SAE Update - August 2021 - 30

ENGINEERING
EVENTS
Modern approaches to electric
vehicle noise and vibration
Often what comes to mind when discussing
electric vehicles are range, charging
infrastructure, fast charging, battery costs,
etc. Often overlooked are the electric
vehicle's noice and vibration characteristics
and how they align with consumer
expectations.
One of the most interesting aspects of
electric vehicles is the absence of the
internal-combustion-engine noise, which
often masks other types of noises such as
wind, road, and vehicle accessories. Wind
and road noise can be very incessant; it is
heard throughout the entire duration of the
trip. For very long, high-speed vehicle
travel, road and wind noise commonly
cause driver fatigue and have an overall
negative effect on the passenger
experience.
" If you are a performance car guy, you
may want to hear the engine-but nobody
buys a car and wants to hear the road
noise, " said Andrea Frey, senior NVH
project engineer at Autoneum North
America Inc. in Novi, Mich.
Vehicle accessory noise from sources
such as HVAC systems, power steering, and
switching mechanisms also becomes more
prominent. Because these noises are
typically masked by the internalcombustion
engine, operators will often
perceive this sound as something being
mechanically wrong with the car-often
30 August 2021
resulting in many trips to the dealership or
local mechanic.
Electric motors offer some unique
challenges with respect to vehicle noise.
The motors themselves are quiet, but the
sound quality coming from them can be
very high-pitch and tonal. Many consumers
often report a " whining " noise with electric
motors.
Sound solutions
Vehicle designers and NVH experts are
looking at a variety of solutions-systems
design, material sound packaging, active
noise control, etc.-to address these noise
concerns. Design engineers have been
addressing electric motor whine by
controlling the motor to create
complementary low-order tone, said
Sumanth Dadam, software engineer and
powertrain Calibration Controls NVH at
Ford Motor Company in Dearborn, Mich.
The motor is controlled to generate random
dithering noise to raise masking noise floor.
It also reduces the tone-to-noise ratio
around tonal targets, combining
complementary injection at low frequency
and dithering at high frequency.
Materials engineers have also developed
many products designed to suppress the
unique unwanted noise from electric
vehicles. " The big challenge is learning how
UPDATE
SAE Update - August 2021

Table of Contents for the Digital Edition of SAE Update - August 2021
