Energy Efficiency of Electric Vehicles

Figure 16. HEV
New Generation of Electric Vehicles
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parallel circuit of the individual battery modules – this helps to maximize the safety, reliability
and service life of the battery. As in Formula 1, the battery is charged by means of targeted
recuperation during deceleration whilst the car is being driven [51].
A high-performance electronic control system converts the direct current from the high-
voltage battery into the three-phase alternating current which is required for the synchronous
motors and regulates the energy flow for all operating conditions. Two low-temperature
cooling circuits ensure that the four electric motors and the power electronics are maintained
at an even operating temperature. A separate low-temperature circuit is responsible for cooling
the high-voltage lithium-ion battery. In low external temperatures, the battery is quickly
brought up to optimum operating temperature with the aid of an electric heating element. In
extremely high external temperatures, the cooling circuit for the battery can be additionally
boosted with the aid of the air conditioning. This also helps to preserve the overall service life
of the battery system [51].
Ideally the EV is charged with the aid of wall box. As it could be installed in a home garage,
this technology provides a 22 kW quick-charge function, which is the same as the charging
performance available at a public charging station. A high-voltage power cable is used to
connect the vehicle to the wall box, and enables charging to take place in around three hours.
Charging takes around 20 hours without the wall box [51].
To ensure maximum safety, the SLS AMG Coupé Electric Drive, one of the most advanced
high-performance EV today, makes use of an eight-stage safety design. This comprises the
following features: