Automotive Powertrain Control — A Survey

This paper surveys recent and historical publications on automotive powertrain control. Control-oriented models of gasoline and diesel engines and their aftertreatment systems are reviewed, and challenging control problems for conventional engines, hybrid vehicles and fuel cell powertrains are discussed. Fundamentals are revisited and advancements are highlighted. A comprehensive list of references is provided.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72023/1/j.1934-6093.2006.tb00275.x.pd

NETWORKED MICROGRID OPTIMIZATION AND ENERGY MANAGEMENT

Military vehicles possess attributes consistent with a microgrid, containing electrical energy generation, storage, government furnished equipment (GFE), and the ability to share these capabilities via interconnection. Many military vehicles have significant energy storage capacity to satisfy silent watch requirements, making them particularly well-suited to share their energy storage capabilities with stationary microgrids for more efficient energy management. Further, the energy generation capacity and the fuel consumption rate of the vehicles are comparable to standard diesel generators, for certain scenarios, the use of the vehicles could result in more efficient operation. Energy management of a microgrid is an open area of research especially in generation constrained scenarios where shedding of low-priority loads may be required. Typical metrics used to assess the effectiveness of an energy management strategy or policy include fuel consumption, electrical storage energy requirements, or the net exergy destruction. When considering a military outpost consisting of a stationary microgrid and a set of vehicles, the metrics used for managing the network become more complex. For example, the metrics used to manage a vehicle’s onboard equipment while on patrol may include fuel consumption, the acoustic signature, and the heat signature. Now consider that the vehicles are parked at an outpost and participating in vehicle-to-grid power-sharing and control. The metrics used to manage the grid assets may now include fuel consumption, the electrical storage’s state of charge, frequency regulation, load prioritization, and load dispatching. The focus of this work is to develop energy management and control strategies that allow a set of diverse assets to be controlled, yielding optimal operation. The provided policies result in both short-term and long-term optimal control of the electrical generation assets. The contributions of this work were: (1) development of a methodology to generate a time-varying electrical load based on (1) a U.S. Army-relevant event schedule and (2) a set of meteorological conditions, resulting in a scenario rich environment suitable for modeling and control of hybrid AC/DC tactical military microgrids, (2) the development of a multi-tiered hierarchical control architecture, suitable for development of both short and long term optimal energy management strategies for hybrid electric microgrids, and (3) the development of blending strategies capable of blending a diverse set of heterogeneous assets with multiple competing objective functions. This work could be extended to include a more diverse set of energy generation assets, found within future energy networks

Conceptual design and cost analysis of hydraulic output unit for 15 kW free-piston Stirling engine

A long-life hydraulic converter with unique features was conceptually designed to interface with a specified 15 kW(e) free-piston Stirling engine in a solar thermal dish application. Hydraulic fluid at 34.5 MPa (5000 psi) is produced to drive a conventional hydraulic motor and rotary alternator. Efficiency of the low-maintenance converter design was calculated at 93.5% for a counterbalanced version and 97.0% without the counterbalance feature. If the converter were coupled to a Stirling engine with design parameters more typcial of high-technology Stirling engines, counterbalanced converter efficiency could be increased to 99.6%. Dynamic computer simulation studies were conducted to evaluate performance and system sensitivities. Production costs of the complete Stirling hydraulic/electric power system were evaluated at $6506 which compared with$8746 for an alternative Stirling engine/linear alternator system

A Numerical Investigation of a Spark Ignition Opposed Piston Linear Engine Fueled by Hydrogen

The traditional Slider-Crank Engine, also known as the Internal Combustion Engine (ICE), has been criticized for its complex structure, friction loss, low efficiency and high maintenance cost. In contrast, the Free-Piston Linear Engine (FPLE) reduces this friction due to its simpler design. With rising concerns about air quality and stricter regulations, there\u27s a renewed interest in hydrogen as a carbon-free fuel for ICEs. The Opposed Piston Linear Generator (OPLG) system is an integrated arrangement of parts operating harmoniously to generate power efficiently. By leveraging synchronized pistons, accurate fuel distribution, and seamless thermodynamic cycles, it transforms kinetic energy into electrical energy. Dynamic control ensures its operations are both efficient and eco-friendly. However, despite the potential benefits of the OPLG, the intricacies of its operations have posed several challenges, such as misfiring, overfueling, instantaneous transient changes, stalling, and piston control, which can reduce its efficiency and increased emission levels. This dissertation deployed the nuances of suitable correlational, analytical, numerical and control models to better illustrate the performance of the OPLG as against its limitations. The model introduces a non-dimensional streamlined symmetric analytical solution, succeeded by a broader general analytical resolution, with careful attention to the significant influence of thermodynamic effects at each phase, offering insights into the engine\u27s dynamic performance. The Runge-Kutta technique guarantees swift and dependable computational outcomes, which captures cyclic variation as typical ICE compression ratios are reproduced. The study showed a nearly linear interaction between thermal efficiency and the translator\u27s starting position within specific ranges for OPLE. However, maintaining the engine within a narrow high-efficiency band requires precise control, crucial for harnessing the full potential of the OPLG system without compromising its performance. Precise control of TDC piston clearance is crucial for optimizing combustion efficiency and load management. The Model Predictive Control (MPC) algorithm forecasts the pistons\u27 future positions by considering current control inputs and system behaviors. Concurrently, the closed-loop bisection method observer refines the piston position estimates by comparing actual and projected outputs. This algorithm is specifically chosen for its dichotomy feature in finding the roots of equations, which is essential for confining the pistons’ locus within the line of symmetry. This method plays a significant role in refining the control strategy, making it more responsive and accurate in adjusting to the engine\u27s dynamic needs and operational changes. Comparative studies are conducted between the Opposed Piston Linear Engine (OPLE) and the slider-crank engine, fueled by hydrogen. This comparison incorporates hydrogen metering and its interaction with nitrogen oxides. The engine\u27s characteristic includes a volumetric compression ratio of 12 and a fuel equivalence ratio of 0.5, so chosen because hydrogen engines typically require nearly double the air amount for complete combustion. This lean mixture is essential as it leads to combustion temperatures below the threshold for thermal nitric oxide (NOx) formation. Consequently, NOx emissions are virtually non-existent, underscoring a notable environmental benefit of FPLE with its unique combustion characteristics compared to the equivalent slider-crank engines. Simulations highlight OPLE\u27s potential superiorities in engine dynamics, performance, and emission patterns

Component control for the Zero Inertia powertrain

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Torque Accuracy Improvement Via Explicit Torque Feedback Control For Internal Combustion Spark Ignition Engines

At the present time, both control and estimation accuracies of engine torque are causes for under-achieving optimal drivability and performance in today’s production vehicles. The major focus in this area has been to enhance torque estimation and control accuracies using existing open-loop torque control and estimation structures. Such an approach does not guarantee optimum torque tracking accuracy and optimum estimation accuracy due to air flow and efficiencies estimations errors. Furthermore, current approach overlooks the fast torque path tracking which does not have any related feedback. Recently, explicit torque feedback control has been proposed in the literature using either estimated or measured torques as feedback to control the torque using the slow torque path only. I propose the usage of a surface acoustic wave torque sensor and in-cylinder pressure sensor to measure the engine brake and indicated torques respectively and feedback the signals to control the torques using both the fast and slow torque paths utilizing an inner-outer loop control structure. The fast torque path feedback is coordinated with the slow torque path by a novel method using the potential torque and is adapted to the sensors readings. The torque signals enable a fast and explicit torque feedback control that can correct torque estimation errors and improve drivability, emission control, and fuel economy. Control-oriented engine models for the 3.6L engine are developed. Computer simulations are performed to investigate the advantages and limitations of the proposed control strategy, versus the existing open loop control strategies. The findings include an improvement of 14% in gain margin and 60% in phase margin when the torque feedback is applied to the cruise control torque request at the simulated operating point. This study demonstrates that the direct torque feedback is a powerful technology with promising results for improved powertrain performance and fuel economy

Energy efficient engine: Flight propulsion system preliminary analysis and design

The characteristics of an advanced flight propulsion system (FPS), suitable for introduction in the late 1980's to early 1990's, was more fully defined. It was determined that all goals for efficiency, environmental considerations, and economics could be met or exceeded with the possible exception of NOx emission. In evaluating the FPS, all aspects were considered including component design, performance, weight, initial cost, maintenance cost, engine system integration (including nacelle), and aircraft integration considerations. The current FPS installed specific fuel consumption was reduced 14.2% from that of the CF6-50C reference engine. When integrated into an advanced, subsonic, study transport, the FPS produced a fuel burn savings of 15 to 23% and a direct operating cost reduction of 5 to 12% depending on the mission and study aircraft characteristics relative to the reference engine

Aeronautical Engineering. A continuing bibliography with indexes, supplement 142

This bibliography lists 398 reports, articles, and other documents introduced into the NASA scientific and technical information system in November 1981