Browsing by Subject "Hybrid vehicles"

Now showing 1 - 4 of 4
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    A hierarchical control strategy for hybrid vehicles.
    (2010-07) Mensing, Felicitas Barbara
    With increasing gasonline prices and the rise of environmental concerns the demand for cleaner, more fuel efficient vehicles rises. The development of an environmentally friendly transportation technology is necessary. Hybrid vehicles were found to have high potential in decreasing fuel consumption in the transportation sector. Fuel efficiency increases with additional flexibility in the drive train due to multiple power sources. With growing complexity in the drive train appropriate control is critical to achieve maximum fuel economy. Research conducted by the Test Bed 3 group in the Center for Compact and Efficient Fluid Power at the University of Minnesota is investigating the potentials of fluid power power trains to drastically decrease fuel consumption in hybrid vehicles. In the scope of the Test Bed 3 project controls algorithms are developed for implementation on the hybrid vehicle. In this thesis a control strategy based on hierarchical control is proposed. A generic three level control strategy that is applicable to any hybrid vehicle configuration is derived. On the example of two power split hybrid drive trains the use of this controls framework will be illustrated in simulation. Case studies were performed using an off-line simulation approach. These investigate optimal sizing of the power train, optimal operation of a power split configurated vehicle and the relationship of hydraulic efficiency and fuel consumption. Three hybrid architectures are compared in fuel economy. Fuel savings through hybridization of a conventional vehicle are discussed. Using an input coupled hydraulic hybrid vehicle the implementation of the proposed strategy in real time is discussed. System level control implementation is shown and results from test drives are presented.
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    Rural and Small Urban Multimodal Alternatives for Minnesota
    (Minnesota Department of Transportation, 2014-11) Becker, Carol
    This paper looks at alternatives for promoting and strengthening multimodal transportation in rural and small urban areas. It outlines 65 different innovative activities around the United States that have been undertaken to promote multimodalism in rural areas and smaller towns. These activities are grouped into six categories: improving transit options; accommodating alternative vehicles; supporting pedestrian and bicycle travel; multimodal land use planning; the use of financial incentives to promote multimodal land use development; and other alternatives that do not fit in these five categories. From this, six case studies have been developed. These case studies include retrofitting sidewalks in Olympia Washington: the network of interurban transit options in North Dakota; providing mileage reimbursement for seniors arranging their own rides in Mesa Arizona; the State of Oregon’s “Main Street as a Highway” guidance for integrating highways into the fabric of smaller towns; the use to transportation impact fees to fund transportation infrastructure, including concurrency fees, development fees and special district fees; and a “Complete Streets” project in Clinton, Iowa.
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    Superbus Phase I: Accessory Loads Onboard a Parallel Hybrid- Electric City Bus
    (Center for Transportation Studies, University of Minnesota, 2009-08) Campbell, Jeffrey; Kittelson, David
    This paper describes the results from the first phase of the Superbus Project, which explores the input power trends and dependencies of the major accessories on a parallel hybrid urban transit bus. More specifically, this paper examines the elimination of both “accessory overdrive”, where more power is delivered to an accessory than is required by the function, and “parasitic loading”, where the accessory consumes power with no useful output. The bus was equipped with an array of sensors and a programmable data acquisition system (DAQ), and was driven on routes in Minneapolis during August and September, 2008. The accessories analyzed were the hydraulic pumps, the air compressor, the alternator, and the air conditioning system. Collection and processing methods are described, and the influence of accessory overdrive and parasitic loading are demonstrated. The average input power to the accessories was 11.0 kW when the air conditioning was off and 19.3 kW when the air conditioning was on. By removing the effects of accessory overdrive and parasitic loading, it is estimated that replacing mechanically driven accessories with their electrically driven counterparts would reduce the accessory power demand by 34% (no air conditioning) and 31% (with air conditioning). Under the somewhat conservative assumption that with the air conditioning on, 50% of the bus’ fuel is consumed by its accessories, it is estimated that accessory electrification would result in a 13-15% improvement in overall fuel economy.
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    Techno-Economic Analysis of Implementing Hybrid Electric Utility Vehicles in Municipal Fleets
    (Minnesota Department of Transportation, 2020-07) Northrop, Will; Zarling, Darrick; Haag, Shawn
    This research quantified fuel economy improvements by implementing hybrid electric utility vehicles in municipal fleets. The research team analyzed utility vehicle data and built computer vehicle simulations of utility trucks with three powertrain types: conventional, charge sustaining hybrid, and charge depleting hybrid plug-in hybrid vehicle (PHEV). Driving cycles were recorded from three vehicle groups, ¾-ton pickup trucks, ½-ton pickup trucks, and SUVs using portable onboard diagnostics loggers. Collected data were used in vehicle simulations to determine the fuel economy improvement possible when implementing hybrid powertrain architectures in municipal fleets. The magnitude of benefits from implementing hybrid vehicles was highly dependent on driving cycles and the electric motor/battery combination of the PHEV. The highest kinetic intensity (KI) values, representing urban driving, were found to lead to the greatest fuel economy improvements for hybrid vehicles over conventionally powered vehicles. The results depended heavily on the electric motor/battery combination, with the higher battery capacity plug-in hybrid vehicles yielding the highest levels of fuel economy improvement. It is recommended that fleets consider driving cycle as the primary factor for determining the economic benefits of purchasing alternative powertrain vehicles. Hybrid vehicles should be placed on routes that are more urban, while rural/highway routes would be better served by conventionally powered vehicles. Idling time was also calculated for all the drive cycles and needs to be separately accounted for when analyzing driving cycle data. Idling for over 50% of the driving cycle can lead to about a 10% reduction in fuel economy based on the modeling conducted for ¾ ton pickup trucks in this study. The research team further recommends that aggressive driving be reduced as it will negate the fuel economy advantages possible from hybrid powertrain architectures.