Semi-analytical Calculation of Field and Loss Distribution in the Tooth Tips of Electrical Machines

This chapter investigates a novel approach to calculate the iron loss distribution in the stator tooth tips of electrical machines. First, an analytical field calculation approach is presented beginning with a Schwarz-Christoffel mapping of the tooth tip to a rectangular shape. Solving the Laplace equation for this geometry and deriving the correct boundary conditions allow the calculation of the normal component of the flux density on the tooth surface. The field distribution inside the tooth is calculated with a magnetic admittance network solved using nodal analysis. Besides presenting the calculation of the spatial and time-dependent field distribution in the tooth tip, an iron loss model is introduced. The overall agreement of the model with measurements is very good over a large frequency and flux density range. To validate the field calculation results, both the semi-analytical field calculation results and 2D FEA results are used as input for the introduced loss model. Comparisons indicate a very good match between the presented approach and FEA.