IEEE Electrification Magazine - June 2014 - 52

two or more sources of power on board the vehicle. They
save energy and minimize pollution by combining an electric motor and an internal combustion engine in such a
way that the most desirable characteristics of each can be
used. Hybrid vehicles are generally classified as series, parallel, or plug-in hybrids, as shown in Figure 1. A series
hybrid vehicle is essentially an EV with a battery being
charged on board by the engine-driven generator or by a
fuel cell. In a parallel hybrid vehicle, the engine and the
electric motor are used to drive the vehicle. A plug-in HEV
(PHEV) could be a series or a parallel hybrid with its battery
restored to full charge by connecting it through a charger to
an external electric power source as in an EV. Hence, the
PHEV provides greater EV range compared to other types of
hybrid vehicles. GM's Chevrolet Volt, Toyota Prius, Ford, and
C-Max Energi are some of the PHEVs that are readily available in the market.
Hybrid vehicles are also classified as microhybrids, mild
hybrids, or full hybrids (Figure 2), depending on the role
played by the engine and the electric motor and the mission that the system is designed to achieve. In a microhybrid vehicle, such as a Toyota Crown, the electric machine
power is of the order of 1.5-3 kW, replacing the alternator
in the automobile. The electric machine functions as a beltdriven starter/generator system. In addition to the function
of recharging the 12-V battery in the vehicles, the system is
used for start/stop operation and part regeneration. The
mild hybrid system, such as that in the Honda Insight, provides part electric propulsion by assisting the engine in
passing other vehicles and climbing hills. The electric
machine is generally mounted between the transmission
and the engine and is used for starting the engine and for
regenerative operation. The electric machine power is of
the order of 10-20 kW. The full hybrid system, such as that
in the Toyota Prius, provides the possibility of full electric
propulsion. The engine and the electric motor together can

TAble 1. Power Generation Capability

in Some of the Aircraft.
Aircraft

Electric Power Generation Capability

B717

2 × 40 kVA

B737NG

2 × 90 kVA

B767-400

2 × 120 kVA

B777

2 × 120 kVA and 2 × 20 kVA backup

A340

4 × 90 kVA

B747-X

4 × 120 kVA

A380

4 × 150 kVA and 2 × 120 kVA APU

B787

4 × 250 kVA and 2 × 225 kVA APU

high-performance electrical power components and systems. This article examines the synergies between the
electrical components for electric/hybrid vehicle and MEA
systems and how the systems/technologies developed for
automotive applications can be used for MEAs and vice
versa. This article will further examine the power electronics requirements, operating temperatures, system dc
voltage tradeoffs, electric machines, and energy storage.
The current trends and advances in the research and
technology by the automotive companies for EVs/HEVs
and by the aircraft companies for the MEA systems will
also be presented.

electric Architectures
Electric and Hybrid Vehicles
In EVs, the propulsion is provided by an electric motor powered by a battery with the associated power converter.
Hybrid vehicles have two or more sources of energy and/or

Engine

Generator
Inverter

Inverter

Motor

Inverter

Gearbox
Motor
Battery

Pure Electric

Gearbox

Motor
Battery

Series Hybrid

Figure 1. The electric and hybrid vehicle configuration.

Motor

I E E E E l e c t r i f i c ati o n M agaz ine / j un e 2014

Battery

Parallel Hybrid

Plug-In Parallel Hybrid

Table of Contents for the Digital Edition of IEEE Electrification Magazine - June 2014