A symmetrical (healthy) cage may be replaced by a wound three-phase rotor. Let us first deal with the inductance matrix. An assembly of resistances, self inductances, and mutual inductances is thus obtained. THE PHASE COORDINATE MODEL The induction machine may be viewed as a system of electric and magnetic circuits which are coupled magnetically and/or electrically. Autonomous generator transients are left out as they are treated in the chapter dedicated to induction generators. Finally the FEM coupled field circuit approach is dealt with. Modeling transients with the computation of cage bar and end-ring currents is required when cage and/or end-ring faults occur. Reduced order d–q models are used to simplify the study of transients for low and large motors, respectively. The abc–dq model is then derived and applied, as it is adequate for nonsymmetrical voltage supplies and PWM converter-fed IMs. Saturation is also included in the space-phasor (d–q) model. Both single and double rotor circuit models are dealt with. Subsequently, the space phasor (d–q) model is derived. We will deal first with phase-coordinate abc model with inductance matrix exhibiting terms dependent on rotor position. Modeling the transients of induction machines may be carried out through circuit models or coupled field/circuit models (through FEM). So, modeling transients is required for power-grid-fed (constant voltage and frequency) and for PWM converter-fed IM drives control. On the other hand more and more induction motors are used in variable speed drives with fast electromagnetic and mechanical transients. Sudden short-circuits, at the terminals of large induction motors lead to very large peak currents and torques.

Bus switching for large power induction machines feeding urgent loads also qualifies as large deviation transients.

Reconnecting an induction machine after a short-lived power fault (zero current) is yet another transient. Turning on or off the power grid leads to starting transients an induction motor. INTRODUCTION Induction machines undergo transients when voltage, current, and (or) speed undergo changes. Author: Ion Boldea, S.A.Nasar………… ……… Chapter 13 INDUCTION MACHINE TRANSIENTS 13.1.

The homopolar handbook