Method to optimize NVH-behaviour of a brushless electrically excited synchronous machine

As part of the ongoing NGC-project (Next Generation Car) related to the research of new technologies for future road vehicles at the DLR, this paper is dedicated to the substitution of an optimization method of a brushless electrically excited synchronous machine for use in electrical vehicles. In this application high torque densities and small vibrations are needed, so an optimization of torque and torque ripple is done. As optimization parameters torque ripple reduction techniques as skewing, cosine formed tooth and width of tooth are chosen. The combined multi-parameter optimization is necessary because of interactions between the optimization parameter effects. An analysis for a machine of 25 kW, used in urban electric vehicles, is done with different excitations to build up the working points. The results show a large effect of increasing skewing to decrease torque and increase ripples independent of excitation. The effects of the other techniques are smaller. The cosine form has in the example optimization a strong dependency on excitation.