Optimization of design and manufacturing processes of electric motors based on magnetic measurements

Accurate design and prediction of electric motor performance is not a trivial task. Motor design engineers make use of advanced numerical and analytical methods for electromagnetic and thermal analysis, and still find considerable differences in efficiency of modelled and manufactured machines. One of the primary sources for this mismatch is the inaccuracy in stator lamination magnetic properties, such as BH curve and power loss, which are used as input data for calculating flux linkages of the coils and heat dissipation, and consequently determining the main motor parameters including torque and operating temperature. Typically, the magnetic properties implemented in motor modelling are provided by the material supplier based on the Epstein frame measurements, according to the International Standard IEC 60404-2. The effects of processing of the magnetic materials during motor manufacturing are neglected which gives rise to uncertainty in prediction of motor performance. In this presentation the results from numerous industrial case studies involving advanced magnetic measurements will be presented, including characterization of stress sensitivity of soft magnetic materials, optimization of stamping and stacking methods in production of stator cores, as well as evaluation of manufacturing technologies for mitigation of eddy current loss in permanent magnets.