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T
his article offers a survey of recent solutions involv-
ing electric drives and power chargers for fully elec-
tric vehicles (EVs) and hybrid EVs (HEVs). Based on
our research and experimental activities regarding
electric drives, we also show experimental data from proto-
types. After reviewing the opportunities and challenges of
vehicle electrification, the article analyzes electric
machines and power converters for two main market
trends: 1) low-voltage (48-V) HEVs, allowing for a smooth
transition from internal combustion engine vehicles
(ICEVs), and 2) full EVs, operating above 200 V. First, we dis-
cuss a 48-V integrated belt-driven starter generator (BSG),
together with its tightly coupled power control electronics.
Substituting a 12-V alternator, the BSG provides torque
assistance to ICEVs for low-speed, start-stop and regenera-
tive-braking functionalities, and electric power generation
for onboard loads. Instead, new topologies of electric
machines are needed for full EVs.
To this end, we discuss and compare three types
of permanent-magnet (PM) electric motors, with out-
put power and torque levels of up to 64 kW and 511
Nm, respectively: interior PM (IPM), flux-switching PM
(FSPM), and Vernier PM (VPM). Energy efficiency and
pollutant emissions reduction can be further improved
by adopting bidirectional power converters for HEV/
EV charging. Hence, we review a bidirectional charging
system, also using renewable energy sources (RESs), to-
gether with its power converter.
Emerging Trends for Powertrain Electrification
In vehicle design, the electrification of propulsion [1]–[7]
is mainly performed to reduce the emission of pollutants
in the air as well as the use of fossil fuels. The evolution
toward electric and hybrid mobility has been accelerated
by “Dieselgate” in Europe and the United States [2] and by
the high economic cost (for ICEVs) of restrictive regula-
tions over greenhouse gases. The key components that
enable such a revolution are power converters [3] as well
as electric machines and energy storage components [4]–
[7]. Acceptable levels of carbon dioxide ( ) CO2 emissions
in the United States, the European Union (EU), Japan, and
China have been lowered from roughly 200 g of CO2 per
traveled km in the 2000s to fewer than 100 g/km in 2020.
For example, because of Euro 6.2 regulation, CO2 emis-
sions in Europe should be reduced to within the limit of 95
ELECTRIC DRIVES AND
POWER CHARGERS
Recent Solutions to Improve Performance and Energy
Efficiency for Hybrid and Fully Electric Vehicles
Sergio Saponara, Christopher H.T. Lee, Nelson Xuntuo Wang, and James L. Kirtley, Jr.
Digital Object Identifier 10.1109/MVT.2019.2959343
Date of current version: 14 January 2020