Study of the Thermal Conductivity of Soft Magnetic Materials in Electric Traction Machines

Abstract

The power density of traction drives can be increased with advanced cooling systems or reduced losses. In induction machines with housing and shaft cooling, the produced heat in the stator and rotor winding system needs to be extracted over the rotor and stator lamination. The influence of soft magnetic material parameters, such as texture, thickness or alloy components on the magnetization and loss behavior, are well studied. Studies about influencing factors on the thermal conductivity are hard to find. Within this study, eight different soft magnetic materials are analyzed. An analytical approach is introduced to calculate the thermal conductivity. Temperature-dependent measurements of the electric resistivity are performed to obtain sufficient data for the analytical approach. An experimental approach is performed. The thermal diffusivity, density, and specific heat capacity are determined. An accuracy study of all measurements is performed. The analytical and the experimental approach show good agreement for all materials, except very thin specimens. The estimated measurement error of those specimens has high values. The simplified case study illustrates the significant influence of the different soft magnetic materials on the capability to extract the heat in the given application.

Influence of winding and shaft cooling on the thermal characteristics of a traction machine for heavy-duty distribution transport

“…One cuboidal element in the rotor per axial slice proofed to be sufficient due to the solid rotor bar. The thermal conductivity of the soft magnetic material is determined by an indirect measurement approach of the thermal diffusivity as described in [10]. The convective heat transfer in stator and housing cooling is calculated using flow-dependent dimensionless correlations [11].…”

The Performance of Induction Machines

“…Eleven scientific papers were collected in this Special Issue [1][2][3][4][5][6][7][8][9][10][11]. These papers concern many aspects of the theory, design, control, optimization, supervision, and use of induction machines (IMs).…”

“…In [2], the thermal conductivity of soft magnetic materials in electric traction machines was studied and presented. Within this study, eight different soft magnetic materials were analyzed.…”