Hybrid-electric road vehicles -- Exhaust emissions and fuel consumption measurements

This document specifies a chassis dynamometer test procedure to measure the exhaust emissions and the electric energy and fuel consumption for the vehicles. This document applies to vehicles with the following characteristics: — vehicles classified as passenger cars or light duty trucks, as defined in the relevant regional applicable driving test (ADT) standard; — the nominal energy of the rechargeable energy storage system (RESS) is at least 2 % of the total energy consumption over an ADT; — internal combustion engine (ICE) only using liquid fuels (for example, gasoline and diesel fuel). NOTE In the case of the vehicles with ICE using other fuel [for example, compressed natural gas (CNG), liquefied petroleum gas (LPG), hydrogen], this document can apply except the measurement of consumed fuel; otherwise the measurement method for those using the corresponding fuel can apply. This document proposes procedures for correcting the measured emissions and fuel consumption of hybrid-electric vehicles (HEVs), in order to obtain the values when the state of charge (SOC) of the RESS does not remain the same between the beginning and the end of an ADT. It can also be applied to measurement procedures for exhaust emissions and fuel consumption of externally chargeable HEVs when a vehicle is not externally charged and operated only in the charge sustaining (CS) state, as described in ISO 23274‑2.

Véhicules routiers électriques hybrides -- Mesurages des émissions à l'échappement et de la consommation de carburant

General Information

Status
Published
Publication Date
28-Aug-2019
Current Stage
6060 - International Standard published
Start Date
02-Aug-2019
Completion Date
29-Aug-2019
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INTERNATIONAL ISO
STANDARD 23274-1
Second edition
2019-08
Hybrid-electric road vehicles —
Exhaust emissions and fuel
consumption measurements —
Part 1:
Non-externally chargeable vehicles
Véhicules routiers électriques hybrides — Mesurages des émissions à
l'échappement et de la consommation de carburant —
Partie 1: Véhicules non rechargeables par des moyens externes
Reference number
ISO 23274-1:2019(E)
ISO 2019
---------------------- Page: 1 ----------------------
ISO 23274-1:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 23274-1:2019(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Test conditions and instrumentation ............................................................................................................................................. 3

4.1 Test conditions ........................................................................................................................................................................................ 3

4.1.1 General...................................................................................................................................................................................... 3

4.1.2 Ambient temperature .................................................................................................................................................. 3

4.1.3 Vehicle conditions ........................................................................................................................................................... 3

4.1.4 Chassis dynamometer conditions ..................................................................................................................... 4

4.2 Test instrumentation ......................................................................................................................................................................... 5

5 Measurement of exhaust emissions and fuel consumption ..................................................................................... 5

5.1 General ........................................................................................................................................................................................................... 5

5.2 Test procedure ......................................................................................................................................................................................... 5

5.2.1 Vehicle preconditioning ............................................................................................................................................. 5

5.2.2 Vehicle soak .......................................................................................................................................................................... 5

5.2.3 Vehicle movement to the test room ................................................................................................................. 5

5.2.4 Measurement over ADT ............................................................................................................................................. 5

5.3 Correction of the test results ...................................................................................................................................................... 6

5.3.1 General...................................................................................................................................................................................... 6

5.3.2 Allowable range of RESS energy balance .................................................................................................... 6

5.3.3 Correction procedure by correction coefficient .................................................................................... 6

6 Calculations and expressions .................................................................................................................................................................. 6

Annex A (informative) Linear correction method using a correction coefficient ..................................................7

Annex B (informative) Calculation of allowable range of RESS energy change .....................................................10

Annex C (informative) Theory for the linear regression method ........................................................................................12

Annex D (informative) Guidelines for charge balance measurement .............................................................................14

Bibliography .............................................................................................................................................................................................................................23

© ISO 2019 – All rights reserved iii
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ISO 23274-1:2019(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso

.org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 37,

Electrically propelled vehicles.

This second edition cancels and replaces the first edition (ISO 23274-1:2013), which has been technically

revised.
The main changes compared to the previous edition are as follows:

— the content of ISO/TR 11955:2008, Hybrid-electric road vehicles —Guidelines for charge balance

measurement was merged with this document as Annex D.
A list of all parts in the ISO 23274 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved
---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 23274-1:2019(E)
Hybrid-electric road vehicles — Exhaust emissions and
fuel consumption measurements —
Part 1:
Non-externally chargeable vehicles
1 Scope

This document specifies a chassis dynamometer test procedure to measure the exhaust emissions and

the electric energy and fuel consumption for the vehicles.
This document applies to vehicles with the following characteristics:

— vehicles classified as passenger cars or light duty trucks, as defined in the relevant regional

applicable driving test (ADT) standard;

— the nominal energy of the rechargeable energy storage system (RESS) is at least 2 % of the total

energy consumption over an ADT;

— internal combustion engine (ICE) only using liquid fuels (for example, gasoline and diesel fuel).

NOTE In the case of the vehicles with ICE using other fuel [for example, compressed natural gas (CNG),

liquefied petroleum gas (LPG), hydrogen], this document can apply except the measurement of consumed fuel;

otherwise the measurement method for those using the corresponding fuel can apply.

This document proposes procedures for correcting the measured emissions and fuel consumption of

hybrid-electric vehicles (HEVs), in order to obtain the values when the state of charge (SOC) of the RESS

does not remain the same between the beginning and the end of an ADT.

It can also be applied to measurement procedures for exhaust emissions and fuel consumption of

externally chargeable HEVs when a vehicle is not externally charged and operated only in the charge

sustaining (CS) state, as described in ISO 23274-2.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 10521 (all parts), Road vehicles — Road load
ISO/TR 8713, Electrically propelled road vehicles — Vocabulary
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO/TR 8713 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
© ISO 2019 – All rights reserved 1
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ISO 23274-1:2019(E)
3.1
applicable driving test
ADT
single driving test schedule which is specified for a relevant region

Note 1 to entry: Chassis dynamometer test schedules for a relevant region are the Worldwide Light-duty Test

Cycle (WLTC) or the Urban Dynamometer Driving Schedule (UDDS), for example.
3.2
charge balance of RESS
change of charge in the RESS (3.10) during fuel consumption measurement
Note 1 to entry: Normally expressed in ampere hours (Ah).
3.3
coulomb efficiency
Ah efficiency

efficiency of the battery, based on electricity in coulomb for a specified charge/discharge procedure,

expressed by output electricity divided by input electricity
3.4
energy balance of RESS
RESS
change of RESS (3.10) energy state during an applicable driving test (3.1)
Note 1 to entry: Normally expressed in watt hours (Wh).

Note 2 to entry: For practical use, the energy balance of RESS is approximated by multiplying the charge balance

of RESS (3.2) in ampere hours (Ah) by the nominal voltage in volts (V).
3.5
energy efficiency
Wh efficiency

efficiency of the battery, based on energy for a specified charge/discharge procedure, expressed by

output energy divided by input energy
3.6
externally chargeable HEV

HEV (3.7) with a RESS (3.10) that is intended to be charged from an external electric energy source

Note 1 to entry: External charge for the purpose of conditioning of the RESS is not included.

Note 2 to entry: Externally chargeable HEVs are widely known as plug-in HEVs (PHEVs).

3.7
hybrid-electric vehicle
HEV
vehicle with both a RESS (3.10) and a fuelled power source for propulsion

EXAMPLE Internal combustion engine or fuel cell systems are typical types of fuelled power sources.

3.8
non-externally chargeable HEV

HEV (3.7) with a RESS (3.10) that is not intended to be charged from an external electric energy source

3.9
rated capacity

supplier’s specification of the total number of ampere hours that can be withdrawn from a fully charged

battery pack or system for a specified set of test conditions such as discharge rate, temperature and

discharge cut-off voltage
2 © ISO 2019 – All rights reserved
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ISO 23274-1:2019(E)
3.10
rechargeable energy storage system
RESS

rechargeable system that stores energy for delivery of electric energy for the electric drive

EXAMPLE Batteries or capacitors.
3.11
regenerative braking

braking with conversion of kinetic energy into electric energy for charging the RESS (3.10)

3.12
state of charge
SOC

available capacity of a RESS (3.10) or RESS subsystem expressed as a percentage of rated capacity (3.9)

4 Test conditions and instrumentation
4.1 Test conditions
4.1.1 General

For test conditions, 4.1.2 to 4.1.4 apply. Otherwise, the test conditions of the relevant regional ADT

standards apply.
4.1.2 Ambient temperature
Tests shall be conducted at ambient temperature of (25 ± 5) °C.
4.1.3 Vehicle conditions
4.1.3.1 Vehicle conditioning

Prior to testing, the test vehicle with RESS shall be stabilized as specified by the manufacturers, or the

mileage shall be accumulated to above 3 000 km and less than 15 000 km.
4.1.3.2 Vehicle appendages

Vehicles shall be tested with normal appendages (mirrors, bumpers, etc.). When the vehicle is on the

dynamometer, certain items (e.g. hub caps) should be removed for safety reasons, where necessary.

4.1.3.3 Vehicle test mass

The vehicle test mass shall be selected in accordance with the relevant regional ADT standards.

4.1.3.4 Tyres
4.1.3.4.1 General

The correctly rated tyres as recommended by the vehicle manufacturer shall be used.

4.1.3.4.2 Tyre pressure

The vehicle tyres shall be inflated to the pressure specified by the vehicle manufacturer in accordance

with the test chosen (track or chassis dynamometer).
© ISO 2019 – All rights reserved 3
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ISO 23274-1:2019(E)
4.1.3.4.3 Tyre conditioning
The tyres shall be conditioned as recommended by the vehicle manufacturer.
4.1.3.5 Lubricants
The vehicle lubricants normally specified by the manufacturer shall be used.
4.1.3.6 Gear shifting

If the vehicle is fitted with a manually shifted gear box, gear shifting positions shall correspond to the

relevant regional ADT standard. However, the shift positions should be selected and determined in

accordance with the vehicle manufacturer’s specification.
4.1.3.7 Regenerative braking

If the vehicle has regenerative braking, the regenerative braking system shall be enabled for all

dynamometer testing except where specified in 4.1.4.4 determining the dynamometer load coefficient.

If the vehicle is tested on a single axle dynamometer and is equipped with systems such as an antilock

braking system (ABS) or a traction control system (TCS), those systems may inadvertently interpret

the non-movement of the set of wheels that are off the dynamometer as a malfunctioning system. If

so, these systems shall be temporarily disabled for adjustment to achieve normal operation of the

remaining vehicle systems, including the regenerative braking system.
4.1.3.8 RESS conditioning

The RESS shall be conditioned with the vehicle as specified in 4.1.3.1, or by equivalent conditioning.

4.1.4 Chassis dynamometer conditions
4.1.4.1 General

The vehicle should generally be tested on a single axle chassis dynamometer. A vehicle with four-wheel

drive shall be tested by modifying the drive train of the vehicle. When the vehicle is modified, the

details shall be explained in the test report.

Double axle chassis dynamometer testing should be performed if a modification for single axle chassis

dynamometer testing is not possible for a specific four-wheel drive vehicle.
4.1.4.2 Dynamometer calibration

The dynamometer shall be calibrated in accordance with the specifications indicated in the service

manual provided by the dynamometer manufacturers.
4.1.4.3 Dynamometer warm-up
The dynamometer shall be warmed up sufficiently prior to testing.
4.1.4.4 Determining the dynamometer load coefficient

The determination of vehicle road load and the reproduction on a chassis dynamometer shall conform

to the ISO 10521 series Vehicles equipped with regenerative braking systems that are activated at least

in part when the brake pedal is not depressed shall have regenerative braking disabled during the

deceleration portion of coast-down testing on both the test track and dynamometer.

4 © ISO 2019 – All rights reserved
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ISO 23274-1:2019(E)
4.2 Test instrumentation

Test instrumentation shall have accuracy levels as shown in Table 1, unless specified differently by the

relevant regional ADT standards.
Table 1 — Accuracy of measured values
Item Unit Accuracy
Time s ±0,1 s
Distance m ±0,1 %
Temperature °C ±1 °C
Speed km/h ±1 %
Mass kg ±0,5 %
Current A ±0,5 %
Capacitor voltage V ±0,5 %
Accuracy for measure value: ±0,5% full scale deflection or ±1% of
reading, whichever is greater.
5 Measurement of exhaust emissions and fuel consumption
5.1 General

The ADT procedure shall be selected according to the relevant regional ADT standards. Common

requirements, if not described in the relevant regional ADT standards, are described below.

5.2 Test procedure
5.2.1 Vehicle preconditioning

Vehicle preconditioning shall be carried out in accordance with the relevant regional ADT standard, if

necessary.

If necessary, the RESS SOC may be preadjusted by charging or discharging, to obtain a suitable energy

balance of RESS between the beginning and the end of the test.
5.2.2 Vehicle soak

The vehicle shall be soaked in accordance with the relevant regional ADT standards.

5.2.3 Vehicle movement to the test room

When the vehicle is brought into the test room, and moved during the test if necessary, it shall be

pushed or towed (neither driven nor regenerative recharged). The test vehicle shall be set on the chassis

dynamometer after the chassis dynamometer has warmed up just before the test. The vehicle shall not

be activated during soak until right before starting the test.
5.2.4 Measurement over ADT

Energy balance of RESS, consumed fuel and exhaust emissions shall be measured in each ADT. The

conditions of the vehicle during the ADT shall follow the relevant regional ADT standards.

© ISO 2019 – All rights reserved 5
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ISO 23274-1:2019(E)
5.3 Correction of the test results
5.3.1 General

Measured fuel consumption and exhaust emissions shall be corrected if these test results are influenced

by RESS energy balance during the test. However, the correction is not necessary if the RESS energy

balance satisfies the conditions in 5.3.2. The guidelines for charge balance measurement are described

in Annex D.
5.3.2 Allowable range of RESS energy balance

The correction is not necessary if RESS energy balance is within the following range [see Formula (1)]:

||Δ≤EE00, 1× (1)
RESS CF
where
ΔE is the energy change in RESS over the ADT in Wh;
RESS
E is the energy of consumed fuel over the ADT in Wh.
Practical methods that apply to battery and capacitor are described in Annex B.
5.3.3 Correction procedure by correction coefficient

The vehicle manufacturer shall deliver the correction coefficient to calculate the fuel consumption

and the exhaust emission at ΔE = 0. The correction coefficient can be obtained in accordance with

RESS

Annex A. When the measured value is independent of ΔE , a correction is not required. See also

RESS
Annex C for theory of the linear regression method (in case of batteries).
6 Calculations and expressions

To calculate the resultant exhaust emission and fuel consumption for an ADT, the relevant regional

standards should be taken into consideration.
6 © ISO 2019 – All rights reserved
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ISO 23274-1:2019(E)
Annex A
(informative)
Linear correction method using a correction coefficient
A.1 General

This annex describes the calculation procedure to determine the exhaust emissions and fuel

consumption at ΔE = 0.
RESS
A.2 Method for correcting the exhaust emissions and fuel consumption
A.2.1 Data required for correction coefficient
A.2.1.1 General

The exhaust emissions and fuel consumption test shall be repeated several times to determine the

correction coefficient defined in A.2.1.2.1. See Figure A.1. The ΔE shall be measured during the test.

RESS

The SOC and ΔE should be in the normal range specified by the vehicle manufacturer.

RESS
© ISO 2019 – All rights reserved 7
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ISO 23274-1:2019(E)
Key
X1 energy balance (in Wh), discharge
X2 energy balance (in Wh), charge
Y exhaust emissions M (in g) or consumed fuel M (in l)
E F
1 data
2 premeasured data for determination of correction coefficient
3 exhaust emission K or consumed fuel K
ME MF
exhaust emission
4 measured value (C , M )
s E,s
C is the energy balance (in Wh)
M is exhaust emission (in g)
E,s
5 corrected value (M ) = M - K × C
E,c E,s ME s
fuel consumption
4 measured value (C , M )
s F,s
C is the energy balance (in Wh)
M is fuel consumption (in l)
F,s
5 corrected value (M ) = M - K × C
F,c F,s MF s
Figure A.1 — Example of data collected from ADT
A.2.1.2 Corrections
A.2.1.2.1 Exhaust emission and fuel consumption correction coefficient

The exhaust emission correction coefficient, K , in g/Wh, for each exhaust emission component in

exhaust gas such as CO, HC, NO and CO for an ADT shall be calculated.
X 2
The correction coefficients shall be calculated using Formula (A.1):
nC×∑ MC−∑ ×∑M
iiE, iiE,
K =
(A.1)
nC×∑ −∑()C
8 © ISO 2019 – All rights reserved
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ISO 23274-1:2019(E)
where
M is each exhaust gas component, in grams per test, in an ADT;
E,i
C is the energy balance at the test, in Wh (use the minimum unit);
n is the number of data.

The exhaust emission correction coefficient shall be a four-significant digit figure by rounding the fifth

significant digit figure.

The fuel consumption correction coefficient, K , in l/Wh, for an ADT shall be calculated.

The correction coefficients shall be calculated using Formula (A.2):
nC×∑ MC−∑ ×∑M
iiF, iiF,
K = (A.2)
nC×∑ −∑C
where
M is each fuel consumption result in an ADT, in litres per test;
F,i
C is the energy balance at the test, in Wh (use the minimum unit);
n is the number of data.

The fuel consumption correction coefficient shall be a four-significant digit figure by rounding the fifth

significant digit figure.
A.2.1.2.2 Exhaust emission and fuel consumption at ΔE = 0, M
RESS EC

The value of each exhaust emission, M , at ΔE = 0, is derived from Formula (A.3):

EC RESS
MM=−KC× (A.3)
EC E,sMES
where
M is each exhaust emission in grams per test;
E,s
K is the correction coefficient defined in A.2.1.2.1;
C is the energy balance of RESS, in Wh (use the minimum unit).
The value of fuel consumption, M , at ΔE = 0, is derived from Formula (A.4):
FC RESS
MM=−KC× (A.4)
FC F,sMFS
where
M is fuel consumption in litres per test;
E,s
K is the correction coefficient defined in A.2.1.2.1;
C is the energy balance of RESS, in Wh (use the minimum unit).
© ISO 2019 – All rights reserved 9
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ISO 23274-1:2019(E)
Annex B
(informative)
Calculation of allowable range of RESS energy change
B.1 General

The allowable energy change in RESS, expressed by Formula (1) in 5.3.2, may be rewritten as

Formula (B.1), using the net heating value (NHV) of fuel:
ΔEJ≤×00,/13×m 600
(B.1)
RESS NHVfuel
where
ΔE is the energy change in RESS over the ADT, in Wh;
RESS
J is the net heating value (per consumable fuel analysis), in J/kg;
NHV
m is the total mass of fuel consumed over the ADT, in kg.
fuel

For batteries or capacitors, this allowable energy change can be expressed as shown in Formulae B.2 to

and B.5 below.
B.2 Batteries

The energy balance in the battery over the ADT, ΔE , in Wh, can be calculated from the measured

charge balance, ΔQ, and is expressed as follows:
ΔΔEQ=×V (B.2)
bsystem
where
ΔQ is the charge balance of the battery over the ADT, in Ah;
V is the nominal system voltage of battery system, in V.
system
NOTE V means the same as nominal voltage.
system
For batteries, the formula above may be rewritten as follows:
Jm× /3600
NHVfuel
ΔQ ≤×00, 1 (B.3)
system
B.3 Capacitors

The change of energy stored in the capacitor over the ADT, ΔE , in Wh, is expressed as follows:

ΔE =× VV− /3600 (B.4)
Cfinal initial
10 © ISO 2019 – All rights reserved
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ISO 23274-1:2019(E)
where
C is the nominal capacitance of the capacitor, in F;
V is the terminal voltage of the capacitor at the end of the test, in V;
final
V is the terminal voltage of the capacitor at the beginning of the test, in V.
initial
For capacitors, the formula above may be rewritten as follows:
2××Jm
NHVfuel
VV−≤00, 1× (B.5)
finalinitial
© ISO 2019 – All rights reserved 11
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ISO 23274-1:2019(E)
Annex C
(informative)
Theory for the linear regression method

This annex shows how the linear regression method can theoretically be applied to the correction

method for determining the fuel consumption of HEVs.

The consumed energy of HEVs is composed of the fuel energy consumed by the ICE power train system

and the electric energy consumed by electric power train system. It is necessary to estimate the

consumed fuel during the test in zero charge balance condition (ΔE = 0) in other words that the

RESS

battery SOC after the test is equal to the SOC before the test. Assuming that the average efficiency of

the ICE power train system during the test period is equal to that in the estimated zero charge balance

condition, then Formula (C.1) applies.
αα×=EE× +×βκ× E (C.1)
() ()
0f e
where
α is the average efficiency of ICE power train system during the test period;

β is the average efficiency of electric power train system during the test period;

κ is the average efficiency of battery system during the test period;
E is the consumed energy of fuel during the test period;
E is the consumed/regenerated energy of electricity during the test period;

E is the estimated consumed energy of fuel during the test period, in zero charge balance

condition.

By applying the additional values listed below, Formula (C.1) can be rewritten to Formula (C.2):

αα××γγUU=× × +×βκ×E (C.2)
() ()
0m e
where
γ is the volume energy density of fuel;

U is the estimated consumed fuel during the test period, in zero charge balance condition;

U is the consumed fuel during the test period.

By dividing the consumed values from Formula (C.2) by the distance travelled, L, and introducing the

corresponding consumption values listed below, Formula (C.2) can be rewritten as Formula (C.3):

αγ××FC =× αγ ×+FC βκ××EC (C.3)
() ()
0 mm
12 © ISO 2019 – All rights reserved
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ISO 23274-1:2019(E)
where

FC is the estimated fuel consumption rate in the test period, in zero charge balance condition;

FC is the fuel consumption rate during the test period;
EC is the electric energy consumption rate during the test period;
m signifies "measured".

Therefore, the measured fuel consumption rate, in certain charge balance condition, FC , can be

expressed as follows:
βκ×
 
FC =−FC EC (C.4)
mm0  
αγ×
 
Electric energy consumption rate, EC , can be expressed as follows:
EC ≅×V (C.5)
where
V is the system voltage, in V;
ΔQ is the charge balance of the battery during the test period, in Ah;
L is the distance covered in the test period, in km.
Formula (C.4) and Formula (C.5) lead to following Formula (C.6):
VQβκ× Δ
FC =−FC × × (C.6)
m 0
γ α L

Formula (C.6) shows that FC is the function of charge balance per distance (ΔQ/L). Refer to D.3.2 for

further information.

Formula (C.6) also shows that the gradient of this formula is in proportion toβ/α, namely to the ratio

of electric and ICE traction system efficiency. It also shows that the y-axis-crossing value in

...

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