Research: Hybrid-electric light vehicles - technologies and trends to 2015

Date published: Wednesday, June 15, 2011

Tags: Electric Vehicles, Hybrids / HEVs / PHEVs, Powertrain.

Description

Because electric vehicles preceded those powered by an internal combustion engine (ICE), vehicles with hybrid drivetrains that combined an ICE with electric propulsion arrived shortly after the first use of the ICE for road vehicles.

However, the rapid development of the ICE made the need for the additional power of an electric motor redundant and the technology was largely overlooked until petroleum fuel prices became an issue with the first OPEC oil shocks of the 1970s.

Various research projects followed but it was not until Toyota launched the Prius in 1997 that the modern ICE-electric hybrid arrived. Prior to the downturn of 2008, global hybrid market growth was dramatic with compounding annual sales growth of almost 70% from 2002 to 2007. Following a decline of 4.4% in 2008, sales growth has continued at around 30% per year globally although the pattern has shifted with sales declining significantly in the US but increasing elsewhere, particularly in Japan.

Although an ICE and an electric propulsion system can be configured in several different ways, light passenger hybrids have so far been of ‘parallel’ or combined ‘parallel/series’ configurations in which both the ICE and the electric drive can directly power the driving wheels. However, ‘series’ hybrids, in which the ICE simply drives a generator to power the battery in what is otherwise an electric vehicle, are now entering the market and could have a strong future as consumer interest in the fuel economy of electrically-powered propulsion builds.

As governments and consumers become increasingly concerned about petroleum fuel consumption and carbon dioxide (CO2) emissions, hybrid technology presents an appealing route because it can, according to several OEMs, reduce fuel consumption by as much as 35% in the case of a parallel hybrid and further reduce both fuel consumption and operating costs through the use of plug-in recharging technology. This has led some governments to offer incentives and tax structures that favour hybrids and other low-emissions vehicles.

Working against the widespread adoption of hybrid vehicles, however, is the matter of cost. The technology adds a considerable number of components to the drivetrain and its management systems, and batteries, in particular, account for a major slice of the incremental cost accompanied by the prospect of an expensive refit at some point.

Because of this, consumers in several countries, most notably in Europe, clearly prefer diesel-powered vehicles, which can offer almost the same fuel economy benefits over a gasoline-powered equivalent and carry a substantially lower purchase price premium.

With technology and consumer focus broadening to include pure electric and fuel cell vehicles, questions regarding the future of hybrids, particularly parallel hybrids, remain. Nevertheless, some OEMs, such as Toyota, which plans to have all models available with hybrid drive by 2020, and GM, which has invested heavily in both its two-mode parallel and ‘range-extending’, series hybrid systems, are committed to the technology.

Enabling technology
Batteries
Lead-acid
Sodium nickel halide
Nickel metal hydride
Lithium
Super iron
Redox
Nickel hydrogen
Magnesium-sulphur
Super-capacitors
Electric motors
Integrated starter generator
Belt-driven alternator starter (BAS)
Stop-start
Regenerative braking
Electrically-driven ancillaries
Electronic components
Intelligent control

Research: Hybrid-electric light vehicles - technologies and trends to 2015

Description

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