Integrated Energy and Catalyst Thermal Management for Plug-In Hybrid Electric Vehicles

Abstract

With plug-in hybrid electric vehicles (PHEVs), the catalyst temperature is below the light-off temperature due to reduced engine load, extended engine off period, and frequent engine on/off shifting. The conversion efficiency of a three-way catalyst (TWC) and tailpipe emissions were proven to depend heavily on the temperature of the catalyst. The existing energy management strategy (EMS) of the PHEVs focuses on the improvement of fuel efficiency and emissions based on hot engine characteristics, but neglects the effect of catalyst temperature on tailpipe emissions. This paper presents a new EMS that incorporates a catalyst thermal management method. First, an additional cost is established to implement additional constraints on catalyst temperature, and then the global cost function is created using this additional cost and the fuel consumption. Second, we find the global optimal solution using Pontryagin's minimum principle method, which provides an optimal control policy and state trajectories. Then, based on the analysis of the optimal control policy, an engine on/off filter (eng on/off filter) is introduced to command the engine on/off shifting. This filter plays an important role in adjusting both the energy and catalyst thermal management strategy for PHEVs. Finally, a practical approach based on the eng on/off filter is developed, and a genetic algorithm is applied to optimize the time constants of this filter. Simulation results demonstrate that the proposed approach's fuel consumption increased slightly, but the tailpipe emissions of HC (hydrocarbons), CO (carbon monoxide) and NOx (nitrogen oxide) significantly decreased compared with the standard approach.

Energy-efficient heating strategies of diesel oxidation catalyst for low emissions vehicles

“…It is crucial to achieving the highest performance of the aftertreatment system at the lowest temperature and as soon as possible. During engine cold-start and warm-up, the functionality of these catalytic converters deteriorate due to low temperature [11], and the engine consumes more fuel than normal conditions in order to reach the aftertreatment system catalyst activation temperature [12]. Up to 80% of CO and HC emissions are emitted during the cold-start period [13].…”

Multi-Objective Optimization for Plug-In 4WD Hybrid Electric Vehicle Powertrain

“…Parameter optimization of PHEVs is related to the energy management strategy, and energy management strategies need to be developed before parameter optimization. At present, the research on the energy management strategy for PHEVs mainly focuses on the development of the advanced optimization algorithm, such as the algorithm based on the minimum equivalent fuel consumption [26][27][28][29], the dynamic programming algorithm [30][31][32], stochastic dynamic programming [33], the algorithm based on convex optimization [2,34] and the model predictive control algorithm [35][36][37][38]. Although the above-mentioned optimization algorithm can obtain the local or global optimum, it is difficult to apply to real vehicle control for hardly knowing the driving cycles beforehand or the large amount of calculation.…”

Adaptive Real-Time Energy Management Strategy for Plug-In Hybrid Electric Vehicle Based on Simplified-ECMS and a Novel Driving Pattern Recognition Method

“…The instantaneous optimization-based-EMSs mainly encompass convex programming-(CP-) based-EMS [16][17][18], Pontryagin's minimum principle-(PMP-) based-EMS [19][20][21], and equivalent consumption minimization-(ECMS-) based-EMS [22][23][24]. CP-based-EMS to PHEV has been reported in the recent literature.…”