NVH challenges and solutions to mitigate cabin noise in electric vehicles

Abstract

The vibration of a vehicle often causes discomfort, fatigue and even injury to passengers. Therefore reducing vibration levels to a tolerable range is one of the most important goals in electric vehicle design. Since ride comfort is determined by road roughness and vehicle properties, the uncertainty of ride comfort results from uncertainties of road roughness and vehicle property data. A general multi-body dynamics formulation is employed to obtain dynamic response to evaluate the ride comfort uncertainty. The effects of individual and overall design variable uncertainties on the ride comfort are investigated for the reliability analysis and NVH acceptability of the electric vehicle under consideration. In order to control exterior Noise and Vibration, the sound pressure levels (SPL) of the car exterior structure-borne noise is investigated and suitable NVH solutions was implemented. The sound package schemes for controlling car exterior and interior noise were designed, implemented and analyzed to meet the customer comforts and requirements. The sound quality for the motor and transmission whine sound in the electric vehicle was investigated and gear profile changes and to maintain the consistency of the produced components. Many of the NVH solutions for energy-efficient lightweight electric vehicles were implemented by prototype method, analyzed through detailed objective assessment and put into production. Methods and analysis tools used in this study are highly up-to-date. Electric Vehicles in particular pose challenge for car manufacturers, suppliers and customers. NVH sound package for electric vehicle solutions which includes sound design & perception. In order to address the road and wind noise, vehicle integration processes were fine-tuned and controlled. Lightweight structures such as foams butyl pads, rubbers and liquid foams were used to avoid squeak & rattle. HVAC noise was tackled by optimizing the compressor and blower noise system performance, without compromising the cabin comfort. External & internal noise, incl. system design, aero-acoustics, tyres and road noise, noise radiation and pass-by noise. In comparison to the benchmark vehicle meeting In cabin noise comfort level in electric car is all the more challenging as engine noise is absent, which generally camouflages low frequency noise, tyres noise, road & transmission noise.