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A
n advanced EV drivetrain design by the company the author
represents, in collaboration with the Zest WEG Group, is using
highly efficient Permanent Magnet (PM) motors and a direct
current (dc) input version of the WEG CFW 11 three phase inverter.
This system has been installed in various conventional vehicles by
removing the original engines and fitting in their place a combination
of electric motor, motor controller (inverter) and lithium batteries.
of Chobe Game Lodge has started the process of converting its entire
4x4 and boat fleet to electric power.
Talking efficiency
The energy efficiency of EVs is about 83% comparing the energy
used to charge the vehicles to the energy ultimately transferred onto
the vehicle drivetrain. This compares to 25% for petrol engines and
40% for diesel engines in terms of the efficiency for converting fossil
fuel energy placed in the tank to useful mechanical energy. These
efficiencies are based on a steadily running engine under a constant
load. A petrol or diesel internal combustion engine will exhibit far lower
overall efficiencies in the real world, where stopping, starting and idling
occurs frequently. The efficiency drop under these conditions with an
electric vehicle is by contrast very small.
The more efficient transfer of energy to the vehicle drive system
means lower cost of operation. The use of solar energy to charge EVs
eliminates direct costs and operational CO
2
gas generation altogether
and relies purely on an upfront investment in a photovoltaic array and
a stationary battery for night time charging.
The 83%efficiency is very much the leading edge in EV design and
is made possible by the WEG ‘Wmagnet’ PMmotor with an efficiency
of 95,3% [1] the WEG CFW11 Inverter of 97% [2], the charger of 93%
[3] and the ‘round trip’ (charge – discharge) efficiency of the Lithium
Iron Phosphate cells of 97% [4]. The formula therefore is:
Overall Efficiency = 0,95 x 0,93 x 0,97 x 0,97 = 0,83, or 83%.
Electric mobility solutions – enormous
operational energy cost savings
A English, FreedomWon
The energy efficiency of Electric Vehicles (EVs) described in this
article has resulted in an operational energy cost saving of up to
90%. This is substantiated by case study data from a game lodge
in Botswana, which is operating FreedomWon Electric 4x4 game
drive vehicles and electric river boats.
The substantial reduction in operational costs results not only from
the fact that the energy input cost is as little as 10% of a conventional
vehicle, but because there is no drivetrain maintenance on these EVs.
Chobe Game Lodge in Botswana is operating two Electric Land
Rovers and an electric boat. These vehicles are used for game viewing
excursions around the Chobe National Park and on the Chobe River.
The lodge records the monthly energy consumption on its electric fleet
and is able to compare this to the consumption figures achieved by the
same vehicles before they were converted. This data has been used
as real world unequivocal evidence of the excellent possibilities for
reduction in energy consumption and carbon generation by using EVs.
As a result of the extremely positive data obtained as well as the
obvious benefit of a silent electric game drive vehicle, the management
Slow driving through the game park in sandy conditions accentuates
the efficiency comparison because the WEG PM motor maintains its
efficiency of 95% through most load and speed scenarios, whereas
a diesel or petrol motor becomes significantly less efficient in such
an erratic and high-load drive profile.
Figure 1: A 2010 Fiat500 which has been converted to pure electric
drive.
Figure 2: PM motor attached to the Land Rover Defender Transfer
Case with a special adaptor housing ready to be installed into an
EV Conversion.
1
No conversation about electrical energy could be complete without
including transportation. Electric vehicles have been around since
the development of storage devices, but only recently have they been
seriously considered.
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ENERGY EFFICIENCY MADE SIMPLE 2015