Cars GlobalMag October 2013

100 km/h. The high-performance 12,000-rpm
motor and, also developed by Volkswagen, the
single-speed gearbox (EQ 270) with integrated
differential and mechanical parking brake form a
compact module. The motor/gearbox unit is made
in Volkswagen’s components plant in Kassel, Germany.
Depending on route profile, driving style and payload,
the driving range is between 130 and 190
km; at very low outdoor temperatures, driving range
may lie below these figures. Good range will be
ensured not only in fine weather but in the winter
too by a newly developed, optional heat pump. Offered
as an add-on module for the electric heating
(high-voltage heater) and the electric air conditioning
compressor, the heat pump utilises both the
heat from the ambient air and the heat given off
by the drive system components. In this way the
high-voltage heater’s consumption of electric power
is significantly reduced. Through use of the
heat pump the e-Golf’s range increases in winter
by up to 20 per cent.
The Golf Mk7 was developed from the outset as
a version which could use an electric powertrain.
By virtue of the innovative flexibility of the new
Modular Transverse Matrix (MQB), on which the
current Golf design is based, Volkswagen was
able to integrate the lithium-ion battery in spacesaving
fashion within a stabilising frame in the
vehicle floor (under the front and rear seats and
in the area of the centre tunnel). Like the motor
elements of the powertrain, the battery was also
developed in-house at Volkswagen. The e-Golf
has a kerb weight of 1,510 kg, of which 318 kg
are accounted for by the lithium-ion battery. It is
made up of a total of 264 individual cells, which
are integrated into 27 modules (each with six or
twelve cells). The cells add up to a nominal voltage
of 323 V. Battery capacity: 24.2 kWh. When the
car is not in use or in the event of a crash, power
from the battery is automatically cut off.
The power electronics module
A central element of the drive system is the power
electronics module. Acting as the link, this module
controls the flow of high-voltage energy betwe-
en the e-motor and the lithium-ion battery. In the
process the power electronics module converts
the direct current (DC) stored in the battery into
alternating current (AC). The power electronics
therefore have the following interfaces: the traction
circuit connection to the battery; the 3-phase
connection to the e-motor; the plug connector
from the DC/DC converter to the 12-V power circuit
and a connection for the high-voltage power
distributor.
As with the smaller e-up!, there are several different
ways of charging the battery in the e-Golf.
As the conventional solution, the charging cable
supplied as standard with the car is plugged into
a 230-volt mains electrical socket. The battery of
the e-Golf is charged in this way at a charge level
of 2.3kW of alternating current (AC) from the
mains. If it is completely flat, it will be fully charged
again within a maximum of 13 hours. As an
optional extra Volkswagen is offering a wall box
for the garage or carport. This charges at a level
of 3.6 kW. If completely flat (which in practice
is rare), the battery would thus be fully charged
again after around eight hours. There are also
public charging stations that ‘refuel’ electric cars
at a power level of 3.6 kW. The e-Golf can also
optionally be prepared for the combined charging
system (CCS) using a DC power supply. In this
case the Volkswagen can be recharged via special
CCS charging stations at power levels of up to 40
kW, allowing the battery to be charged to 80 per
cent in around 30 minutes.
Driving profiles and regenerative braking
Two technologies of primary importance in relation
to optimal utilisation of the vehicle’s energy are the
two driving profiles designed for energy economy
(‘Eco’ and ‘Eco+’) and the four different levels of
regenerative braking (‘D1’, ‘D2’, ‘D3, and ‘B’).
The e-Golf is equipped as standard with three
driving profiles: ‘Normal’, ‘Eco’ and ‘Eco+’. The
Volkswagen is automatically started in ‘Normal’
mode. For drivers wanting to extend the range, the
first option is the ‘Eco’ mode. The effects of selecting
this mode include paring back the e-motor’s
maximum power output to 70 kW and the starting