A simplified approach for accurate estimation of transverse magnetic forces in micro-actuators having inclined pole faces

This paper proposes a fringing range method for accurately evaluating trans verse magnetic forces in micro-actuators having inclined pole faces. In thi s method, the fringing Bur in an air gap is assumed to be uniformally distr ibuted in a range that is represented by a fringing coefficient, which is t hen adjusted systematically to ensure the magnetic forces are accurately de termined under defined conditions of actuator physical symmetry. Although t his approach can be generalized to other cases, this paper focuses on its a pplication to the case of semi-infinite inclined pole faces. It is shown th at the fringing range method can be used with good accuracy if the pole thi ckness is much larger than the air-gap length. This method was applied in d esigning a micro magnetic bearing actuator whose diameter is 2.6 mm.