Division 3.5 Calculation of the statistical margin

United Kingdom

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

s_{\bar{η_{{MG}_{i}}}} = \frac{s_{η_{{MG}_{i}}}}{\sqrt{m}} = \sqrt{\frac{\sum_{m}^{j = 1} {(η_{{MG}_{i_{j}}} - \bar{η_{{MG}_{i}}})}^{2}}{m (m - 1)}}

The standard deviation of the efficiency value of the efficient 48V motor generator ( $s_{η_{MG}}$ ) shall be calculated in accordance with Formula 9:

Formula 9

s_{η_{MG}} = \sqrt{\sum_{i = 1}^{4} {(h_{i} \times s \bar{η MG i})}^{2}}

The standard deviation of the efficiency value of the 48V/12V DC/DC converter ( $s \bar{η DC ∕ DC}$ ) shall be calculated in accordance with Formula 10:

Formula 10

s \bar{η DC ∕ DC} = \sqrt{\frac{\sum_{1}^{j = 1} {(η_{DC ∕ {DC}_{i_{j}}} - \bar{η_{DC ∕ {DC}_{i}}})}^{2}}{l (l - 1)}}

The standard deviation of the motor generator efficiency ( $s_{η_{MG}}$ ) and of the 48V/12V DC/DC converter ( $s_{\bar{η_{DC ∕ DC}}}$ ) lead to an uncertainty in the CO₂ savings ( $s_{C_{{CO}_{2}}}$ ). That uncertainty is calculated in accordance with Formula 11:

Formula 11

s_{C_{{CO}_{2}}} = \frac{(P_{RW} - P_{TA})}{η_{TOT}} \times \frac{V_{Pe} \times CF}{v} \times \sqrt{{(\frac{s_{η_{MG}}}{η_{MG}})}^{2} + {(\frac{s \bar{η DC ∕ DC}}{\bar{η_{DC ∕ DC}}})}^{2}}