Search

Multi-phase (more than three phases) drives possess several advantages over conventional three-phase drives such as: reducing the amplitude and increasing the frequency of torque pulsations, reducing the rotor harmonic currents, reducing the current per phase without increasing the voltage per phase, lowering the dc link current harmonics and higher reliability. By increasing the number of phases it is also possible to increase the power/torque per rms ampere for the same volume machine. This paper, therefore, presents a simple d-q model of a multi-phase induction machine suitable for analyzing the transient, steady state and dynamic behavior of the machine under balanced operating condition. In the analytical model, the effects of common mutual leakage reactance between the two three-phase winding sets have been included. The model has been developed in general reference frame and is suitable for analysis of the machine behavior with an arbitrary angle of displacement. Keywords: Analysis; Induction machine; Multi-phase; Modeling; Simulation

This paper presents a numerical model of the three-phase, cage induction motor. This model has been represented as a system of differential equations for flux linkages and angular velocity determination. The differential equations for the flux linkages of the stator windings have been expressed in phase coordinates, while the differential equations for the flux linkages of the rotor circuits have been expressed in orthogonal coordinates, which are fixed in respect with the stator of the motor. The skin effect in the rotor deep bars has been taken in account by representing the rotor as two parallel-connected resistive-inductive circuits. Using the developed model the starting, restarting, running-down modes and three-phase, line-to-line, line-to-ground short-circuits as well as the steady-state conditions can be analyzed. The modes of sudden three-phase short-circuit at the motor terminals, sudden single line-to-ground fault at the high-voltage side of the power supply system and the motor starting process followed by steady-state conditions have been computed. Keywords: Induction motor; Numerical model; Phase coordinates; Orthogonal axes

The stability study of a multi-phase (six-phase) induction machine has been performed by applying the eigenvalues stability criterion to the small displacement equations obtained by linearization about an operating point. The eigenvalues provide a simple means of predicting the behavior of an induction machine at any balanced operating condition. The eigenvalues are dependent upon the parameters of the machine and it is difficult to relate analytically a change in an eigenvalue with a change in a specific machine parameter. It is possible, however, to identify an association between eigenvalues and machine variables. Therefore, in this paper, the stability of the machine under small perturbation of machine variables has been examined from the placement of the eigenvalues. The effect of common mutual leakage reactance, which depends upon the winding pitch and the displacement angle between the two three-phase stator winding sets, and the effect of harmonics have been included in this study. Keywords: Analysis; Induction machine; Multi-phase; Modeling; Stability