No abstract

Summary This study presents classical direct torque control (DTC) performance of line‐start permanent magnet synchronous motor (LSPMSM). An LSPMSM is designed based on an actual IM with finite element analysis. To present an in‐depth analysis, a comparison of a simple classical DTC performance of a three‐phase four‐pole LSPMSM and its equal induction motor (IM) in different conditions is provided. In addition, to evaluate the effectiveness of this method, simulation results from matlab/Simulink software are presented for both line‐starting and adjustable speed drive applications under the same conditions. Furthermore, both nominal voltage and voltage sag conditions are simulated for the aforementioned situations, and it shows that on one hand, the starting and synchronization process of LSPMSM often encounter problems for voltage sag conditions. On the other hand, a better transient and steady‐state response of an LSPMSM drive is obtained rather than that of IM, especially for voltage sag conditions. Copyright © 2014 John Wiley & Sons, Ltd.

No abstract

A magnetohydrodynamic (MHD) thruster is a type of electric motors which does not have mechanical moving parts and directly converts electrical energy into mechanical energy. In this study, the effect of magnetic field intensity and seawater electrical conductivity on the performance of a marine MHD thruster model is investigated using fully three-dimensional numerical simulations. For the first time, all electric, magnetic and fluid flow fields are considered in three dimensions. The effects of seawater electrolysis and end loss are taken into account in all simulations and a simple analytical model is developed to verify the numerical results. It is shown that increasing the magnetic field intensity or the electrical conductivity of the working fluid decreases the electrochemical and ohmic losses of the thruster at a specific velocity. Therefore, a higher efficiency can be achieved at higher magnetic field strengths and higher seawater electrical conductivities. Also, it is revealed the end loss of the channel increases with an increase in the electrical conductivity of the working fluid and decreases with an increase in the magnetic field intensity.

No abstract