Simulation-based design integration improves hybrid vehicle reliability

Electric vehicles were previously developed to attack the problems of higher fuel costs and increased tailpipe emissions. They suffered, however, from limited driving range and lack of support infrastructure (i.e. charging stations). The hybrid vehicle was advanced as the bridge between the internal combustion engine and electric vehicles. Hybrid vehicles offer the increased fuel efficiency and reduced emissions of the electric vehicle, and the long-distance range and readily available support infrastructure of an internal combustion engine vehicle.

In a hybrid vehicle, the drive train contains components from both the internal combustion engine and electric vehicles. The list of system components includes a battery pack, an electric motor/generator, and an internal combustion engine. The internal combustion engine provides electric and mechanical power to the system. The electric motor/generator and battery back provide an electric drive for the system and a way to store electrical energy. Drive trains for hybrid vehicles come in three configurations: series, parallel, and combined series-parallel. Regardless of the configuration, reliable vehicle operation depends on the successful integration of the drive train components.

Mechatronic systems
Both standard and hybrid vehicles depend on the integration of electrical, mechanical, and software technologies, where automotive electronics and software are used increasingly to control or replace mechanical operations. The intersection of these three design disciplines is called mechatronics. Hybrid vehicles are the locus of a mechatronics design.

Combining these technologies in a standard vehicle, where electronic and software control is used in non-drive source applications, is a complicated design challenge. A hybrid vehicle has this same design challenge of integrating non-drive automotive electronics source systems, with the added complexity of electronic and software control of the vehicle drive. Because of this integration requirement, hybrid vehicles are among the most complex systems to design, manufacture, and maintain.

As vehicle complexity increases, so do concerns about reliability. Designing hybrid vehicle systems, therefore, requires a systematic, organized approach to development. To ensure system reliability, this organized approach requires that reliability issues be an integral part of the design process from the very beginning. A Robust Design methodology provides the organized framework needed to design reliable hybrid vehicle systems.