Reluctance synchronous motor asynchronous operation

Abstract

Although a synchronous machine is under consideration in this paper, the asynchronous performance of the reluctance synchronous machine is the relevant consideration. The machine starting procedure and its ability to synchronize successfully, even with high inertia loads, are also important issues to be considered in this paper. The knowledge of the cage parameters is fundamental in this phase of operation and also for obtaining a good machine model for the simulations. Therefore, a conventional three-phase reluctance synchronous machine that comprises a cage in its rotor is analyzed for the determination of its steady state and dynamic characteristics. The machine equivalent circuit for synchronous operation is obtained considering the iron core losses. A vector diagram, which is obtained from the Park equations is the theoretical approach that is used in this work. Some laboratory measurements are also carried out for measuring the machine parameters. Obtaining parameter values from measurements may present some difficulty if a damper or a cage is present in the rotor. The d-axis and q-axis machine reactance parameters that are required in the model were obtained via the conventional load test that was devised by Honsinger. Cage-rotor reluctance synchronous motor reliable models for synchronous and asynchronous operations are still under development. As the cage allows starting the reluctance motor directly from the mains - like the induction motors - many of the reluctance motors used in industry are comprise cages in their rotors. In synchronous operation the cage plays the role of damper for the oscillations in the speed. Although the parameters of cage-rotor reluctance motors do not influence the steady-state modeling of this machine, they are very important to stability studies and predictions of starting or transient performance. Several laboratory tests for the machine characteristics were carried out. The results that were obtained are presented in this paper.