Measurement set-up

Noise is measured close to electric powertrain. A 1d accelerometer is placed on the stator housing close to the middle of the lamination. A run-up is done with maximum torque up to 100 km/h in free field environment.

Sound file and spectrograms

Sound of Hyundai IONIC electric powertrain during run-up at maximum torque (EV HEV NVH)

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E-NVH interpretations

This sound file illustrates electromagnetically-excited noise of the electric powertrain of Hyundai IONIC EV. High pitch, whining noise with increasing frequency is due to pole/slot electromagnetic excitations. Higher frequency sound occuring around multiples of switching frequency is due to PWM effects. Abrupt changes on PWM strategy can be noticed. Indeed, switching frequency is initially asynchronous starting at 5.5kHz, then stepping down at 2.5kHz. Then from a given speed (at 12s on the spectrogram), PWM strategy is synchronous up to reaching a switching frequency of 5.5kHz. A resonance is visible in the acoustic spectrogram near 6 kHz which corresponds to the match between an electromagnetic forces of wavenumber 0 and breathing mode natural frequency of the stator lamination housing assembly. As seen in most EV HEV NVH studies, stator breathing mode is responsible for high-pitch airborne noise. For a more detailed analysis, EOMYS provides technical trainings dedicated to EV HEV NVH.

Application to MANATEE

MANATEE software can be used to quickly calculate EV HEV NVH due to electromagnetic forces both in early design and detailed design phase, including PWM and slotting effects.