Division 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 14,3 V. 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

All efficiency measurements are to be performed consecutively at least five (5) times. The average of the measurements at each operating point ( $\stackrel{–}{{\eta }_{{\mathrm{TOT}}_i}}$ ) shall be calculated.

The efficiency of the generation function (η_TOT) 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.