Analysis Of Magnetic Field In A Brushless High Speed PM Motor

There is increasing interests in high speed motors in industry applications such as gas turbines, machine tool spindle drives, information storage disk drives and etc. In this paper, recent development of high speed motors is presented, among which Brushless PM motors, a particular kind of brushless permanent magnet dc motor, is highlighted as the most promising technology. Such motor, which has slotted topology in particular, is considered by means of both analytical and numerical method.At first, on the basis of an analytical technique for predicting the instantaneous magnetic field distribution in the airgap region of brushless permanent magnet d c motors under any specified load condition, an improved method for modeling the effect of stator slotting on the magnetic field distribution in the airgap sleeve -magnet region of a high speed brushless permanent magnet motor equipped with a surface mounted magnet rotor enclosed by a sleeve is presented., which make use of con- formal transformation with the help of numerical integration. This method can easily combined with analytical method and provide nearly the same efficiency and insight as the classic model but much more accuracy than analytical solution.Second, the preliminary result of core losses in above motor is provided based on a time-stepped finite element analysis, in which great effort has been made to simplify the previous method,so that all the results could be acquired more efficient. In the processing of getting hysteresis losses, a kind of Preisach model is adapted.