Time Domain Modeling of Induction Machines

Abstract

We will now consider the transient (time domain) behavior of electro-mechanical devices which are activated by a voltage or current source, such as motors or actuators. The voltage (current) source for such devices may be time-dependent. One cannot specify a priori the numerical value of the current density in all of the conductive source regions of the device. The finite element procedures which we used previously required current density as a known input to the analysis. In addition, it may be necessary to attach external circuit components between the voltage or current sources and the region to be modelled by finite elements. The lumped components may represent the internal impedance of the voltage or current source, or they may be used to approximate the effects of the parts of the device which are outside the region modelled by finite elements. The corresponding transient circuit equations must be coupled to the transient finite element field equations. Moreover, in the case of the motor or actuator, there are movable components. Magnetic forces in part determine the position of these components, and the positions, in turn, affect the magnetic field within the device. Provisions must be made for the transient modeling of such a coupled electro-mechanical system.