12 V SoC – Monitoring - Assessment of Tolerances Audi AG 8.11.2011 WLTP-DTP-LabProcICE-105.

12 V SoC – Monitoring - Assessment of Tolerances

Audi AG 8.11.2011

WLTP-DTP-LabProcICE-105

2 Dr. F. Mühlberger, Dr. M. Bergmann, Dr. Kolesa AUDI AG

Regulation R 101

► 5.3. Test results

► 5.3.1. The test results (fuel consumption C [l/100 km] and CO2-emission M [g/km]) of this test are corrected in function of the energy balance ΔEbatt of the vehicle’s battery.

► The corrected values (C0 [l/100 km] and M0 [g/km]) should correspond to a zero energy balance (ΔEbatt = 0), and are calculated using a correction coefficient determined by the manufacturer as defined below.

► …

► 5.3.1.1. The electricity balance Q [Ah], measured using the procedure specified in appendix 2 to this annex, is used as a measure of the difference in the vehicle battery’s energy content at the end of the cycle compared to the beginning of the cycle….


Regulation R 101 (ctd)

► 5.3.2. Under the conditions below, it is allowed to take the uncorrected measured values C and M as the test results:

► 1) in case the manufacturer can prove that there is no relation between the energy balance and fuel consumption,

► 2) in case that ΔEbatt always corresponds to a battery charging,

► 3) in case that ΔEbatt always corresponds to a battery decharging

and ΔEbatt is within 1 per cent of the energy content of the

consumed fuel (consumed fuel meaning the total fuel consumption over 1 cycle).

► The change in battery energy content ΔEbatt can be calculated from

the measured electricity balance Q as follows:

► ΔEbatt = ΔSOC(%) ·ETEbatt ≅ 0.0036·|ΔAh|·Vbatt = 0.0036·Q·Vbatt (MJ)

► with ETEbatt [MJ] the total energy storage capacity of the battery and

Vbatt [V] the nominal battery voltage.


Regulation R 101 (ctd)

► 5.3.3. Fuel consumption correction coefficient (Kfuel) defined by

the manufacturer

► 5.3.3.1. The fuel consumption correction coefficient (Kfuel) shall

be determined from a set of n measurements performed by the manufacturer. This set should contain at least one measurement with Qi < 0 and at least one with Qj > 0.

► …..

► …..


Equipment for Monitoring of SoC

0,1% rdg and 0,2% f.s. 0,5% rdg and 0,05% f.s.

rdg accuracy (0,12+0,52) = 0,51 %f.s. accuracy (0,22+0,052) = 0,21 %

f.s. = full scalerdg = readingError depends on full

scale and actual values


Theoretical approach – 200 A over NEDC

0

10

20

30

40

50

60

70

80

-200

-150

-100

-50

0

50

100

150

200

0 200 400 600 800 1000 1200

current [A] electrical charge [Ah] charge ± tolerance [Ah]

[A]

[Ah]

[t]

error = ±0.72 %

Max dev. = 0.48 AhCurrent constant @ 200 A


Theoretical approach – instationary test, 3 Ah over NEDC

Max dev = 0.16 Ah

(In WLTC ~ 5 Ah corresponds to Ebatt = 1% Energy of consumed fuel @ ~100 g/km CO2)

-5

-4

-3

-2

-1

0

1

2

3

4

5

-200

-150

-100

-50

0

50

100

150

200

0 200 400 600 800 1000 1200

current [A] electrical charge [Ah] charge ± tolerance [Ah]

[A]

[Ah]

[t]

error = ±6 %


Tolerance of CO2-Measurement

► The error in the determination of CO2 is a result of tolerances in various systems within the

complete emission test procedure:

► Tolerance of measurement equipment

• Span Gas

• Linearization of Analyzer

• Span Gas Divider

• Dyno specifications (tolerances)

► Tolerance of vehicle (e.g.)

• Battery energy management

(charging/decharging)

• Operational strategies (adaptions etc.)

• Reference fuel (density)

► Tolerance of lab processes

• Speed trace – shifting points

• Soak temperature

With improved WLTP procedures and reduced tolerances an overall tolerance of 2 % in CO2 measurement is estimated.

Results of Validation Phase 2 and Correlation will provide further evidence


Assessment of Tolerances for Correction of CO2 as f(SoC)

0 Ah+10 Ah - 10 Ah - 5 Ah+ 5 Ah

100

95

90

105

CO2

g/km

Delta SoC 12 V Battery

Vehicle with Turbo Diesel Engine FC 3,8 l/100 km = 100 g/km CO2

Test Cycle: WLTC Battery Voltage: 12.8 V Tolerance CO2 Measurement: 2 % Tolerance SoC Monitoring: 6 %

Meas. Tolerance of CO2

and SoC

Function of CO2 vs. SoC =>

1,6 g CO2 per Ebatt /% of consumed fuel

Evaluation of CO2/SoC ratio with tolerances (R101)

=>max 2,6 g/km CO2 / Ebatt

min 0,6 g/km CO2 / Ebatt

Ebatt= +-1% of consumed fuel

Ebatt= +-2% of consumed fuel

Application of R101 provision


Conclusion

► The error in the determination of electrical charge with an typical ammeter consists of full scale and reading error. For a typical current of a conventional engine it is assessed at 6 %. The error in the determination of CO2 is estimated at

minimum 2 % over the whole chain of measurement equipment, vehicle and lab process.

► For a vehicle emitting 100 g/km CO2 in WLTC Cycle, Ebatt of 1 % of consumed fuel

energy is about 5 Ah. The tolerance of measured energy - depending on charging

strategy - is about 0.3 Ah.

► For correction of CO2 following R101 the ratio measurements at different Ebatt of

the low voltage batteries have to be performed (feasibility of this proposal for low voltage batteries is still to be evaluated)

► The assessed tolerances of CO2 and SoC measurement result in an overall

tolerance in the determination of the ratio CO2 / Ebatt of about 60 %.

► The correction process for CO2 as f(Ebatt) for a low voltage

battery is still very much uncertain. Further data have to be provided through VP2


Proposal

Options:

► Make no proposal from OICA (Tuev Nord proposed following R101)

► Apply R101, but stay with a correction threshold of Ebatt

> 2 % of consumed fuel energy for low voltage batteries monitoring. Further evidence will be available after Validation Phase 2 and WLTP Correlation.

► Use of a fix correction function dependent on used battery energy (1 % of consumed fuel energy = 1,6 g/km CO2) without threshold.

…..

12 V SoC – Monitoring - Assessment of Tolerances Audi AG 8.11.2011 WLTP-DTP-LabProcICE-105.

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