Environmental Engineering Reference
In-Depth Information
Electrical
Stator
M/G
LUC
Rotor
B1
B2
C1
C2
R
C3
S2
C1
S1
Input
Output
Figure 4.6 Lepelletier transmission
planetary) and applied to the Ravigneaux compound planetary set. Output is taken
from the Ravigneaux ring gear. One drawback, if it could be called that, is that a
Lepelletier architecture is not able to realize a direct drive (1:1) ratio from input to
output as both the Simpson and Wilson types do.
4.1.3.4 Summary of transmission types
The three main types of stepped automatic transmissions differ mainly in the
number of planetary gear sets, type of planetary gear sets, and the number of
clutches, brakes, and OWCs required. Figure 4.7 illustrates the number and usage
by transmission type.
In Figure 4.7, the clutch, brake and OWC activation for each gear are listed.
There are also brake activations in the Simpson and Wilson configurations
for hybrid M/G braking (or coasting braking). These activations are not listed in
Figure 4.7. The key attributes of each transmission type to point out are the number
of supporting clutches and brakes necessary. The Lepelletier architecture is simpler
and has less control activity than the other two types.
In the Wilson architecture the 1-2, 2-3 and 3-4 shifts are OWC shifts, and 4-5
is a clutch to clutch shift.
4.2 Sizing the propulsion motor
An electric machine is at the core of hybrid propulsion regardless of whether or not the
vehicle is gasoline-electric, diesel-electric or fuel cell electric. Propulsion is via an ac
drive system consisting of an energy storage unit, a power processor, the M/G and
vehicle driveline and wheels. Figure 4.8 is a schematic of the hybrid propulsion system
in a multi-converter architecture. The system in Figure 4.8 can be upgraded by the
addition of an interface converter (e.g. booster) to the ultra-capacitor bank for max-
imum performance when non-alkaline electrolyte storage batteries are used. For
example, a lead-acid battery system benefits the most from a converter interface to an
ultra-capacitor bank. In that case the total ESS weight and cost are minimized. With
alkaline electrolyte advanced batteries the benefits of adding an ultra-capacitor begin
to diminish and with lithium (Li) ion the benefits are minimal [4].
The M/G is sized as follows: maximum input speed at transmission is restricted
to < 12,000 rpm from the engine side by the rev-limiter function in the electronic
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