Design of an Automotive Fuel Cell APU Using a Top-Down Design Methodology

When designing a fuel system, integration of components is a critical task. Early in the design process, engineers often have limited information about the specific components to be used in the design. Only toward the end of the design process are the actual components available for system integration. A top-down design methodology using mixed-technology simulation is well suited to this sort of design process.

In a top-down design process that utilizes simulation, integration engineers start with simple simulation models of each component to get a general idea of how all components will work together. This top-level design might also be used to create specifications for individual components. Then, as more detailed information becomes available from component suppliers about the actual behavior of real components, simple models are progressively replaced with more accurate simulation models. In the final stages of a design process, integration engineers use accurate models for critical components and simple models for non-critical components to verify performance specifications under operating conditions.

Throughout the top-down design process, the ability to simulate high-level abstract systems through low-level device-based systems in a single software package is critical. Availability of a Mixed Technology Hardware Description Language is also critical.