ABSTRACT
To investigate induction machine (IM) transients or their control system design, rotor-position-independent machine inductance models are required to simplify the mathematics. This chapter derives the d-q model of three-phase IMs from the phase-coordinate model by the so-called Park transformation directly in space-phasor form in general coordinates if the slot openings are neglected or considered globally. It derives the steady-state equivalent circuit and space-phasor diagram and illustrates via a numerical example. IMs undergo transients when voltage, current, and/or speed undergo changes. Modelling the transients of IMs may be carried out through circuit models or through coupled field/circuit models. Starting of large IMs causes not only heavy starting currents but also high torsional torque due to the large masses of the motor and load which may exhibit a natural torsional frequency in the range of electric torque oscillatory components. The soft starter modifies the voltage amplitude while keeping the frequency constant.
