Optimal design of three phase induction motors and their comparison with a typical industrial motor Jawad Faiz a , Mohammad B.B. Shari®an b, * a Department of Electrical & Computer Engineering, Faculty of Engineering, University of Tehran, Tehran, Iran b Department of Electrical Engineering, Faculty of Engineering, University of Tabriz, Tabriz, Iran Received 28 June 1999; accepted 22 December 1999 Abstract Three optimally designed three-phase squirrel-cage induction motors are compared with an industrial (conventional) motor having the same ratings. The Hooke±Jeeves search routine is used for optimization and three objective functions, namely eciency, eciency±cost and cost, are considered. Comparison of the optimum designs with the initial and industrial design reveals that better than the proposed performance can be obtained by a simple optimization method. It is interesting to note that the industrial design satis®es some performance of the cost optimum design, and eciency optimum design, of course with a lower eciency. The most desirable variation of motor performance with line voltage and output power is due to the eciency optimum design. 7 2000 Elsevier Science Ltd. All rights reserved. Keywords: Design optimization; Squirrel-cage induction motor; Objective functions 1. Introduction In recent years there has been an increasing interest for the optimum design of three phase induction motors. This optimum design can be carried out from dierent point of views. With increasing material cost, there has been a tendency to reduce the frame size of these machines for a given output at the expense of poorer eciency. The corresponding objective function is generally employed for an economic manufacturing of motors [1±4]. Such a research eort was Computers and Electrical Engineering 27 (2001) 133±144 0045-7906/01/$ - see front matter 7 2000 Elsevier Science Ltd. All rights reserved. PII: S0045-7906(00)00010-0 www.elsevier.com/locate/compeleceng * Corresponding author. Fax: +21-877-8690. E-mail address: faiz-j@sofe.ece.ut.ac.ir (M.B.B. Shari®an).