|
Abstract
|
Induction motors were traditionally used in industrial applications ranging from a fraction of horse-power up to several Megawatts due to their substantial benefit s. Induction drives with more than three phases are superior to the 3-phase induction drives in terms of overall volume, torque fluctuations, current passing each stator-winding, ohmic loss, efficiency, and reliability in the case of stator-windings open-circuit fault. These benefi ts are particularly more attractive in variable speed drivers due to the reduced capacity of power-electronic switches. This paper aims to develop an optimal electromagnetic-thermal design procedure of a high-power seven-phase induction motor suitable for variable-speed applications. In this multi-objective design approach, the objective function is defi ned aiming to increase the effciency, power-factor, power-to-weight ratio, and starting-torque as well as reduce the starting-current. Furthermore, the electrical, mechanical, dimensional, magnetic, and thermal limitations are included in this optimization study in order to ensure practical realization of the designed machine.
The coupled-circuit method is employed for nonlinear electromagnetic modeling, while
the current displacement phenomenon is considered in calculations of rotor parameters.
A lumped-parameter-thermal model is established for calculating heat rises of di erent
parts at each iteration of optimization study. Finally, the performance characteristics of
the optimally designed 1-MW 4-pole motor are veri ed based on 2D FE analyses.
|