A demonstration of useful electric energy generation from piezoceramics in a shoe

The feasibility of harnessing electric energy using piezoelectric inserts in a sport sneaker has been demonstrated. Continuing in that spirit, this thesis compares regulation schemes for conditioning the electric energy harnessed by a piezoceramic source imbedded in a shoe insole. Two off-line, dc-dc direct converter hybrids (buck and forward) are proposed and implemented to improve the conversion efficiency over previously demonstrated conditioning schemes. A rigid, bimorph piezoceramic transducer was developed and integrated into an off-the-shelf orthopedic insert. The insert consists of two THUNDER™ PZT unimorphs connected in parallel and mounted on opposing sides of a Be-Cu backplate. The bimorph absorbs the energy of the heel strike and lift during walking, thereby inducing a charge differential across the faces of the PZT. The energy stored in this charge is removed at its peak and converted into a useful form using a high-frequency switching technique. The power conditioning circuitry consists of the following stages: Rectification, high-frequency switching (and step-down transformation), CMOS "555" timing and switcher control, low-side output filtering, load stage on/off control, and output regulation. Finally, it is important to note that, although the proposed conditioning scheme was designed for the transducer developed herein, it could be applied to any similar low-frequency, piezoelectric source.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

1999

Author dc:creator

• Shenck, Nathan S. (Nathan Scott), 1975-

Advisor dc:contributor.advisor

• Paul A. Rosenstarch and Joseph A. Paradiso.

• Electrical Engineering and Computer Science

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/9800

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/9800