Truck & Off-Highway Engineering - April 2021 - 20

HIGH-VOLTAGE HYBRIDS
On Road CO2 Improvement Relative Baseline [%]
(Grams of CO2 per ton mile basis)
40
30
20

10
0

P1 48V P2 48V P3 48V P4 48V P1 PY2 P2 PY2 P3 PY2 P4 PY2

Freight Ton Efficiency Improvement Relative Baseline [%]
(Ton miles per gallon basis)
40
35
30
25
20
15
10
5
0

33
24
17

27
21

P1 48V P2 48V P3 48V P4 48V P1 PY2 P2 PY2 P3 PY2 P4 PY2

Figure 5. CO2 improvement and freight-ton efficiency
improvement comparison.
Figure 3. Tradeoff analysis of 48V mild and full-hybrid configurations.

Figure 4. Comparison of different parallel architectures based on added cost,
weight and battery life.
Figure 3 compares the fuel consumption reduction, battery capacity, battery voltage and motor power for the four different parallel
hybrid architectures at two different voltage levels against the total
payback period. For each configuration with the 48V mild hybrid system, only one unique solution is presented, representing the maximum fuel consumption reduction within a two-year payback period.
20 April 2021

For the full-hybrid configuration, multiple battery capacity, voltage and motor solutions are presented
based on the different payback periods.
When comparing the various architectures at higher
voltages (>150V), the 350V P3 configuration provides
the maximum fuel-consumption (FC) benefit across
the complete range of payback periods considered.
The higher FC reduction with the 350V P3 configuration is achieved due to the integration of the electric
motor after the transmission. In the P3 configuration,
the electric motor is able to achieve higher regeneration efficiency due to the elimination of the losses
from the transmission and engine during regeneration
when compared to the P1 and P2 configurations.
The P4 configuration, which provides the maximum
regeneration capability, shows limited FC reduction due
to the relatively lower motor power applied. In the P4
configuration, the maximum applied motor speed is
TRUCK & OFF-HIGHWAY ENGINEERING

ALL IMAGES: FEV NORTH AMERICA

Figure 6. EPA 2027 Phase-2 GHG regulations for Class 6-7 urban
vocational applications.

Truck & Off-Highway Engineering - April 2021

Table of Contents for the Digital Edition of Truck & Off-Highway Engineering - April 2021