Energy storage systems (ESS) have been a major research area
in electric, hybrid electric, and plug-in hybrid electric vehicles
(EVs, HEVs, and PHEVs) for a long time [1]-[9]. Of all the
energy storage devices, battery is one of the most widely used.
However, using battery as the sole energy storage system has
several disadvantages [1]-[4]. In order to approach the
performance of a conventional car, the energy storage system
of a hybrid or electric vehicle shall have an equivalent or
similar power capability as a gasoline engine. Unfortunately,
most available batteries have relative low power density.
Although there are high power density batteries available, the
price is much higher; also with the increased power density, the
thermal management of the battery will be a challenge. The life
of the battery is another major area of concern. In advanced
automotive applications, because the load profile varies rapidly
according to the road conditions and the driver’s behavior, the
energy storage system suffers from random charges
(regenerative barking) and discharges (acceleration command),
which have a negative effect on the life of the battery [6], [7]