Abstract-A Mean Value Model (MVM) for a HomogeneousCharge Compression Ignition (HCCI) engine is presented. Using a phenomenological zero-dimensional approach with five continuous and three discrete states we first model the effects of the Exhaust Gas Recirculation (EGR) valve, the exhaust Rebreathing Lift (RBL), and the fueling rate on the state of charge in the cylinder at intake valve closing. An Arrhenius integral is then used to model the start of combustion, θsoc. A series of simple algebraic relations that captures the combustion duration and heat release is finally used to model the state of charge after the HCCI combustion and the Location of Peak Pressure (LPP). The model is parameterized and validated using steady-state test data from an experimental engine at the General Motors Corporation.The simple model captures the temperature, pressure, airto-fuel ratio, and inert gas fraction of the exhausted mass flow. This characterization is important for the overall HCCI dynamics because the thermodynamic state (pressure, temperature) and concentration (oxygen and inert gas) of the exhausted mass flow affect the next combustion event. The high dilution level in HCCI engines increases the significance of this internal feedback that generally exists to a smaller extent in conventional spark-ignition and compression-ignition internal combustion engines.

Hybrid vehicle techniques have been widely studied recently because of their potential to significantly improve the fuel economy and drivability of future ground vehicles. Due to the dual-power-source nature of these vehicles, control strategies based on engineering intuition frequently fail to fully explore the potential of these advanced vehicles. In this paper, we will present a procedure for the design of a near-optimal power management strategy. The design procedure starts by defining a cost function, such as minimizing a combination of fuel consumption and selected emission species over a driving cycle. Dynamic programming (DP) is then utilized to find the optimal control actions including the gear-shifting sequence and the power split between the engine and motor while subject to a battery SOC-sustaining constraint. Through analysis of the behavior of DP control actions, near-optimal rules are extracted, which, unlike DP control signals, are implementable. The performance of this power management control strategy is studied by using the hybrid vehicle model HE-VESIM developed at the Automotive Research Center of the University of Michigan. A tradeoff study between fuel economy and emissions was performed. It was found that significant emission reduction could be achieved at the expense of a small increase in fuel consumption. Index Terms-Hybrid electric vehicle, power management strategy, powertrain control. I. INTRODUCTION M EDIUM and heavy trucks running on diesel engines serve an important role in modern societies. More than 80% of the freight transported in the U.S. in 1999 was carried by medium and heavy trucks. The increasing reliance on the trucking transportation brings with it certain negative impacts. First, the petroleum consumption used in the transportation sector is one of the leading contributors to the import oil gap. Furthermore, diesel-engine vehicles are known to be more polluting than gasoline-engine vehicles, in terms of nitrogen oxides (NOx) and Particulate Matters (PM) emissions. Recently, hybrid electric vehicle (HEV) technology has been proposed as the technology for new vehicle configurations. Owing to their dual on-board power sources and possibility of regenerative braking, HEVs offer unprecedented potential Manuscript

Abstract-A Mean Value Model (MVM) for a HomogeneousCharge Compression Ignition (HCCI) engine is presented. Using a phenomenological zero-dimensional approach with five continuous and three discrete states we first model the effects of the Exhaust Gas Recirculation (EGR) valve, the exhaust Rebreathing Lift (RBL), and the fueling rate on the state of charge in the cylinder at intake valve closing. An Arrhenius integral is then used to model the start of combustion, θsoc. A series of simple algebraic relations that captures the combustion duration and heat release is finally used to model the state of charge after the HCCI combustion and the Location of Peak Pressure (LPP). The model is parameterized and validated using steady-state test data from an experimental engine at the General Motors Corporation.The simple model captures the temperature, pressure, airto-fuel ratio, and inert gas fraction of the exhausted mass flow. This characterization is important for the overall HCCI dynamics because the thermodynamic state (pressure, temperature) and concentration (oxygen and inert gas) of the exhausted mass flow affect the next combustion event. The high dilution level in HCCI engines increases the significance of this internal feedback that generally exists to a smaller extent in conventional spark-ignition and compression-ignition internal combustion engines.

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