Performance characterization and torque-ripple reduction in induction motor adjustable speed drives using time-stepping coupled finite element state space techniques

In this paper, the time-stepping coupled finite element state space (TSCFE-SS) model developed in the first of two companion papers is applied here for the assessment of effects of machine geometry and magnetic circuit design modifications and the effects of pulse-width modulation carrier frequency on the performance characteristics of induction motor drives. Namely, this has been accomplished through analysis of developed torque profile ripples and harmonic spectra of mid-airgap radial flux density waveforms of the case-study motor. Furthermore, consequent effects of design modifications pertaining to, geometry and/or magnetic circuit modifications, and pulse-width modulation carrier frequency on ohmic and iron core losses are investigated. The investigation has been performed on a case study motor which is a Y-connected, single-layer, 3-phase, 2-pole, 1.2-hp, 208 Volts squirrel-cage induction motor with 24 stator slots, and a cage with 34 rotor bars.