Influences of Material Degradation Due to Laser Cutting on the Operating Behavior of PMSM Using a Continuous Local Material Model

Abstract

During manufacturing of electrical machines, shape giving production steps such as punching and cutting introduce plastic deformations and residual stress to the soft magnetic material. As a result, the magnetic properties of the material decrease and locally both static and dynamic hysteresis losses increase in the vicinity of the cut surfaces. For consideration of local permeability deteriorations, different models have been published. These are capable of describing the changing local magnetization and loss behavior. Current approaches subdivide the magnetic core into slices of different magnetic properties, thereby discretizing the continuous deterioration. This paper analyzes the effects of material degradation due to cutting on the performance and machine parameters of a permanent magnet synchronous machine using a continuous material model for efficient numerical modeling of the local magnetization behavior. By replacing inefficient sliced models, the continuous model is independent of the discretization and converges in case of coarse meshes to the sliced model. Influences on the machine behavior are studied in terms of local flux density distributions, iron losses, efficiency, torque, and inductances on the operating map and an exemplary working point.