Unified modeling of hybrid electric vehicle drivetrains

Hybridizing automotive drivetrains, or using more than one type of energy c onverter, is considered an important step toward very low pollutant emissio n and high fuel economy. The automotive industry and governments in the Uni ted States, Europe, and Japan have formed strategic initiatives with the ai m of cooperating in the development of new vehicle technologies. Efforts to meet fuel economy and exhaust emission targets have initiated major advanc es in hybrid drivetrain system components, including: high-efficiency high- specific power electric motors and controllers; load-leveling devices such as ultracapacitors and fly-wheels; hydrogen and direct-methanol fuel cells; direct injection Diesel and Otto cycle engines; and advanced batteries. Th e design of hybrid electric vehicles is an excellent example of the need fo r mechatronic system analysis and design methods, If one is to fully realiz e the potential of using these technologies, a complete vehicle system appr oach for component selection and optimization over typical driving situatio ns is required. The control problems that arise in connection with hybrid p ower trains are significant and pose additional challenges to power-train c ontrol engineers. The principal aim of this paper is to propose a framework for the analysis, design, and control of optimum hybrid vehicles within th e context of energy and power flow analysis. The approaches and results pre sented in this paper are one step toward the development of a complete tool box for the analysis and design of hybrid vehicles.