Energy Efficiency of Electric Vehicles

• that it can be applied to any type of engine if the only known data are on motor nameplate;
• to demonstrates a high degree of robustness in the case of disruption load torque;
• Demonstrates a high degree of robustness in the case of motor parameter variations.
Beside the standard electric motors, solutions specially made for EV are developing.
Therefore, switched reluctance motor (SRM) is gaining much interest as a candidate for
electric vehicle (EV) and hybrid electric vehicle (HEV) electric propulsion for its simple
and rugged construction, ability of extremely high-speed operation, and insensitivity to
high temperatures. However, because SRM construction with doubly salient poles and its
non-linear magnetic characteristics, the problems of acoustic noise and torque ripple are
more severe than these of other traditional motors. Power electronic technology has
made the SRM an attractive choice for many applications. The SRM is a doubly salient,
singly excited synchronous motor. The rotor and stator are comprised of stacked iron
laminations with copper windings on the stator, as shown in Fig. 5 [4]. The motor is ex‐
cited with a power electronic inverter that energizes appropriate phases based on shaft
position. The excitation of a phase creates a magnetic field that attracts the nearest rotor
pole to the excited stator pole in an attempt to minimize the reluctance path through the
rotor. The excitation is performed in a sequence that steps the rotor around.
Figure 5. A switched-reluctance motor with 8 stator poles and 6 rotor poles
The SRM is similar in structure to the stepping motor, but it is operated in a manner that allows
for smooth rotation. Because there are no permanent magnets or windings on the rotor, all of
the torque developed in the SRM is reluctance torque. While the SRM is simple in principle, it
is rather difficult to design and develop performance predictions. This is due to the nonlinear
magnetic characteristics of the motor under normally saturated operation.
The special design of electric motors used in direct-drive vehicles where the engines are
installed in each wheel. This will be discussed more in the mechanical transmission part.
Energy Efficiency of Electric Vehicles
http://dx.doi.org/10.5772/55237
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