Acoustic Analysis of an Active Noise Control Exhaust System on HiL

Acoustic Analysis of an Active Noise Control Exhaust System on HiL

Acoustic Analysis of an Active Noise Control
Exhaust System on HiL Test bench
2015 GT-SUITE European Conference
26-10-2015 , Frankfurt / Main
F. Buganza, D. Tajic, J. Krüger, T. Rose, M. Conrath
DRIVING THE MOBILITY OF TOMORROW
Active Noise Control
1st Patent (Paul Lueg 1933)
•
•
•
•
“Active sound compensation by anti-noise”
Measurement of source-noise sound waves via
microphone.
Calculation Procedure.
Projection of anti-noise (anti-phase signals) through a
speaker
Historical Limitations:
•
•
noise
residual noise
•
Anti-noise calculation involves complex mathematical
algorithms.
High-quality electronics & calculation speed is
necessary to realize in any dynamic environment
First practical application in Headphone for pilots
anti-noise
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Eberspächer's ActiveSilence-technology
Principle Advantages for exhaust systems
Packaging:
Very effective in reducing basic engine firing &
sub-firing orders, replacing the primary drivers for
larger muffler volume:
=> eliminate silencers.
Backpressure/Performance:
No need for reflection, expansion chambers or
other restrictive acoustic devices:
=> more power and torque.
Sound Design Flexibility:
Software control of engine orders allowing an
adaptive sound design:
=> easy sound customization.
Engine
Tailpipe
Exhaust Pipe
Actuator with
Loudspeaker
Error
Microphone
Engine Speed &
Load Signal (CAN)
Controller
Engine
Firing Sound
Speaker
Anti-noise
System Modularity
Versatile muffler construction leading to more
carry-over-parts, simplified tooling and
development procedures:
=> reduced development time and cost.
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ActiveSound / ActiveSilence
Typical System Layout and results
Passive exhaust system:
• dual line, 4x mufflers
• 27 kg
• 50 Liters
ActiveSilence system:
• single line, 1x muffler
• 18 kg
• 23 Liters
Engine
control unit
Actuator
CAN-bus
Error sensor
ANC control unit
Achieved results:
single active exhaust line
-33%
-33% weight
weight and
and
-54%volume
-54%volume
backpressure similar to series
free sound
design:
free
sound
design
acoustic comfort / sport sound
[dB(A)] Sound Pressure Level
100
90
Passive Muffler
ANC off
ANC on
OVL
80
70
60
50
1000
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1,8m behind car
2nd EO
2000
3000
4000
5000
6000
Rotational Speed [1/min]
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ActiveSilence-HiL : what? why?
The aim of the silence-HIL is to simulate till a certain grade of accuracy the real system and allow a very fast
calibration as well as an easier continuous engineering of the ANC software.
Acoustic
requirements
fast acoustic
design (SW
calibration
target exhaust
system
fast muffler
design
ECU
Development
exhaust system
simulation
estimation of
microphone best
positioning
validation of new
SW/HW features
ANC control unit
Expected advantages of the HiL-System:
•
at least 80% of design verification can be done on HIL system
less tests on roller dyno or real engine necessary
•
faster design of the passive muffler, including microphone placement
•
fast prototyping (SW and HW)
•
100% repeatability of test-environment,
easy simulation of all possible environmental conditions
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ActiveSilence-HiL : Simulation requirements
Exhaust sound pressure level (NOISE):
System noise/
uncertainty
Engine:
CAN-bus simulation
Exhaust gas mass flow
simulation
Amplitude of 2 most significant engine orders through
GT-Realtime shall be the same as in GT-Suite
The phase relationship between the 2 most significant
engine orders through GT-Realtime shall remain the
same as the simulation through GT-Suite
Spectrum: the frequency range is [25..500] Hz
CAN-bus
Actuator sound pressure (ANTI-NOISE):
The actuator mechanics shall be modelled
input of the model is the speaker membrane
displacement
Error microphone: sound
pressure and electrical
conversion
ANC control unit
Sampling frequency:
for a realistic simulation
the Exhaust model shall be
simulated @5kHz rate
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ActiveSilence-HiL: Architecture
GT-Suite-RT
Simulink
HIL Software
[Mass flow]
exhaust sound
pressure model
cold-end
model
[Exhaust temperature]
[Membrane
displacement]
[RPM, Torque]
GT- Realtime:
acoustics +mechanics
[Acoustic
pressure]
actuator
mechanical model
actuator electrical
model
HiL
Control
Simulink: electrical
microphone
model
cold end
temperature
model
central CPU, I/O interfaces :sensors, speaker emulation, battery supply...
battery
model
HIL
HIL Hardware
Hardware
ANC control unit
[CAN BUS]
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ActiveSilence-HiL – design of the GT-Suite-RT model
catalytic converter
model
Mass flow &
engine
temperature
model
junction
actuator
coldend
Muffler
model
actuator
mechanics
Loudspeaker
membrane
x0
x0+x(t)
error
sensor
p(t)
outlet
juction
this is the GT-Suite
model used in numerical
simulations
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let´s make the
Real-Time version to be
integrated on HiL…
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ActiveSilence-HiL – design of the GT-Suite-RT model
STEP I
Muffler-out mass flow
and temperature from
numerical simulation
were introduced as
“inputs” to the active
system only.
STEP II
Modified discretization,
time step-size to ensure RT
convergence:
internal 2x oversampling
step-size = 100µs
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ActiveSilence-HiL – design of the GT-Suite-RT model
HiL control-SW
(Simulink model)
STEP III
Actuator
electric
model
Integration in the Simulink
Model
STEP V
Hil can finally run!
STEP IV
Code Generation through
Simulink Realtime
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ActiveSilence-HiL: Numeric (“full system”) vs.
realtime simulations
2nd E.O.
2nd E.O.
4th E.O.
4th E.O.
6th E.O.
6th E.O.
1000rpm
2nd E.O.
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3000rpm
φ
A
deviation
4500rpm
φ
deviation
2nd engine
order
< 1dB
1°
1dB
4°
< 1dB
1°
4ht engine
order
< 1.5dB
11°
<3dB
5°
< 1dB
11°
deviation
A
deviation
φ
A
deviation
deviation
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ActiveSilence-HiL: realtime simulation results
ANC OFF
ANC ON
ANC calibration:
cancellation on 1st, 2nd, 4th and 6th engine order
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ActiveSilence-HiL: realtime simulation results
SPL at error microphone
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Conclusions
the development of HiL fulfills the expectations
Realtime simulation @ 5kHz is possible, CPU usage ~40%
accurate simulations results
easy workflow
For several duties, the HiL is a valid substitute of expensive acoustic test on
vehicle
Use case
as usual for SW/HW development
for dimensioning of ANC exhaust systems
Next improvements:
muffler shall be modelled on GT-Suite RT
improvement of sensor-noise modelling
sound reflections to speaker membrane and muffler shall be modelled as well
aggressive usage of multicore CPUs / multithreading to allow even more complex
simulations
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Thank You very much for Your attention!
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