Analysis of starting performance and frequency characteristics of synchronous reluctance motors

Line-start synchronous reluctance motors are a viable option to compete with induction motors in some applications because of their accurate speed and high efficiency during steady-state operation. The frequency characteristics of synchronous motors, X_d(js) and X _q(js), represent the motor´s d and q axis reactances at different slips, s, which in turn, represent the motor saliency at different slips. In this paper, the relationship between synchronous reluctance motor starting performance and the motor´s frequency characteristics have been derived based upon Park´s equations. This relationship is illustrated using phasor diagrams. A new method of determining the frequency characteristics of synchronous machines for small slips, based upon the phasor diagram and asynchronous data, is also proposed