Preliminary induction motor electromagnetic sizing based on a geometrical approach

A methodology to design three-phase squirrel-cage induction motors is presented. The main aim of the study is the preliminary electromagnetic sizing of the machine, obtaining the machine overall dimensions (diameters, core axial length and rough stator and rotor shape) and a draft of the stator winding specifications (turn number and wire area). The procedure is based on a simple geometrical approach and self-consistent equations, without any use of empirical/corrective coefficients. In the proposed design tool, the machine geometrical dimensions are automatically computed starting from a few design specifications imposed by the user, such as rated voltage and torque and electric and magnetic material solicitations. In this study, the design procedures and algorithms are described step-by-step and, for each step, the used equations are reported in detail, in order to allow readers to develop own `do-it-yourself` software for induction motor electromagnetic design. The authors developed this software in a Microsoft Excel electronic sheet using embedded Visual Basic for Applications. To prove the goodness and accuracy of the proposed design tool, a comparison with two commercial software for electrical machine design and analysis has been done and discussed.