Estimation of PM Machine Efficiency Maps from Limited Experimental Data

This paper investigates the accuracy of the estimation of efficiency maps for permanent magnet (PM) machines using the \pmbd-\pmbq equivalent circuit model and limited experimental data. The study is based on the detailed finite-element results for 50-kW surface and interior PM machines. It discusses the variation of the flux-linkages and losses with \pmbId and \pmbIq. It examines the effect of modeling the flux-linkage characteristics using saturating and linear models and modelling the non-copper losses using the open-circuit and short-circuit losses. The effect of these approximations on the output torque versus speed capability curve and efficiency contours are shown. Guidelines are proposed for fast and reasonably accurate calculation of efficiency maps.