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Division 3.3 Calculation of the uncertainty of the CO2 savings

United Kingdom

Original text. Later amendments are not shown.

The uncertainty of the CO2 savings calculated in accordance with point 3.2 shall be quantified.

For this, the following calculations are needed.

First, the standard deviation of the efficiency of the 48V motor-generator at each operating point [%] shall be calculated in accordance with Formula 9.

Formula 9

where

  • is the number of measurements j undertaken at each operating point i for the 48V motor-generator efficiency, as referred to in point 2.1

  • is the efficiency of the 48V motor-generator calculated for an individual measurement j at operating point i as referred to in point 2.1 [%]

  • is the average efficiency of the 48V motor-generator calculated for an operating point i, as determined in point 2.1 [%]

    • Next, the standard deviation of the efficiency of the 48V motor-generator [%] shall be calculated in accordance with Formula 10.

    Formula 10

    where

  • is as determined by Formula 9 [%]

    • hi

  • is the frequency of operating point i, as set out in Table 1.

    • Then, the standard deviation of the efficiency of the 48V/12V DC/DC converter [%] shall be calculated in accordance with Formula 11.

    Formula 11

    where

    L

  • is the number of measurements l undertaken for the 48V/12V DC/DC converter, as referred to in point 2.2

  • is the efficiency of the 48V/12V DC/DC converter calculated for an individual measurement l as referred to in point 2.2 [%]

  • is the efficiency of the 48V/12V DC/DC converter, as determined in point 2.2 [%]

    • Finally, the uncertainty in the CO2 savings of the 48V motor-generator combined with the 48V/12V DC/DC converter shall be calculated in accordance with Formula 12 and shall not exceed 30 % of the CO2 savings.

    Formula 12

    where

  • is the power requirement under ‘real-world’ conditions, which is 750 W

  • is the power requirement under type-approval conditions, which is 350 W

  • is the total efficiency of the 48V motor-generator combined with the 48V/12V DC/DC converter as determined in point 2.3 [%]

  • is the consumption of effective power as specified in Table 2 [l/kWh]

  • is the fuel conversion factor as specified in Table 3

  • is the mean driving speed of the WLTP, which is 46,6 km/h

  • is standard deviation of the efficiency of the 48V motor-generator as determined in accordance with Formula 10 [%]

  • is the efficiency of the 48V motor-generator, as determined in point 2.1 [%]

  • is the standard deviation of the efficiency of the 48V/12V DC/DC converter, as determined in accordance with Formula 11 [%]

  • is the efficiency of the 48V/12V DC/DC converter as determined in point 2.2 [%]