Modelling and multiobjective optimization analysis of a permanent magnet synchronous motor design

Abstract

An alternative to traditional low‐speed/high‐torque drive systems, which are currently used in industry, could be the use of a permanent magnet synchronous motor directly coupled to the load and running at low speed, instead of the induction motor along with its mechanical transmission parts. The paper—in this context—deals with the analytical design procedure, optimization, and evaluation of such a motor (5 kW/50 rpm) and focuses on 2 topologies, ie, with inner and outer rotor. Finite element method designs of the permanent magnet machines are implemented as solutions of a complex optimization problem and several goals (multiobjectives) are considered (ie, machine weight minimization or efficiency maximization) with respect to relevant constraints. Three optimization methods are adopted and applied and a weighted cost function is proposed. The effectiveness of our problem design formulation approach and the use of these methods, in finding alternative and competitive permanent magnet synchronous motor designs, are also evaluated. The results reveal satisfactory design solutions and present acceptable performance. Moreover, by means of simulations, the application of several commercially available ferromagnetic materials for the motors' stator and rotor cores is performed. Last but not least, the effect of pole‐arc per pole‐pitch ratio along with the magnets length variation is also investigated.

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