Fidelity Enhancement of Power-Split Hybrid Vehicle HIL (Hardware-in-the-Loop) Simulation by Integration with High Voltage Traction Battery Subsystem 2018-01-0008

Due to the increasing concerns on energy and environmental issues, the automotive industry has seen increased growth and development of electric and electrified vehicles [1]. The power-split design is one of the most common drivetrain configurations of a hybrid or electrified vehicle. The propulsion system of a power-split hybrid vehicle typically comprises of an engine drive system in which the engine, drivetrain and generator are mechanically coupled on a planetary gear set driveline while the electric drive system consists of a high voltage battery and a traction motor [2]. In recent years, Hardware-in-the-Loop (HIL) simulation has become an increasingly common approach for controls rapid prototyping and validation as part of the automotive product development cycle [2, 3]. Traditionally, HIL simulations of hybrid vehicle controls and high-voltage battery controls have been implemented on separate HIL benches which are exclusively targeted for hybrid vehicle controls and battery controls simulations respectively. This research demonstrates an implementation of enhanced fidelity of a power-split hybrid vehicle powertrain controls HIL by integrating it with high-voltage traction battery subsystem HIL by networking the two aforementioned HIL systems together. The power-split hybrid vehicle HIL typically use simplified battery plant and controller models, and therefore, the addition of the high-voltage battery HIL provides a more detailed simulation of the high-voltage battery in which each cell is modeled such that cell voltage varies based on initial State-of-Charge (SOC) and temperature, capacity, fan speed, self-discharge, and other chemistry-based parameters. The integration of the battery HIL also provides the high-voltage interface to the battery controller hardware. The 2017 Ford Fusion Hybrid is used as the platform for this research. The battery subsystem performance of the vehicle is used as the baseline for comparison between the battery subsystem performances of the simplified power-split hybrid vehicle HIL and the networked HIL setup to understand the increased fidelity and accuracy of the latter.