January 2018: sound samples of electric motors, workshop on NVH of electrical machines, GCD

New materials on e-NVH

EOMYS has recently enriched and reorganized its sound library on electrical Noise, Vibration and Harshness (e-NVH). Noise of electric powertrains from Tesla, Renault, Nissan and Toyota can be listened on the e-NVH sound samples webpage. PNG - 373.6 kb

Ongoing MANATEE developments

MANATEE (Magnetic Acoustic Noise Analysis Tool for Electrical Engineering) software logo

Based on the increasing feedback of MANATEE users, EOMYS team continuously improves the development of its unique software for the fast and accurate calculation of electromagnetically-excited noise and vibrations in electrical machines:
- new saturation modeling strategies to account for non-linearity in subdomain and permeance/mmf models
- extension of subdomain models to wound rotor synchronous machines

Zoom on MANATEE feature

MANATEE sensitivity and optimization tools include scripting features to easily include some specific acoustic noise components as output variables. For instance, one can minimize the A-weighted sound pressure level at a specific speed of 1500 rpm, or use the sound power level at 6f (electrical order 6) as a sensitivity study output variable. This process is detailed in a specific article on how to set-up MANATEE output variables.

Conferences and Events

EOMYS organizes with the support of TU Darmstard a one-day technical workshop on the vibro-acoustic design of electrical machines on the 13th of April 2018 focusing on acoustic noise and vibrations due to Maxwell forces in Permanent Magnet Synchronous Machines (PMSM). More details are available on the registration webpage on the event.

Publication of the Month

The publication work of the month is:

  • S. G. Min and B. Sarlioglu, "Modeling and Investigation on Electromagnetic Noise in PM Motors with Single and Double Layer Concentrated Winding for EV and HEV Application," in IEEE Transactions on Transportation Electrification, vol. PP, no. 99, pp. 1-1., doi: 10.1109/TTE.2017.2747585

The authors of this work analyze the effect of slot/pole combination of PMSM on torque ripple and electromagnetic noise using semi-analytical technique based on Schwartz-Christoffel conformal mapping to calculate the relative airgap permeance technique. It is shown than the lowest radial magnetic force wavenumber is not always given by GCD(Zs,2p) at full load, it can be equal to GCD(Zs,2p)/2 for certain single layer fractional slot windings.

The authors of this work try to analytically find the best slot per pole combination in terms of cogging torque, torque ripple, and noise and vibration by avoid Unbalanced Magnetic Pull and maximizing the lowest force wavenumber. However, having a low GCD does not mean that electromagnetically-excited noise and vibration will be high: as an example, on applications with high stator slot number and high pole numbers, a low GCD can be reached with a combination of high ranks of stator slot permeance harmonics and high ranks of rotor magnet magnetomotive forces (high ranks meaning low magnitude).

EOMYS has experienced noisy machines with GCD=22 compared to machine with same electromagnetic performances with GCD=2.

This shows that vibroacoustic simulation is necessary, and this calculation is not necessarily long when using semi-analytical MANATEE software models - only a few seconds to estimate noise at variable speed.

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