Back electromotive force enhancement for a new single-phase synchronous motor

In this article, the back electromotive force (emf) of a new single-phase s ynchronous motor of the two-pole type useful in aquarium application is stu died. Based on a two-dimensional model, the finite-element method is used t o numerically analyze the magnetic field distribution inside the motors, fr om which the back emfs can be computed. Three different shaping schemes on the stator are investigated, with the objective of enhancing the back-emf c onstant as well as eliminating the starting dead point. Experiments are con ducted on one of the shaping schemes, where the measured data are found to agree very well with the numerical results. To predict the transient behavi or of the motors in the startup period, parameters extracted from the numer ical results are built into a database. From this database a set of dynamic equations governing the current and angular speed can be constructed, whic h provides significant accuracy as compared with the experimental values. ( C) 1999 American Institute of Physics. [S0021-8979(99)61808-4].