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Estimation of the Effects of Auxiliary Electrical Loads on Hybrid Electric Vehicle Fuel Economy

Ford Motor Company-Kevin Rhodes, Daniel Kok, Pallav Sohoni, Evan Perry, Marvin Kraska, Michael Wallace
Published 2017-03-28 by SAE International in United States
In recent years the fuel efficiency of modern hybrid electric vehicle (HEV) powertrains has progressed to a point where low voltage auxiliary electrical system loads have a pronounced impact on fuel economy (FE). While improving the energy consumption of an individual component may result in minor improvements, the collective optimization of such loads across a complete vehicle system can result in meaningful FE gains. Traditional methods using chassis dynamometer testing alone to quantify the impact of a specific auxiliary load can lead to issues where signal state changes are too small for accurate detection. This presents difficulties in accurately predicting the influence of such loads on FE of next-generation electrified vehicles under development. This paper describes a newly developed method where dynamometer test results are combined with computer simulation analyses to create a practical technique for assessing the impact of small changes in auxiliary load energy consumption. The process combines the best features of empirical testing with model-based system engineering and accurately estimates the effect of small changes in total average oncycle auxiliary load power.…
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Incorporating an Electric Machine into the Transmission Control of Ford's Modular Hybrid Transmission

Ford Motor Company-Walter Ortmann, Daniel Colvin, S. Robert Fozo, Michael Encelewski, Marvin Kraska
Published 2004-03-08 by SAE International in United States
Ford recently introduced an industry first Modular Hybrid Transmission (MHT) in the Model U concept vehicle at the 2003 North American International Auto Show. The MHT is a full function hybrid system (i.e. capable of electric drive) that utilizes a modular approach to leverage high volume conventional driveline components to create a lower-cost hybrid system [1]. In the MHT, the torque converter of a conventional automatic transmission is removed and in its place is packaged a single high voltage electric machine and an engine disconnect clutch. Advanced controls are used to enable hybrid functions. A critical element in the development of the MHT is the ability to replicate the functions of the torque converter without compromise to the vehicle drivability.In this paper, the control of four transmission functions in the MHT will be discussed: 1) transmission engagement, 2) vehicle launch, 3) power-on up-shift and 4) coast downshift. Data from test vehicles will be presented that demonstrates the ability of the MHT to meet the drivability requirements of today's production automatic transmissions.
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