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An aging model of Ni-MH batteries for use in hybrid-electric vehicles

Somogye, Ryan H.

Abstract Details

2004, Master of Science, Ohio State University, Electrical Engineering.

The increasing consumer performance and federal emission demands for automobiles have forced improvements in every technological aspect of the vehicle. Now that hybrid-electric vehicles are in production, they immediately need a battery as advanced as the rest of the power train. Battery technology has lagged behind, so a model is needed that, in addition to dynamic effects, models how the batteries will age with the life of the car.

This document examines the characteristics of Ni-MH cells, the chemistry currently popular in hybrid vehicles, and explains the methods by which they degrade. Electrode deformation and chemical breakdown are most responsible for diminishing cell health. Popular models of batteries, those used for non-hybrid applications, concentrate only on dynamic effects instead of incorporating information about cell life. Even though these models fail in this area, there is a wealth of information available as to how the Ni- MH battery ages. This knowledge is in the form of personal experience with the Buckeye Bullet land speed car, researched data from the tests of others, and experimental data done on the Sanyo 2.6 amp-hour sub-C cell specifically for this topic.

A hypothesis is postulated that connects environmental conditions with the resulting effects in battery performance, weather it be a reduction in capacity, an increased internal resistance, or a change in transient behavior. To prove, or disprove, the hypothesis, a specially built, computer controlled battery test bench conducts experimental testing over a variety of environmental and usage variables. This test bench implements algorithms to detect a full charge and record data, making the tests exactly repeatable. The results of this experimental data are analyzed and conclusions are drawn that directly support and simultaneous contradict different parts of the supposed hypothesis.

Classical behavior-based modeling techniques are used to construct electrical and thermal model of the Ni-MH cell. Fuzzy logic is then used to implement the connection between environmental conditions and aging effects. The resulting computer model can mimic the experimental tests and well as the expected behavior of the Ni-MH in a hybrid-electric application.

This resulting "aging model" moves toward an implementation of life data into an otherwise all-electrical model to provide a test forum for early evaluations of different power train algorithms. Future uses of the fuzzy-based aging model include reliability studies and future refinement with a greater experimental test base.

Stephen Yurkovich (Advisor)
156 p.

Recommended Citations

Citations

  • Somogye, R. H. (2004). An aging model of Ni-MH batteries for use in hybrid-electric vehicles [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1134658219

    APA Style (7th edition)

  • Somogye, Ryan. An aging model of Ni-MH batteries for use in hybrid-electric vehicles. 2004. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1134658219.

    MLA Style (8th edition)

  • Somogye, Ryan. "An aging model of Ni-MH batteries for use in hybrid-electric vehicles." Master's thesis, Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1134658219

    Chicago Manual of Style (17th edition)