ANNEXMethodology to determine the CO2 savings of the SEG Automotive Germany GmbH High efficient 48V motor generator (BRM) plus the 48V/12V DC/DC converter fitted in vehicles in compliance with the conditions set out in Article 1
1.INTRODUCTION
In order to determine the CO2 emission reductions that can be attributed to the use of the generation function of the SEG Automotive Germany GmbH High efficient 48V motor generator (BRM), hereinafter referred to as 48 V motor generator or motor generator, plus the 48V/12V DC/DC converter, for use in vehicles in compliance with the conditions set out in Article 1, it is necessary to specify the following:
- (1)
The test conditions;
- (2)
The test equipment;
- (3)
The procedure to determine the total efficiency;
- (4)
The procedure to determine the CO2 savings;
- (5)
The procedure to determine the uncertainty of the CO2 savings.
Two alternative methods can be used to determine the CO2 savings. The methods are described as follows.
2.SYMBOLS, PARAMETERS AND UNITS
Latin symbols
CO2 savings [g CO2/km]
- CO2
Carbon dioxide
- CF
Conversion factor (l/100 km) - (g CO2/km) [gCO2/l] as defined in Table 3
- h
Frequency as defined in Table 1
- i
Number of operating points
- I
Current intensity at which the measurement shall be carried out [A]
- l
Number of measurement of the sample for the 48V/12V DC/DC converter
- m
Number of measurement of the sample for the 48V motor generator
- M
Torque [Nm]
- n
Rotational frequency [min– 1] as defined in Table 1
- P
Power [W]
Standard deviation of the 48V/12V DC/DC converter efficiency mean [%]
Standard deviation of the 48V motor generator efficiency [%]
Standard deviation of the 48V motor generator efficiency mean [%]
Standard deviation of the total efficiency [%]
Standard deviation of the total CO2 savings [g CO2/km]
- U
Test voltage at which the measurement shall be carried out [V]
- v
Mean driving speed of the New European Driving Cycle (NEDC) [km/h]
- VPe
Consumption of effective power [l/kWh] as defined in Table 2
Greek symbols
- Δ
Difference
- ηB
Baseline alternator efficiency [%]
- ηDCDC
48V/12V DC/DC converter efficiency [%]
Mean of the 48V/12V DC/DC converter efficiency [%]
- ηMG
48V motor generator efficiency [%]
Mean of the 48V motor generator efficiency at operating point i [%]
- ηTOT
Total efficiency [%]
Subscripts
Index (i) refers to operating point
Index (j) refers to measurement of the sample
- MG
Motor generator
- m
Mechanical
- RW
Real-world conditions
- TA
Type approval (NEDC) conditions
- B
Baseline
3.METHOD 1 (‘SEPARATE METHOD’)
3.1.Efficiency of the 48V motor generator
The efficiency of the 48V motor generator shall be determined in accordance with ISO 8854:2012, with the exception of the elements specified in this section.
Evidence shall be provided to the type approval authority that the rotational frequency ranges of the efficient 48V motor generator are consistent with those set out in Table 1. The measurements shall be conducted at different operating points, as set out in Table 1. The efficient 48V motor generator current intensity shall be defined as half of the rated current for all operating points. For each rotational frequency, the voltage and the output current of the motor generator shall be kept constant, the voltage at 52V.
Operating pointi | Holding time[s] | Rotational frequencyni [min– 1] | Frequencyhi |
---|---|---|---|
1 | 1 200 | 1 800 | 0,25 |
2 | 1 200 | 3 000 | 0,40 |
3 | 600 | 6 000 | 0,25 |
4 | 300 | 10 000 | 0,10 |
The efficiency at each operating point shall be calculated in accordance with Formula 1:
Formula 1
The efficiency of the generation function (ηMG) shall be calculated in accordance with the following Formula 2:
Formula 2
3.2.Efficiency of the 48V/12V DC/DC converter
The efficiency of the 48V/12V DC/DC converter shall be determined under the following conditions:
Output voltage of 14,3V
Output current of nominal power of the 48V/12V DC/DC converter divided by 14,3V
The nominal power of the 48V/12V DC/DC converter shall be the continuous output power at the 12V side guaranteed by the manufacturer of the DC/DC converter at the conditions specified in the ISO 8854:2012.
3.3.Total efficiency and saved mechanical power
The total efficiency of the 48 V motor generator plus the 48V/12V DC/DC converter shall be calculated using Formula 3:
Formula 3
The 48 V motor generator plus the 48V/12V DC/DC converter generation function lead to saved mechanical power under real-world conditions (ΔPmRW) and type approval NEDC conditions (ΔPmTA) as set out in Formula 4.
Formula 4
ΔPm = ΔPmRW – ΔPmTA
Where the saved mechanical power under real-world conditions (ΔPmRW) shall be calculated in accordance with Formula 5 and the saved mechanical power under type-approval NEDC conditions (ΔPmTA) in accordance with Formula 6:
Formula 5
Formula 6
where
- PRW
Power requirement under ‘real-world’ conditions [W], which is estimated at 750W
- PTA
Power requirement under NEDC type-approval conditions [W], which is estimated at 350W
- ηB
Efficiency of the baseline alternator [%], which is 67 %
3.4.Calculation of the CO2 savings
The CO2 savings of the 48 V motor generator plus the 48V/12V DC/DC converter shall be calculated in accordance with Formula 7:
Formula 7
Where:
- v
Mean driving speed of the NEDC [km/h], which is 33,58 km/h
- VPe
Consumption of effective power specified in Table 2:
Table 2Consumption of effective powerType of engine
Consumption of effective power (VPe)[l/kWh]
Petrol
0,264
Petrol Turbo
0,280
Diesel
0,220
- CF
Conversion factor (l/100 km) - (g CO2/km) [gCO2/l] as defined in Table 3
Table 3Fuel conversion factorType of fuel
Conversion factor (l/100 km) - (g CO2/km) (CF)[gCO2/l]
Petrol
2 330
Diesel
2 640
3.5.Calculation of the statistical margin
The statistical margin of the results of the testing methodology caused by the measurements shall be quantified. For each operating point the standard deviation shall be calculated in accordance with Formula 8:
Formula 8
Formula 9
Formula 10
Formula 11
4.METHOD 2 (‘COMBINED METHOD’)
4.1.Efficiency of the 48V motor generator plus the 48V/12V DC/DC converter
The efficiency of the 48V motor generator plus the 48V/12V DC/DC converter shall be determined in accordance with ISO 8854:2012, with the exception of the elements specified in this section.
Evidence shall be provided to the type approval authority that the speed ranges of the efficient 48V motor generator are consistent with those set out in Table 1.
The measurements shall be conducted at different operating points, as set out in Table 1. The efficient 48V motor generator plus the 48V/12V DC/DC converter current intensity shall be defined as half of the rated current of the 48V/12V DC/DC converter for all operating points.
The rated current of the 48V/12V DC/DC converter is defined as the output nominal power of the 48V/12V DC/DC converter divided by 14,3V. The nominal power of the 48V/12V DC/DC converter shall be the continuous output power at the 12V side guaranteed by the manufacturer of the DC/DC converter at the conditions specified in the ISO 8854:2012.
For each speed the voltage and the output current of the motor generator shall be kept constant, the voltage at 52 V.
The efficiency at each operating point shall be calculated in accordance with Formula 12:
Formula 12
The efficiency of the generation function (ηTOT) shall be calculated in accordance with Formula 13:
Formula 13
The measurement set up has to allow the measurement of the 48V motor generation efficiency alone.
4.2.Demonstration of conservativeness of the 48V motor generator plus 48V/12V DC/DC converter efficiency determination
In order to use the procedure specified in 4.1 for the determination of ηTOT, it has to be demonstrated that the efficiency of the 48V motor generator alone obtained with the conditions specified in 4.1 is lower than the efficiency obtained with the conditions specified in 3.1.
4.3.Saved mechanical power
The 48 V motor generator plus the 48V/12V DC/DC converter generation function lead to saved mechanical power under real-world conditions (ΔPmRW) and type approval conditions (ΔPmTA) as set out in Formula 14.
Formula 14
ΔPm = ΔPmRW – ΔPmTA
Where the saved mechanical power under real-world conditions (ΔPmRW) shall be calculated in accordance with Formula 15 and the saved mechanical power under type-approval conditions (ΔPmTA) in accordance with Formula 16:
Formula 15
Formula 16
where
- PRW
Power requirement under ‘real-world’ conditions [W], which is estimated at 750W
- PTA
Power requirement under type-approval NEDC conditions [W], which is estimated at 350W
- ηB
Efficiency of the baseline alternator [%], which is 67 %
4.4.Calculation of the CO2 savings
The CO2 savings of the 48 V motor generator plus the 48V/12V DC/DC converter shall be calculated in accordance with Formula 17:
Formula 17
Where:
- v
Mean driving speed of the NEDC [km/h], which is 33,58 km/h
- VPe
Consumption of effective power specified in Table 2
- CF
Conversion factor (l/100 km) - (g CO2/km) [gCO2/l] as defined in Table 3
4.5.Calculation of the statistical margin
The statistical margin of the results of the testing methodology caused by the measurements shall be quantified. For each operating point the standard deviation shall be calculated in accordance with Formula 18:
Formula 18
Formula 19
Formula 20
5.ROUNDING
Each value used in the calculation of the CO2 savings can be applied unrounded or must be rounded to the minimum number of decimal places which allows the maximum total impact (i.e. combined impact of all rounded values) on the savings to be lower than 0,25 gCO2/km.
6.STATISTICAL SIGNIFICANCE (for both methods)
It shall be demonstrated for each type, variant and version of a vehicle fitted with the efficient 48V motor generator that the uncertainty of the CO2 savings calculated in accordance with Formula 7 or Formula 17 is not greater than the difference between the total CO2 savings and the minimum savings threshold specified in Article 9(1) of Implementing Regulation (EU) No 725/2011 and Commission Implementing Regulation (EU) No 427/20147 (see Formula 21).
Formula 21
Where:
- MT
minimum threshold [g CO2/km]
total CO2 saving [g CO2/km]
standard deviation of the total CO2 saving [gCO2/km]
- CO2 correction coefficient due to the positive mass difference between the efficient 48V motor generator plus 48V/12V DC-DC converter and the baseline alternator. For the data in Table 4 is to be used.Table 4CO2 correction coefficient due to the extra mass
Type of fuel
CO2 correction coefficient due to the positive mass difference ()[g CO2/km]Petrol
0,0277 · Δm
Diesel
0,0383 · Δm
Δm (in Table 4) is the extra mass due to the installation of the 48V motor generator and the 48V/12V DC-DC converter. It is the positive difference between the mass of the 48V motor generator plus the 48V/12V DC-DC converter and the mass of baseline alternator. The mass of the baseline alternator is 7 kg. The extra mass is to be verified and confirmed in the verification report to be submitted to the type approval authority together with the application for certifications.