Environmental Engineering Reference
In-Depth Information
Table 6.2 Technical
specifications of the electrical
drive
Type of drive
Brushless
Maximum power
3.5 kW
Rated current
32 A
Maximum current
100 A
Link voltage
48 V
Motor voltage
35 V
Rated speed
3000 rpm
Maximum speed
6000 rpm
Fig. 6.3 Characteristic
curves of the electric engine
The electric drive is selected among those commercially available for appli-
cations on electric mopeds. In particular, a brushless electric drive with a rated
power of 3.5 kW and maximum speed of 6000 rpm is used. The technical spec-
ifications of this electrical drive are reported in Table
6.2
, while the Fig.
6.3
shows
its characteristic curves in terms of power and torque versus revolution speed.
This engine is supplied by an inverter and is coupled to an eddy current braking
machine. The electric drive performs the speed regulation electronically in forward
and backward directions, for this reason the ratio between the engine and wheel
speed is fixed for this kind of vehicle and therefore no gear is present, but only a
speed reducer between the wheel and motor shaft. A flywheel, previously designed
taking into account the vehicle inertia, is interposed between the electric motor and
the electric brake. The vehicle mass was fixed considering a commercial electric
scooter as reference vehicle (178 kg driver included).
The electric brake is an eddy current brake, which can simulate different
aerodynamic drags, rolling resistances, and driving cycles using a specific software
developed in Labview.
The stack output voltage ranges from 34 V at open circuit to 22 V at full load,
while the electric motor is supplied at 48 V DC. For this reason, a DC-DC con-
verter (see
Sect. 5.2
) is used to match the stack output voltage with that required by
the engine. In Table
6.3
, the technical specifications of the DC-DC converter are
shown.
