Environmental Engineering Reference
In-Depth Information
IC Engine
TRASMISSION
DC-AC
CONVERTER
ELECTRIC
MOTOR
TANK
Electric Drive
Rechargeable
BATTERY
Fig. 5.17
Series hybrid configuration
hybrid, the mechanical force for the traction of the vehicle comes from the electric
drive, which is supplied either by a rechargeable battery pack, or by an electric
generator driven by an IC engine, or by both of them. Whereas, in the parallel
hybrid the mechanical force for the traction of the vehicle can come either from an
IC engine, or from the electric drive, or from both of them at once.
The electric connections shown in Figs.
5.17
and
5.18
evidence that in series
hybrid configuration the battery can be recharged by both the IC-based generator
and the electric drive, while in parallel configuration only by the electric drive. The
electric drive for both the configurations can operate also as a generator to recover
energy into battery during the regenerative braking operations, when the kinetic
energy of the vehicle can be converted in electric energy.
The series hybrids are actually used only for particular applications, and the
principal ones are diesel powered railway engines, ships, vehicles with a separated
motor for each wheel. The main disadvantage of the series hybrid is that there is
only an energy flow from the storage system to wheels, which must pass through
all components of the configuration, while the fundamental advantage consists in a
considerably low cost of the system.
On the other hand, the parallel hybrid has two main energy fluxes from the
storage systems to wheels (from battery or fuel tank), with the advantage that the
machines and the other components can be smaller and cheaper, because only part
of the total energy that reaches the wheels has to pass through them. Moreover, a
parallel hybrid can operate in different ways. For instance, the IC engine can be
switched off, in that case the vehicle is powered only electrically with batteries,
and this operation could result particularly advantageous in city districts with
restrictions on the environmental pollution. Another simple way to operate this
configuration is when the batteries are disconnected and only the IC engine give
power to the vehicle, an operative way useful when traveling on highways and a
low constant power is required. Alternatively, a parallel hybrid vehicle can
