Impact of IM pole count on material cost increase for achieving mandatory efficiency requirements

This paper presents a study about cost-optimal induction machines fulfilling particular efficiency requirements. As an increase of efficiency inevitably causes higher material costs, the tradeoff for these two conflicting objectives is analyzed in particular. Optimization scenarios comprising crucial design parameters are investigated and evolutionary algorithms are employed to reduce the overall computational cost. To obtain results in satisfactory time, the performance of machine designs is determined by means of an analytic approach. A case study for rated power of 11kW is presented. All number of poles and efficiency classes considered in corresponding regulations are investigated. This allows a comparison of the relative cost increase with regard to mandatory efficiency requirements, starting from IE1 up to the IE4 class. The results further provide interesting insights into optimal length to diameter ratios, air gap flux densities, and stator current densities.