The Mild
Hybrid Vehicle
Hybrid vehicles have been around for some time. The main elements of a hybrid
vehicle are an engine and electric motor combined at the drive shaft to work in
tandem for optimum efficiency. The electric motor takes over when the vehicle
is moving slowly, when gaining speed or in traffic. When the vehicle gets up to
speed, the engine takes over and continues until the vehicle speed reduces for
the electric motor to kick in.
The limitation of the Hybrid vehicle is its dependability on the engine. Hybrids
always require an active engine to operate. This lead to the introduction of the
Plug-in Hybrid. The configuration of the plug in hybrid enables the electric motor
or engine to operate independently. This provides a driving range of up to
200km on the electric motor. The battery capacity is larger than a Hybrid and is
ideal for city driving where the vehicle can be driven solely on the electric motor.
The third type of hybrid is the Mild Hybrid where a separate powered 48 Volt
battery system is used to operate specific engine components during driving
conditions such as coasting or start/stop. The conventional starter and
alternator under the bonnet are replaced with an integrated starter generator
and is directly linked to the 48V battery system. The 48V battery system is also
connected to the cars 12V battery by a low voltage DC-DC charger. The 12V
battery still performs the cold engine start up but most other functions are
offloaded to the 48V battery system. The system is used to operate heavy
start/stop functions, keep the air conditioning running when the engine is shut,
operate turbo compressors and superchargers, power steering unit, power
electric anti-roll bars and recuperate energy. An intelligent unit within the 48V
system monitors the driving/operating condition of the vehicle and disengages
the clutch if coasting is detected at low speeds.