Investigation of Loss Calculation Methods for PMSMs and Implementation of Loss Functionality on a Developed FEM Model

Abstract

Accurate estimation of losses is one of the major challenges in electromagnetic machinery modelling. Where permanent magnet synchronous machines are attractive for high performance applications, making them relevant for investigation with regard to optimal design. This thesis concerns the investigation of loss calculation methods for permanent magnet synchronous machines. As well as implementation of loss functionality in the further development of a permanent magnet synchronous machine, modelled in the finite element method program COMSOL Multiphysics. The model is developed in a previous master thesis, were losses were neglected for simplicity. A process of evaluation and testing of the developed model will also naturally take place.

The method chosen to estimate the core losses separates the loss into hysteresis and eddy-current components. This is a well established model and has been shown to give satisfactory results, coupled with finite element method modelling, in previous studies. The method was deemed feasible to implement and should in theory give an adequate evaluation of the core losses. However mismatch between the time and frequency domain solutions, as well as an imbalance in the flux distribution, due to conflicting interactions within the model, puts the validity of the implemented functionality into question.

Losses in the windings and the permanent magnets are accounted for by modelling the resistive losses for their corresponding domains, as the magnets can be assumed resistance limited. The eddy-current losses in the magnets are affected by their size and structure, where sectioning could be implemented to decrease losses. In the case of the windings problematic integration of their properties in the model results in unrealistic loss values.