Abstract
The international automotive industry will be making a step change in the level of vehicle technology through the market introduction of hybrid electric vehicles and the future commercialisation of fuel cell vehicles. The technical complexity and development time pressures associated with this work both demand new approaches to the design process.
The traditional model within the automotive industry has focussed on incremental product refinement as one means of concurrently improving product quality while reducing new product development costs and time-to-market. However, when considering a fundamental technological change, such as substituting the internal combustion engine with a fuel cell, a strategy of continued incremental evolution of the vehicle design will lead to a compromised vehicle architecture which will ultimately increase the risk of product failure.
In order to ascertain the most innovative powertrain solution manufacturers are concurrently investigating different vehicle concepts. However, many development programmes follow the existing automotive design model, in which the system design is driven from a bottom-up, component-centric, perspective. This is known to result in a system architecture that is highly complex and dependent on the specific implementation of the technology. In order to address these issues, an increasing number of institutions are investigating the application of whole system design and the use of object orientated, service-based, control architectures within the automotive domain. Whole system design is focused on achieving vehicle level targets, rather than the localised optimisation of specific components and subsystems.
Contained within this paper is part of the technical work associated the design and development of the integrated whole vehicle control solution for the LIFECar vehicle. LIFECar is a lightweight hybrid fuel cell vehicle based on the chassis of the Morgan Aero-8 motor car. The proposed powertrain comprises of a 26kW fuel cell stack and four electrical machines, each machine being directly coupled to a road wheel. A bank of ultracapacitors, connected in parallel with the fuel cell, provide the transient power that is required for vehicle acceleration. The ultracapacitors are also used as an energy storage medium, thereby allowing the benefits of regenerative braking.
The design of the integrated whole vehicle control system is used as the basis for demonstrating how the principles of object orientation and service-based system design can yield a flexible control architecture that is not only capable of meeting the requirements of the LIFECar vehicle, but is also capable meeting the needs of other hybrid electric and fuel cell vehicle applications.
Keywords:Control, Architecture, Fuel Cell Vehicles, Object Orientation, UML