Analysis of Flux Density and Iron Loss Distributions in Segmented Magnetic Circuits Made With Mixed Electrical Steel Grades

Abstract

This paper presents the potential contribution of segmented stator magnetic circuits of rotating permanent magnets electrical machines with concentric winding. Two magnetic materials are mixed, FeSi Non-Oriented Electrical Steel (NOES) and FeSi Grain Oriented Electrical Steel (GOES). The choice of using GOES is based on the high performance it offers in terms of permeability and iron losses compared to conventional NOES, particularly when GOES is magnetised in the Rolling Direction (RD). The goal is to analyse the contribution of the mixed magnetic circuit on the losses and electromagnetic torque, but also the drawbacks due to the cut process and to the assembly. The behaviour of the magnetic field at the junction between the segments is studied by comparing different geometrical connection shapes and compared to a reference magnetic circuit fully made with NOES sheets. This comparison is experimentally made with a model representative of the existing phenomena in an electrical machine. In addition, numerical calculations using finite elements software are carried out, by considering both the magnetic anisotropy and the saturation of the GOES.

Power density improvement of axial flux permanent magnet synchronous motor by using different magnetic materials

“…The maximum rotation speed can be increased but is limited by mechanical constraints: the peripheral speed and the transmission system (Borisavljevic, 2013; Pyrhnen et al , 2008; Rezzoug and El Hadi Zaïm, 2012). The use of permanent magnets with very high energy density is recommended (NdFeB, SmCo) (Dwivedi et al , 2006; Nagorny et al , 2005), but their environmental footprint is nonnegligible. The use of magnetic materials with high permeability, high saturation flux density and low specific losses is also a way to analyze grain-oriented electrical steel (GOES) or iron-cobalt Permendur electrical steel (Co-Fe) (Bloch et al , 2007; Kowal et al , 2010; Rebhaoui et al , 2022b). …”

“…The use of magnetic materials with high permeability, high saturation flux density and low specific losses is also a way to analyze grain-oriented electrical steel (GOES) or iron-cobalt Permendur electrical steel (Co-Fe) (Bloch et al , 2007; Kowal et al , 2010; Rebhaoui et al , 2022b).…”

“…The high level of saturation allows to reduce the size of the stator teeth and rotor yoke and, thus, to increase the power density at iso-torque (Bhagubai and Fernandes, 2020). The low specific losses increase the efficiency of the machine (Rebhaoui et al , 2022b).…”

Investigation and Application of Magnetic Properties of Ultra-Thin Grain-Oriented Silicon Steel Sheets under Multi-Physical Field Coupling

“…Similarly, in literature [ 18 ], the good performance of grain-oriented silicon steel splicing electrical machine was verified based on the grain characteristics of grain-oriented silicon steel with clear grain boundaries observed in the metallographic experiment and the comparative analysis of thermal simulation. With the gradual deepening of research, literature [ 19 , 20 ] began to study the influence of yoke splicing shapes on electrical machine performance, and pointed out that circular splicing was an optimal scheme, which reduced electrical machine iron loss by 36.5%. The unique Epstein measurement structure was used to separate and calculate the loss in the stator core, and the effects of different stitching shapes, stitching angles and the depth of the yoke on the performance of the electrical machine were further studied.…”