Experimental NVH evaluation of a pure electric vehicle in transient operation modes

Many driving schools adopt existing vehicle platform for integration with electric powertrains to reduce fuel consumptions. The special car consists of a conventional manual transmission but a driving motor for driving instruction. This modification can create unique challenges for noise, vibration and harshness (NVH) refinement. This paper presents an experimental NVH evaluation of the special electric vehicle, which lays more emphasis on transient operations. The powertrain mounting system, the driving motor and the transmission are tested and their NVH performances are analyzed at different transient modes. The results indicate that the transmission and the final drive contribute to the medium frequency range of interior noise due to the missing masking of the internal combustion engine. In addition, the vibration isolation performance of electric powertrain mounting system is assessed by calculating transmissibility characteristics of the powertrain mounts. It is pointed out that the transmissibility of 20 dB, which means ninety percent of the vibration energy has been reduced, may no longer be suitable for an electric powertrain mounting system. Furthermore, interior vibration behaviors such as the acceleration amplitude of seat track should be subordinated to the assessment of the powertrain mounting system.