are utilized for dynamic studies. Two typical loading scenarios are examined: step and ramp loading. The interior permanent magnet synchronous motor (IPMSM) showed superior asynchronous performance under no load, attaining faster synchronism compared to the surface permanent magnet synchronous motor (SPMSM). With step load of 10 Nm at 2 s the combined effect of the excitation and the reluctance torque forced the IPMSM to pull into synchronism faster than the SPMSM which lacks saliency. The ability of the motors to withstand gradual load increase, in the synchronous mode, was examined using ramp loading starting from zero at 2 s. SPMSM lost synchronism at 12 s under 11 Nm load while the IPMSM sustained synchronism until 41 seconds under 40 Nm load. This clearly suggests that the IPMSM has superior load-withstand capability. The superiority is further buttressed with the steady state torque analysis where airgap torque in IPMSM is enhanced by the reluctance torque within 90E to 180E torque angle.

Effectiveness analysis of selected attention models

Włodarczyk M., Kryjak T., Wolski P.

Bio-Algorithms and Med-Systems

2011

Vol. 7, no. 1

49--56

The aim of this study was an empirical verification of five different computer models of exogenous human attention. These models allow to predict the likely fixations on a static image and calculate saliency maps which show how distinctive the image elements are. The basis for the verification of the models was a modified cuing task , originally developed by Posner. Using the algorithms provided by the authors of the models an analysis of selected images was performed. Then the effectiveness of the models was verified in experimental studies: an image was presented to the subject, then on this image a visual stimulus appeared and the reaction time was measured. It was assumed that the emergence of a stimulus at the point where previously an attention attracting element appeared would accelerate the reaction. The study was conducted on a set of over 300 different, emotionally neutral, natural images. Obtained results indicate the potential usefulness of the proposed schema for testing the efficiency and refinement of attention models.