WLTP-08-32e
Status Report of the WLTP coasting TF
Author: Thomas Vogel (chairman)
Presenter: Heinz Steven
with contributions from the Bosch presentation at the WLTP coasting TF telco
at 06.11.2014
WLTP IG, 8th meeting, Pune, Nov 2014
Coasting TF proposals (reviewed since 7th WLTP IG)
1
Synthetic differential supplemental CO2 test:
Combine different coast sequences, which
represent real life coasting time share and
WLTP speed distribution. Compare cycle with
different deceleration: engine drag vs. coasting
2x ~15 min hot CO2 test
2
Weighted CO2 difference of
original WLTP vs. modified WLTP
(PSA proposal)
CO2 final = CO2 WLTP original +
Utility Factor * (CO2 WLTP coast
modified – CO2 WLTP original)
2x hot WLTP or 1x cold
3
Post calculated CO2 difference:
accumulate filtered 1Hz
resolved CO2 measured data
from the WLTP test
(Bosch proposal)
~5 min coast function test
Japan position regarding Coasting
• Japan cannot support PSA proposal, because it is cycle
modification.
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• Japan has no objection to continue discussion with Bosch 3
proposal on WLTP level.
• A methodology needs to address the following concerns and
confirmed by data before adopted.
• The methodology is able to evaluate various kind of sailing
(coasting) technologies fairly.
• The methodology must be robust and reflect real-world CO2
benefit. (regional difference/driver-behavior difference etc)
• The methodology doesn't create CO2 flexibility.
2
Remaining 3rd proposal (Bosch)
1. Perform cold unmodified WLTP test:
– with disabled coasting function.
– Measure modal CO2 or
– use (bag normalized) OBD fuel flow data
(1Hz resolved time aligned CO2 data)
2. OEM declares (coast calculation critical) parameters
– prove with a simple supplemental test (no CO2 measurement)
3. Post calculation:
– with variable filtered measured WLTP 1Hz data
– accumulate delta CO2,
– until time share meets a Coast Time Share
(CTS*1800s) target,
– Correct for SOC & engine restart energies
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Coasting in WLTP - Bosch Proposal
Proof of Technology & Op. Strategy while TA



Additional simple test procedure, conducted after std. TA measurements
(no CO2 measurement !)
OEM has to declare his implemented Coasting strategy in advance. Relevant parameters:
 entry and exit speed limits,
 IDC vs. SSC speed limits,
 delay time(s) completeness to be checked
Vehicle driving short test on dyno (e.g. 5 min, vehicle warm) consisting of different constant
speed levels & following coast down to a minimum speed (e.g. 15km/h).
Indication to test driver of act. speed, act. gear (MT) & when to release gaspedal
 measured parameters tbd. proposal:
vehicle speed, engine speed, powertrain connected/disconnected condition
Output of test:
 Proof of technology
 Operating strategy according OEM statement.
Gasoline Systems
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Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction,
editing, distribution, as well as in the event of applications for industrial property rights.
speed

time
Coasting in WLTP/Bosch Proposal
Calculation Sequence
INPUT
ALGORITHM
Measurement data
Pre-Calculation
 vehicle parameter: mass, friction, …
 vehicle speed
 fuel consumption (mass flow)
 vehicle driving power
 acceleration
Limitations
vmin, vmax
amin, amax
OUTPUT
Restrict data points
 Vehicle speed in range
 Acceleration
in range
Determine Coasting Phases
preset Pthreshold
• Identify data points i w/
vehicle power demand < power threshold
• calculate coasting time (sum of data points)
Real life coasting
Coasting
implementation
quality in vehicle
coasting time share
tcoast
idle consumption
mfidle
time share reached?
Post-Calculation
Replace fuel consumption of data points i w/
 coasting w/ engine on  idle consumption
 coasting w/ engine off  zero consumption
NO: increase power threshold
coasting benefit
S replaced fuel consumptions
Gasoline Systems
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Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction,
editing, distribution, as well as in the event of applications for industrial property rights.
Coasting in WLTP/Bosch Proposal
Coasting Share  CO2 Benefit in WLTC
Variation of coasting time share compares to:
 variation of power threshold
18%
10 kW
16%
IDC
Relative benefit [%]
14%
SSC
6 kW
12%
4 kW
10%
3 kW
8%
2 kW
1 kW
6%
0.1 kW
4%
2%
0%
5
10
15
20
25
Coasting time share [%]
Reference: Data WLTC measurement on test bench, Audi A3 1.4L TSI, MT6
Time resolved fuel consumption measured by test bench equipment (sample rate1 Hz)
Gasoline Systems
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Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction,
editing, distribution, as well as in the event of applications for industrial property rights.
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Coasting in WLTP/Bosch Proposal
Coasting Share: Representative average base value



Coasting time shares are based on driver statics influenced by:
 Regional infrastructure: grade, roads, traffic,
 Coast function implementation: driver info, navi,

Average Coasting Time Share found: 25%* (=30% Coasting Distance Share)
 GER route: FKFS near Stuttgart: 17%...35% (Audi A3, probands, normal driving)
 US route: Farmington Hill cycle: 22%** (average of 11%...56%)
 JRC Monograph: Porsche field data indicate 26% CTS
 Representative average base value for most vehicles & drivers

Additional tests shall show regional & implementation influence
25% CTS assumed to be representative base (for BOSCH implementation)
Operating strategy has to be considered in algorithm
Gasoline Systems
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* Base: BOSCH Operating Strategy, based on total cycle time/distance with powertrain open until engine re-start
@vehicle speed ≥0km/h
** VW Passat with DCT
Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction,
editing, distribution, as well as in the event of applications for industrial property rights.
Next steps of Coasting TF
 Review calculation methodology in detail
– Calculation method (Excel sheet)
– Vehicle bandwidth study
 Discuss possible / recommended modifications
– Time resolved CO2 measurement alternatives
– Distance compensation in calculation
 Plan for additional tests to determine Coasting Time Share
– Review existing coast data
– OEM to deliver vehicles for additional tests
– Institutes to perform tests or witness OEM tests
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