Finite-Element Based Shape-Optimization of Electric Motors

By introducing spectral or polynomial functions to perturb the shape of the rotor in an electrical machine that was previously optimized by conventional means, it was shown that performance parameters can be further improved, in some cases significantly. This was accomplished by developing and applying an optimization method designed for use with a commercial finite element simulation software (Maxwell). This report describes the method and its development. Also issues the user must consider when applying the method, e.g. related to accuracy or choice of objectives, are discussed. Further, some results from the optimizations are presented - even though not all details can be published for confidentiality reasons. The results shows a success in improving the objectives (e.g. torque ripple and/or power factor) while keeping other parameters of the motor unchanged (e.g. inductances). The method can take different load points into consideration, and works for different kinds of motors. The improvement can be significant, for one motor design, torque ripple and power factor were simultaneously improved: reduced by 13 %-units and increased by 2.5 %-units, respectively. This is a public version of an internal ABB report, and hence some sources of information and results are confidential