Initial Comparison of analytical methods for noise prediction of future electric aircraft powertrains

Increasing requirements regarding greenhouse gas emissions produced in the aviation sector require new technologies for aircraft propulsion systems. A suitable technology for a more sustainable and low emission aircraft is the electrification of the powertrain. The noise emission by electric machines becomes an important contribution to the overall aircraft noise, especially since future aircraft will need high-power density electric machines that pose additional challenges regarding design and manufacturing. Electric machines with power densities of 10 kW/kg and higher are currently not available for detailed measurements, to get a first impression of the dominating noise sources of electric motors, models for predicting the noise emission are necessary. Compared to numerical methods, analytical models offer a fast estimation of the noise generated by electric motors. In this paper, analytical models for noise prediction generated by electric motors suitable for aircraft propulsion systems are presented. The most advanced model includes the calculation of the excitation forces acting on the stator due to the magnetic flux density that is coupled with a sound radiation analysis of the outer surface of the motor. By varying the basic parameters for each model under investigation, the noise radiation of a permanent magnet synchronous electric motor is assessed.