Environmental Engineering Reference
In-Depth Information
3. Thermal management of very high power electronics is economically per-
formed using hermetically sealed, 2-phase cooling, units with passive heat
pipes to conduct heat from the switching devices. Recent advances in jet
impingement cooling are also potential solutions.
Only in rare instances do hybrid passenger vehicles use boiling pool, or
2-phase cooled, power electronics. Continental Group, ISAD Systems, has demon-
strated such cooling techniques under the trade name 'RED Pipe' for reduced
electronics device in a pool of CFC that boils as switching elements dissipate their
heat to the 2-phase liquid. More generally, passenger vehicles continue to rely on
water-ethylene-glycol mixtures for cold plate cooling. These systems are generally
more bulky, requiring pumps, fans and condensers and vehicle plumbing, all of
which are prone to damage.
Diesel locomotive drives have transitioned to ac drives in lieu of dc drives
mainly because of their lower maintenance and ruggedness. The complete front end
of the diesel locomotive drive shown in Figure 2.4 is the same for dc drives with the
exception of the power electronic boxes (diodes versus GTOs). The on-cost of
introducing ac drives into locomotives is higher than that for dc drives, but the
durability and operating costs are much lower.
2.1.2 Series-parallel switching
An intermediate step between a series and a parallel architecture hybrid vehicle con-
sists of means to connect the electric M/G to either the engine alone, the driven wheels
alone or both. In 2002 Toyota group of companies announced (December 2002) a new
switchable series-parallel hybrid propulsion system that can operate independently in
either mode. The project to develop this novel powertrain was performed under con-
tract to NEDO ACE (Japan) for high efficiency, clean urban public transportation
system. Figure 2.5 depicts the switchable series-parallel architecture.
w
r
w
f
E-steer
e-mtr
FD
ICE
XM
C1
C2
3
Battery
pack
Figure 2.5 Switchable series-parallel hybrid architecture
The switchable series-parallel hybrid powertrain consists of a diesel engine,
permanent magnet electric M/G, a conventional transmission and final drive, but
with two key exceptions - the addition of disconnect clutch C1 and drive clutch C2
