Abstract
As the rotor ring of a hysteresis motor becomes tihck, the magnetic field inside the rotor ring is expressed by an elliptic rotating field in general. For the motor of the thick ring, or the multipolar, and also permeability of the rotor ring is very small, the field inside the rotor ring becomes an elliptic rotating field, and becomes a circular rotaing field in the extreme case. In this paper, two calculation methods in which the elliptic rotating field is considered are proposed. In the first method, the actual elliptic rotating hysteresis loss is replaced with the equivalent circular rotating hysteresis loss which is equal to the elliptic one. The motor characteristics are calculated from the equivalent circuit of this circular rotating hysteresis. In the second method, the magnetic constants of the rotor ring for the elliptic rotating field, for example, a permeability, a hysteresis angle, are determined. The former is determined from the equivalent circuit of the alternating field, the latter is determined from the elliptic rotating hysteresis loss. This method is one proposed newly by this paper. The motor characteristics are calculated from the equivalent circuit of the elliptic rotating field. From the comparison between the calculated and experimental results, it is clear that the first method is useful when the axial ratio of the elliptic rotating field inside the rotor ring is from 0.8 to 1, and that the second method is useful when the field configuration inside the rotor ring is the ellipse in general.
