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Languages : en
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Book Description
Plug-in hybrid electric vehicle (PHEV) technologies have the potential for considerable petroleum consumption reductions, possibly at the expense of increased tailpipe emissions due to multiple 'cold' start events and improper use of the engine for PHEV specific operation. PHEVs operate predominantly as electric vehicles (EVs) with intermittent assist from the engine during high power demands. As a consequence, the engine can be subjected to multiple cold start events. These cold start events may have a significant impact on the tailpipe emissions due to degraded catalyst performance and starting the engine under less than ideal conditions. On current hybrid electric vehicles (HEVs), the first cold start of the engine dictates whether or not the vehicle will pass federal emissions tests. PHEV operation compounds this problem due to infrequent, multiple engine cold starts. The research is broken down into two (2) distinct phases, involving both analytical and experimental areas. Phase I of the research, addressed in this document, focuses on the design of a vehicle supervisory control system for a pre-transmission parallel PHEV powertrain architecture. A suitable control system architecture is created and implemented into a standard vehicle modeling tool (in this case, the Powertrain Systems Analysis Toolkit). Energy management strategies are evaluated and implemented in a virtual environment for preliminary assessment of petroleum displacement benefits and rudimentary drivability issues. Engine cold start events are aggressively addressed in the development of this control system, which leads to enhanced pre-warming and energy-based engine warming algorithms that provide substantial reductions in tailpipe emissions over the baseline supervisory control strategy. The flexibility of the PHEV powertrain offers the potential for decreased emissions during any engine starting event through powertrain 'torque shaping' algorithms. The analytical work presented here is experimentally validated during Phase 2, the subject of a follow on paper.