Electric and hybrid vehicles are a common sight on the roads these days. The electric machine is known to be quiet, but sometimes high-frequency sounds are observed when driving. Over the years many different solutions have been developed to make the electric machine quieter, but
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Electric and hybrid vehicles are a common sight on the roads these days. The electric machine is known to be quiet, but sometimes high-frequency sounds are observed when driving. Over the years many different solutions have been developed to make the electric machine quieter, but almost no research looks into the possibility to generate sounds. This thesis looks into the possibility to produce nice sounds and reduce annoying sounds with electric machines. This is done by introducing harmonics into the current and creating additional excitations of the structure. To gain a complete understanding of this topic the electromagnetic domain and the structural domain have been analysed. A mathematical description of the forces has been created to be able to make predictions about the forces created by an injected current harmonic. Using the electromagnetic model the exact influence of current harmonics on the forces has been verified. The sound power level produced by the forces acting on the structure is calculated using the structural model. By properly selecting the current properties it is possible to create new temporal orders that produce sounds. For the analysed electric machine the sound power level of the desired sound is on average approximately 20dB lower than the sound power level of the fundamental current. Furthermore the sound power level is dominated by the excitation of the breathing modes. Using current injection existing sounds can be reduced. Using brute force optimisation the average radial forces were reduced. This reduces the sound power level during most of the run-up and reduces the influence of the breathing mode by up to 11dB. At some points during the run-up more sound is produced, because the tangential forces are increased, while the radial forces are decreased. In the end it is shown that the influence of the introduced current harmonics on the acoustics can be analysed using mathematics and the simulation results. New sounds can be produced, but the sound power level is limited by structural design of the electric machine.