Simulation Based Development, Component Optimization and Integration for a Metropolitan Hybrid Electric Vehicle

The authors of this technical paper conceptualize and illustrate a powertrain architecture for a hybrid electric vehicle coupled with a unique strategy to reduce a real life problem of driving in snail paced traffic. This architecture utilizes a relatively low powered hybrid electric prime mover that is generally used in mild hybrid vehicles, in an arrangement similar to a parallel hybrid system. Here, the electric machine is mounted on the input shaft of the gearbox and the clutch is actuated automatically through an Automated Manual Transmission (AMT) system. Therefore, it is possible to completely disengage the engine from the driveline and drive the vehicle independently through an appropriately sized electric prime mover. The high gear ratio between the drivetrain and the electric prime mover at lower gears can be leveraged to provide low velocity electric creep mode during which the vehicle can function as a pure Electric Vehicle (EV) while engine remains off.

This technical paper explores these factors and comments on the optimum sizing and selection of the hybrid components through detailed powertrain system simulation. Importantly when and how the creep mode should be activated. Stimulus from various sources like live GPS maps and low cost sensors can be used effectively to identify specific scenarios for creep on road. In this publication the authors also present a few innovative and uniquely cost effective solutions towards the identification of the requirement for creep operation. Furthermore, this paper covers the simulation and selection of an optimal strategy for achieving the desired refinement in drivability and fuel efficiency targets. Through simulation, the authors have also identified and quantified the improvement in the fuel efficiency and ease of driving that can be achieved through the use of such architecture.