Vibro -Acoustic Response Analysis of Electric Motor 2017-01-1850

The Environmental Protection Agency (EPA) requirement for 54.5mpg by 2025 to reduce greenhouse gases has pushed the industry to look for alternative fuels to run vehicles. Electricity is of those green energies that can help auto industry to achieve those strict requirements. However, the electric or hybrid-electric vehicles brought new challenges into science and engineering world including the Noise and Vibration issues which are usually tied up with both airborne and structural noises. The electromagnetic force plays a significant role in acoustic noise radiation in the electric motor which is an air-gap radial Maxwell force.

This paper describes an innovative approach to model the physics of noise radiated by the electric motor. In order to compute the sound power level radiated by electric motor, the dynamic response of the structure is obtained by decomposing the electromagnetic force integrated with the Finite Element (FE) modelling of stator structure as an equivalent cylinder subjected to several sinusoidal distributed loads. Moreover, the modal response through Frequency Response Function (FRF) which is characterized by spatial orders is experimentally identified by measurement through the acoustic test. In the next step, an acoustic FE/BE model is used by taking the vibration velocity into account as a boundary condition for calculation of the vibrating structure radiation and the radiated sound pressure. Finally, the noise radiated by electric motor is identified through the FE simulation and confirmed by experimental measurement. This methodology gives rise to a fundamental understanding of how the electric motor as a noise and vibration subsystem behaves.