Thermal Responses of Connected HEVs Engine and Aftertreatment Systems to Eco-Driving

Abstract

Connected and automated vehicles (CAVs) have been recognized as providing unprecedented opportunities for substantial fuel economy improvement through CAV-based vehicle speed trajectory optimization (eco-driving). At the same time, the implications of the CAV operation on thermal responses, including those of engine and exhaust aftertreatment system, have not been fully investigated. To this end, firstly, a sequential optimization framework for vehicle speed trajectory planning and powertrain control in hybrid electric CAVs is proposed in this paper. Next, the impact of eco-driving and power split optimization on the engine and catalytic converter thermal responses, as well as on the tailpipe emissions is characterized. Despite an average 16% improvement in fuel economy through sequential optimization, this study shows that eco-driving slows down the thermal responses, which could unfavorably affect the tailpipe emissions.

Experimental Validation of Eco-Driving and Eco-Heating Strategies for Connected and Automated HEVs

“…in our previous works, where a physics-based and experimentally validated model of a power-split HEV was used for energy consumption analysis in MATLAB/Simulink ® environment. The simulation results in [12,22] showed an average fuel saving of 13% achieved through eco-driving as compared to the baseline case, where the same vehicles were assumed to be driven by human drivers under similar traffic conditions. For more details, see [12,22,26].…”

“…As shown in previous studies [11][12][13][14][15], integrated power and thermal management (iPTM) of CAVs can greatly benefit from leveraging the coupling between power and thermal loads and accounting for the timescale separation between power and thermal dynamic responses. Along these lines, energy-efficient strategies for cooling (i.e., eco-cooling) of cabin [11,[16][17][18] and battery [13,[19][20][21], as well as iPTM strategies for co-optimization of engine, cabin, and aftertreatment systems [12,14,15,22,23] have been developed. When conflated with technologies focused on traction power optimization (e.g., eco-driving), efficient thermal management of CAVs is shown to have the potential for delivering fuel-savings of up to 18-20% [12,22,24].…”

“…Along these lines, energy-efficient strategies for cooling (i.e., eco-cooling) of cabin [11,[16][17][18] and battery [13,[19][20][21], as well as iPTM strategies for co-optimization of engine, cabin, and aftertreatment systems [12,14,15,22,23] have been developed. When conflated with technologies focused on traction power optimization (e.g., eco-driving), efficient thermal management of CAVs is shown to have the potential for delivering fuel-savings of up to 18-20% [12,22,24]. While previous publications have been touting the energysaving potential of iPTM, many if not all of the previous approaches are demonstrated using simulations.…”

Long-Term Vehicle Speed Prediction via Historical Traffic Data Analysis for Improved Energy Efficiency of Connected Electric Vehicles

“…It can be seen that the ecotrajectory planning, by making the speed profiles of the CAVs smoother, reduces the aggressiveness in driving and limits the absolute maximum of the acceleration/ deceleration to 2 m=sec 2 . See Amini et al and Yang et al for a detailed analysis of the proposed eco-driving strategy impact on the energy consumption of HEVs (9,12,25).…”

“…For electrified vehicles, including hybrid electric vehicles (HEVs), plug-in HEVs (PHEVs), and fully electric vehicles (EVs), while traction power demand is the major power consumption source, thermal management of the electric battery, cabin air, engine, and exhaust aftertreatment system can have a significant impact on the electric battery energy consumption, as well as the overall energy efficiency of the vehicle (8)(9)(10)(11)(12). As an example, for EVs with relatively large battery packs, the electric battery is the only source of power to satisfy the driving demand, that is, traction power, and auxiliary loads, including those for powering the electric compressor of the air conditioning (A/C) system.…”