Permanent-magnet synchronous machines (PMSMs) are widely used in electric vehicles owing to many advantages, such as high power density, high efficiency, etc. Iron losses can account for a significant component of the total loss in permanent-magnet (PM) machines. Consequently, these losses should be carefully considered during the PMSM design. In this paper, an analytical calculation method has been proposed to predict the magnetic field distribution and stator iron losses in the surface-mounted permanent magnet (SPM) synchronous machines. The method introduces the notion of complex relative air-gap permeance to take into account the effect of slotting. The imaginary part of the relative air-gap permeance is neglected to simplify the calculation of the magnetic field distribution in the slotted air gap for the surface-mounted permanent-magnet (SPM) machine. Based on the armature reaction magnetic field analysis, the stator iron losses can be estimated by the modified Steinmetz equation. The stator iron losses under load conditions are calculated according to the varying d-q-axis currents of different control methods. In order to verify the analysis method, finite element simulation results are compared with analytical calculations. The comparisons show good performance of the proposed analytical method.

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A new and rapid analytical method for the simultaneous determination of six EPHEDRA alkaloids (ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine, methylephedrine, and methylpseudoephedrine) in Ephedrae Herba by high performance liquid chromatography (HPLC) has been developed. Recoveries of each alkaloid were 96.0-101.6% with coefficients of deviation of 1.7-3.0%. The contents of six alkaloids in three species of EPHEDRA indigenous to China are determined and reported.

design scheme of wind-magnetic water heater was proposed in this paper, based on the characteristics of wind energy and the principle of eddy current heating effect. Some factors affected the vortex heat power were analyzed on an equation deduction basis. A device was designed and made for verifying the effect of some factors to the temperature rising of heating plate, including rotary speed and gap between turntable and heating plate. By regression analysis, an empirical equation was derived for guiding further development of the heating system.