IEEE Electrification Magazine - June 2020 - 12

Electrical systems
in vehicles have
evolved since the
invention of the first
horseless carriage,
when internal
combustion autos
lacked electric
features entirely.

Electrical systems in vehicles have
evolved since the invention of the
first horseless carriage, when internal
combustion autos lacked electric features entirely. Then, for the first half
of the 1900s, 6-V architectures were
incorporated to power basic features
like lights and radios. For the nearly
50 years since, the 12-V system has
been standard, although it was
momentarily threatened in the 1990s
by a 42-V system concept. However,
improvements to the 12-V system,
along with challenges related to the
complete overhaul of the electrical
system required by a move to 42 V,
made the concept short-lived.
Although today's 12-V system can provide ample power
for lighting, infotainment, and other traditional light-load
components, the rapid adoption of fuel-saving and performance technologies, such as electrified turbochargers,
advanced suspension systems, brake energy recuperation
and electric boosting by hybrid powertrains, and, ultimately,
full electrification, requires more robust electric power.
Recent improvements in power electronics, electric
machines, and battery technology are enabling the change
to 48-V systems, which provide benefits like increased
power capabilities, energy recuperation, and uninterrupted
power to electric components during an engine stop. These

HV ISG

48-V iBAS

HV On-Axis

P2 48-V/HV Off-Axis

improved technologies, along with an
increasing awareness of fuel consumption, CO2 emissions, and environmental impacts, have driven the idea of
the electrified powertrain.
While the eventual future of full
electrification is almost certain, the
incremental steps to achieve it have
many possible paths. For example, as
electrified technology is adopted, the
internal combustion engine is being
adapted to gain full optimization.
Except for the battery electric vehicles (EVs) and extended-range EVs,
the traditional engine still contributes to overall system efficiency significantly. The increased complexity
of merging the conventional and electrified technologies
requires careful assessment of system architecture and
component design.

Mild Hybrid Architectures
One of the most promising ways to achieve significant
efficiency and performance with limited additional cost
increases is through the application of a mild hybrid vehicle architecture. The conventional powertrain relies on
hydraulic and 12-V systems. Reducing the drain of inefficient hydraulic power systems and increased electrical
loads requires a better solution. Mild 48-V hybrid

P3 48-V/HV MGU

HV eAWD

P4 48-V eAWD

BEV HV Off-Axis

HV PS

HV On-Axis

HV BISG
Hybrid Architecture-"P" Modes

Figure 1. The mild electrification-system architecture. BISG: belt-integrated starter generator; iBAS: integrated belt alternator starter; HV: hybrid
vehicle; ISG: integrated starter generator; MGU: motor-generator unit. (Source: BorgWarner.)

I E E E E l e c t r i f i cati o n M agaz ine / J UN E 2020

IEEE Electrification Magazine - June 2020

Table of Contents for the Digital Edition of IEEE Electrification Magazine - June 2020