Homogenization and Eddy Current Loss Approximation of Soft Magnetic Composite Material for Electrical Machines

This paper investigates the soft magnetic composite (SMC) material consisting of irregular grains with induced eddy currents using finite element analysis (FEA). SMC material is made up of iron grains separated by insulation gap. The geometry of the material has been determined using an algorithm based approach and an image based approach.The effective reluctivity has been determined using two homogenization techniques. The first homogenization technique makes use of an energy formulation. The eddy current effects are evaluated taking into consideration the fill factor of the 2-D SMC material.A low frequency approximation is realized for the homogenized material. In the second technique, non-linear properties are determined using the time-stepping technique. A method has been proposed in FEA for directly including an analytical eddy current loss formula for rotating electrical machines with SMC material cores. The eddy current loss and torque have been determined for the radial flux permanent magnet synchronous machine (PMSM) having an SMC stator core and the results are then compared with the laminated stator core machine.