Starting winding parameters influence on starting characteristics of salient-pole synchronous motor

Abstract

The asynchronous method of starting a salient-pole synchronous motor (SPSM), its starting characteristics, which are the dependence of the current I of the stator and the electromagnetic moment  M to the slip s at constant stator winding feed voltage U and frequency f have been analyzed. A mathematical model that considers magnetic and electrical asymmetry was designed. The magnetic asymmetry of the SPSM is cased by the salient-pole structure of the rotor, and the electric - due to the different number of windings along the longitudinal and transverse axes. To consider the magnetic and electrical asymmetry of SPMS carry out the following transformations: 1) replacing of the three-phase stator winding with two-phase, where the magnetic axis of one of the windings coincides with the longitudinal axis d, and the magnetic axis of the second winding - with the transverse axis q of the fixed coordinate of the orthogonal system dq; 2) the starting short-circuited winding is replaced by two windings: a longitudinal starting winding, the magnetic axis of which coincides with the d-axis, and a transverse starting winding, the magnetic axis of which coincides with the q-axis; 3) the movable rotor of the engine is considered stationary. The developed mathematical model showed that the starting properties of SPSM and the type of its starting characteristics depend on both: the parameters of the stator windings and the parameters of the rotor windings - the starting winding and the excitation windings. During the SPSM design process, the specified starting properties can be achieved by the variation of the starting winding parameters, which depend on the number of rods, sizes, and materials of rod and short-rings, as well as the size (width and height) of the slot groove. A computer program for calculating its starting characteristics with a given set of parameters for researching SPSM according to the described mathematical model was developed.