Drivetrain Modeling, Simulation, and Analysis Using VHDL-AMS 2003-01-0861

VHDL-AMS, approved by the IEEE in 1999, is the first industry standard hardware description language (HDL) for modeling the many mixed-technology components that exist in modern automotive systems and subsystems. Technologies include electrical (analog and digital), mechanical (rotational and translational), fluidic, magnetic, thermal, etc. VHDL-AMS is a valuable tool for understanding the complex interaction between these technologies, which is essential for the today's engineers in achieving their design goals. In this study, the VHDL-AMS language is used to mathematically model the individual components that form the drivetrain system of an automobile. The components modeled are the engine, clutch, transmission, final drive (differential), drive shaft, brake, wheel, chassis, air drag, and driver. A graphical design environment is used to interconnect the components into system and subsystem models for simulation and analysis. The components have been arranged based on the “forward-facing” approach, where the driver model uses the drive cycle and the actual speeds to develop the appropriate accelerator, brake, gear, and clutch commands. The simulation is performed using the European Driving Cycle, and the results can be used to analyze the effects of system parameters, such as engine ratings and transmission gear ratios, on the overall system performance.