Numerical analysis of flux distribution in permanent-magnet stepping motors

The flux distribution and torque characteristics of a stepping motor used in an analogue electronic watch are examined. In such an ultraminiature motor, it is difficult to investigate the flux distribution experimentally. The flux distributions at various rotor positions are numerically, analyzed by using the finite element method. Torque characteristics are obtained from these results. The effects of the exciting current and the shape of the stator and rotor on the flux distributions and the torques are discussed. These results give useful suggestions improving the design of stepping motors.