What is a
hybrid vehicle?
A hybrid vehicle is a
vehicle using an on-board rechargeable energy
storage system and a fuelled power source for vehicle propulsion.
The HV pollutes less and uses
less fuel. The
different propulsion power systems may have common subsystems or
components. The
HV provides better fuel economy
than a conventional vehicle because the engine is
smaller
and may be run at
speeds providing more efficiency.
*image taken from
http://www.columbia.edu/
How are the components in a hybrid
vehicle arranged?
Many hybrid systems use the same
major components: an internal combustion engine (ICE), an electric
motor, a electrical storage device (batteries or capacitors) and
a generator.
In a series system, the ICE is used to run the
generator which provides electrical energy recharging the
batteries. Only the electric motor is used to drive the vechicle
while the ICE runs when the batteries need to be charged. The ICE
can run at its most fuel efficient speed while running the
generator by using a continuously variable transmission.
*image taken from
http://www.hybridsynergydrive.com/
A parallel system allows either the ICE, the electric
motor or both to drive the vehicle. This setup requires a power
splitting device that can switch between power sources or allow
both to drive at the same time. A parallel system allows each
motor to be used in their optimum power ranges or both can be used
to provide peak power during acceleration. The power splitting
devices commonly used are planetary gear sets.
*image taken from
http://www.hybridsynergydrive.com/
There are many
variations on these two basic systems resulting some of the
following names: Series-Parallel, Mild-Parallel, Split-Series,
etc. Some names are manufacturer specific. The important thing
to remember is the same basic components are used in the system
although they may be arranged in different methods.
*image taken from
www.howstuffworks.com
What is regenerative braking?
When a vehicle is stopped, the
kinetic energy must be lowered by changing it to another form of
energy. In a conventional brake system, the mechanical braking
action changes the kinetic energy into heat energy through
friction between the brake components. This heat energy can not
be reused to power the vehicle. Regenerative braking is an
attempt to recapture the kinetic energy of the vehicle during
braking to allow it to be used later. This is typically
accomplished with DC generators acting as brakes. When the brakes
are engaged, the generators slow the vehicle by converting the
rotating energy of the driveshafts into electrical energy. This
energy is stored in the batteries for future use increasing the
efficiency of the vehicle.
*NOTE* Reprint from
http://en.wikipedia.org/wiki/Hybrid_car
