Analytical approach and solution for start-up behavior of line-start permanent magnet synchronous machines (LSPSM)
This paper presents a derivation for the maximum transient current and torque peak values for small non-salient line starting permanent magnet synchronous machine (LSPSM) on base of permissible approximations. First the equations for locked rotor operation and secondly for constant speed operation are deduced. This paper is focused on derivation of the analytical calculation process to get an approach for transient current and torque. Saturation and speed dependency of parameters are not considered. With the derived equations, effects of parameters on the peak values of torque and current at starting can be shown.
Asynchronous Torque of Line-Starting Permanent-Magnet Synchronous Motors
A modified theory and a proposed analytical approach clarified asynchronous torque characteristics of line-starting permanent-magnet (PM) motors, taking into consideration the mutual effect among the fields due to armature current, cage-bar current, and PMs. Theoretical and analyzed results revealed that cage torque had an oscillating component with slip frequency due to magnetic saturation. This component cannot be seen in the conventional theory. It was also found that the coupling effect between PM flux and cage-bar flux caused on magnet torque larger oscillation and more significant negative dc component, compared with the case in the conventional theory. The theoretical and analyzed results were validated on the basis of experimental approaches. Results are given for a two-pole prototype motor with PN = 5 kW, nN = 3000 min-1, VN = 200 V, and Y-connection.
Commentary: Scholarship as a Way of Life—Character and Virtue in the Age of Big Humanities
From the Renaissance to the nineteenth century, most European scholars considered moral cultivation as the primary purpose of the humanities. The humanities were human not just because they concerned the products of the human mind but also because they transformed scholars and students into better human beings. During the late nineteenth and early twentieth centuries, the rise of Big Humanities questioned this moral purpose. However, Big Humanities also reemphasized the importance of epistemic virtues for scholarship. The language of epistemic virtues helped scholars create new communities of learning and scholarship. Within these communities, the language of virtues established common standards of collaboration and granted scholars a sense of purpose. Many of these scholars also continued to associate epistemic virtues with moral virtues.