Environmental Engineering Reference
In-Depth Information
Chapter 2
Hybrid architectures
We know now that no particular power train architecture would be suitable for all
vehicles in all markets. Today, pre-transmission parallel and power split archi-
tectures have found their principal application in passenger vehicles in the compact
and mid-size segments. Series and series-parallel switching architectures are either
in production or under prototype development for city buses, commercial trucks and
other heavy vehicles. Subcompact and compact vehicles, including minivans, are
being converted to continuously variable transmission (CVT) hybrids where the
CVT, generally of the belt type, has integrated into it the traction M/G. Because of
the high actuation forces necessary in a CVT, an ancillary electric drive for the oil
pump is necessary, generally in the 2-2.5 kW power rating. Higher rated power split
and series-parallel shifting configurations are being introduced in small sport utility
and larger vehicles. Fuel cell powered vehicles are strictly series hybrids because
electric propulsion is the only option.
All the major automotive companies continue development of fuel cell powered
vehicles. Daimler Chrysler Corp., for example, began their developments with the
NECAR3 followed by NECAR4 and NECAR5. DCX also converts production
vehicles to fuel cell powered alternative drive concepts such as their Jeep Com-
mander 2, and Chrysler Town and Country minivan, the Natrium. Honda Motor Co.
is a clear front-runner in fuel cell powered vehicles since they have gone into limited
production of the FCX
1
minivan in 2002 (Figure 2.1). The FCX is developed around
a Ballard Power Systems 78 kW PEM fuel cell supported by a 156 L compressed
hydrogen gas storage tanks and an ultra-capacitor bank for transient energy storage.
The prevailing rationale for introducing hybrid propulsion systems into mass
market personal transportation vehicles is to reduce the emissions of greenhouse
gases by curtailing their consumption rate. Other measures such as raising fuel
prices through additional taxes would reduce the consumption rate by pricing it out
of reach of a good portion of the public. North America continues to consume 42%
of the US petroleum resources for transportation (Table 2.1) and 25% of global
petroleum production in total [1]. In the US, electric utilities have decreased their
dependence on petroleum from 17% in 1973 to just 1% in 2007. Residential and
1
FCX-V3 was introduced in CY2000, followed by FCX-V4 in CY2001. In 2002 the US EPA and CARB
certified the FCX for commercial use as a ZEV. In 2005 Honda introduced its own fuel cell stack. Then
in 2008 the FCX Clarity was equipped with a 288 V lithium ion battery.
