Volvo XC90 TWIN ENGINE Owner's Manual page 457

All-wheel drive
All-wheel drive, AWD (All Wheel Drive), means
that the car is driving all four wheels at the same
time, which improves traction.
The electric motor that drives the rear wheels
enables electric all-wheel drive functionality.
To achieve the best possible traction, the motive
force is distributed automatically to the wheels
with the best grip. The system continuously cal-
culates the need for torque to the rear wheels,
and can immediately redistribute up to half of the
motor's torque to the rear wheels.
All-wheel drive also has a stabilising effect at
higher speeds. Under normal driving conditions,
the majority of power is transmitted to the front
wheels. When stationary, the all-wheel drive is
always engaged in preparation for maximum trac-
tion during acceleration.
All-wheel drive characteristics vary depending on
the selected drive mode.
Related information
•
Drive modes (p. 457)
•
Low speed control (p. 465)
•
Gearbox (p. 450)
2 The figure is schematic, the layout may vary depending on car model or updated software.
CISG (Crank Integrated Starter Generator) - Combined high-voltage generator and starter motor.
3
Drive systems
Volvo's Twin Engine combines an internal com-
bustion engine that drives the front wheels with
an electric motor that drives the rear wheels.
Two drive systems
Depending on the driver-selected drive mode and
available electric energy, the two drive systems
can be used either individually or in parallel.
The electric motor is supplied its energy from a
hybrid battery fitted in the tunnel console. The
hybrid battery can be charged in a wall socket, or
in a special charging station. The internal com-
bustion engine can also charge the hybrid battery
with a special high-voltage generator.
Both the internal combustion engine and electric
motor can generate motive force directly to the
wheels. An advanced control system combines
the properties of both drive systems in order to
provide optimum driving economy.
STARTING AND DRIVING
Hybrid battery - The function of the hybrid
battery is to store energy. It receives energy
when charging from the mains power circuit,
during regenerative braking or from the high-
voltage generator. It provides energy for elec-
tric operation as well as for temporarily oper-
ating the electric air conditioning during the
preconditioning of the passenger compart-
ment.
Internal combustion engine - The internal
combustion engine starts when the energy
level in the hybrid battery is insufficient for
the engine power that the driver requests.
3
High voltage generator - Charges the hybrid
battery. Starter motor for the internal com-
bustion engine. Can support the internal
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